Modal Register Research Articles

An investigation of the laryngeal system as the resonance source of the singer's formant

Since its introduction, the Sundberg model of the laryngeal system as the resonance source of the singer's formant has gained wide acceptance. However, no studies directly testing this hypothesis in vivo have previously been reported. Thus, the present study was undertaken to test this hypothesis on three classically trained professional male singers. The vocal behaviors of the singer-subjects were evaluated during model and pulse register phonation via magnetic resonance imaging, strobolaryngoscopy, and acoustic analysis. Results indicated the subjects did not achieve the laryngopharyngeal/laryngeal outlet cross-sectional area ratio requisite to the model and that the formant remained robust in pulse register phonation. It was concluded that these subjects' behaviors were not consistent with Sundberg's model and that the model was inadequate to account for the generation of the singer's formant in these three subjects.

Vocal breaks from the modal to falsetto register.

The study offers measurements of the vocal breaks occurring from the modal to the falsetto register in an untrained barytone. The breaks were achieved by increasing the expired airflow. An analogy with a labial pipe served as a help. The voice phenomena were divided into three regions. In the region of low modal frequencies (A-e) a simultaneous sounding of both the modal and falsetto registers was investigated. This was registered perceptually as vocal roughness. Under special conditions a subharmonic tone was produced. In the medium frequency region (e-g1) the vocal breaks occurred. The break intervals occupied the mean value of about a quint on the modal tone e. With increasing modal frequency, the break intervals decreased. In the high-tone region (g1-e2) only the falsetto register could be produced.

Physiologie und akustische Analysen der Pfeifstimme der Frau

Only a few singers are able to use to whistle voice, normally to produce extremely high pitches at the upper limit of their range. The laryngeal mechanism of the whistle voice is not completely understood. Stroboscopy shows only a horizontal vibration, the entire length of the vocal cords vibrating. The vocal cords are stretched to their maximal length. The spectral analysis of the whistle voice shows that the first two partials are much more pronounced than the higher ones. The 3D-PAN of the modal register is more complex than that of the whistle register.

About the so called “resonance tubes” used in Finnish voice training practice: An electroglottographic and acoustic investigation on the effects of this method on the voice quality of subjects with normal voice

Phonation into narrow glass tubes is used by some Finnish speech therapists and voice trainers for the treatment of phonasteny. The purpose of this study was to find out how the tubes affect the voice quality of normal subjects and whether the effect is related to the length of the tube or the fundamental frequency for speech range and modal register phonation. Two female subjects produced close vowels /i:, y:, u:/ and phonated into the tubes of 26, 27 and 28 cm in length at every semitone in the range of e-e1 (164–330 Hz). The results of electroglottographic and acoustic analyses (including measurement of spectral slope and signal-to-noise ratio) suggest that the tubes tended to improve the voice quality especially at the middle of the speech range. At high speech range the tubes made phonation more difficult. Neither the analyses nor the subjects' comments disclosed any systematic differences between the tubes at any fundamental frequency studied.

Assessment of the Dynamics of Vocal Fold Contact From the Electroglottogram

Electroglottographic (EGG) and acoustic records from 10 normal men prolonging the vowel /a/ at 60-68 dB, 70-78 dB, and 80-88 dB SPL were obtained. "Contact quotient" (EGG duty cycle) was shown to vary directly with vocal SPL. The mean contact quotient was 0.57 (SD = 0.07) and varied on the order of 1% over the course of a given phonation. "Contact index", a metric of EGG symmetry, also tended to vary with SPL. Consistent with previous qualitative descriptions of EGG morphology in modal register voice, the contact index averaged -0.52 (SD = 0.08), indicating that the EGG "closing phase" represents about 24% of the entire "contact phase". Contact index was more variable than contact quotient on consecutive EGG waves, varying by about 10% during phonation. Subjects were also instructed to produce a slow crescendo. Sound pressure and EGG data indicated that both the slope of increasing EGG contact and EGG duty cycle were significantly related to the amplitude of the acoustic signal. These results suggest that quantitative electroglottography may provide powerful insights into the control and regulation of normal phonation and into the detection and characterization of pathology.

