Biomechanics of sound production in high-pitched classical singing.

Voice production of humans and most mammals is governed by the MyoElastic-AeroDynamic (MEAD) principle, where an air stream is modulated by self-sustained vocal fold oscillation to generate audible air pressure fluctuations. An alternative mechanism is found in ultrasonic vocalizations of rodents, which are established by an aeroacoustic (AA) phenomenon without vibration of laryngeal tissue. Previously, some authors argued that high-pitched human vocalization is also produced by the AA principle. Here, we investigate the so-called "whistle register" voice production in nine professional female operatic sopranos singing a scale from C6 (≈ 1047 Hz) to G6 (≈ 1568 Hz). Super-high-speed videolaryngoscopy revealed vocal fold collision in all participants, with closed quotients from 30 to 73%. Computational modeling showed that the biomechanical requirements to produce such high-pitched voice would be an increased contraction of the cricothyroid muscle, vocal fold strain of about 50%, and high subglottal pressure. Our data suggest that high-pitched operatic soprano singing uses the MEAD mechanism. Consequently, the commonly used term "whistle register" does not reflect the physical principle of a whistle with regard to voice generation in high pitched classical singing.

Does forced whisper have an impact on voice parameters?

OBJECTIVES: There has been the assumption that whispering may impact vocal function, leading to the widespread recommendation against its practice after phonosurgery. However, the extent to which whispering affects vocal function and vocal fold oscillation patterns remains unclear. METHODS: 10 vocally healthy subjects (5 male, 5 female) were instructed to forcefully whisper a standardized text for 10 min at a sound level of 70 dB(A), measured at a microphone distance of 30 cm to the mouth. Prior to and following the whisper loading, the dysphonia severity index was assessed. Simultaneously, recordings of high speed videolaryngoscopy (HSV), electroglottography, and audio signals during sustained phonation on the vowel /i/ (250 Hz for females and 125 Hz for males) were analyzed after segmentation of the HSV material. RESULTS: The pre-post analysis revealed only minor changes after the intervention. These changes included a rise in minimum intensity, an increase in the glottal area waveform-derived open quotient, and the glottal gap index. However, no statistically significant changes were observed in the harmonic-to-noise-ratio, the glottal- to-noise-excitation-ratio, and the electroglottographic open quotient. CONCLUSION: Overall, the study suggests that there are only small effects on vocal function in consequence of a forced whisper loading.

Boys Choirs in the Pandemic: Effects of Distance and Other Factors on Spectral and Temporal Accuracy.

During the Covid-19 pandemic, choral singing has been either completely prohibited or regulated with safety measures due to increased transmission risks. However, the impact of larger inter-singer spacings on the performance and educational process in boys' choirs is unclear. This study analyzed recordings of six groups of five singers each from two boys' choirs aged 7-16 who sang Beethoven's Ode to Joy while standing on an arc with a 4 m radius and an inter-subject spacing of 0.5-3 m. The effects of singers' masks, distance, group age, and relative position on the timing of articulation and fundamental frequency were investigated, along with the amount, rate, and sign of pitch drift and loudness. The ANOCOVA results showed that onsets were robust to the tested factors, while errors in fundamental frequency tended to decrease with increasing age/experience. Loudness was affected by distance, mask, and relative position, with increasing loudness as spacing decreased. Understanding influencing factors can inform recommendations for choral singing and education.

Articulatory and Phonatory Precision When Singing Staccato at Different Speeds.

INTRODUCTION: Vocal tract adjustments are important for resonatory modification of the voice and also with respect to interactions concerning the voice source production. It is not clear, however, how fast, separated notes (staccato) influence vocal tract adjustments. MATERIAL AND METHODS: Twelve professional singers (four sopranos, three mezzo-sopranos, three tenors, and two baritones/basses) were recorded with dynamic real-time 2D-magnetic resonance imaging (MRI) with 25 fps singing a scale in legato and different staccato speeds (60, 120, 180, and 240 bps). From the MRI material, the lip opening, jaw opening, jaw protrusion, tongue position, pharynx width, and larynx position were measured. Furthermore, the fundamental frequency was analyzed from the simultaneously recorded audio signal after noise cancellation. RESULTS: The data show only very small differences between the legato and the staccato tasks and no great variations for different staccato speeds. During the pauses in between the staccato notes, minimal vocal tract adjustments were only detectable for the slowest staccato task. CONCLUSION: There are no great differences in the vocal tract shapes for legato singing in contrast to staccato phonation and no great differences for different staccato speeds.

