Glottal Adduction and Subglottal Pressure in Singing

CPPS and Voice-Source Parameters: Objective Analysis of the Singing Voice

INTRODUCTION

In recent years cepstral analysis and specific cepstrum-based measures such as smoothed cepstral peak prominence (CPPS) has become increasingly researched and utilized in attempts to determine the extent of overall dysphonia in voice signals. Yet, few studies have extensively examined how specific voice-source parameters affect CPPS values.

OBJECTIVE

Using a range of synthesized tones, this exploratory study sought to systematically analyze the effect of fundamental frequency (fo), vibrato extent, source-spectrum tilt, and the amplitude of the voice-source fundamental on CPPS values.

MATERIALS AND METHODS

A series of scales were synthesised using the freeware Madde. Fundamental frequency, vibrato extent, source-spectrum tilt, and the amplitude of the voice-source fundamental were systematically and independently varied. The tones were analysed in PRAAT, and statistical analyses were conducted in SPSS.

RESULTS

CPPS was significantly affected by both fo and source-spectrum tilt, independently. A nonlinear association was seen between vibrato extent and CPPS, where CPPS values increased from 0 to 0.6 semitones (ST), then rapidly decreased approaching 1.0 ST. No relationship was seen between the amplitude of the voice-source fundamental and CPPS.

CONCLUSION

The large effect of fo should be taken into account when analyzing the voice, particularly in singing-voice research, when comparing pre and posttreatment data, and when comparing inter-subject CPPS data.

Aerodynamic Parameters in Byzantine Chant Voices: Comparisons Across Pitch and Loudness

OBJECTIVE

This study was designed to assess the impact of phonation frequency and loudness increase on aerodynamic parameters of the singing voice in Byzantine chant (BC).

DESIGN

Aerodynamic measurements in BC were obtained and statistically analyzed.

METHOD

Fifteen experienced BC chanters, all baritones, performed the ascending notes G2, C3, E3, G3, C4, E4, and G4, at normal and high levels of loudness within a mask, while repeating strings of /pi/ syllables. The parameters of airflow (FR), subglottal pressure (Psub), and sound pressure level (SPL) were directly measured, and from them, the glottal flow resistance (Rg) and vocal efficiency (VE) were calculated. All the parameters' values were statistically analyzed.

RESULTS

Statistically significant differences for FR, Psub, and SPL parameters in BC between the two loudness levels, at constant pitch, and for Psub, SPL, Rg, and VE among different pitches, at constant loudness levels were detected. When loudness increases, a) only the mean values of FR, Psub, and SPL, within C3-C4, increase, whereas those of Rg and VE do not show any change, and b) at G2, only the mean Psub increases, while in the upper range E4-G4, both mean SPL and mean VE decrease. When pitch is raised, a) for each level of loudness, within G2-E4 pitch range, the means of Psub, SPL, Rg, and VE increase while this is not the case for FR, and b) in the highest range (E4-G4), average SPL and VE drop while Rg and Psub remain stable. Our findings suggest that: a) most participants increase Psub and SPL without modification of Rg when loudness increases, and b) most participants increase both SPL and Psub while changing Rg with pitch rise. Idiosyncratic differences among the participants were detected in Rg and Psub, because of pitch rise, and, also, in Rg and VE due to loudness increase.

CONCLUSIONS

The results from this study reveal that, within the C3-C4 pitch range: a) there is independent control between the loudness and glottal adduction, and b) Psub is the main tool for increasing both the loudness and SPL. For some exceptions among the participants, either the Rg alteration or other modifications of the vocal system are, possibly, the cause of the loudness increase. The increased mean values of SPL, Rg, and Psub with pitch rise, for most participants, suggest that both glottal adduction and Psub increase together with the SPL and pitch increase. The VE increase within G2-E4 pitches reaches a maximum value at E4. Some exceptions among the participants exist that suggest the possible use of different phonatory strategies when changing either the pitch or the vocal loudness.

Dynamic changes of vocal tract dimensions with sound pressure level during messa di vocea)

The messa di voce (MdV), which consists of a continuous crescendo and subsequent decrescendo on one pitch is one of the more difficult exercises of the technical repertoire of Western classical singing. With rising lung pressure, regulatory adjustments both on the level of the glottis and the vocal tract are required to keep the pitch stable. The dynamic changes of vocal tract dimensions with the bidirectional variation of sound pressure level (SPL) during MdV were analyzed by two-dimensional real-time magnetic resonance imaging (25 frames/s) and synchronous audio recordings in 12 professional singer subjects. Close associations in the respective articulatory kinetics were found between SPL and lip opening, jaw opening, pharynx width, uvula elevation, and vertical larynx position. However, changes in vocal tract dimensions during plateaus of SPL suggest that perceived loudness could have been varied beyond the dimension of SPL. Further multimodal investigation, including the analysis of sound spectra, is needed for a better understanding of the role of vocal tract resonances in the control of vocal loudness in human phonation.