Regulation of Phonatory Efficiency by Vocal Fold Tension and Glottic Width in the Excised Canine Larynx

An excised canine larynx was used to assess the effects of glottic width and vocal fold tension on acoustic power, aerodynamic power, and vocal efficiency. Multiple regression analysis of the data obtained from 10 larynges revealed that with increased vocal fold tension there is a logarithmic decline in radiated acoustic power, while aerodynamic power remains constant (p less than .05). Vocal efficiency has a similar logarithmic decrease with increased tension (p less than .05). With narrowing of the glottis, the acoustic power increases more than the aerodynamic power delivered to the larynx, and the efficiency increases. The inverse relationships glottic width has with acoustic power and vocal efficiency are best described by a reciprocal model (p less than .01). There is a negative linear relationship between glottic width and aerodynamic power. These results suggest that within the larynx the energy conversion is regulated by glottic aperture and longitudinal vocal fold tension. The optimal width for efficiency appears to be the narrowest width that produces phonation within the modal register, whereas increased tension decreases the efficiency of the glottis.

Influence of mean sound pressure level on jitter and shimmer measures

Summary The purpose of this investigation was to obtain information about the relationship between vocal sound pressure level (SPL) and the magnitude of cycle-to-cycle vocal fundamental frequency (jitter) and amplitude (shimmer) perturbation. Ten normal adult men prolonged the vowel/a/ in a modal register phonation in three SPL ranges: 60–68 dB (“soft”), 70–78 dB (“moderate”), and 80–88 dB (“loud”). A consistent trend related percent jitter and shimmer to the sound pressure level of the subjects' voices, such that the degree of perturbation was inversely related to the acoustic amplitude of the vowel. However, the relationship was more variable and less pronounced for shimmer measures, as only differences between the soft and loud SPL conditions were significant. These results nonetheless indicate that mean vocal intensity must be controlled or accounted for to maintain the validity and reliability of voice perturbation measurements. Possible physiologic explanations of the results and potential clinical implications are discussed.

On the relationship between vocal sound-pressure level and the magnitude of jitter and shimmer in the normal voice

The relationship between vocal sound-pressure level (SPL) and the magnitude of cycle-to-cycle fundamental frequency (jitter) and amplitude (shimmer) perturbation measured in the voice was examined. Ten normal adult men prolonged the vowel /ɑ/ in a modal register phonation maintained within three SPL ranges: 60–68 dB (“soft”), 70–78 dB (“moderate”), and 80–88 dB (“loud”). Statistically significant differences were found between measured mean and percent jitter and shimmer and the sound-pressure level of the subjects' voices, such that the degree of perturbation was inversely related to the acoustic amplitude of the vowel. These results indicate that mean phonatory frequency and intensity must be controlled or accounted for to maintain the validity and reliability of voice perturbation measurement, especially when such measures are intended as aids to the detection and discrimination of vocal pathology.

A model for vocal fold vibratory motion, contact area, and the electroglottogram.

The electroglottogram (EGG) has been conjectured to be related to the area of contact between the vocal folds. This hypothesis has been substantiated only partially via direct and indirect observations. In this paper, a simple model of vocal fold vibratory motion is used to estimate the vocal fold contact area as a function of time. This model employs a limited number of vocal fold vibratory features extracted from ultra high-speed laryngeal films. These characteristics include the opening and closing vocal fold angles and the lag (phase difference) between the upper and lower vocal fold margins. The electroglottogram is simulated using the contact area, and the EGG waveforms are compared to measured EGGs for normal male voices producing both modal and pulse register tones. The model also predicts EGG waveforms for vocal fold vibration associated with a nodule or polyp.

