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Voice Education for All Types of Expressive Choral Singing

We human beings have two memory systems in us, each with different but overlapping neurochemical circuitry.  In the published neuropsychobiological literature, each system is referred to with two different labels. 
The declarative memory system and the explicit memory system are two different terms that refer to the same memory phenomena.  This system is activated by experiences that occur within conscious awareness so that language can be used to represent it and talk about it (thus, it's declarative).  The memory and learning that are formed and consolidated can include experiences in which sensory, motor, cognitive, and emotional processing can be, and usually are involved, and these types of experiences also include deliberate, effortful memorization of language/musical 'information.' 
The procedural memory system and the implicit memory system also are two different terms that refer to the same memory phenomena.  This system is almost always activated outside conscious awareness.  The memory and learning that are formed and consolidated occur also include experiences in which sensory, motor, cognitive, and emotional processing are involved, but...the main difference is that the learning happens without conscious knowledge so that language canot be employed to discuss it until the learning is brought into conscious awareness.  
A hugely important feature of these memory phenomena is that the two systems commonly function simultaneously.  So, how can this science-based information be used in the practical world of singing in choirs? 
Learning a new piece of music
(1) Experience the whole piece of music from beginning to end (sight-singing or listening to a recording of it and then begin rehearsing it)
(2) Examine collaboratively what the words and music are expressing about human beings or the 'human condition' (celebration, remembrance, emotional reactions to a situation or an event, etc.) to create memory 'tags'
(3) After about the first three times singing through a portion of a piece (or the whole piece if choir members are adept at singht-singing), then ask the singers to do an "...experiment, just to find out what happens.  Close your music and let's find out how far you can get without it.  Just for the fun of it."  The singers need to be looking closely at the words and music
Most of the time, singers will be surprised at how much they remembered.  [You've already figured out what happens during the 'experiment,' right?
Help them 'get off the book' ASAP by helping them learn the music.  Cease and desist using the words "memorize," "memorization," "sing from memory," etc.  [Wonder why? Figure it out for yourself.]
Another hugely important feature of these memory phenomena is that memory consolidation can and does happen during sleep.  Items numbered 1) and 4) in Joshua Bronfman's previous post have been researched scientifically and shown to be 'real' effects of sleep.  Naps after learning also have been researched with the same results...greater memory consolidation during the sleep.
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3.2. The neural basis of polyphony

Harmonization resembles monophonic singing in that both involve the creation of a single melodic line. Harmonization differs from simple melody formation, however, in that it is done in coordination with a simultaneous musical template. One complication in interpreting activation differences between the harmony and melody tasks in this study is that both tasks activated functional brain regions closely overlapping with those elicited by monotonic vocalization. Bearing this in mind, there appeared to be a trend toward greater bilaterality in higher-level auditory areas (both BA 22 and BA 38) for harmony than for melody (when contrasted with rest). It is not possible to determine yet whether the bilaterality seen in our harmony tasks is due to a true specialization of left-hemisphere auditory areas for harmony processing or merely a quantitative acoustic effect due to the presence of a greater number of notes and a thicker musical texture in the harmony condition [35]. A study in which note number is directly controlled for will be needed to resolve this issue.

Although there are computational differences between the processing of melody and harmony in particular tasks, neuroimaging studies at the current limits of resolution provide limited support for the view that harmony is mediated by brain areas distinct from those underlying melody. If this null hypothesis were to be confirmed by studies at higher resolution and with a variety of other paradigms of comparison, it would imply that the capacity to perceive and produce harmony is essentially contained within a basic melodic system, perhaps suggesting that the human harmony system emerged from a basic melodic system in which individual parts were temporally blended with one another following developments in temporal processing. This line of investigation may provide insight into a classic debate regarding whether the origins of music are to be found in melody [63] or in harmony [58].

3.3. Neural systems for antiphonal imitation

It has been proposed that there is a system of “mirror neurons” specialized for the kinds of imitative behaviors that underlie such things as antiphonal imitation, or what have been referred to as resonance behaviors [62]. During resonance behaviors, organisms act by mirroring the activities of others, either behaviorally or cognitively. The focus of such a mirror system has generally been on visual/manual matching (but see [36]); however, such a system would be an equally plausible foundation for audiovocal matching functions such as song and speech. Both music and speech, like many forms of bird song, develop ontogenetically through a process of imitation of adult role models during critical periods in brain development [39, 50, 55 and 74]. These are additional instances of vocal learning, wherein developing organisms acquire their species-specific communication repertoires through imitative processes [30 and 31].

One region of the monkey brain that has been shown to possess mirror neurons is a premotor area thought to be the human homologue of Broca's area bilaterally. This region overlaps the opercular area identified bilaterally in the current study as being important for the template-matching processes underlying the antiphonal production of song. From this point of view, then, the frontal operculum may be part of a mirror system involved in audiovocal template matching for both pitch and rhythm. Template matching is also essential to discrimination processes, and tasks in which music-related stimuli are discriminated often show activations in the frontal operculum. This has been shown to be the case for the discrimination of pitch [24, 81, 83 and 84], chords [43], durations [24], rhythms [51], time intervals [59], sound intensities [2], chords, keys and timbres [35], melodies and harmonies [8], and melody and harmony performance during score reading [51]. Hence, it appears that the frontal operculum is equally important for pitch and rhythm processing in music, and that its functional role transcends motor aspects of vocalization. In sum, a mirror function for Broca's area may have as much explanatory power for imitative audiovocal processes underlying music and speech as it does for visuomanual matching processes underlying a proposed gestural origin of language [61] (see also [27]). If so, this might suggest that the song system of the human brain evolved from a vocalization system based on antiphonal imitation [6] in which the frontal operculum developed a specialized role to mediate this function.


We are grateful to Tim Griffiths, Carol Krumhansl, Aniruddh Patel, Frederic Theunissen, Barbara Tillmann, and Patrick Wong for their insightful comments on the manuscript. This work was supported by a grant from the ChevronTexaco Foundation.

3. Discussion

3.1. The human song system

These data provide a picture of the auditory and vocal components of the human song system as well as those neural areas involved in imitation, repetition, and the pitch-tracking processes underlying harmonization. The cortical activations observed here can be grouped hierarchically in terms of primary auditory and vocal areas, secondary auditory and vocal areas, and higher-level cognitive areas. All three vocal tasks showed strong activations in the primary auditory cortex (BA 41) and in the mouth region of the primary motor cortex (BA 4) [19]. Furthermore, all three vocal tasks showed activations in the auditory association cortex (BA 42 and BA 22), supplementary motor area (BA 6), frontal operculum (BA 44/6), and left insula. An activation in the anterior cingulate cortex (BA 24) was seen exclusively in the monotonic vocalization task. Finally, the two high-level music tasks, but not monotonic vocalization, showed activations in the planum polare (BA 38), implicating this area in higher-level musical processing. Interestingly, although the stimuli for the melody repetition and harmonization tasks changed key from sample to sample, we did not observe activations in the ventromedial prefrontal region identified as being important for tracking key changes [29].

Although we observed only a single occipital activation in this study—in calcarine cortex for the harmonization task—several studies of music perception and musical imagery have shown cortical activations in parietal and occipital areas [e.g., [26, 29, 40, 66 and 84]. In addition to cortical activations, we observed several activations in non-cortical areas. The left-lateralized putamen activations in all three of our vocalization tasks are consistent with findings on vocalization processes in animals and humans [33, 34 and 78]. The right globus pallidus was likewise activated in all three tasks. Further research is required to determine the exact function of this area for these tasks. Activation was detected in midbrain but only for harmonization (minus rest). At the resolution of PET used here, this activity may originate in substantia nigra or nucleus ambiguus, structures involved in the motor control of vocalization. Finally, the posterior cerebellum, especially the quadrangular lobule (VI), was active in all three tasks, as discussed below.