High and Wide: An In Silico Investigation of Frequency, Intensity, and Vibrato Effects on Widely Applied Acoustic Voice Perturbation and Noise Measures

OBJECTIVES

This in silico study explored the effects of a wide range of fundamental frequency (fo), source-spectrum tilt (SST), and vibrato extent (VE) on commonly used frequency and amplitude perturbation and noise measures.

METHOD

Using 53 synthesized tones produced in Madde, the effects of stepwise increases in fo, intensity (modeled by decreasing SST), and VE on the PRAAT parameters jitter % (local), relative average perturbation (RAP) %, shimmer % (local), amplitude perturbation quotient 3 (APQ3) %, and harmonics-to-noise ratio (HNR) dB were investigated. A secondary experiment was conducted to determine whether any fo effects on jitter, RAP, shimmer, APQ3, and HNR were stable. A total of 10 sinewaves were synthesized in Sopran from 100 to 1000 Hz using formant frequencies for /a/, /i/, and /u/-like vowels, respectively. All effects were statistically assessed with Kendall's tau-b and partial correlation.

RESULTS

Increasing fo resulted in an overall increase in jitter, RAP, shimmer, and APQ3 values, respectively (P < 0.01). Oscillations of the data across the explored fo range were observed in all measurement outputs. In the Sopran tests, the oscillatory pattern seen in the Madde fo condition remained and showed differences between vowel conditions. Increasing intensity (decreasing SST) led to reduced pitch and amplitude perturbation and HNR (P < 0.05). Increasing VE led to lower HNR and an almost linear increase of all other measures (P < 0.05).

CONCLUSION

These novel data offer a controlled demonstration for the behavior of jitter (local) %, RAP %, shimmer (local) %, APQ3 %, and HNR (dB) when varying fo, SST, and VE in synthesized tones. Since humans will vary in all of these aspects in spoken language and vowel phonation, researchers should take potential resonance-harmonics type effects into account when comparing intersubject or preintervention and postintervention data using these measures.

It Sounds like It Feels: Preliminary Exploration of an Aeroacoustic Diagnostic Protocol for Singers

To date, no established protocol exists for measuring functional voice changes in singers with subclinical singing-voice complaints. Hence, these may go undiagnosed until they progress into greater severity. This exploratory study sought to (1) determine which scale items in the self-perceptual Evaluation of Ability to Sing Easily (EASE) are associated with instrumental voice measures, and (2) construct as proof-of-concept an instrumental index related to singers' perceptions of their vocal function and health status. Eighteen classical singers were acoustically recorded in a controlled environment singing an /a/ vowel using soft phonation. Aerodynamic data were collected during a softly sung /papapapapapapa/ task with the KayPENTAX Phonatory Aerodynamic System. Using multi and univariate linear regression techniques, CPPS, vibrato jitter, vibrato shimmer, and an efficiency ratio (SPL/PSub) were included in a significant model (p < 0.001) explaining 62.4% of variance in participants' composite scores of three scale items related to vocal fatigue. The instrumental index showed a significant association (p = 0.001) with the EASE vocal fatigue subscale overall. Findings illustrate that an aeroacoustic instrumental index may be useful for monitoring functional changes in the singing voice as part of a multidimensional diagnostic approach to preventative and rehabilitative voice healthcare for professional singing-voice users.

Differences Among Mixed, Chest, and Falsetto Registers: A Multiparametric Study

INTRODUCTION

Typical singing registers are the chest and falsetto; however, trained singers have an additional register, namely, the mixed register. The mixed register, which is also called "mixed voice" or "mix," is an important technique for singers, as it can help bridge from the chest voice to falsetto without noticeable voice breaks.

OBJECTIVE

The present study aims to reveal the nature of the voice-production mechanism of the different registers (chest, mix, and falsetto) using high-speed digital imaging (HSDI), electroglottography (EGG), and acoustic and aerodynamic measurements.

STUDY DESIGN

Cross-sectional study.

METHODS

Aerodynamic measurements were acquired for twelve healthy singers (six men and women) during the phonation of a variety of pitches using three registers. HSDI and EGG devices were simultaneously used on three healthy singers (two men and one woman) from which an open quotient (OQ) and speed quotient (SQ) were detected. Audio signals were recorded for five sustained vowels, and a spectral analysis was conducted to determine the amplitude of each harmonic component. Furthermore, the absolute (not relative) value of the glottal volume flow was estimated by integrating data obtained from the HSDI and aerodynamic studies.