Frequency pertubation characteristics of pulse register phonation

Examination of some acoustic characteristics of sustained pulse register phonation in normal adults confirmed the existence of two distinct waveform patterns. Trains of similar, highly damped waves with relatively uniform spacing predominated, but the “dicrotic” pattern previously described accounted for about 15% of the total sample. Average differences in the periods of continguous cycles (jitter) were extremely large—on the order of 20% of the fundamental period. Jitter did not vary with fundamental frequency according to the pattern documented in modal register and, thus, jitter ratio is not a useful normalizing descriptor of pulse register pertubation.

Frequency characteristics of male and female speakers in the pulse register

Ten subjects (five male, five female) participated in a study of pulse register. Subjects produced the vowels /i/, /a/, and /u/ at three levels within their modal register, and at three levels within their pulse register. Significant differences were found between male and female groups in the modal register, but no significant difference was noted in their pulse register productions. Speculations on the mechanisms that account for this fundamental frequency equality in pulse register are given.

Cues for speaker‐sex identification

Studies emphasizing laryngeal fundamental as the cue for speaker sex do not account for the fact that in modal register there is a large range of f0 that is produceable by both sexes. Evidence that vocal tract resonance characteristics are a cue to speaker sex is presented. Listeners rated whispering voices on a confidence scale as to speaker‐sex identification. A significant nonparametric correlation was found between a measure of vocal tract resonance characteristics and listener ratings. The fact that the male voice with the vocal tract resonance characteristics most like those of the females was the only voice not confidently and accurately identified and the fact that when the distinctly female and distinctly male voices were taken separately there was no significant correlation suggest that there is a cutoff point between what is considered female voice quality and male.

More on “doubling.”

The occurrence of multiple harmonics between the harmonics of the natural f0 in modal and high registers has been described in previous work (Buhr and Keating, 1977). The present study explores the claim that such “doubling” occurs at the extreme ranges of modal register in infants and children, and that its occurrence is associated with production “instability” at these ranges. Spectral and waveform analysis tend to support this claim. Furthermore, waveform analysis of utterances in which “doubling” is occurring suggests that this instability may be inherent in the phonation of infants and children, but not in adults, except under certain circumstances. The predictability of this phenomenon will also be discussed.

Fundamental frequency in the speech of infants and children.

Fundamental frequency ranges of six normal infants and children from 33 to 169 weeks were determined by narrow-band spectrographic analysis. Fundamental frequency values ranged from 30 to 2500 Hz, well outside the values reported in previous studies of noncry utterances. The use of fry, modal, and high registers is also discussed.

Spectrographic effects of register shifts in speech production

Infants and children use a wide range of fundamental frequency values in their vocal production, often using more than one vocal register within a single utterance. Adult speech is also characterized by the occurrence of more than one register in the same utterance. Spectrographic analysis of utterances containing shifts between registers frequently reveals the occurrence of what appear to be multiple harmonics during these shifts, in between the harmonics of the f0. This effect may be the result of instability at extreme ranges of the modal register. For example, a combined sample for five children for whom a large corpus is available indicates these shifts occur across a range of 160–250 Hz in shifts between modal and Fry registers, and across a range of 380–800 Hz in shifts between modal and high registers. Additional evidence for this effect in adults will also be presented, along with results of waveform analysis of this phenomenon.

Vertical laryngeal position during continuous and discrete vocal frequency change.

Six young adult male subjects produced sustained phonation throughout their vocal frequency ranges: first, in a glissando or continuous frequency change maneuver, and second, in discrete intervals at separate trials. Measures of intrinsic and extrinsic laryngeal muscle activity and vertical laryngeal position were related to voice fundamental frequency in the two conditions. Each subject consistently positioned his larynx at a resting level when he was instructed to relax or when he was not performing experimental tasks. All larynx positions during experimental tasks were measured as deviations from this resting level. Subjects showed a close correspondence between their vertical laryngeal positions and voice frequencies--more so for the glissando maneuver than for changes in discrete frequency tasks. In general, subjects lowered their larynges from the resting position for low-frequency phonation and raised their larynges for higher fundamental frequencies. Absolute larynx position for the same frequency was quite varied both within and between subjects. Vertical laryngeal position during phonation most often was directly related to the activity of the thyrohyoid and sternothyroid muscles. Neither vertical laryngeal movement nor intrinsic laryngeal activity showed any pattern of relationship to changes between modal and falsetto voice registers.