Overall, our results are in broad agreement with the two other studies of song production. In the PET study of Perry et al. [53], non-musicians sang simple monotone sequences using the vowel /ä/ at a target rate of 0.8 Hz, based on a presented target pitch. The activation profile seen by Perry et al. was quite similar to that observed here, with major activations occurring in the primary and secondary auditory cortices, primary motor cortex, supplementary motor area, anterior cingulate cortex, insula, and frontal operculum. In an fMRI study by Riecker et al. [60], non-musicians either overtly or covertly sang a familiar melody without words. As in both the present study and that of Perry et al., major activations occurred in the primary motor cortex, supplementary motor area, anterior insula, and posterior cerebellum. Each of the latter areas has been implicated in vocalization. The primary motor cortex is, of course, a critical mediator of voluntary vocalization. Our major focus of activation for the primary motor cortex was in the mouth area [19]. While it is possible that there were activations as well in the larynx area, we were not able to distinguish them from the activations in the frontal operculum at the spatial resolution of this study. Interestingly, nonhuman primates lack a direct connection between the larynx representation of the primary motor cortex and the nucleus ambiguus, the major peripheral neural center for vocalization [32], and as a result, no primate except the human is capable of phonatory vocal learning, such as that underlying the acquisition of song. Moreover, there is firm evidence that the supplementary motor area (SMA) plays a key role in higher-level motor control, and it is often activated during overt speech tasks in imaging experiments [75]. Direct electrical stimulation of SMA produces vocalization in humans but not other mammals [33], and damage to SMA (as with many other structures) is associated with mutism [86]. The anterior insula has long been associated with vocalization processes, and damage to this structure has been linked to disorders of articulation [15]. Its role in vocalization has been confirmed by imaging studies of counting, nursery-rhyme recitation, and propositional speech [9]. Finally, the posterior cerebellum has been implicated in vocalization processes, particularly the quadrangular lobule (VI) [75], observed both in the present study and that of Perry et al. to be activated during singing. The exact contribution of the cerebellum to song is unclear because activations in this structure could be involved in motor, auditory or somatosensory processing [51].

Activations in the primary and secondary auditory regions were seen for all three singing tasks in this study, as with Perry et al.'s monotone task. Activation in the primary auditory cortex was less in the repetition task than either the monotonic vocalization or harmonization task, for reasons that are not currently clear to us. The activations in the superior temporal gyrus (BA 22) were strongly right-lateralized for all three tasks. Activations in this region could have been due to at least two major sources: the presented stimuli and the subject's own voice. The superior temporal gyrus has been implicated in melody processing, most especially the right hemisphere [26, 81, 84 and 85] (see also Zatorre et al. [87] for a discussion of right-hemisphere dominance of the primary auditory cortex for spectral processing). Indeed, the peak activations observed here at (60, −28, 6) for harmonization and at (60, −26, 4) for melody repetition correspond to that at (64, −26, 5) when musically experienced listeners tracked a melody as it changed keys [29]. However, the elimination of BA 22 in the subtractions of monotonic vocalization from both melody repetition and harmonization suggests that BA 22 sits at a lower position in the auditory-processing hierarchy than BA 38, which was not eliminated in the same contrasts. This suggests that BA 38 might, in fact, be a form of tertiary auditory cortex. Additional studies will be needed to determine the relative contributions of the posterior and anterior regions of the superior temporal gyrus to musical processing.

In general, activations in primary and secondary auditory areas (BAs 41, 42, 22, 21) in the left hemisphere were more posterior than those in the right hemisphere. Over the group of three tasks, the mean y location of activations in these areas was −25 on the left and −15 on the right. A similar effect was observed in an fMRI study of non-musicians passively listening to melodies presented in different timbres [45]. In that study, the mean y location of activations was −24 on the left and −8 on the right. The 10-mm difference observed across our tasks is in accord with the morphological difference of 8–11 mm in the location of left and right auditory cortex [56]. However, this difference was much more pronounced for melodic repetition than for the other two tasks. Specifically, the average y value for these areas in the melodic repetition task was −31 on the left and −11 on the right; however, in the monotonic vocalization task, it was −23 on the left and −17 on the right, and in the harmonization task, it was −22 on the left and −15 on the right. Further research is necessary to clarify whether there is in fact such a functional asymmetry in auditory areas for music-related tasks.

Another source of auditory stimulation in this study was the subject's own vocalization. Voice-selective cortical areas have been demonstrated along the extent of the superior temporal sulcus (between BA 21 and 22), with a dominance for the right hemisphere [3 and 4]. Such work represents an important perceptual counterpart to our work on song production, particularly since any evolutionary account of the song system must take into account parallel communicative adaptations for perception and production. Although a distinction has been observed between speech and non-speech vocal sounds in these voice-selective areas [3], it will be important to examine whether there is specificity for singing versus other non-speech phonatory sounds in these regions. Such an investigation would be a fruitful counterpart to similar work with songbirds.

All three singing tasks also showed strong activations in the frontal operculum. This region, along with the more dorsal part of Broca's area proper, has been observed to be active in several neuroimaging studies of music, typically in discrimination tasks (discussed below). In addition, strong activations in right frontal operculum are observed when subjects are asked to imagine continuations of the opening fragments of familiar songs without words [26]. Previous work has established that mental imagery for motor behavior, vision, or audition can activate similar brain areas as actual action or perception. Therefore, mental imagery for melodic continuations can be viewed as a form of covert music production, in other words covert singing. Such results, in combination with the present findings and those of Riecker et al. [60] and Langheim et al. [40], suggest that musical imagery tasks can produce activations similar to those for music perception and production tasks. Activations of the frontal operculum during covert singing tasks may provide further support for a key role of this area in the human song-control system (and conceivably instrumental performance as well). This may be especially true for tasks that require active musical processing (e.g., imitation, discrimination, improvisation) rather than automatic processing based on long-term storage [40]. The frontal operculum has been shown to be activated during tasks that involve the processing of rhythm and time-intervals in addition to the processing of pitch (see below). So it is conceivable that rhythm processing contributed to the activations seen in the frontal operculum in this study. Further studies will be needed to distinguish pitch and rhythm effects in this region. At the same time, prefrontal cortex is thought to be involved generally in temporal sequencing of actions as well as in planning and expectancy [21]. Thus, the effects observed here in the frontal operculum may be due to basic aspects of temporal and sequence expectancies [73] (see later section on antiphonal imitation).

A hierarchical feature of the song system revealed in this study was the activation of the planum polare (BA 38) during complex musical tasks but not monotonic vocalization. This accords well with the results of Griffiths et al. [23], who performed a parametric analysis of brain regions whose activity correlated with increasing musical complexity using iterated rippled noise, which produces a sense of pitch by means of temporal structure. The planum polare was one of only two regions whose activity correlated with the degree of musical complexity, especially vis-à-vis monotonic sequences. Moreover, in another parametric analysis, Zatorre and Belin [82] demonstrated that activity in this region co-varied with the degree of spectral variation in a set of pure-tone patterns. The anterior temporal region has been implicated in a host of findings related to musical processing. For example, it has been shown that surgical resection of the anterior temporal lobe of the right hemisphere that includes the planum polare often results in losses in melodic processing [65 and 80]. Koelsch et al. [35] demonstrated strong bilateral activations in planum polare during discrimination tasks involving complex chord sequences, in which discriminations were based on oddball chords or timbres. Likewise, bilateral activations were observed in this region when expert pianists performed Bach's Italian Concerto from memory [51]. Finally, in a related study, this area was observed to be active in discrimination tasks for both melody and harmony [8]. The coordinates of our BA 38 activation—at (50, 8, −4) in melody repetition—is nearly identical to the right hemisphere activation reported by Zatorre and Belin [82] in their subtraction analysis of spectral vs. temporal processing for pure tones (with coordinates at [50, 10, −6]), and were just inferior to those reported by Koelsch et al. [35] during discrimination processing for chord clusters, deviant instruments and modulations (with coordinates at [49, 2, 2]).

