Phonational profiles of female professional singers and nonsingers

Measures of the SFF, vocal intensity, phonational range, and habitualpitch level are reported for 39 professional singer and 39 nonsinger females, who were divided into three age groups (young, middle, and old age), with the professionals further divided into sopranos and altos. Each read the “Rainbow Passage” and spoke extemporaneously, from which measures of the SFF and vocal intensity were calculated; phonational range and habitual pitch levels were also determined. No significant differences were noted between the reading and speaking tasks. The SFF and intensity levels were significantly higher for the professionals in comparison to the nonsingers, but only for certain age groups. Moreover, whereas the nonsinger SFF levels varied significantly as a function of age, those for the professional singers did not. Although trends occurred, no significant differences were found for the mean phonational range or habitual pitch levels when the professionals and nonsingers were compared.     

Vocal tract resonances in singing: Strategies used by sopranos, altos, tenors, and baritones

The first two vocal tract resonances (R1 and R2) of 22 classically trained sopranos, altos, tenors, and baritones were measured while they sang four different vowels over their normal pitch range. The resonances of the tract and the harmonics of the voice were measured simultaneously by injecting a broadband acoustic current into the tract at their mouth. Sopranos were found to tune R1 close to the fundamental frequency f(0) (R1:f(0) tuning) over at least part of their upper range for all vowels studied, particularly when f(0) was around or above the value of R1 for speech. Additionally, most sopranos employed R2:2f(0) tuning over some of their range, often simultaneously with R1:f(0) tuning. Altos used R1:f(0) tuning for vowels having lower values of R1 in speech, but can switch to R1:2f(0) tuning in the lower part of their range. Tenors and baritones generally used R1:2f(0) and R1:3f(0) tunings over part of their range and employed a number of different tunings to higher harmonics at lower pitch. These results indicate that singers can repeatedly tune their resonances with precision, and that there can be considerable differences in the resonance strategies used by individual singers, particularly for voices in the lower ranges.     

Acoustic Analyses of Trained Singers Perceptually Identified from Speaking Samples

This study investigated selected acoustic cues in the speaking voices of five professional singers; cues that may have enabled na?ve listeners to differentiate them from nonsingers and other trained singers who were not consistently identified from their speaking voices. Subjects were divided into three groups based on listeners' perceptual judgments. Group I, the identified singers, consisted of five professional singers, three males and two females, with an average identification score, from their speaking utterances, of 79%. Group II, the unidentified singers, consisted of 15 trained singers, seven males and eight females, who, as a group, were identified correctly from their speaking utterances only 52% of the time. Group III consisted of 20 nonsingers who were incorrectly identified from their speaking utterances as singers only 36% of the time, that is, they were correctly identified as nonsingers from their speech 64% of the time. Acoustic parameters chosen for measurement from vowel productions were: (1) percent jitter, (2) percent shimmer, and (3) noise-to-harmonic ratio. The second sentence of the "Rainbow Passage" was selected to compare several frequency and duration measures between the three groups. These were: (1) mean speaking fundamental frequency, (2) standard deviation of the fundamental frequency, (3) sentence duration, (4) word duration, and (5) consonant/vowel ratio. The data indicated that the acoustic parameters that most consistently distinguished the identified singers from the unidentified singers and the nonsingers were fundamental frequency variation and durational differences. The identified singers varied their speaking fundamental frequency significantly more than did both the unidentified singers and the nonsingers. The identified singers also had longer vocalic segments than did the others.     

Velum Behavior in Professional Classic Operatic Singing

The velopharyngeal opening (VPO) is analyzed in 17 professional operatic singers, 3 high sopranos, 3 sopranos, 2 mezzo-sopranos, 3 tenors, 2 baritones, 2 bass-baritones, and 2 basses singing the vowels [a, i, u] at middle degree of vocal loudness at different pitches throughout their pitch range. Three methods were used for detection of a VPO. One was nasofiberscopy, which revealed VPO of various shapes in several singers. Another method was recording nasal and oral airflow by means of a divided flow mask. These measurements showed a nasal DC airflow at least at some pitches in a majority of the singers. A third method was a comparison of the level of the fundamental in the nasal and oral airflow signals; this level difference was less than 15 dB in cases where a nasal DC airflow was observed. Values less than 15 dB were observed in some cases, thus suggesting the presence of a VPO. The tokens produced by the singers were assessed by an expert panel with respect to nasal quality of the vowel timbre; no correlation was found between rated nasal quality and the presence of a VPO.     