Some spectrographic and perceptual features of vocal fry, abnormally rough and modal register vowel phonations

Twenty normal-speaking young adult males phonated (at one intensity) in modal register, with simulated abnormal vocal roughness, and in vocal fry register each of the five test vowels, /u/, /i/, /^/, /a/ and /æ/. Each test production was rated for roughness by a panel of 11 listeners; a median of the ratings for each production was then obtained. Additionally, the acoustic wave of each production was analyzed to produce a narrow-band (3 Hz) intensity-by-frequency acoustic spectrum in which multiple (25) measures of spectral noise (inharmonic component) level were obtained. For each test vowel, the median roughness ratings for fry productions were similar in magnitude to those for simulated abnormally rough productions and exceeded ( P < 0.05) those for modal productions. Further, fry and simulated abnormally rough productions did not differ with respect to spectral noise levels, but the spectral noise levels for both fry and abnormally rough productions were greater ( P < 0.05) than those for modal productions. A high degree of linear relationship was demonstrated between the roughness ratings and the spectral noise levels measures for the productions of each test vowel.

On vocal registers

For a considerable length of time, the concept of vocal registers has been the subject of controversy. Various authors have argued that there are as few as one or as many as seven registers and a considerable number of contradictory and confusing names have been used to identify them. Moreover, to date, agreement cannot be obtained even with respect to a reasonable definition of the nature of registers themselves. Accordingly, this paper first provides a definition of vocal registers, viz. a vocal register is totally a laryngeal event; it consists of a series or range of consecutive voice frequencies which can be produced with nearly identical phonatory quality; that there will be little overlap in fundamental frequency between adjacent registers, and that the operational definition of a register must depend on supporting perceptual, acoustic, physiologic and aerodynamic evidence. On the basis of this definition, it is postulated that three major registers exist; they are the pulse, modal and loft registers. It is contended that these registers can be experimentally defined and demonstrated and, while other registers could exist (at least for some individuals), they cannot be identified and described at levels approaching the precision and understanding of the three proposed. Perceptual, acoustical, physiological and aerodynamic data are presented to support postulations relevant to these three registers, and to differentiate among them.

A new inverse-filtering technique for deriving the glottal air flow waveform during voicing.

A method is described for deriving the volume velocity waveform at the glottis during voiced speech by inverse-filtering the volume velocity waveform at the mouth. Unlike the previously used technique of inverse-filtering radiated acoustic pressure, this method provides a signal that is accurate down to zero frequency, not susceptible to low-frequency noise, and easily calibrated in amplitude by a constant air flow. The primary limitation is the need for a transducer that will measure volume velocity at the mouth with adequate fidelity. In this work, volume velocity was recorded from a specially designed circumferentially vented wire screen pneumotachograph mask which provided a time resolution of 1/2 msec, without serious speech distortion. Inverse-filtered volume velocity was recorded with two adult male subjects for voicing in the modal register. Typical results are shown which indicate the way in which the glottal waveform varied with changes of fundamental frequency, subglottal pressure, and a dimension of voice quality related to the degree of compression of the vocal folds. Also considered are the effects of glottal-supraglottal acoustic interaction, and the effect on the glottal waveform of air displaced by the movements of the vocal folds.

The human vocal cords: a mathematical model. I.

Abstract A mathematical model for digital computer simulation of human-like utterances is developed. The overall system consists of a period structure of 16 coupled masses for each of the vocal cords, an 18-section cylindrical tube approximation of the pharynx and mouth, and a similar 12-section nasal tract. Special care has been taken to model separately the functions of the vocal ligament, the vocalic muscle, and the mucosa. Simulated phonation in modal, mixed and falsetto registers is possible. The parameters which control the nature of the phonation are lung pressure, external tension applied to ligament, vocalis, and mucosa, and the internal muscular action of the vocalis. Applications are cited in areas which include vocal physiology, pathology, and pedagogy.