Boys Choirs in the Pandemic: Exploring Qualitative Aspects of Safety Measures.

INTRODUCTION: During the Covid-19 pandemic, choirs had to apply safety measures such as distances and wearing masks. For children's choirs, there is no knowledge of their reaction to these measures, regarding their age and experience. This study aimed to investigate boys choir singers' perceptions of the measures, regarding wellbeing and feasibility, as well as the quality of the performance outcomes. METHODS: Six groups were put together, assembling five singers of the same age (7-16 years, before voice change) and experience level. The boys sang one verse of the same song at inter-subject distances of 3, 1.5, 0.5, 0.5 m plus wearing a mask and again 3 m. Afterward they filled out questionnaires concerning difficulty, irritation, hearing themselves and their neighbors, and if they could imagine singing regularly in the respective setting. Fifteen parents were asked to fill out questionnaires about their opinions about choir safety measures during the pandemic. Six anonymous boys choir experts rated the randomized recordings of all tasks regarding homogenous sound quality, rhythmical precision, and uniform intonation. RESULTS: Even though most of the children preferred smaller distances, they were open to all kinds of settings. The answers given were very specific to the individuals. Masks were voted out by a majority of the subjects. Parents found choir singing very important for their children and did in majority neither fear infection of their children, nor mind precautions. The experts rated the performance outcomes of the largest distance (3 m) as best in most of the cases. CONCLUSION: Different interspatial settings do not harm the children and adolescents and could be introduced as a beneficial approach to give them a broader listening experience and to make them flexible, alert, adaptable, and resilient singers. Singers' masks are only recommended for compelling circumstances.

Sources of Aerosol Dispersion During Singing and Potential Safety Procedures for Singers.

INTRODUCTION: With respect to the Covid-19 pandemic, singing is assumed to be associated with a high potential person-to-person transmission. However, it remains unclear how the impulse dispersion varies with different types of articulation, intensity levels of diction, or body position. Furthermore, it has not been understood in detail how to prevent aerosol dispersion during singing. MATERIAL AND METHODS: Single professional singers from the Bavarian Radio Chorus were asked to sing in different head positions, with different articulation patterns and different masks after inhaling the basic liquid of an e-cigarette. The vapor cloud was segmented and tracked over time. RESULTS: Consonants and exaggeration of diction enhanced the distance reached by the impulse dispersion. Furthermore, the greatest dispersion was reached for a neutral head position. All protection masks stopped the initial jet of the aerosols but the FFP2 masks were the most effective. CONCLUSION: Some protection equipment has been identified to be promising in reducing aerosol dispersion. However, systematic effects have to be evaluated in greater collectives.

Influence of Loudness on Vocal Stability in the Male Passaggio.

INTRODUCTION: Vocal registers and the frequency region where registration events occur, the passaggio, have been in focus of scientific research for almost 200 years. In professional tenors, it has been shown before that singing across the passaggio avoiding a register shift and therefore using their stage voice above the passaggio (SVaP) is associated with greater vocal stability than a register change to the falsetto. However, it is unclarified how much different loudness conditions contribute to this vocal stability. MATERIAL AND METHODS: Six professional tenors were asked to perform four pitch glides from A3 to A4 (220-440 Hz) on the vowel [i:]. These glides included (1) the passaggio from modal register to falsetto. The following glides into SVaP were performed under different loudness conditions, (2) mezzoforte (average loudness), (3) pianissimo (as quietly as possible), and (4) fortissimo (the loudest possible). During phonation, high speed videoendoscopy (HSV), electroglottography, and audio signals were recorded simultaneously. The glottal area waveform was derived based on the HSV material. RESULTS: Modal to falsetto transitions were associated with relatively low sound pressure level and rise of open quotients (OQ) for the falsetto. Transitions to SVaP showed a clear dependence on the intended loudness. The OQs were lower the louder the task was. There was no clear evidence that transitions with softer voice showed greater stability of vocal fold oscillation patterns than louder tasks. CONCLUSIONS: The vocal fold oscillation pattern show- differences among various loudness conditions within the tenors' passaggio but no clear differences with regard to oscillatory stability.

Impulse dispersion of aerosols during playing the recorder and evaluation of safety measures.