Self-reported voice problems among three groups of professional singers

A vocal health questionnaire was administered to three groups of professional singers and a “friendship-matched” group of nonsingers in Melbourne, Australia. The responses of 79 opera, 57 musical theatre and 31 contemporary (excluding rock) singers and 86 nonsingers were analysed. The questionnaire solicited information regarding biographical data speaking and singing voice-use behaviours, and vocal health over the previous 12 months in terms of experiences of vocal impairment, vocal disability, and handicap. Significant differences between singers and nonsingers in the prevalence and nature of voice problems were reported. Of the singers, 44% reported one or more occurrences of a diagnosed vocal condition compared to 21% of nonsingers and 69% of singers experienced vocal disability compared to only 41% of nonsingers, over the previous 12 months. In contrast, no significant differences were found between the three different styles of singers in their experience of vocal impairment, disability or handicap.     

Predicted Singers' Vocal Fold Lengths and Voice Classification—A Study of X-Ray Morphological Measures

Students admitted to the solo singing education at the University of Music Dresden, Germany have been submitted to a detailed physical examination of a variety of factors with relevance to voice function since 1959. In the years 1959–1991, this scheme of examinations included X-ray profiles of the singers' vocal tracts. This material of 132 X-rays of voice professionals was used to investigate different laryngeal morphological measures and their relation to vocal fold length. Further, the study aimed to investigate if there are consistent anatomical differences between singers of different voice classifications. The study design used was a retrospective analysis. Vocal fold length could be measured in 29 of these singer subjects directly. These data showed a strong correlation with the anterior-posterior diameter of the subglottis and the trachea as well as with the distance from the anterior contour of the thyroid cartilage to the anterior contour of the spine. These relations were used in an attempt to predict the 132 singers' vocal fold lengths. The results revealed a clear covariation between predicted vocal fold length and voice classification. Anterior-posterior subglottic-tracheal diameter yielded mean vocal fold lengths of 14.9, 16.0, 16.6, 18.4, 19.5, and 20.9 mm for sopranos, mezzo-sopranos, altos, tenors, baritones, and basses, respectively. The data support the assumption that there are consistent anatomical laryngeal differences between singers of different voice classifications, which are of relevance to pitch range and timbre of the voice.     

Characteristics of Phonatory Function in Singers and Nonsingers With Vocal Fold Nodules

Purpose

The goals of this study were to determine if there were significant differences between singers and nonsingers in the morphology of vocal nodules and the associated impact on vocal function.

Method

Participants were 10 professionally trained singers with nodules, eight nonsingers with nodules, and 10 individuals with healthy normal voice (controls). Surface electromyography (sEMG) from three anterior neck locations and acoustic rise times for vowels /a/ and /i/ were measured in all the participants. In individuals with nodules, dB SPL/cm H₂O, glottal airflow, and nodule location and size were also measured.

Results

There were no significant differences between singers and nonsingers with nodules in terms of airflow, dB SPL/cm H₂O, nodule size, or nodule location. In nonsingers with nodules, airflow and nodule size were significantly correlated, but were not significantly correlated in singers. Vowel rise times and sEMG during vocal tasks did not differentiate among nodule and control groups. Sternocleidomastoid sEMG during initiation of the vowel /a/ was statistically significantly stronger in nonsingers with nodules relative to singers with nodules and controls.

Conclusions

Nodule morphology did not differ between singers and nonsingers, although some behavioral aspects of phonation differed between the groups.     

Singing power ratio: Quantitative evaluation of singing voice quality

This paper presents a parameter for objectively evaluating singing voice quality. Power spectrum of vowel sound / a / was analyzed by Fast Fourier Transform. The greatest harmonics peak between 2 and 4 kHz and the greatest harmonics peak between 0 and 2 kHz were identified. Power ratio of these peaks, termed singing power ratio (SPR), was calculated in 37 singers and 20 nonsingers. SPR of sung / a / in singers was significantly greater than in nonsingers. In singers, SPR of sung / a / was significantly greater than that of spoken / a /. By digital signal processing, power spectrum of sung / a / was varied, and the processed sounds were perceptually analyzed. SPR had a significant relationship with perceptual scores of “ringing” quality. SPR provides an important quantitative measurement for evaluating singing voice quality for all voice types, including soprano.     