RESULTS

For all singers, the subglottal pressure (P_Sub) was the highest for the chest in the three registers, and the mean flow rate (MFR) was the highest for the falsetto. Conversely, the P_Sub of the mix was as low as the falsetto, and the MFR of the mix was as low as the chest. The HSDI analysis showed that the OQ differed significantly among the registers, even when the fundamental frequency was the same; the OQ of the mix was higher than that of the chest but lower than that of the falsetto. The acoustic analysis showed that, for the mix, the harmonic structure was intermediate between the chest and falsetto. The results of the glottal volume-flow analysis revealed that the maximum volume velocity was the least for the mix register at every fundamental frequency. The first and second harmonic (H1-H2) difference of the voice source spectrum was the greatest for the falsetto, then the mix, and finally, the chest.

CONCLUSIONS

We found differences in the registers in terms of the aeromechanical mechanisms and vibration patterns of the vocal folds. The mixed register proved to have a distinct voice-production mechanism, which can be differentiated from those of the chest or falsetto registers.

Simulation of Vocal Loudness Regulation with Lung Pressure, Vocal Fold Adduction, and Source-Airway Interaction

In speaking, shouting, and singing, vocal loudness is known to be regulated with lung pressure, but the degree to which vocal fold adduction and airway shape play a role in loudness control is less well known. When loudness is quantified in sones instead of sound pressure level (SPL), the regulatory mechanisms are even less obvious. Here it is shown computationally that loudness is insensitive to changes in SPL produced with variable adduction. A trade-off exists between a reduction in glottal flow amplitude and a flatter spectral slope. When the airway configuration is changed from a uniform tube to a "belt" or "call" shape, loudness can increase with a slight decrease in SPL. When the airway configuration is changed from a uniform tube to an operatic "ring" shape, loudness is increased with only a small increase in SPL.

Female adolescent singing voice characteristics: an exploratory study using LTAS and inverse filtering

Background and Aim: To date, little research is available that objectively quantifies female adolescent singing-voice characteristics in light of the physiological and functional developments that occur from puberty to adulthood. This exploratory study sought to augment the pool of data available that offers objective voice analysis of female singers in late adolescence.Methods: Using long-term average spectra (LTAS) and inverse filtering techniques, dynamic range and voice-source characteristics were determined in a cohort of vocally healthy cis-gender female adolescent singers (17 to 19 years) from high-school choirs in Aotearoa New Zealand. Non-parametric statistics were used to determine associations and significant differences.Results: Wide intersubject variation was seen between dynamic range, spectral measures of harmonic organisation (formant cluster prominence, FCP), noise components in the spectrum (high-frequency energy ratio, HFER), and the normalised amplitude quotient (NAQ) suggesting great variability in ability to control phonatory mechanisms such as subglottal pressure (Psub), glottal configuration and adduction, and vocal tract shaping. A strong association between the HFER and NAQ suggest that these non-invasive measures may offer complimentary insights into vocal function, specifically with regard to glottal adduction and turbulent noise in the voice signal.Conclusion: Knowledge of the range of variation within healthy adolescent singers is necessary for the development of effective and inclusive pedagogical practices, and for vocal-health professionals working with singers of this age. LTAS and inverse filtering are useful non-invasive tools for determining such characteristics.

Collision Pressure and Dissipated Power Dose in a Self-Oscillating Silicone Vocal Fold Model With a Posterior Glottal Opening

PURPOSE

The goal of this study was to experimentally evaluate how compensating for the adverse acoustic effects of a posterior glottal opening (PGO) by increasing subglottal pressure and changing supraglottal compression, as have been associated with vocal hyperfunction, influences the risk of vocal fold (VF) trauma.

METHOD

A self-oscillating synthetic silicone model of the VFs with an airflow bypass that modeled a PGO was investigated in a hemilaryngeal flow facility. The influence of compensatory mechanisms on collision pressure and dissipated collision power was investigated for different PGO areas and supraglottal compression. Compensatory behaviors were mimicked by increasing the subglottal pressure to achieve a target sound pressure level (SPL).

RESULTS

Increasing the subglottal pressure to compensate for decreased SPL due to a PGO produced higher values for both collision pressure and dissipated collision power. Whereas a 10-mm² PGO area produced a 12% increase in the peak collision pressure, the dissipated collision power increased by 122%, mainly due to an increase in the magnitude of the collision velocity. This suggests that the value of peak collision pressure may not fully capture the mechanisms by which phonotrauma occurs. It was also found that an optimal value of supraglottal compression exists that maximizes the radiated SPL, indicating the potential utility of supraglottal compression as a compensatory mechanism.

CONCLUSIONS

Larger PGO areas are expected to increase the risk of phonotrauma due to the concomitant increase in dissipated collision power associated with maintaining SPL. Furthermore, the risk of VF damage may not be fully characterized by only the peak collision pressure.

PHARYNGEAL, UPPER ESOPHAGEAL SPHINCTERIC AND ESOPHAGEAL PRESSURES RESPONSES RELATED TO VOCAL TASKS AT THE LIGHT OF HIGH RESOLUTION MANOMETRY

BACKGROUND

High-resolution manometry (HRM) represents a potential tool for measuring pharyngoesophageal phonation pressures.