INTRODUCTION: Group musical activities using wind instruments have been restricted during the CoVID19 pandemic due to suspected higher risk of virus transmission. It was presumed that the aerosols exhaled through the tubes while playing would be ejected over larger distances and spread into the room due to jet stream effects. In particular, the soprano recorder is widely used as an instrument in school classes, for beginners of all age groups in their musical education, in the context of leisure activities and in professional concert performances. Understanding the aerosol impulse dispersion characteristics of playing the soprano recorder could assist with the establishment of concepts for safe music-making. METHODS: Five adult professionally trained soprano recorder players (4 female, 1 male) played four bars of the main theme of L. van Beethoven's "Ode to Joy" in low and in high octaves, as well as with 3 different potential protection devices in the high octave. For comparison they spoke the corresponding text by F. Schiller. Before each task, they inhaled .5 L of vapor from an e-cigarette filled with base liquid. The vapor cloud escaping during speaking or playing was recorded by cameras and its spread was measured as a function of time in the three spatial dimensions. The potential safety devices were rated for practicability with a questionnaire, and their influence on the sound was compared, generating a long-term average spectrum from the audio data. RESULTS: When playing in the high octave, at the end of the task the clouds showed a median distance of 1.06 m to the front and .57 m diameter laterally (maxima: x: 1.35 m and y: .97 m). It was found that the clouds' expansion values in playing the recorder with and without safety measures are mostly lower when compared to the ordinary, raised speaking voice of the same subjects. The safety devices which covered the instrument did not show clear advantages and were rated as unpractical by the subjects. The most effective reduction of the cloud was reached when playing into a suction funnel. CONCLUSION: The aerosol dispersion characteristics of soprano recorders seem comparable to clarinets. The tested safety devices which covered holes of the instrument did not show clear benefits.

The Effect of Water Resistance Therapy on the Impulse Dispersion of Aerosols During Sustained Phonation.

INTRODUCTION: Group singing has been associated with higher transmission risks via exhaled and spread aerosols in the CoVID19 pandemic. For this reason, many musical activities, such as rehearsals and lessons, but also voice therapy sessions, have been restricted in many countries. Consequently, transmission risks and pathways have been studied, such as aerosol amounts generated by exhalation tasks, convectional flows in rooms, or the impulse dispersion of different kinds of phonation. The use of water resistance exercises such as those utilizing LAX VOX®, are common in voice lessons and as vocal warm-ups. With this context, this study investigates the impulse dispersion characteristics of aerosols during a voiced water resistance exercise in comparison to normal singing. METHODS: Twelve professional singers (six male, six female) were asked to phonate a stable pitch through a silicone tube into a bottle filled with water, holding the end of the tube 5 cm below the surface. Before performing the tasks, the singers inhaled the vapor consisting of 0.5 L base liquid from an e-cigarette. The exhaled gas cloud coming out of the bottle was recorded in all three spatial directions and the dispersion was measured as a function of time. RESULTS: At the end of the phonation task, the median distance to the front was 0.55 m and the median of the lateral expansion of the cloud was 0.89 m, the maximum to the front reached 0.88 m, and the maximum of lateral expansion 1.05 m. For the upwards direction of the clouds a median of 1.00 m and a maximum of 1.34 m from the mouth were measured. Three seconds after the end of the task, the medians were declining. CONCLUSION: The exhaled aerosol cloud can expand despite the obstacle of the water when using LAX VOX® during phonation.

Impulse dispersion of aerosols during playing wind instruments.

Musical activities, especially singing and playing wind instruments, have been singled out as potentially high-risk activities for the transmission of SARS CoV-2, due to a higher rate of aerosol production and emission. Playing wind instruments can produce condensation, droplets of saliva, and aerosol particles, which hover and spread in the environmental air's convectional flows and which can be potentially infectious. The aim of this study is to investigate the primary impulse dispersion of aerosols that takes place during the playing of different wind instruments as compared to breathing and to speaking. Nine professional musicians (3 trumpeters, 3 flautists and 3 clarinetists) from the Bavarian Symphony Orchestra performed the main theme from the 4th movement of Ludwig van Beethoven's 9th symphony in different pitches and loudness. The inhaled air volume was marked with small aerosol particles produced using a commercial e-cigarette. The expelled aerosol cloud was recorded by cameras from different perspectives. Afterwards, the dimensions and dynamics of the aerosol cloud were measured by segmenting the video footage at every time point. Overall, the flutes produced the largest dispersion at the end of the task, reaching maximum forward distances of 1.88 m. An expulsion of aerosol was observed in different directions: upwards and downwards at the mouthpiece, at the end of the instrument, and along the flute at the key plane. In comparison, the maximum impulse dispersions generated by the trumpets and clarinets were lower in frontal and lateral direction (1.2 m and 1.0 m towards the front, respectively). Also, the expulsion to the sides was lower.