Airway Considerations for Professional Singers—A Survey of Expert Opinion

The objective of this study was to survey physician experts in voice disorders/treatment to establish consensus guidelines for translaryngeal intubation (TLI) and tracheotomy when treating professional singers or other voice professionals. A written survey was sent to all physician members of the Voice Foundation seeking opinions/recommendations about route of TLI, duration of TLI before tracheotomy, size of endotracheal and tracheotomy tubes, and special interventions during patient care as these might differ between professional singers and nonsingers. Fifty-five percent of the physicians responded, of whom 73% classified their experience in voice care as “extensive.” A strong consensus (76%) favored a smaller endotracheal tube for singers (6–7 mm I.D. for males and 6.0 mm I.D. for females) via the oral (46%) versus nasal (36%) route. Intubation/extubation by the most expert/experienced personnel was emphasized so as to minimize direct trauma to the larynx. While intubated, strong recommendations were made to suppress gastric acid production and to minimize motion of the endotracheal tube, including patient sedation. Preferences for an early tracheotomy (6 days) versus their usual time (10 days) were approximately equal (44% vs. 50%, respectively) and most respondents (69%) recommended the same size tracheotomy tube (8.0 mm I.D. for males and 6.0 mm I.D. for females) for singers and nonsingers. Post extubation/decannulation care emphasized voice rest, retraining, continued gastric acid suppression, and the possibility of direct laryngoscopy to assess post-TLI or tracheotomy injuries.     

Singer's Formant in Sopranos: Fact or Fiction?

Although it is generally agreed that the singer's formant (F_S) is a prerequisite for successful stage performance, the results of this research do not support its presence in the soprano voices of trained female singers. Results are based on a recent investigation testing 10 advanced/professional sopranos in two groups singing sustained vowels at three frequencies: high (932 Hz), mid (622 Hz), and low (261 Hz). Spectrographic analysis shows that the nature of harmonic energy varies in relation to pitch. A resonance band somewhat resembling the tenor F_S was usually evident in vowels sung at low and mid pitch. However, unlike the F_S of typically less than 1 kHz bandwidth associated with tenors, sopranos singing similar pitches produced corresponding bandwidths which were significantly broader, usually at least 2-kHz wide. Vowels sung by sopranos at high-pitch levels exhibited strong fundamental frequency production with strong reinforcement of adjacent harmonics extending to 5 kHz and beyond. This type of production in essence nullifies the necessity for a typical F_S. Absence of the F_S in strong soprano voices might also imply the adaptation of a sufficiently different overall vocal tract configuration, so that techniques geared to developing maximal projection should not be the same as those developed to maximize the F_S in other voices.     

Some physical characteristics of the male falsetto voice

Previous research indicated that, as groups, male (bass/baritone) and female (soprano) professional singers tend to exhibit differing vocal tract and voice source behaviours. The use of an objective measure of voice [xeroradiographic-electrolaryngographic analysis (XEL)] revealed differences between the two voice types, especially at the highest sample pitches (e, 330 Hz for bass/baritones, and e″, 1,320 Hz for sopranos). XEL analysis combines two known techniques, i.e., soft-tissue radiographic imaging (xeroradiography), and an analysis of voice-source vibratory patterning (electrolaryngography). Subsequent to this investigation, interest centered on the male professional falsetto voice over a two-octave range (E 165 Hz to e′ 660 Hz) using a sample (n=9) of professional countertenors. Results suggest that there are characteristic trends in the patterning of the male professional falsetto register, but there is also evidence of within-group variability. The subjects significantly increased the size of the pharyngeal tube area during phonation. ANOVA and Trend Analysis revealed ventricular space as the only measure to expand systematically and consistently as sung pitch increases.     

Preferred self-to-other ratios in choir singing.