OBJECTIVE

This study aims to evaluate pharyngeal, esophageal upper sphincteric and esophageal pressures during different phonation tasks.

METHODS

12 (six males, mean age 27 years) professional singers underwent HRM and produced four different vocal tasks at low, medium and high vocal loudness: vowel /ae/, ascending five note scale, word /hey/ and word /go/. Pressures were measured at pharynx, upper esophageal sphincter (UES) and esophagus. Visual analysis of the HRM topographic plots were performed.

RESULTS

Esophageal pressures are higher during vocalization than at rest. Pharyngeal and UES phonation pressures does not differ significantly from rest pressures. Visual analysis of the topographic plots showed an important UES pressure increasement during phonation.

CONCLUSION

HRM is a valuable tool for measuring pharyngoesophageal pressures during phonation. Esophageal pressures are higher during phonation than at rest and tend to increase with vocal loudness increment. The topographic plot provides additional data about phonatory mechanism physiology, especially at the UES region.

Regulation of laryngeal resistance and maximum power transfer with semi-occluded airway vocalization

Steady airflow resistances in semi-occluded airways as well as acoustic impedances in vocalization are quantified from the lungs to the lips. For clinical and voice training applications, the primary focus is on two airway conditions, an oral semi-occlusion and a semi-occlusion above the vocal folds. Laryngeal airflow resistance is divided into glottal airflow resistance and epilaryngeal airway resistance. Maximum aerodynamic power is transferred to the vocal tract if the glottal airflow resistance is reduced while the epilaryngeal airway resistance is increased. A semi-occlusion at the lips helps to set up this condition. For the acoustic power transfer, the epilaryngeal airway also serves to match the impedance of the source to the impedance of the vocal tract.

Laryngeal strategies to minimize vocal fold contact pressure and their effect on voice production

The goal of this study is to identify laryngeal strategies that minimize vocal fold contact pressure while producing a target sound pressure level (SPL) using a three-dimensional voice production model. The results show that while the subglottal pressure and transverse stiffness can be manipulated to reduce the peak contact pressure, such manipulations also reduce the SPL, and are thus less effective in reducing contact pressure in voice tasks targeting a specific SPL level. In contrast, changes in the initial glottal angle and vocal fold vertical thickness that reduce the contact pressure also increase the SPL. Thus, in voice tasks targeting a specific SPL, such changes in the initial glottal angle and vertical thickness also lower the subglottal pressure, which further reduces the peak contact pressure. Overall the results show that for voice tasks with a target SPL level, vocal fold contact pressure can be significantly reduced by adopting a barely abducted glottal configuration or reducing the vocal fold vertical thickness. Aerodynamic measures are effective in identifying voice production with large initial glottal angles, but by themselves alone are not useful in differentiating hyperadducted vocal folds from barely abducted vocal folds, which may be better differentiated by closed quotient and voice type measures.

Objective Characterization of Phonation Type Using Amplitude of Flow Glottogram Pulse and of Voice Source Fundamental

Phonation type, a phonatory dimension ranging from hypofunctional/breathy to hyperfunctional/pressed, is important both from a clinical and acoustical point of view; hyperfunctional voice can lead to voice disorders and hypofunctional voice reduces text intelligibility. Five male singers sang diminuendo sequences of the syllable /pae/ and three of them also produced speech or singing samples with different phonation types which were rated for phonatory pressedness by a panel of voice experts. The sequences were analyzed by inverse filtering and the associated subglottal pressures were estimated as the oral pressures during the /p/ occlusion. The results showed strong quasi-linear correlations between the peak-to-peak amplitude of the flow glottogram (henceforth pulse amplitude) and mean subglottal pressure, mean airflow, and the level difference between the first and second voice source partials L₁-L₂. These correlations were found to vary systematically with phonation type. Regardless of phonation type, the correlation between the pulse amplitude and the amplitude of the voice source fundamental frequency was very close to 1.0. The level difference between the first and second spectrum partials L₁-L₂ in narrow-band long-term-average spectra of speech and singing was found to vary systematically with phonation type in a manner related to voice experts' ratings of perceived degree of pressedness. The findings support the assumption that the combination of subglottal pressure and level of the voice source fundamental is useful for an objective measure of phonation type.

Laryngeal Image Processing of Vocal Folds Motion

This review provides a comprehensive compilation, from a digital image processing point of view of the most important techniques currently developed to characterize and quantify the vibration behaviour of the vocal folds, along with a detailed description of the laryngeal image modalities currently used in the clinic. The review presents an overview of the most significant glottal-gap segmentation and facilitative playbacks techniques used in the literature for the mentioned purpose, and shows the drawbacks and challenges that still remain unsolved to develop robust vocal folds vibration function analysis tools based on digital image processing.