Aerosol Dispersion During Different Phonatory Tasks in Amateur Singers.

INTRODUCTION: Due to increased aerosol generation during singing, choir rehearsals were widely prohibited in the course of the CoVID-19 pandemic. Most studies on aerosol generation and dispersion focus on professional singers. However, it has not been clarified if these data are also representative for amateur singers. METHODS: Nine non-professional singers (four male, five female) were asked to perform five tasks; speaking (T+), singing a text softly (MT-) and loudly (MT+), singing on the vowel [ə] (M+) and singing with a N95 mask (MT+N95). Before performing the tasks, the singers were asked to inhale 0.5 L vapor produced by an e-cigarette consisting of the basic liquid. The spread of the exhaled vapor was recorded in all three dimensions by high-definition cameras and the impulse dispersion was detected as a function of time. RESULTS: Regarding the median dispersion to the front, all tasks showed comparable distances from 0.69 m to 0.82 m at the end of the tasks. However, the maximum aerosol dispersion showed a larger variety among different subjects or tasks, respectively. Especially in the M+ task a maximum distance of 1.96 m to the front was reached by a single subject. Although singing with a N95 mask resulted in a slightly increased median dispersion to the front, the maximum dispersion was decreased from 1.47 m (MT+) to 1.04 m (MT+N95). CONCLUSION: The maximum dispersion distance to the front of 1.96 m at the end of the M+ task and 1.47 m at the end of the MT+ task showed higher values in comparison to professional singers. Differences in phonation, articulation and mouth opening could lead to greater impulse dispersion. Singing in loud phonation with a N95 mask reduced the maximum impulse dispersion to the front to 1.04 m. Taking all results into consideration, a slightly larger safety distance should be necessary for non-professional singers.

The Effect of Singers' Masks on the Impulse Dispersion of Aerosols During Singing.

BACKGROUND: During the Covid-19 pandemic, singing activities were restricted due to several super-spreading events that have been observed during rehearsals and vocal performances. However, it has not been clarified how the aerosol dispersion, which has been assumed to be the leading transmission factor, could be reduced by masks which are specially designed for singers. MATERIAL AND METHODS: Twelve professional singers (10 of the Bavarian Radio-Chorus and two freelancers, seven females and five males) were asked to sing the melody of the ode of joy of Beethoven's 9th symphony "Freude schöner Götterfunken, Tochter aus Elisium" in D-major without masks and afterwards with five different singers' masks, all distinctive in their material and proportions. Every task was conducted after inhaling the basic liquid from an e-cigarette. The aerosol dispersion was recorded by three high-definition video cameras during and after the task. The cloud was segmented and the dispersion was analyzed for all three spatial dimensions. Further, the subjects were asked to rate the practicability of wearing the tested masks during singing activities using a questionnaire. RESULTS: Concerning the median distances of dispersion, all masks were able to decrease the impulse dispersion of the aerosols to the front. In contrast, the dispersion to the sides and to the top was increased. The evaluation revealed that most of the subjects would reject performing a concert with any of the masks. CONCLUSION: Although, the results exhibit that the tested masks could be able to reduce the radius of aerosol expulsion for virus-laden aerosol particles, there are more improvements necessary to enable the practical implementations for professional singing.

Are source-filter interactions detectable in classical singing during vowel glides?

In recent studies, it has been assumed that vocal tract formants (Fn) and the voice source could interact. However, there are only few studies analyzing this assumption in vivo. Here, the vowel transition /i/-/a/-/u/-/i/ of 12 professional classical singers (6 females, 6 males) when phonating on the pitch D4 [fundamental frequency (ƒo) ca. 294 Hz] were analyzed using transnasal high speed videoendoscopy (20.000 fps), electroglottography (EGG), and audio recordings. Fn data were calculated using a cepstral method. Source-filter interaction candidates (SFICs) were determined by (a) algorithmic detection of major intersections of Fn/nƒo and (b) perceptual assessment of the EGG signal. Although the open quotient showed some increase for the /i-a/ and /u-i/ transitions, there were no clear effects at the expected Fn/nƒo intersections. In contrast, ƒo adjustments and changes in the phonovibrogram occurred at perceptually derived SFICs, suggesting level-two interactions. In some cases, these were constituted by intersections between higher nƒo and Fn. The presented data partially corroborates that vowel transitions may result in level-two interactions also in professional singers. However, the lack of systematically detectable effects suggests either the absence of a strong interaction or existence of confounding factors, which may potentially counterbalance the level-two-interactions.