Choir singers need to hear their own voice in an adequate self-to-other ratio (SOR) over the rest of the choir. Knowing singers' preferences for SOR could facilitate the design of stages and of choral formations. In an experiment to study the preferred SOR, subjects sang sustained vowels together with synthesized choir sounds, whose loudness tracked that of their own voice. They could control the SOR simply by changing their distance to the microphone. At the most comfortable location, the SOR was measured. Experimental factors included unison and four-part tasks, three vowels and two levels of phonation frequency. The same experiment was run four times, using sopranos, altos, tenors, and basses, with stimulus tones adapted for each category. The preferred self-to-other ratios were found to be similar to SORs measured previously in actual performance, if a little higher. Preferences were quite narrow, typically +/- 2 dB for each singer, but very different from singer to singer, with intrasubject means ranging from -1 to +15 dB. There was no significant difference between the unison and the four-part tasks, although this might have been caused by systematic differences in the stimulus sounds. Some effects of phonation frequency and vowel were significant, but interdependent and difficult to interpret. The results and their relevance to live choir singing are discussed.     

The association between upper trapezius activity and thorax movement in classical singing

This study aimed to examine in classical singing the phasing of the activity in upper trapezius (TR) to upper and lower thorax movement and to the phasing of activity in the intercostals (INT) and in the lateral abdominal (OBL) muscles. Electromyographic (EMG) activity was recorded from the TR, INT, and OBL muscles on the right side. Thorax movement (TX) was traced with two strain gauge sensors placed around the upper and lower thorax. Four professional opera singers (soprano, mezzo, tenor, and baritone) and four advanced student classical singers (three sopranos and one mezzo) participated. Three of the professional singers were 33 years, and one was 40 years. The students were between 23 and 30 years. Different arias, freely chosen by the singers from their professional repertoire, served as the singing task for the opera singers. All students sang “Summertime” from Porgy and Bess. All subjects performed their task three times with variation in vocal loudness (normal, forte, piano). Thereafter, for all subjects, a biofeedback (BF) procedure was performed on TR to lower TR activity and a repeat performance of the singing tasks was carried out. EMG activity from the three recording sites and upper and lower TX circumference were compared before and after BF. A phasing of upper TR activity to INT and OBL activity was discovered, all muscles supporting the expiration phase. During phonation, the upper TR contributes in the compression of upper TX, thus serving as an accessory muscle of expiration. Group results from both opera singers and student singers showed that EMG activity was significantly lowered after BF. The lowered TR activity resulted in an expanded upper TX circumference and less TX respiratory movement after BF.     

Comparisons of Voice Onset Time for Trained Male Singers and Male Nonsingers During Speaking and Singing

This study was designed to examine the temporal acoustic differences between male trained singers and nonsingers during speaking and singing across voiced and voiceless English stop consonants. Recordings were made of 5 trained singers and 5 nonsingers, and acoustically analyzed for voice onset time (VOT). A mixed analysis of variance showed that the male trained singers had significantly longer mean VOT than did the nonsingers during voiceless stop production. Sung productions of voiceless stops had significantly longer mean VOTs than did the spoken productions. No significant differences were observed for the voiced stops, nor were any interactions observed. These results indicated that vocal training and phonatory task have a significant influence on VOT.     

Pitch-matching accuracy in singers and nonsingers

The present study determined the accuracy and the effect of repeated trials for singers and nonsingers when matching their vocal fundamental frequency to a preset tone near the midpoint of their modal-loft phonational range. Two measures of accuracy were obtained for nine trials for five singers and five age-matched nonsingers: (a) the difference between the target frequency and the first measureable waveform, and (b) the difference between the target and the average of the first five measureable waveforms. The results indicate that singers are more accurate than nonsingers are in their ability to match the first measureable waveform and the mean of the first five measureable waveforms to targets presented aurally. In addition, singers as a group improved from the first three trials to the final three trials in accuracy for both measures, whereas the nonsingers did not demonstrate a group trend toward improvement. The results suggest that singers as a group may rely on their training or experience to perform a pitch-matching task superiorly to nonsingers.     

Perceptual and acoustic study of professionally trained versus untrained voices

Acoustic and perceptual analyses were completed to determine the effect of vocal training on professional singers when speaking and singing. Twenty professional singers and 20 nonsingers, acting as the control, were recorded while sustaining a vowel, reading a modified Rainbow Passage, and singing "America the Beautiful." Acoustic measures included fundamental frequency, duration, percent jitter, percent shimmer, noise-to-harmonic ratio, and determination of the presence or absence of both vibrato and the singer's formant. Results indicated that, whereas certain acoustic parameters differentiated singers from nonsingers within sex, no consistently significant trends were found across males and females for either speaking or singing. The most consistent differences were the presence or absence of the singer's vibrato and formant in the singers versus the nonsingers, respectively. Perceptual analysis indicated that singers could be correctly identified with greater frequency than by chance alone from their singing, but not their speaking utterances.     