Upper high notes: auditory-perceptual analysis of voice and self-reporting among professional sopranos

PURPOSE

To describe the emission of upper high notes by professional sopranos by means of the auditory-perceptual evaluation of the singers' voices and self-reports.

METHODS

Five professional sopranos performed an excerpt from a Bellini opera which involved the emission of an upper high note. The auditory-perceptual evaluation was carried out by three speech-language therapists and three singing teachers, who considered brightness, loudness, metal quality, vibrato, breathiness, and resonance on a visual-analytical scale, based on each singer's emission of high notes. After the recording, the singers were asked to answer a proprioceptive questionnaire on the physical sensations that they had as they emitted upper high notes. An inferential analysis of the data from the auditory-perceptual evaluation was conducted, and the singers' self-reports were summarized and then orthographically transcribed.

RESULTS

In the auditory-perceptual analysis, the emission of upper high notes was characterized according to the presence of brightness, loudness, metal quality, vibrato, and anterior resonance, as perceived by speech-language therapists and singing teachers. In the proprioceptive report, all singers reported laryngeal elevation and a need to use respiratory support in order to emit upper high notes.

CONCLUSION

Upper high notes are characterized by a bright vocal emission, enhanced loudness, with a metallic quality and vibrato, little or no breathiness, accompanied by a sensation of laryngeal elevation and a need for respiratory support.

Vocal Loudness Variation With Spectral Slope

Objective This investigation addresses the loudness variations in sones achievable with spectral slope variations (higher harmonic energy) in human vocalization and compares it to the sound pressure level (SPL) variations typically reported in the voice range profile (VRP). Method The primary methodology was computational. The ISO standard 226 was used to convert SPL values to sones for a 125- to 1000-Hz range of fundamental frequency and a -3 dB/octave to -12 dB/octave range of spectral slope. In addition, a retrospective analysis of human subjects' VRPs was conducted, and the experimental results were compared to the theoretical results. Results A very small range of SPL variation (less than 5 dB) in the VRP can produce a large range of loudness. The sensitivity can be on the order of 4 sones per dB SPL change. Conclusion For vocalization in the modal register, loudness variation is not well described by SPL change in dB, especially at high fundamental frequencies where the SPL range in the VRP becomes very small but sizeable loudness variations are still possible.

Assessing and Quantifying Air Added to the Voice by Means of Laryngostroboscopic Imaging, EGG, and Acoustics in Vocally Trained Subjects

OBJECTIVE

To assess and quantify singers' strategies for adding air to phonation to sound "breathy" in a healthy manner STUDY DESIGN: Case-control study with 20 professional singers.

METHODS

Twenty singers were recorded performing sustained vowels in the Complete Vocal Technique Neutral vocal mode with and without audible air added to the voice by means of laryngostroboscopic imaging using a videonasoendoscopic camera system, electroglottography, long-term average spectrum, as well as acoustic signals and audio perception. Singers completed Voice Handicap Index and Reflux Symptom Index questionnaires prior to examination.

RESULTS

Air added to the voice resulted in an expected glottal gap along the length of the vocal folds, with little to no further difference in the supraglottic area, as compared with the Neutral phonation. Air added resulted in lowered Qx, mean Sound Pressure Level, and Cepstral Peak Prominence, but higher Harmonics-to-Noise Ratio, Jitter, and Shimmer, with decreased energy at the fundamental frequency. Adding audible air to the phonation did not exhibit similar effects on acoustics for males and females. Also, for females, H1-H2 difference decreased with air added, while it increased for males.

CONCLUSION

Singers produce an audible airy phonation similar yet significantly different to the breathy phonation reported for both healthy and pathological speakers.

Voice Stress Analysis: A New Framework for Voice and Effort in Human Performance

People rely on speech for communication, both in a personal and professional context, and often under different conditions of physical, cognitive and/or emotional load. Since vocalization is entirely integrated within both our central (CNS) and autonomic nervous system (ANS), a mounting number of studies have examined the relationship between voice output and the impact of stress. In the current paper, we will outline the different stages of voice output, i.e., breathing, phonation and resonance in relation to a neurovisceral integrated perspective on stress and human performance. In reviewing the function of these three stages of voice output, we will give an overview of the voice parameters encountered in studies on voice stress analysis (VSA) and review the impact of the different types of physiological, cognitive and/or emotional load. In the section "Discussion," with regard to physical load, a competition for ventilation processes required to speak and those to meet metabolic demand of exercised muscles is described. With regard to cognitive and emotional load, we will present the "Model for Voice and Effort" (MoVE) that comprises the integration of ongoing top-down and bottom-up activity under different types of load and combined patterns of voice output. In the MoVE, it is proposed that the fundamental frequency (F0) values as well as jitter give insight in bottom-up/arousal activity and the effort a subject is capable to generate but that its range and variance are related to ongoing top-down processes and the amount of control a subject can maintain. Within the MoVE, a key-role is given to the anterior cingulate cortex (ACC) which is known to be involved in both the equilibration between bottom-up arousal and top-down regulation and vocal activity. Moreover, the connectivity between the ACC and the nervus vagus (NV) is underlined as an indication of the importance of respiration. Since respiration is the driving force of both stress and voice production, it is hypothesized to be the missing-link in our understanding of the underlying mechanisms of the dynamic between speech and stress.