In sum, a convergence of results suggests that the superior part of the temporal pole bilaterally may be a type of tertiary auditory cortex specialized for higher-level pitch processing such as that related to complex melodies and harmonies, including the affective responses that accompany such processing. However, the exact nature of the processing in the planum polare during these tasks is unclear. The responses may reflect increases in memory load per se for musical information across the contrasted tasks, or reflect processing for musical grammar used to organize the musical production for the melody repetition and harmonization tasks. This area was not active when musically experienced listeners tracked a melody as its tonality changed [29], suggesting that the area is not involved in this aspect of tonality. Further investigation is necessary to refine functional accounts of this area in humans. There may not be a strict homologue of this region in non-human primates. The anterior superior temporal gyrus in monkey seems to be involved in auditory processing, possibly converging with limbic inputs [48 and 54], and so the activations seen here in the current study might even reflect a role in emotional processing. In addition, because cells in monkey anterior superior temporal gyrus are selectively responsive to monkey calls, it has been proposed that this region may be part of the “what” stream of auditory processing [72].

None of the activations for the melodic repetition and harmonization tasks (minus rest) coincided with the areas reported in prior studies of musical rhythm, such as anterior cerebellum, left parietal cortex, or left frontal cortex (lateral BA 6) [51 and 64]. This suggests that the rhythmic variation present in the melody repetition and harmonization tasks, but absent in monotonic vocalization, was not affecting the pattern of activations attributed to singing. This validates our intuition in designing the study to illuminate brain representations of melodic and harmonic, rather than rhythmic, information. We selected an isometric monotonic control task expecting that differences in brain activity for isometric versus variable-rhythm stimuli would be so small as to not obscure the differences in brain activity between monotonic sequences and musical sequences.

An unexpected finding of this study was the robust overlap in activity amongst the monotonic vocalization, melody repetition, and harmonization tasks. This overlap suggests that, despite the use of the carrier syllable /da/ in our monotone task (Materials and methods), monotonic vocalization is more “musical” than “syllabic” in nature. Indeed, this monotonic vocalization task may embody most of the cardinal features of human music. Seven aspects of this task connect it more with simple music than simple speech: (1) a fixed pitch (i.e., spectral specificity) was employed; (2) the vocalization tempo was relatively slow (with an overall syllable rate of 1.67 Hz compared to a rate of around 8–10 Hz for connected speech) and the vowel was extended in duration; (3) the vocalizing was repetitive; (4) the vocalization rhythm was isometric; (5) the subject was required to match pitch; (6) the subject was required to match rhythm; and (7) the subject was required to sing in alternation with another “musician” (i.e., a digital piano). So, this antiphonal monotonic vocalization task should not be seen as a non-musical control but instead as a model of some of the most important features of music. Monotones, in fact, are an integral component of the world's music, as seen in many chants and drones.

Another unexpected result was the absence of strong activations in the dorsolateral prefrontal cortex or associated areas during the melody repetition and harmonization tasks, tasks that clearly required the storage of pitch information in working memory. We observed an activation in the dorsolateral prefrontal cortex (BA 46/9) for the monotonic vocalization task. Weaker activations were found in the identical location in the melody repetition and harmonization tasks, but these were below the threshold of significance for our tables (z values of 3.13. and 3.63, respectively). Despite the presence of activations in these regions, we are still surprised by their weakness, especially given the requirements of the tasks. For the moment, we do not have a good explanation for these results. Another manner in which such prefrontal activations might have shown up was in relation to the abrupt transitions occurring the monotone task, but again these were not seen when monotonic vocalization was compared to rest.

In sum, our results differ in the following respects from those of the previous studies of singing. First, Perry et al.'s [53] study of monotone singing did not show activations in BA 38. This was the case for our monotone task as well. The BA 38 activations were observed only when complex musical stimuli involving full melodies were used, as in our melody repetition and harmonization tasks. Second, Riecker et al.'s [60] study of the singing of familiar songs did not produce activations in the frontal operculum. As we argue throughout, the frontal operculum activations appear to be related to specific features of our tasks, namely a requirement for matching musical templates. Recalling familiar melodies from long-term memory does not seem to activate this process, whereas all three of our imitative tasks require subjects to match the pitch and rhythm of novel sequences. Overall, then, the use of complex and novel melodies enabled identification of the roles of two regions of the musical brain, namely the superior part of the temporal pole (BA 38) and the opercular part of the inferior frontal gyrus (BA 44/6).

2. Results

The mean cerebral blood flow increases for the Monotonic Vocalization task, as contrasted with Rest (Fig. 2, Table 1), showed bilateral activations in the primary auditory cortex (Brodmann Area [BA] 41) and the mouth region of the primary motor cortex (BA 4). Bilateral activations were observed in the auditory association cortex (BA 42 and posterior BA 22), frontal operculum (inferior parts of BA 44, 45 and 6), and supplementary motor area (SMA; medial BA 6), with trends towards greater right hemisphere activations; it is important to note that for the frontal operculum, the left hemisphere activation was reproducibly more posterior than that in the right hemisphere, extending into BA 6. The anterior cingulate cortex (BA 24) was also seen to be activated in this task. Other notable activations occurred in left anterior putamen, right globus pallidus, and posterior cerebellar hemispheres. The activations in basal ganglia—putamen on the left and globus pallidus on the right—most likely supported processes in the ipsilateral cerebral hemispheres [13]. Broadly speaking, then, this task produced bilateral activations in primary auditory and vocal areas and more right-lateralized activations in higher-level cortical areas.

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Fig. 2. Axial views of cerebral blood flow changes during Monotonic Vocalization contrasted to Rest. The Talairach coordinates of the major activations (contrasted to Rest) are presented in Table 1. The averaged activations for 10 subjects are shown registered onto an averaged brain in all the figures. The right side of the figure is the right side of the brain in all the figures. At the left end of the figure are two color codes. The upper one (yellow to red) is a scale for the intensity of the activations (i.e., blood blow increases), whereas the lower one (green to blue) is a scale for the intensity of the deactivations (i.e., blood blow decreases). The group mean blood-flow decreases showed no obvious pattern related to the tasks or to the blood-flow increases and are thus not reported in the text. Note that the same set of five slice-levels is shown in Fig. 2, Fig. 3 and Fig. 4. Note also that bilateral activations are labeled on only one side of the brain. The label SMA stands for supplementary motor area. The intensity threshold in Fig. 2, Fig. 3 and Fig. 4 for all tasks is z>2.58, p<0.005 (one-tailed).

Table 1. Stereotaxic coordinates and z-score values for activations in the Monotonic Vocalization task contrasted with Rest

Brain atlas coordinates are in millimeters along the left-right (x), anterior–posterior (y), and superior–inferior (z) axes. In parentheses after each brain region is the Brodmann area, except in the case of the cerebellum, in which the anatomical labels of Schmahmann et al. [67] are used. The intensity threshold is z>3.72, p<0.0001 (one-tailed).

Melody Repetition minus Rest (Fig. 3a, Table 2), compared to the results with Monotonic Vocalization, showed no cingulate activation, much less activation in the primary auditory cortex, and activation in the superior part of the temporal pole (planum polare, BA 38). In general, the pattern of activation for Melody Repetition closely overlapped that for Monotonic Vocalization. Thus, when Monotonic Vocalization was subtracted from Melody Repetition (Fig. 3b), there was little signal above threshold in most auditory and motor areas. Only the activation in the planum polare (BA 38) remained after this subtraction, implicating this area in higher-level musical processing.

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Fig. 3. Axial views of cerebral blood flow changes during Melody Repetition contrasted with (a) Rest and (b) Monotonic Vocalization. The Talairach coordinates of the major activations (contrasted to Rest) are presented in Table 2. Subtraction of Monotonic Vocalization from Melody Repetition eliminates many of the significant activations but leaves the signal in the planum polare (BA 38) at z=−8. The peak voxel for BA 38 in the Melody Repetition minus Monotonic Vocalization subtraction (panel b) was located at (48, 6, −6) in the right hemisphere and (−42, 4, −7) in the left.

