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.     

The Acoustic Characteristics of Professional Opera Singers Performing in Chorus Versus Solo Mode

In this study, members of a professional opera chorus were recorded using close microphones, while singing in both choral and solo modes. The analysis included computation of long-term average spectra (LTAS) for the two song sections performed and calculation of singing power ratio (SPR) and energy ratio (ER), which provide an indication of the relative energy in the singer's formant region. Vibrato rate and extent were determined from two matched vowels, and SPR and ER were calculated for these vowels. Subjects sung with equal or more power in the singer's formant region in choral versus solo mode in the context of the piece as a whole and in individual vowels. There was no difference in vibrato rate and extent between the two modes. Singing in choral mode, therefore, required the ability to use a similar vocal timbre to that required for solo opera singing.     

Effect of artificially lengthened vocal tract on vocal fold oscillation's fundamental frequency.

The fundamental frequency of vocal fold oscillation (F(0)) is controlled by laryngeal mechanics and aerodynamic properties. F(0) change per unit change of transglottal pressure (dF/dP) using a shutter valve has been studied and found to have nonlinear, V-shaped relationship with F(0). On the other hand, the vocal tract is also known to affect vocal fold oscillation. This study examined the effect of artificially lengthened vocal tract length on dF/dP. dF/dP was measured in six men using two mouthpieces of different lengths. Results: The dF/dP graph for the longer vocal tract was shifted leftward relative to the shorter one. Conclusion: Using the one-mass model, the nadir of the "V" on the dF/dP graph was strongly influenced by the resonance around the first formant frequency. However, a more precise model is needed to account for the effects of viscosity and turbulence.     

Soft Phonation in the Male Singing Voice: A Preliminary Study

Sustained high notes, diminishing gradually from the loudest to the softest phonation within a maneuver called messa di voce, are examined in two contrasting professional tenor voices. Signals of the sound pressure level, electroglottograph, and mean esophageal pressure are recorded, and similar maneuvers by the same subjects are examined stroboscopically. The lyric voice is found to make a gradual diminuendo while maintaining nearly constant posture of the vocal tract together with a phase of complete closure in the glottal cycle. The robust voice, by contrast, passes abruptly from a production of high subglottal pressure and a high closed quotient to one of low pressure and incomplete closure, and the transition is marked by a sudden opening of the previously constricted laryngeal collar. It is proposed that the mode of soft voice production demonstrated by the robust voice be recognized as a distinct register of the singing voice.     

An investigation of the third formant of /a/ in prepubertal children

The third formant (F₃) of /a/ recorded from 209 healthy children (104 male and 105 female; ages 3 to 12 years) and 40 adults (20 men and 20 women) was studied by spectral analysis. Contrary to the traditional concept, the results of this study showed that there is significant difference in voice F₃ of /a/ between male and female children. This difference was found to begin to develop at the age of 3 years and became substantial by the age of 6 years. In this study, the value of F₃ obtained from female children at the age of 6 years was unexpectedly higher than that from the male children at the same age, which indicates that there is a difference in timbre in small children of both sexes.     

Experimental Findings on the Nasal Tract Resonator in Singing

SUMMARY: Many professional operatic singers sing the vowel /a/ with a velopharyngeal opening.(1) Here resonatory effects of such an opening are analyzed. On the basis of CAT scan imaging of a baritone singer's vocal tract and nasal cavity system, including the maxillary sinuses, acoustic epoxy models were constructed, in which velopharyngeal openings were modeled by different tubes. The sound transfer characteristics of this model were determined by means of sine-tone sweep measurements. In an idealized (iron tube) model, the VPO introduced a zero in the transfer function at the frequency of the nasal resonance. In the epoxy models, however, the resonances of the nasal system, and hence the zero, were heavily damped, particularly when the maxillary sinuses were included in the nasal system. A velopharyngeal opening was found to attenuate the first formant in /a/, such that the relative level of the singer's formant increased. A similar effect was observed in a modified epoxy model shaped to approximate the vocal tract of an /u/ and an /i/, although it also showed a substantial widening of the first formant bandwidth. Varying the size of the velopharyngeal opening affected the transfer function only slightly. It seems likely that singers can enhance higher spectrum partials by a careful tuning of a velopharyngeal opening.     

Long-Term-Average Spectrum Characteristics of Country Singers During Speaking and Singing

Five premier male country singers involved in our previous studies spoke and sang the words of both the national anthem and a country song of their choice. Long-term-average spectra were made of the spoken and sung material of each singer. The spectral characteristics of county singers' speech and singing were similar. A prominent peak in the upper part of the spectrum, previously described as the "speaker's formant," was found in the county singers' speech and singing. The singer's formant, a strong spectral peak near 2.8 kHz, an important part of the spectrum of classically trained singers, was not found in the spectra of the country singers. The results support the conclusion that the resonance characteristics in speech and singing are similar in country singing and that county singing is not characterized by a singer's formant.