The Role of the Pelvic Floor in Respiration: A Multidisciplinary Literature Review

OBJECTIVE

To conduct an interdisciplinary literature review on the function of the pelvic floor musculature during respiration and its role in phonation, particularly singing.

STUDY DESIGN

This is a literature review.

METHODS

A literature review was conducted using three electronic databases: PubMed, Scopus, and Google Scholar. An index search was also performed for the NATS Journal/Journal of Singing utilizing the keywords from the original search, as these articles did not appear in the original search. Peer-reviewed articles from 1985 to 2017 were gathered on the respiratory musculature and/or support mechanisms for phonation (anatomy and physiology). Articles that pertained to the muscular function of the respiratory system in breathing and/or phonation were utilized in the review. Eighty-five articles were included in this review.

RESULTS

Breathing and support strategies were variable and nonspecific in much of the singing voice literature. The voice science literature was a rich source of articles written about breathing and support for singing. Multiple studies looked at musculature utilized in respiration and breath support and subglottal pressure generation for muscular support. However, little or no mention was made specifically of the pelvic floor. The physical medicine literature includes the pelvic floor musculature as having an important role in respiration, as a key player in the generation of intra-abdominal pressure, and as a primary expiratory muscle.

CONCLUSIONS

The information gleaned from this literature review suggests that a cross-pollination between areas of science is needed, because quite obviously, the pelvic floor is a topic in physical medicine, but it is not (so much) in the voice literature. Reaching a consensus on how we describe the function of the respiratory musculature and specifically including the role of the pelvic floor in respiration and phonation deserves future attention. Further research looking specifically at the role of the pelvic floor in phonation is also warranted.

Quantifying syringeal dynamics in vitro using electroglottography

The complex and elaborate vocalizations uttered by many of the 10,000 extant bird species are considered a major driver in their evolutionary success, warranting study of the underlying mechanisms of vocal production. Additionally, birdsong has developed into a highly productive model system for vocal imitation learning and motor control, where, in contrast to humans, we have experimental access to the entire neuromechanical control loop. In human voice production, complex laryngeal geometry, vocal fold tissue properties, airflow and laryngeal musculature all interact to ultimately control vocal fold kinematics. Quantifying vocal fold kinematics is thus critical to understanding neuromechanical control of voiced sound production, but in vivo imaging of vocal fold kinematics in birds is experimentally challenging. Here, we adapted and tested electroglottography (EGG) as a novel tool for examining vocal fold kinematics in the avian vocal organ, the syrinx. We furthermore imaged and quantified syringeal kinematics in the pigeon (Columba livia) syrinx with unprecedented detail. Our results show that EGG signals predict (1) the relative amount of contact between the avian equivalent of vocal folds and (2) essential parameters describing vibratory kinematics, such as fundamental frequency, and timing of syringeal opening and closing events. As such, EGG provides novel opportunities for measuring syringeal vibratory kinematic parameters in vivo Furthermore, the opportunity for imaging syringeal vibratory kinematics from multiple planar views (horizontal and coronal) simultaneously promotes birds as an excellent model system for studying kinematics and control of voiced sound production in general, including in humans and other mammals.

Effect of Bhramari Pranayama on the Acoustic and Aerodynamic Parameters of Voice in Normophonic Females

Summary. Objective

Pranayama is known for improving various health conditions. The present study is aimed at investigating the effects of bhramari pranayama on aerodynamic and acoustic parameters of voice in healthy individuals.

Study Design

This is a pretest-posttest design study.

Methods

A total of 24 participants in the age range of 20 to 25 years completed the bhramari pranayama regimen for 30 sessions. Aerodynamic and acoustic assessments were done before and after pranayama sessions. Maximum phonation duration, pitch, loudness, subglottal pressure, glottal airflow, laryngeal resistance and conductance along with acoustical parameters such as average F0, jitter, and shimmer, soft phonation index, noise to harmonic ratio, cepstral peak prominence, and smoothened cepstral peak prominence were analysed.

Results

The results revealed significant improvement in the maximum phonation duration, glottal airflow and pressure, average fundamental frequency, and cepstral peak prominence after practice suggesting that it has an effect on voice parameters.

Conclusion

Bhramari pranayama is effective in improving the acoustic and aerodynamic parameters of voice. The same needs to be investigated in hyper- and hypofunctional voice disorders in the future studies.