Table 2. Stereotaxic coordinates and z-score values for activations in the Melody Repetition task contrasted with Rest

Legend as in Table 1.

Harmonization minus Rest, as compared to the results for Melody Repetition, showed more intense activations in the same song-related areas (Fig. 4a, Table 3). In addition, there appeared to be a nonsignificant trend toward greater bilaterality of the temporal lobe activations (including BA 38) for the Harmonization task compared to the Melody Repetition task. However, when the Melody Repetition task was subtracted from the Harmonization task, no activations remained above threshold (data not shown). This can be explained in part by the results of the contrast with Monotonic Vocalization (Fig. 4b). Interestingly, even the activation in the planum polare (BA 38) was eliminated in this subtraction (not shown). In sum, harmony generation and melody generation produced closely overlapping patterns of activation. Interestingly, we predicted that dorsolateral prefrontal cortex (BA 46 and 9) would be activated in the Repetition and Harmonization tasks due to the need for subjects to keep the melodic template of the stimulus in working memory. However, such activations, while present, were below the z threshold used in our tables.

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Fig. 4. Axial views of cerebral blood flow changes during Harmonization contrasted with (a) Rest, and (b) Monotonic Vocalization. The Talairach coordinates of the major activations (contrasted to Rest) are presented in Table 3. The peak voxel for BA 38 in the Harmonization minus Monotonic Vocalization subtraction (panel b) was located at (46, 8, −6) in the right hemisphere and (−42, 6, −10) in the left.

Table 3. Stereotaxic coordinates and z-score values for activations in the Harmonization task contrasted with Rest

Legend as in Table 1.

1. Materials and methods

1.1. Subjects

Five male and five female neurologically healthy amateur musicians, with a mean age of 25 years (range 19–46 years), participated in the study after giving their informed consent (Institutional Review Board of the University of Texas Health Science Center). Each individual was right-handed, as confirmed by the Edinburgh Handedness Inventory [49]. All subjects were university students, many in their first or second years as music education majors, with a mean of 5.3 years of formal music instruction in voice or instrument. Subjects began music instruction at a mean age of 12.4 years old, having had an involvement in musical production (e.g., school bands, church choirs) for an average of 12.6 years prior to the study. None of them had absolute pitch, as based on self-report. Their musical specializations included voice, flute, trumpet, trombone, piano, drums, bass, guitar, percussion, and clarinet. Subjects underwent a detailed behavioral screening procedure in order to determine their suitability for the study. Each potential subject was presented with 35 melody repetition samples and 26 harmonization samples. Criteria for inclusion in the study included the following: (1) a proficiency at singing in key, (2) an ability to sing at least 50% of the repetition samples with perfect accuracy, and (3) an ability to sing at least 50% of the harmonization samples in such a manner that the melodic contour of the original melody was shadowed perfectly, in accordance with the rules of tonal harmony (see Tasks below). The 10 subjects who were used in this study were taken from a pool of 36 amateur musicians who underwent the screening procedure.

1.2. Tasks

Stimuli for the vocal tasks were sequences of digitized piano tones generated using Finale 2001 (Coda Music Technology). Subjects performed three vocal tasks and eyes-closed rest (see Fig. 1). The carrier syllable /da/ was used for all the singing tasks; this was done to avoid humming, to control head and mouth movement, and to permit adequate respiration during performance of the tasks. (1) Monotonic Vocalization. Subjects heard a piano tone (147 Hz; D below middle C), played 4 to 11 times isometrically (in an equal-interval, regular rhythm). The notes were played at a rate of 100 beats per minute, or 1.67 Hz, with a note duration of 600 ms. Subjects had to sing back the same pitch at the same tempo and rate (i.e., isochronously) whenever the piano stopped playing the note, doing so in continuous alternation with the piano. As with each sequence of piano tones, the response period allowed time for the singing of 4–11 tones. Each successive sequence was different in the number of tones from the prior one. The goal of this arrangement was to ensure that subjects, in attempting to match pitch and rhythm, were not cognitively engaged in counting piano tones; subjects did not need to count piano tones because their singing was interrupted when the piano tones of the succeeding trial began. Hence their goal was simply to match the pitch and rhythm of these tones. (2) Melody Repetition. Subjects listened to a series of tonal melodies, and had to sing back each one after it was played. Each melody was 6 s in duration, followed by a 6-s period for response generation. The inter-trial interval was 1 s. Consecutive samples were never in the same key. (3) Harmonization. Subjects listened to a series of melodies accompanied by chords and had to spontaneously sing a harmonization with each melody as it was being replayed. Each melody was 6 s in duration. A “prompt tone” was provided after the first presentation of each melody, which subjects were instructed to use as the first note of their harmonization. This tone was typically a major third above the first note of the melody, which itself was frequently the tonic pitch of the scale. When melodies started on the third degree of the scale, the prompt tone was a perfect fifth above the tonic. The loudness of the stimulus heard during harmonization was reduced by 67% so that subjects could hear their singing. The inter-trial interval was 1 s. Consecutive samples were never in the same key. Subjects were instructed to create harmonizations that conformed to the rules of tonal harmony. While they generally sang the harmonizations in thirds, there were points in the melody where the rules of harmony dictated the use of other intervals, such as fourths, as a function of the implicit harmonic structure of the melody at that point.

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Fig. 1. Representative stimuli for the three singing tasks performed in this study: Monotonic Vocalization, Melody Repetition, and Harmonization. The note with the asterisk over it in Harmonization is the “prompt tone” that was provided to subjects as the first note of their harmonization (see Materials and methods).

1.3. Stimuli

All stimuli for the vocal tasks were presented to both ears as piano tones, and were generated using Finale 2001. The source material consisted of folk-music samples from around the world, modified to fit the time and musical constraints of the stimulus set. Pilot testing (n=7) confirmed that all stimulus material was novel for our subject population. A hypothetical standard for the stimulus set consisted of a sample with 10 quarter-notes at a tempo of 100 beats per minute in 4/4 time. The stimuli for the Melody Repetition and Harmonization conditions were varied with regard to tempo (slower and faster than the standard), number of notes (fewer or more notes than the standard), tonality (major and minor), rhythm (duple [2/4, 6/8], triple and quadruple time), motivic pattern (e.g., dotted vs. non-dotted rhythms), and melodic contour (ascending and descending patterns). The samples covered a wide range of keys. Volume was approximately constant among the stimuli. The Monotonic Vocalization task consisted of a single tone (147 Hz) in a comfortable vocal range of males and females, although subjects were given the option of singing the tone one octave higher. This task was designed to control for the average number of notes that a subject would both hear and produce in the other two singing conditions.

1.4. Procedure

During the PET session, subjects lay supine in the scanning instrument, with the head immobilized by a closely fitted thermal-plastic facial mask with openings for the eyes, ears, nose, and mouth. Auditory stimuli were presented through the earpieces of headphones taped over the subjects' ears. During scanning, subjects were told to close their eyes, lie motionless, and to clench their teeth lightly so as to make the syllable /da/ when singing. Pre-scan training enabled the subjects to perform the vocalization tasks with minimal head movement. Each subject had two PET scans for each of the vocal tasks and one of rest. Task order was counterbalanced pseudo-randomly across subjects. The subjects began each task 30 s prior to injection of the bolus. Bolus uptake required approximately 20 s to reach the brain, at which time a 40-s scan was triggered by a sufficient rate of coincidence-counts, as measured by the PET camera. At the end of the 40-s scan, the auditory stimulus was terminated and the subject was asked to lie quietly without moving during a second scan (50 s). From the initiation of the task until the start of the second scan, each subject had responded to six to seven stimuli.

1.5. Imaging

PET scans were performed on a GE 4096 camera, with a pixel spacing of 2.0 mm, and inter-plane, center-to-center distance of 6.5 mm, 15 scan planes, and a z-axis field of view of 10 cm. Images were reconstructed using a Hann filter, resulting in images with a spatial resolution of approximately 7 mm (full-width at half-maximum). The data were smoothed with an isotropic 10-mm Gaussian kernal to yield a final image resolution of approximately 12 mm. Anatomical MRI scans were acquired on an Elscint 1.9 T Prestige system with an in-plane resolution of 1 mm2 and 1.5-mm slice thickness.