Duration of biodynamic changes associated with water resistance therapy.

INTRODUCTION: In current voice research, there is a growing interest in semi-occluded vocal tract exercises and their contribution to an increased vocal efficiency. However, there are only few studies on the lasting effects. MATERIAL AND METHODS: Eight vocally healthy subjects were asked to sustain a phonation at a comfortable loudness on the vowel /i/, with a Fundamental Frequency of 250 Hz (females) or 125 Hz (males). During phonation the subjects were simultaneously recorded with transnasal High Speed Videoendoscopy (HSV, 20,000fps), electroglottography, and audio signals. The subjects then performed a water resistance therapy (WRT) for 10 min (tube: 30 cm length, 5 cm below water surface, diameter 9 mm). Repeated measurements of sustained phonation were performed 0, 5, 10, 20, and 30 min after exercising. From the HSV material the Glottal Area Waveform (GAW) was segmented and GAW parameters were computed. RESULTS: There were strong inter-individual differences concerning the changes of different measures over time after WRT. In general, directly after WRT there was a lowering of the GAW derived Period Perturbation Quotient, a lowering of the Closing Quotient and an increase of the Sound Pressure Level (SPL) in comparison to the pre-intervention measurement. However, only 5 min post WRT there was no longer a clear difference compared to baseline results before WRT. Other values such as Open Quotients exhibited no evident changes by WRT at any timepoint. CONCLUSIONS: WRT showed strong inter-individual effects concerning the changes in the evaluated measures post-intervention. General tendencies of some measures directly after the intervention showed a brief effect of only a few minutes.

The Effect of Nasalance on Vocal Fold Oscillation Patterns During the Male Passaggio.

INTRODUCTION: It is generally assumed that when singing across the region where registration events for untrained voices occur (the passaggio), singers modify the voice production system in order to avoid changes of voice quality. In this context, it has been postulated that nasalance could be used to stabilize vocal function throughout the passaggio. However, whether nasalance is frequently used by professional singers and if so, if it has a stabilizing effect on vocal fold oscillation patterns, is not yet fully understood. MATERIAL AND METHODS: Eight western classically trained professional male singers (6 tenors and 2 baritones) were asked to perform transitions (1) from modal to falsetto register and (2) from modal to stage voice above the passaggio (SVaP) during ascending pitch glides from A3 (ƒo approx. 220 Hz) to A4 (ƒo approx. 440 Hz) on the vowel /i/. Transnasal high-speed videoendoscopy at 20.000 fps was captured simultaneously with electroglottographic, nasal and oral flow, and audio signals, recorded using the same frame rate. The nasalance was calculated from both oral and nasal DC-flow signals. RESULTS: Transitions to SVaP showed greater periodicity and regularity than transitions to falsetto. For 5 subjects, nasalance was increased during the passaggio for the transition to SVaP. For 4 subjects the increase of nasalance for the SVaP was associated with a stabilization of the open quotient and occurred at a comparable fundamental frequency as the increase of the open quotient for the transition to falsetto. CONCLUSIONS: Nasalance can be used in order to stabilize oscillatory regularity and open quotient in male singers for singing across the passaggio.

Investigation of resonance strategies of high pitch singing sopranos using dynamic three-dimensional magnetic resonance imaging.

Resonance-strategies with respect to vocal registers, i.e., frequency-ranges of uniform, demarcated voice quality, for the highest part of the female voice are still not completely understood. The first and second vocal tract resonances usually determine vowels. If the fundamental frequency exceeds the vowel-shaping resonance frequencies of speech, vocal tract resonances are tuned to voice source partials. It has not yet been clarified if such tuning is applicable for the entire voice-range, particularly for the top pitches. We investigated professional sopranos who regularly sing pitches above C6 (1047 Hz). Dynamic three-dimensional (3D) magnetic resonance imaging was used to calculate resonances for pitches from C5 (523 Hz) to C7 (2093 Hz) with different vowel configurations ([a:], [i:], [u:]), and different contexts (scales or octave jumps). A spectral analysis and an acoustic analysis of 3D-printed vocal tract models were conducted. The results suggest that there is no exclusive register-defining resonance-strategy. The intersection of fundamental frequency and first vocal tract resonance was not found to necessarily indicate a register shift. The articulators and the vocal tract resonances were either kept without significant adjustments, or the fR1:fo-tuning, wherein the first vocal tract resonance enhances the fundamental frequency, was applied until F6 (1396 Hz). An fR2:fo-tuning was not observed.