Vocal loudness and frequency capabilities of the voice

A phonetogram is a graph showing the sound pressure level (SPL) of softest and loudest phonation over the entire fundamental frequency range of a voice. A physiological interpretation of a phonetogram is facilitated if the SPL is measured with a flat frequency curve and if the vowel /a/ is used. It was found that in soft phonation, the SPL is mainly dependent on the amplitude of the fundamental, while in loud phonation, the SPL is mainly determined by overtones. The short-term SPL variation, i.e., the level variation within a tone, was about 5 dB in soft phonation and close to 2 dB in loud phonation. For two normal voices the long-term SPL variation, calculated as the mean standard deviation of SPL for day-to-day variation, was found to be between 2.4 and 3.4 dB in soft and loud phonation. Speakers who raise their loudness of phonation also tend to raise their mean voice fundamental frequency. Measures obtained from speaking at various voice levels were combined so that typical pathways could be introduced into the phonetogram. The average slope of these pathways was 0.3–0.5 st/dB for healthy subjects. Averaged phonetograms for male singers and male nonsingers did not differ significantly, but averaged phonetograms for female singers and female nonsingers did, in that the upper contour was higher for the female singers. Averaged phonetograms for female patients with non-organic dysphonia showed significantly lower SPL values in loudest phonation as compared to healthy female subjects, while no corresponding difference was seen for males in this regard. With respect to the SPL values for softest phonation, male dysphonic patients showed significantly higher SPL values than healthy male subjects, while no corresponding difference was seen in female subjects. The subglottal pressure mirrored these phonetogram differences between healthy and pathological voices. The averaged phonetograms of female patients after voice therapy showed an increased similarity with those of normal voices. For the male patients the averaged phonetogram did not change significantly after therapy.     

Voice Handicap Index in singers

The Voice Handicap Index (VHI) was developed to assess patients' perception of the severity of their voice disorder. The purpose of this study was to determine the degree of handicap expressed by professional and recreational presenters with a voice complaint. Singers (n = 106) and nonsingers (n = 369) with voice symptoms were studied. The results of the VHI for singers indicate that singers score significantly lower (less severe) on the VHI compared to nonsingers. Singers with vocal fold nodules had a lower mean VHI than singers with vocal fold cysts or polyps. Singers who perform classical music had the lowest mean VHI of all types of singers studied. A low VHI in singers may represent a significant handicap and should not be ignored when considering the severity of a singer's voice problem.     

Effects of singing training on the speaking voice of voice majors

This longitudinal study gathered data with regard to the question: Does singing training have an effect on the speaking voice? Fourteen voice majors (12 females and two males; age range 17 to 20 years) were recorded once a semester for four consecutive semesters, while sustaining vowels and reading the "Rainbow Passage." Acoustic measures included speaking fundamental frequency (SFF) and sound pressure level (SLP). Perturbation measures included jitter, shimmer, and harmonic-to-noise ratio. Temporal measures included sentence, consonant, and diphthong durations. Results revealed that, as the number of semesters increased, the SFF increased while jitter and shimmer slightly decreased. Repeated measure analysis, however, indicated that none of the acoustic, temporal, or perturbation differences were statistically significant. These results confirm earlier cross-sectional studies that compared singers with nonsingers, in that singing training mostly affects the singing voice and rarely the speaking voice.     

Comparison of young adult singers and nonsingers with vocal nodules

Comparisons were made between 10 singers and 10 nonsingers with vocal nodules and two control groups of normals, 10 singers and 10 nonsingers, on a wide range of acoustic, aerodynamic, psychoacoustic, and videostroboscopic measures. Results showed significant differences between the normals and those with nodules as well as differences between the singers and nonsingers. The singers with nodules had smaller nodules, less impairment of vibratory function, and less severe vocal symptoms than their nonsinging counterparts. The singing normals were found to be superior to the nonsinging normals on acoustic measures including jitter, shimmer, and signal-to-noise ratio. In addition, the singers, even in the presence of nodules, had superior maximum performance skills than their nonsinging counterparts.