Imaging procedures and data analysis were performed exactly as described by Parsons and Osherson [52], according to the methods of Raichle et al. [57], Fox et al. [18] and Mintun et al. [47]. Briefly, local extrema were identified within each image with a 3-D search algorithm [47] using a 125 voxel search cube (2 mm3 voxel). A beta-2 statistic measuring kurtosis and a beta-1 statistic measuring skewness of the extrema histogram [17] were used as omnibus tests to assess overall significance [11]. Critical values for beta statistics were chosen at p<0.01. If the null hypothesis of omnibus significance was rejected, then a post hoc (regional) test was done [17 and 18]. In this algorithm, the pooled variance of all brain voxels is used as the reference for computing significance. This method is distinct from methods that compute the variance at each voxel but is more sensitive [71], particularly for small samples, than the voxel-wise variance methods of Friston et al. [20] and others. The critical-value threshold for regional effects (z>2.58, p<0.005, one-tailed) is not raised to correct for multiple comparisons since omnibus statistics is established before post hoc analysis.

1.6. Task performance

As noted above, we selected subjects who were able to perform the tasks with competence. Analysis of recorded task performance confirmed that subjects performed in the scanner in a manner qualitatively identical to their performance during the screening session. Our use of a stringent screening procedure for subject inclusion meant that our subject sample was rather homogeneous, producing minimally variable task performance across individuals. Therefore, by design, we were not in a position to employ covariance analysis to look at the relationship between brain activation and task performance.

REMEMBER, this one is quite technical in neuroanatomy and neurophysiology.  Someday, I'd like to do a 'simplified' summary in more everyday terms.

Singing is a specialized class of vocal behavior found in a limited number of animal taxa, including humans, gibbons, humpback whales, and about half of the nine thousand species of bird. Various functions have been attributed to singing, including territorial defense, mate attraction, pair bonding, coalition signaling, and group cohesion [5, 25, 46 and 76]. Song production is mediated by a specialized system of brain areas and neural pathways known as the song system. This system is also responsible for song learning, as most singing species acquire their songs via social learning during development [30 and 31]. In some species, known as “age-limited learners”, song learning occurs once during a critical period; in “open-ended learners”, song learning occurs throughout much of the life span (e.g., [70]). In many species of bird, singing is a sexually dimorphic behavior, one that is performed mainly by males [12]. In these species, the vocal centers of males tend to be three to five times larger than those of females [41]. However, in species where both sexes sing, the vocal centers of the two sexes tend to be of comparable size [14]. Importantly, the components of the forebrain song system are absent in even taxonomically close bird species that either do not sing or that acquire their songs in the absence of vocal learning [37]. This highlights the notion that song learning through vocal imitation is an evolutionary novelty, one that depends on the emergence of new neural control centers.

Although humans are by far the most complex singers in nature, the neurobiology of human song is much less well understood. A deeper understanding of singing may benefit from a comparative approach, as human singers show features that are both shared with, and distinct from, birds and other singers in nature [22]. Common features include the following: (1) both absolute and relative pitch processing are used for song [42]; (2) combinatorial pitch codes are used for melody generation [44]; (3) there is a capacity for phonatory improvisation and invention [38]; (4) the song is treated as the fundamental unit of communication [68]; (5) songs are organized into repertoires [69]; (6) imitative vocal learning is important for song acquisition [1]; (7) there is year-round rather than seasonal singing [7]; and (8) there is a capacity for acquisition of songs throughout the life span [16]. Along these lines, although there is no systematic evidence for a critical period in human song learning, it is conceivable that the common incidence of “poor pitch singing” (often mislabeled as “tone deafness”) reflects the possibility that vocal behavior (or its absence) during childhood has a strong effect on adult singing abilities.

At the same time, human music has several features distinct from singing in other animals, most notably choral singing and harmony. The temporal synchronization of voices that underlies human choral singing bears little relation to the “dawn chorus” of birds, in which vocal blending is little more than random simultaneity. While there is clear evidence for synchronization of parts in the songs of duetting species, such as gibbons and many tropical birds, none shows the kind of vertical alignment of parts that is the defining feature of harmonic singing in humans. Vertically integrated, multi-part singing is absent in non-human species, thereby suggesting that the human song system is different from that of other species, one specialized for coordinated multi-person blending. Harmonic singing is a characteristic musical style of several distinct regions of the world. Such singing is generally a cooperative behavior, often serving to reinforce collective norms and group actions. Our closest genetic relatives, chimpanzees and bonobos, do not engage in any kind of vocalizations reminiscent of song. Singing, therefore, cannot be seen as an ancestral trait of hominoid species but instead a derived feature of humans.

Such considerations are consistent with the hypothesis that the human song system is an evolutionary novelty and neural specialization, analogous to the song system of birds. However, this hypothesis is difficult to evaluate at the present time as human singing has been little researched. While music and song were the subjects of intense speculation by Enlightenment thinkers (e.g., [10 and 63]), modern neurobiology provides limited pertinent information. There are few studies of vocal amusias but instead various reports of Broca's aphasics whose singing ability, even for lyrics, is spared (e.g., [28, 77 and 79]). Such findings are probably more common than reports of spared musical function in the face of language deficits, as a knowledge of baseline musical-production skills is absent in most “non-musicians” and because neurologists do not generally examine musical capacities in patients who are not musicians. Most noninvasive functional brain imaging studies of music have focused on perceptual rather than productive aspects.

Building on the foregoing achievements and considerations, we designed the current PET study to elucidate the audiovocal system underlying basic musical production processes and to compare the functional neuroanatomy of melody production with that for harmony production. The study was designed to examine these issues more comprehensively than did the two previous studies of song production. Perry et al. [53] looked only at monotone singing, and Riecker et al. [60] looked only at the singing of a single highly familiar melody. In the present investigation, we were interested in examining the vocal processing of novel melodies, as they would serve as more richly engaging stimuli with which to probe the audiovocal system. Amateur musicians performed four tasks while being scanned in this study: (1) Melody Repetition: subjects sang repetitions of novel, one-line, rhythmically varied melodies; (2) Harmonization: subjects sang harmonizations in coordination with novel, chordal, rhythmically varied melodies; (3) Monotonic Vocalization: the two preceding conditions were contrasted with a lower-level task in which subjects sang isochronous monotone sequences in alternation with isochronous sequences of the same piano pitch; and (4) Rest: eyes-closed rest was used as a silent, non-motor baseline condition. A distinct feature of this design compared to the previous studies was an element of imitative vocalizing. The Melody Repetition condition involved tandem repetition of heard melodies, the Monotonic Vocalization condition involved a matching of the pitch and rhythm of a monotone sequence, and the Harmonization condition—while not requiring direct imitation of the presented melodic sequence—required a shadowing of that sequence at a displaced location in tonal pitch space (e.g., a major third above the original melodic line). For terminological purposes, we are using the words “repetition” and “imitation” more or less interchangeably, with “repetition” being used more in the context of our tasks and “imitation” more in the context of general cognitive processing.

We hypothesized that secondary and tertiary auditory areas would be increasingly recruited as the complexity of the pitch, rhythmic and musical aspects of the production task increased from basic monotonic vocalizing to melodic and harmonic singing. We also hypothesized that the Repetition and Harmonization tasks would engage brain areas involved in working memory, compared to the Monotone task. Finally, we hypothesized that regions thought to underlie higher-level motor planning for vocalization—such as the supplementary motor area, Broca's area, and the anterior insula [15, 19, 33 and 86]—would be involved not only in the motor control of song production but in musical imitation as well.