Brain activity during phonation in healthy female singers with supraglottic compression: an fMRI pilot study

This pilot study evaluated the usability of functional magnetic resonance imaging (fMRI) to detect brain activation during phonation in healthy female singers with supraglottic compression. Four healthy female classical singers (mean age: 26 years) participated in the study. All subjects had normal vocal folds and vocal characteristics and showed supraglottic compression. The fMRI experiment was carried out using a block design paradigm. Brain activation during phonation and exhalation was analyzed using Brain Voyager software (Brain Innovation B.V., Maastricht, The Netherlands). An fMRI data analysis showed a significant effect of phonation control in the bilateral pre/postcentral gyrus, and in the frontal, cingulate, superior and middle temporal gyrus, as well as in the parietal lobe, insula, lingual gyrus, cerebellum, thalamus and brainstem. These activation areas are consistent with previous reports using other fMRI protocols. In addition, a significant effect of phonation compared to exhalation control was found in the bilateral superior temporal gyrus, and the pre/postcentral gyrus. This fMRI pilot study allowed to detect a normal pattern of brain activity during phonation in healthy female singers with supraglottic compression using the proposed protocol. However, the pilot study detected problems with the experimental material/procedures that would necessitate refining the fMRI protocol. The phonation tasks were not capable to show brain activation difference between high-pitched and comfortable phonation. Further fMRI studies manipulating vocal parameters during phonation of the vowels /a/ and /i/ may elicit more distinctive hemodynamic response (HDR) activity patterns relative to voice modulation.

Relations among subglottal pressure, breathing, and acoustic parameters of sentence-level prominence in German

This study investigates whether acoustic correlates of prominence are related to actions of the respiratory system resulting in local changes of subglottal pressure (Psub). Simultaneous recordings were made of acoustics; intraoral pressure (Pio), as an estimate of Psub; and thoracic and abdominal volume changes. Ten German speakers read sentences containing a verb ending with /t/ followed by a noun starting with /t/. These /t#t/ sequences were typically realized as one /t:/ with a long intraoral pressure plateau. Sentence-level prominence was manipulated by shifting the position of contrastive focus within the sentences. The slope and peak values of Pio within the /t#t/ sequence were used to estimate differences in Psub across focus positions. Results show that prominence production is related to changes in the slope and maximum value of the pressure plateau. While pressure increases led to higher intensity, the increases did not relate to f0, hence, suggesting that local f0 changes primarily reflect laryngeal activity. Finally, strong individual differences were observed in the respiratory data. These findings confirm past reports of local Psub increases corresponding to sentence-level prominence. Speaker-specific activations of the respiratory system are interpreted in terms of motor equivalence, with laryngeal mechanisms also appearing to contribute to Psub changes.

Autophonic Loudness of Singers in Simulated Room Acoustic Environments

OBJECTIVES

This paper aims to study the effect of room acoustics and phonemes on the perception of loudness of one's own voice (autophonic loudness) for a group of trained singers.

METHODS

For a set of five phonemes, 20 singers vocalized over several autophonic loudness ratios, while maintaining pitch constancy over extreme voice levels, within five simulated rooms.

RESULTS

There were statistically significant differences in the slope of the autophonic loudness function (logarithm of autophonic loudness as a function of voice sound pressure level) for the five phonemes, with slopes ranging from 1.3 (/a:/) to 2.0 (/z/). There was no significant variation in the autophonic loudness function slopes with variations in room acoustics. The autophonic room response, which represents a systematic decrease in voice levels with increasing levels of room reflections, was also studied, with some evidence found in support. Overall, the average slope of the autophonic room response for the three corner vowels (/a:/, /i:/, and /u:/) was -1.4 for medium autophonic loudness.

CONCLUSIONS

The findings relating to the slope of the autophonic loudness function are in agreement with the findings of previous studies where the sensorimotor mechanisms in regulating voice were shown to be more important in the perception of autophonic loudness than hearing of room acoustics. However, the role of room acoustics, in terms of the autophonic room response, is shown to be more complicated, requiring further inquiry. Overall, it is shown that autophonic loudness grows at more than twice the rate of loudness growth for sounds created outside the human body.

A Review of Singing Voice Subsystem Interactions-Toward an Extended Physiological Model of "Support"

During phonation, the respiratory, the phonatory, and the resonatory parts of the voice organ can interact, where physiological action in one subsystem elicits a direct effect in another. Here, three major subsystems of these synergies are reviewed, creating a model of voice subsystem interactions: (1) Vocal tract adjustments can influence the behavior of the voice source via nonlinear source-tract interactions; (2) The type and degree of vocal fold adduction controls the expiratory airflow rate; and (3) The tracheal pull caused by the respiratory system affects the vertical larynx position and thus the vocal tract resonances. The relevance of the presented model is discussed, suggesting, among others, that functional voice building work concerned with a particular voice subsystem may evoke side effects or benefits on other subsystems, even when having a clearly defined and isolated physiological target. Finally, four seemingly incongruous historic definitions of the concept of singing voice "support" are evaluated, showing how each of these pertain to different voice subsystems at various levels of detail. It is argued that presumed discrepancies between these definitions can be resolved by putting them into the wider context of the subsystem interaction model presented here, thus offering a framework for reviewing and potentially refining some current and historical pedagogical approaches.