Vocal fold oscillation pattern changes related to loudness in patients with vocal fold mass lesions.

INTRODUCTION: Vocal fold mass lesions can affect vocal fold oscillation patterns and therefore voice production. It has been previously observed that perturbation values from audio signals were lower with increased loudness. However, how much the oscillation patterns change with gradual alteration of loudness is not yet fully understood. MATERIAL AND METHODS: Eight patients with vocal fold mass lesions were asked to perform a glide from minimum to maximum loudness on the vowel /i/, ƒo of 125 Hz for male or 250 Hz for female voices. During phonation the subjects were simultaneously recorded with transnasal high speed videoendoscopy (HSV, 20,000 fps), electroglottography (EGG), and an audio recording. Based on the HSV material the Glottal Area Waveform (GAW) was segmented and GAW parameters were computed. RESULTS: The greatest vocal fold irregularities were observed at different values between minimum and maximum sound pressure level. There was a relevant discrepancy between the HSV and EGG derived open quotients. Furthermore, the EGG derived sample entropy and GAW values also evidenced different behavior. CONCLUSIONS: The amount of vocal fold irregularity changes with varying loudness. Therefore, any evaluation of the voice should be performed under different loudness conditions. The discrepancy between EGG and GAW values appears to be much stronger in patients with vocal fold mass lesions than those with normal physiological conditions. LEVEL OF EVIDENCE: 4.

Immediate effects of water resistance therapy on patients with vocal fold mass lesions.

INTRODUCTION: Semi-occluded vocal tract exercises, such as water resistance therapy (WRT), are widely used in voice therapy. However, the potential positive effects of such a therapy on vocal fold oscillation patterns in patients indicating a need for phonomicrosurgery have not yet been explored. The presented study aims to analyze the effect of WRT in patients suffering from vocal fold mass lesions. MATERIALS AND METHODS: Eight participants with vocal fold mass lesions were asked to sustain a phonation on the vowel /i/ at a comfortable loudness and a fundamental frequency of 250 Hz (females) or 125 Hz (males). During phonation the subjects were simultaneously recorded with transnasal high-speed videoendoscopy (HSV, 20.000 fps), electroglottography, and audio signals. These subjects then performed a WRT (phonation in a silicone tube of 30 cm length, 5 cm below the water surface) for 10 min. Repeated measurements of sustained phonation were performed 0, 10, and 30 min after exercising. From the HSV data the glottal area waveform (GAW) was segmented and GAW parameters were computed. RESULTS: During WRT there was an increase of the GAW related open quotient and closing quotient. Immediately after WRT, there was a drop of both values followed by a rise of these parameters up to 30 min after the intervention. Furthermore, there was no correlation between GAW and electroglottographical open quotients. CONCLUSIONS: The effects observed after a single session of WRT on participants with vocal fold mass lesions showed a similar pattern to vocal fatigue.

A comparison of electroglottographic and glottal area waveforms for phonation type differentiation in male professional singers.

This study compares the use of electroglottograms (EGGs) and glottal area waveforms (GAWs) to study phonation in different vibratory states as produced by professionally trained singers. Six western classical tenors were asked to phonate pitch glides from modal to falsetto phonation, or from modal to their stage voice above the passaggio (SVaP). For each pitch glide the sample entropy (SampEn) of the EGG signal was calculated to detect the occurrence of phonatory instabilities and establish a "ground truth" for the performed phonation type. The cycles before the maximum SampEn were labeled as modal, and the cycles after the peak were labeled as either falsetto, or SVaP. Three automatic categorizations of vibratory state were performed using clustering: one based only on the EGG, one based on the GAW, and one based on their combination. The error rate (clustering vs ground truth) was, on average, lower than 10% for all of the three settings, revealing no special advantage of the GAW over EGG, and vice versa. Modal voice cycles exhibited a larger contact quotient, larger normalized derivative peak ratio, and lower rise time, compared to SVaP and falsetto. The GAW-based normalized maximum area declination rate was larger in SVaP compared to modal voice.