The song system of the human brain


Steven Browna, Michael J. Martineza, Donald A. Hodgesb, Peter T. Foxa, and Lawrence M. Parsonsa

a Research Imaging Center, University of Texas Health Science Center, 7703 Floyd Curl Drive MSC 6240, San Antonio, TX 78229-3900, USA

b School of Music, University of North Carolina Greensboro, USA

 Accepted 26 March 2004.  Available online 12 May 2004.




Although sophisticated insights have been gained into the neurobiology of singing in songbirds, little comparable knowledge exists for humans, the most complex singers in nature. Human song complexity is evidenced by the capacity to generate both richly structured melodies and coordinated multi-part harmonizations. The present study aimed to elucidate this multi-faceted vocal system by using 15O-water positron emission tomography to scan “listen and respond” performances of amateur musicians either singing repetitions of novel melodies, singing harmonizations with novel melodies, or vocalizing monotonically. Overall, major blood flow increases were seen in the primary and secondary auditory cortices, primary motor cortex, frontal operculum, supplementary motor area, insula, posterior cerebellum, and basal ganglia. Melody repetition and harmonization produced highly similar patterns of activation. However, whereas all three tasks activated secondary auditory cortex (posterior Brodmann Area 22), only melody repetition and harmonization activated the planum polare (BA 38). This result implies that BA 38 is responsible for an even higher level of musical processing than BA 22. Finally, all three of these “listen and respond” tasks activated the frontal operculum (Broca's area), a region involved in cognitive/motor sequence production and imitation, thereby implicating it in musical imitation and vocal learning.


Author Keywords: Singing; Song system; Brain; Music; Melody; Harmony,

Motor Systems and Sensorimotor Integration, Cortex

Here are copies of two ChoralNet site-wide Forum posts, the title of which was Vocal Pedagogy Books.  The writer's Q was on books that had info on male changing voices.  My reply expresses a strong, but reasoned, bias that I have on that subject. Thought that members of this Community might be interested
Date:November 29, 2010
I have read several articles and some research on the male voice change. I have read James C. McKinney's book and he briefly addresses the voice change. Are there any other pedagogy books that address the voice change to a greater extent?
Leon Thurman on November 30, 2010 8:44
Good on you for asking this question.  From my considered perspective, there is only one author to ever consider reading on the subject of male adolescent voice change:  John Cooksey, Ed.D..  I respect other authors for being the caring human beings that they are, and for always doing the best they know how to do when addressing the subject, but....
John's guidelines for changing voice classification and choral part assignment are the ONLY work that has been substantiated through the use of the scientific method of fine-tuned delimitations to personal human bias and the use of objective scientific data-gathering instruments (as opposed to the very subjective and easily 'biasable' data-gathering instrument we call the human brain).  Here are the only published sources that have been authored by him:
Cooksey, John (most recent edition). Working with the Adolescent Voice.  St. Louis, MO: Concordia Press.
Cooksey, J. (2000). Voice transformation in male adolescents. In L. Thurman & G. Welch (Eds.), Bodymind and Voice: Foundations of Voice Education (Rev. Ed., pp. 718-744). Collegeville, MN: The VoiceCare Network & the National Center for Voice and Speech. [presents the science]
Cooksey, J. (2000). Male adolescent transforming voices: Voice classification, voice skill development, and music literature selection. In L. Thurman & G. Welch (Eds.), Bodymind and Voice: Foundations of Voice Education (Rev. Ed., pp. 821-841). Collegeville, MN: The VoiceCare Network & the National Center for Voice and Speech. [presents the practicalities of applying John's guidelines in the real world of male adolescents.]
Information and ordering information about the latter two references can only be obtained at  Before completing his 3-year longitudinal study with two voice scientists (see later reference), John published his theory about voice change in four issues of Choral Journal (see later references).  The data he gathered prompted only one half-step pitch range change in his pre-research theory.
From October, 1978, through June, 1980, John and his research team followed 86 boys through their voice change.  The study's subjects were 12- through 13-year-old boys who were enrolled in grades 7 - 8 of the public schools in Orange County, California, and most of them (45) were vocally inexperienced and had never sung in a school choir (John wanted subjects who were like the inexperienced singers that music/choral educators actually work with). During the three years of the study, each month from October through June(nine times each year), 22 data points were taken of each individual boy, and recordings were made of their voices performing specific vocal tasks that were relevant to voice change.
After the data-gathering, all of the collected data were analyzed to detect patterns within.  For example, over 6,500 sonagrams were made from the recordings that were made of the boys in the course of the study, and those data were then computer analyzed to detect patterns of acoustic change in the output of each boy's voice. A massive amount of data were gathered, obviously, and the still-unpublished report was huge.  Right now, there is only one published source that has printed a summary of the research findings, plus some other studies that John completed over the years since.
Just so you know, Brad, I've heard choral music educators complain that John's voice classification system is "too complex" for them to use in a real-world junior high or middle school setting, and they opt for a watered-down version of John's system or another system altogether.  That's their perception, of course, and in my opinion, they choose an 'easy way out' to the detriment of some of the boys they lead. All I can tell you is that the choral educators who have learned John's system and put it into 'delightful' practice have had spectacular results because ALL of the boys become successful in-tune singers and a large percentage of them choose to continue singing through their later school years and beyond.
That's my perspective, Brad, and here are some more bibliographical sources that may or may not be of interest to you and others.
Cooksey, J.M. (1977a, 1977b, 1977c, 1978). The development of a contemporary eclectic theory for the training and cultivation of the junior high school male adolescent changing voice, Pt. I: Existing theories; Pt. II: scientific and empirical findings: Some tentative solutions; Pt III: Developing an integrated approach to yjr care and training of the junior high school male changing voice; Pt IV: Selecting music for the junior high school male changing voice. Choral Journal, 18(2), 5-14; 18(3), 5-16; 18(4), 5-15; 18(5), 5-18.
Cooksey, J.M. (1985).Vocal-Acoustical measures of prototypical patterns related to voice maturation in the adolescent male. In V.L. Lawerence (Ed.), Transcripts of the Thirteenth Symposium, Care of the Professional Voice, Part II: Vocal Therapeutics and Medicine (pp. 469-480). New York: The Voice Foundation.
[In 1984, I organized a group of voice-informed music/choral educators to give presentations on voice education in school settings at that New York symposium, and John was one of them, of course. In a subsequent panel discussion, one of the members, Dr. Friedrich Brodnitz (considered the 'dean' of ENT docs at the time), had pointedly written and spoken his strong recommendation that boys should not sing at all during their adolescent years. Dr. Robert Sataloff was also on the panel, and the founder of the Voice Foundation, Dr. James Gould, was the moderator. Yikes!! We were on pins and needles, as the saying goes, big time.  Dr. Brodnitz was directly asked if John's presentation had influenced his recommendation of no singing for adolescent males.  We were horrified and held our breath for a while.  Dear, friendly Dr. Brodnitz said, with his famous sense of humor injected, that if adolescent boys were led by people who used Dr. Cooksey's approach to singing, that singing would be just fine and safe for them to do. Wheeww!!!!!]
Cooksey, J.M. (1993).Do adolescent voices 'break' or do they transform? VOICE, The Journal of the Brisish Voice Association, 2(1), 15-39. [Europeans speak of adolescent boys' voices 'breaking.' John took a year-long sabbatical in London, working with our colleague, Dr. Graham Welch, and educating the UK music teachers and the public about voice change--BBC presentation and all that. The BVA journal no longer exists. It was folded into the journal Logopedics Phoniatrics Vocology, published in Europe]
Cooksey, J.M, Beckett, R.L., & Wiseman, R. (1985). A longitudinal investigation of selected vocal, physiological, and acoustical factors associated with voice maturation in the junior high school male adolescent.  Unpublished research report, California State University at Fullerton.  [This is the original report of the Cooksey-Beckett-Wiseman research.]
Harries, M.L.L., Griffin, M., Walker, J., & Hawkins, S. (1996). Changes in the male voice during puberty: Speaking and singing voice parameters. Logopedics Phoniatrics Vocology, 21(2), 95-100.  [This article is a report of research that indicated John's voice classification guidelines matched with chronological data related to male pubertal changes in the field of pediatrics.  Dr. Harries is a pediatrician in the UK.]
There's more, but I'll stop here.  I'll now prepare my defenses against the slings and arrows coming my way from anyone who disagrees with my perspective on male voice change.  Or, maybe a discussion will break out.  Who knows?  Good luck, Brad, and be well.
A really short one, here:
I've heard a good number of good, passionate-about-music-and-singing music/choral educators pronounce the word LARYNX as:  lair-nicks.
Just so everyone knows:  That word is officially pronounced: lae'-rinks.
First syllable vowel is like the vowel in mare, and that syllable is the accented one.
Second syllable vowel, the unaccented syllable, is like the vowel in:  rinks).
Spread the WORD, United Pronunciationists of the World! (and let us all be kind--maybe even private--when we do)

It’s almost never mentioned. 