Morphometric Differences of Vocal Tract Articulators in Different Loudness Conditions in Singing

Introduction

Dynamic MRI analysis of phonation has gathered interest in voice and speech physiology. However, there are limited data addressing the extent to which articulation is dependent on loudness.

Material and Methods

12 professional singer subjects of different voice classifications were analysed concerning the vocal tract profiles recorded with dynamic real-time MRI with 25fps in different pitch and loudness conditions. The subjects were asked to sing ascending scales on the vowel /a/ in three loudness conditions (comfortable = mf, very soft = pp, very loud = ff, respectively). Furthermore, fundamental frequency and sound pressure level were analysed from the simultaneously recorded optical audio signal after noise cancellation.

Results

The data show articulatory differences with respect to changes of both pitch and loudness. Here, lip opening and pharynx width were increased. While the vertical larynx position was rising with pitch it was lower for greater loudness. Especially, the lip opening and pharynx width were more strongly correlated with the sound pressure level than with pitch.

Conclusion

For the vowel /a/ loudness has an effect on articulation during singing which should be considered when articulatory vocal tract data are interpreted.

Freddie Mercury-acoustic analysis of speaking fundamental frequency, vibrato, and subharmonics

Freddie Mercury was one of the twentieth century's best-known singers of commercial contemporary music. This study presents an acoustical analysis of his voice production and singing style, based on perceptual and quantitative analysis of publicly available sound recordings. Analysis of six interviews revealed a median speaking fundamental frequency of 117.3 Hz, which is typically found for a baritone voice. Analysis of voice tracks isolated from full band recordings suggested that the singing voice range was 37 semitones within the pitch range of F#2 (about 92.2 Hz) to G5 (about 784 Hz). Evidence for higher phonations up to a fundamental frequency of 1,347 Hz was not deemed reliable. Analysis of 240 sustained notes from 21 a-cappella recordings revealed a surprisingly high mean fundamental frequency modulation rate (vibrato) of 7.0 Hz, reaching the range of vocal tremor. Quantitative analysis utilizing a newly introduced parameter to assess the regularity of vocal vibrato corroborated its perceptually irregular nature, suggesting that vibrato (ir)regularity is a distinctive feature of the singing voice. Imitation of subharmonic phonation samples by a professional rock singer, documented by endoscopic high-speed video at 4,132 frames per second, revealed a 3:1 frequency locked vibratory pattern of vocal folds and ventricular folds.

Voice pedagogy-what do we need?

The final keynote panel of the 10th Pan-European Voice Conference (PEVOC) was concerned with the topic 'Voice pedagogy-what do we need?' In this communication the panel discussion is summarized, and the authors provide a deepening discussion on one of the key questions, addressing the roles and tasks of people working with voice students. In particular, a distinction is made between (1) voice building (derived from the German term 'Stimmbildung'), primarily comprising the functional and physiological aspects of singing; (2) coaching, mostly concerned with performance skills; and (3) singing voice rehabilitation. Both public and private educators are encouraged to apply this distinction to their curricula, in order to arrive at more efficient singing teaching and to reduce the risk of vocal injury to the singers concerned.

Comparing Vocal Fold Contact Criteria Derived From Audio and Electroglottographic Signals

OBJECTIVES

Collision threshold pressure (CTP), that is, the lowest subglottal pressure facilitating vocal fold contact during phonation, is likely to reflect relevant vocal fold properties. The amplitude of an electroglottographic (EGG) signal or the amplitude of its first derivative (dEGG) has been used as criterion of such contact. Manual measurement of CTP is time consuming, making the development of a simpler, alternative method desirable.

METHOD

In this investigation, we compare CTP values measured manually to values automatically derived from dEGG and to values derived from a set of alternative parameters, some obtained from audio and some from EGG signals. One of the parameters was the novel EGG wavegram, which visualizes sequences of EGG or dEGG cycles, normalized with respect to period and amplitude. Raters with and without previous acquaintance with EGG analysis marked the disappearance of vocal fold contact in dEGG and in wavegram displays of /pa:/-sequences produced with continuously decreasing vocal loudness by seven singer subjects.

RESULTS

Vocal fold contact was mostly identified accurately in displays of both dEGG amplitude and wavegram. Automatically derived CTP values showed high correlation with those measured manually and with those derived from the ratings of the visual displays. Seven other parameters were tested as criteria of such contact. Mainly, because of noise in the EGG signal, most of them yielded CTP values differing considerably from those derived from the manual and the automatic methods, although the EGG spectrum slope showed a high correlation.

CONCLUSION

The possibility of measuring CTP automatically seems promising for future investigations.