Have you ever heard or read that the state of your mouth and teeth can affect your voice health?  Me either.
Turns out that large armies of good and bad bacteria and viral ‘nasties’ fight vicious wars in our teeth, mouths, noses, and throats, and in our ears and on our skin.  They are waaay microscopic, of course; never visible to the unaided eye, but with an electron microscope….  [Hmmm.  Make a great cartoon series with Night on Bald Mountain in the background, eh? (This last sentence was written in the Canadian language, which I am now studying…just so you know.)]
Some context for deep understanding.  The noses, ears, eyes, and teeth-containing mouths of us human beings are huge entryways for “non-us stuff” to get inside our bodies (e.g., foods, liquids, airborne chemicals and particles, microorganisms like bacteria, viruses, fungi). [The word microbe is an abbreviation formicroorganism.]  Non-us stuff gets there in the air we breathe, the food we eat, the liquids we drink, and anything that gets in our eyes or ears, on our lips, or in our noses or mouths, (like fingers, pencils, and such), or between our teeth. 
The absolute first line of defense against those non-us ‘evildoers’ is the mucus that coats the surfaces of all our internal spaces (our upper and lower airways).  Mucus ‘arrests’ those evildoers and puts them in a flowing mucus-jail so that cells of the immune system have many opportunities to execute them before they ‘get us.’  Well, the mucus-jail needs to be abundant and thin so it can flow ‘real good.’  It needs to have a lot of water in it to be thin enough to flow right.  If the jail doesn’t have enough water, the mucus gets thicker and more adhesive to the skin surfaces.  That makes it easier for the bad guys to escape jail and hurt us.
The two major ways that infective (pathogenic) microbes are spread from person to person are:
1. air, e.g., infected people exhale or cough them into surrounding air, then uninfected people inhale them into their airways (noses, mouths, throats, larynges, lungs) and…
2. touch, e.g., infected people cough or exhale them into surrounding air (or they cough them onto their hands or their clothing) and they fall onto nearby objects (computers, cell phones, carrying cases, desks, chairs, and the like).  And then…uninfected people touch the “infecteds” or hug them, or touch the objects they’ve coughed upon, and then rub their own clothes or eyes, wipe their lips, and the like.  [Some of those nasties may remain alive on some surfaces for as long as about 1.5 hours.]
Also, when we eat and drink, microscopic ‘films’ of the food/drink contents attach onto our teeth, and larger bits can become embedded in the “nooks and crannies” of our teeth.  Then, Some of the biochemicals that are in our mouths begin to break those films-and-bits down.  Over enough time, they rot (in a manner of speaking) and can be an attractive environment for various microbes.  So…when we swallow, and when the mucus that coats our airways moves around, a lot of non-us stuff gets moved onto the surface tissues of our throats where viral microbes have a chance to attach themselves onto our local cellular ‘machinery’ and start reproducing themselves and spreading.  And, the bad bacteria have a chance to embed themselves in those tissues and colonize and spread in them. 
But then, (cue strong trumpet fanfare) cells of our immune system charge in and marshal gazillions of ‘non-us-fighters.’  They send out biochemical signals (immunotransmitters) to prepare the infected tissues for battle by producing inflammation.  Blood vessels (usually capillaries) that feed the infected area dilate (expand) and that opens microscopic-sized ‘holes’ in the vessels that are big enough to allow plasma fluid (containing cells of the immune system) to leak into the infected tissue (producing what we refer to as swelling), but are not big enough to allow red blood cells to pass through (vessels have to be ‘crushed’ for bruising to happen).  [Note: The suffix -itis only means that inflammation has happened.  The word that -itis is tagged onto indicates the anatomic area in which the inflammation has occurred, thus gastritis, appendicitis,  and colonitis and so on.] 
Typically, we have upper airway infections (nose/mouth openings to vocal folds).  But…if enough of those bad guys make their way into our trachea and lungs, they have a chance to infect our lower airway. When our throat area becomes inflamed we may say we have pharyngitis.  If the vocal fold area becomes inflamed and we sound hoarse, we say we have laryngitis.  When we have inflammation in the bronchi of our two lungs, we say we have bronchitis
Bacteria have very short lives, but they reproduce themselves rather rapidly.  When they subdivide, their genes create copies of themselves.  But bacteria adapt their genetic expression to the environment in which they live.  So, the genes of bacteria that are more successful at reproduction even when they have encountered antibiotic killers over time, their progeny will become adapted and resistant to the antibiotic killers. 
Eye Health:  When touching your eyes (or mouth), use the backs of your hands/fingers.  Fronts of hands are much more likely to have live ‘evildoer’ microbes upon them.
Ear Health:  Placing objects like hairpins, cotton swabs, or paper clips into your ear canals to clear them, puts your ears at risk.  Vulnerable soft tissues, e.g., an eardrum, can be abraded or ruptured, and the objects may then deposit bad-guy microbes and other materials (e.g., allergens) into your ears to increase the risk of infection.  Microbes can then grow into your middle ear area, and that could bring on big trouble.
To clear your ears of wax buildup and nasties:
·      Gather:  a small syringe, two facial tissues, a pool of warm water in a clean sink, and a bottle of hydrogen peroxide.  It’s cheaper and more effective than brand name over-the-counter (OTC) stuff.
·      With a fairly small amount of hydrogen peroxide in the syringe, lean your head to one side so that your ceiling-pointed ear is nearly level with the floor that you’re standing on.
·      Fillyour ear canal with the hydrogen peroxide.  It will ‘fizz up a storm’ as it loosens the wax.  If de-waxing hasn’t happened in a while, let ‘er fizz for a while.
·      When you think it’s fizzed enough, turn your ‘upper’ ear down to dump the liquid into a facial tissue, or some other absorbent material, then use it to clear your external ear of the excess. 
·      Fill the syringe with the warm water, lean over the sink so the treated ear points down toward it, and then irrigate that ear with pretty good pressure about three times.  Some bits of earwax will 
       likely fall into the sink’s water.  Use the tissue again, to clear your external ear of the excess water.
·      Repeat with the other ear.  If de-waxing hasn’t happened in a while, you may have to irrigate about every three days or so, to get eventually a satisfactory clearing.
Teeth and Mouth Health:  Dentists call it oral hygiene
A major preventative for upper and lower respiratory infections (and for halitosis—bad breath) is brushing and flossing our teeth daily, and using a non-alcoholic mouthwash afterward (check labels). Alcohol in mouthwash contributes to a drying of the mucosal skin surfaces.
1. Mouthwash is for swishing around in the mouth onlyno gargling with it.  Too much of a chance of killing off immune system cells and ‘good’ bacteria in the throat that help keep the infective bacteria in check.  After the swished mouthwash-only is spit out, wait a short while and then swish water around in the ol’ mouth to dilute what’s left, spit that out, then swish more water and do what my voice education colleague from California, Lisa Popeil, calls a “deep gargle,” that is, allow the water into your throat as deeply as you can without triggering a gag reflex.
2. Try swishing and gargling with warmed water.  The ‘soothe’ can feel good.
3. If you add salt to water before you gargle it, add only a small thumb-to-forefinger pinch of it to reasonably match the small degree of salinity that’s in your mucus.  I’ve heard and read recommendations to add a teaspoon of salt to a glass of water and stir it before gargling.  That’s waaaaay too much salt and it becomes an irritant to your mouth and throat tissues. 
Nose Health:  If you are ever afflicted with chronic thickened mucus in your nasal cavity, especially if you feel that it flows down the back of your throat (sometimes called post-nasal drip) and it interferes with your breathing and singing, one way to clear it is to:
1. Purchase:  (1) a Neti pot at a Health Food Store or a Drug Store (Apothecary Shop) and (2) a supply of a liquid that can be used for nasal irrigation (ask a Pharmacist).  The liquid is mostly water, but it is prepared in such a way that it approximates the ‘thin flowability’ (viscosity) and salinity characteristics of normal human-produced mucus. 
2. Pour an appropriate amount of the liquid into the Neti pot, and then follow the provided directions for pouring the liquid into one of your nostrils so that it flows into your nasal cavity and then drains out.  Repeat by pouring into the other nostril.  Nasal clearing is then achieved.  Afflicted people rave about the help that nasal irrigation provides.
General HealthStop frequent use of antibacterial hand soaps for hand washing.  Wide use of antibacterial soaps has resulted in mutations of ‘bad,’ infective bacteria that are resistant to our common medical remedies such as penicillin.  Personally, I use antibacterial soap only when my hands have been in contact with some potentially nasty stuff, like garbage or cleaning old dirty/dusty places.  Nearly all my hand washing is with regular soaps…for whatever that’s worth.
Ahh, choices and adaptations; the adventure of life.
[Coming later is an update of research info about Hydration: The Well-Watered Body]
As you may or may not know, I've spent about 30 years in both voice education and voice health and recovery settings; twelve of those years were at the Fairview Voice Center, Fairview Rehabilitation Services, at the University of Minnesota Medical Center, Fairview. During that time, ENT and Speech Pathologist colleagues have asked me to work with a significant number of choral and solo singers who have had ENT-diagnosed voice disorders. They have ranged in age from 10 to 73 years.
Some of the singers who were of school/college age had recently finished singing in an honor, all-state, or festival choir that had rehearsed for six to eight hours per day over two to six days, followed by a performance. Others had recently completed a choir tour of about seven to 10 days, with lots of talking and singing over wind and motor noise in busses, in-tour extra rehearsals, relatively frequent performnces, and sometimes staying in the homes of generous local hosts, with late-night talking after the performances. At least within a few days of returning home, upper and lower respiratory illness had struck a good many of the singers.
About a decade or so ago, I was an invited presenter at a summertime statewide high school honor choir event. My series of presentations was for any of the state's choral conductors who chose to attend (about 30, as I recall) and the general topic was voice education and voice health. The event also included three days of rehearsals of the singers with an invited conductor, followed by a morning concert. Observing the choir's rehearsal schedule, I spoke with one of the state's choral conducting leaders who had attended my sessions. He agreed that, before these rehearsals had begun, none of the honor choir singers had been rehearsing for three hours in the morning, three hours in the afternoon, and 1.5 hours in the evening. He also agreed that, most likely, very few of the singers had had the opportunity to learn how to speak and sing with optimum vocal efficiency. And we both expressed a belief that these conditions were common any time that honor, all-state, and festival choirs were rehearsed anywhere.
So I suggested that he and I confer and write up some guidelines for organizers of honor, all-state, and festival choirs--and the conductors who conduct them--that would be consistent with good preventive vocal health and voice protection practices--and then submit them to Choral Journal. He indicated that he would have to take the idea to the office-holders of the organization of which he was a member. He did so.
And the idea was rejected by those leaders. To my knowledge, no such guidelines have ever been written.
A common 'first principle' of medical ethics among members of the medical profession is: Primum non nocere ( First, do no harm. ) **
How about members of the choral conductor and voice teaching professions? Do we need choral conductor ethics ? What would they be? What would the 'first principles' be?
Please comment, question, propose, argue, whatever comes to mind.
**Attributed to Thomas Sydenham (1624-1689), regarded as the father of English medicine, and based on the writings of the the Greek physician Hippocrates, in Epidemics, Book I, Section XI. In translation, he wrote ...make a habit of two things--to help, or at least to do no harm.
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The image above is an internal view of Leon Thurman's larynx.  The front of Leon's larynx is at the bottom of the picture (toward his "Adam's apple"), and its rear area is at the top (toward his cervical spine).  In this image, Leon was sustaining the pitch C3.  Note the 'Gothic arch' configuration in the photo (upside-down V shape).
At the bottom of the circle is Leon's epiglottis (attached to the back of his tongue).
At the top of the circle is part of Leon's lower pharyngeal wall, sometimes called the laryngo-pharynx.
Forming the peak of the Gothic arch configuration are the mounds of flesh that cover the tops of Leon's left and right arytenoid cartilages (they do not include the rounded 'bulbs' that are located below the arytenoid mounds). The cartilages were rotated and slid together by his Larynx's vocal fold 'closer muscles.'  Pitch changes were carried out primarily by coordinations of his vocal fold 'shortener and lengthener muscles.'
Leon's left and right true vocal folds appear vertically right in the center of the Gothic arch. His false vocal folds appear to the lateral sides of his true vocal folds.  The left and right false vocal folds are located just above the two true vocal folds, and the two pairs of folds are separated by ventricular 'spaces' (can't be seen; the Ventricles of Morgagni).  The false vocal folds are not usually engaged during speaking and singing.  When they do join the true vocal folds in creating speaking or singing, the voice quality that is produced is the sound that Louie ('Satchmo') Armstrong made when he sang a song.  He's the famous jazz trumpeter-singer of years gone by, e.g., "It's a Wonderful World".
To the lateral sides of the Gothic arch are Leon's two pyriform sinuses (sinus is Latin for 'hollow cavity').  They are the left and right endpoints of the closed entryway into his esophagus.  The image isn't clear enough to show the curved horizontal 'line' that is formed between the pyriform sinuses when the entryway is closed, like they are when we're not swallowing. 
Note: The esophageal entryway is located behind the larynx.  When we human beings swallow a large amount of food or drink, the entire entryway opens to send it on its digestive journey to possibly become 'us.'  When we swallow moderate to small amounts, about one-half the food/drink enters the esophagus through the left or right pyriform sinus, and the other half enters through the other sinus.  In order to prevent food/drink from entering the airway when we swallow, the tongue is pulled backward so that the epiglottis is folded backward over the gothic arch area of the larynx, and at the same time, the larynx is pulled upward by the larynx-pull-up muscles.  Their coordinated 'pincer' action seals off the airway and channels the food/drink into the esophagus. 
Remember what happens when we swallow something and some of it "goes down the wrong way?"  When anything barely touches the tissues that form the closure of larynx and epiglottis, a powerful laryngeal/respiratory reflex action happens, driven by nearby high-speed brainstem neurons, and we cough, cough, cough to expel the possible lung invader.
About the image:
The late, beloved Dr. Van Lawrence was Company Physician for the Houston Grand Opera, and saw many top-line, international opera singers.  He used videostroboscopic images to give the singers feedback about the efficiency with which they sang and spoke.  He was first to identify the 'gothic arch' configuration (see photo above) as a sign of efficient vocal production in both singing and speaking.
The image was taken from a videotape that was made in in Dr. Lawrence's exam room in Houston, Texas, June, 1983.  Dr. Lawrence used a flexible-nasal laryngeal videostroboscope to capture moving images of a variety of efficient and inefficient vocal coordinations that Leon used while speaking and singing.  Subsequently, the tape was used in voice education experiences to illustrate vocal efficiencies and inefficiancies (and the voice qualities they produced) for choral conductors, music educators, singing teachers, speech teachers, theatre directors, speech pathologists, and otolaryngologists (primarily during courses offered by The VoiceCare Network).