Normalized Amplitude Quotient Research Articles

Glottal Features in Vocal Assessment Following Thyroidectomy

ObjectivesVocal dysfunction is a frequent complication following thyroidectomy that can be associated with a negative impact on patient’ quality of life. Although the effect of thyroidectomy on acoustic features has been widely used, the examination of glottal flow characteristics to assess vocal outcomes following thyroid gland surgery has not been included in empirical research, to date. The goal of our study was to evaluate early and short-term vocal outcomes following thyroidectomy based on the analysis of glottal acoustic features during speech production. Study designProspective analytical study Materials and methodsWe evaluated vocal outcomes in patients who underwent thyroidectomy between September 2021 and March 2022. We extracted glottal flow features from their vocal recordings preceding surgery and post-operatively at Day1 and Month1 post-operatively. The extraction of glottal features was performed using a signal processing based approach. We extracted the following features: Open quotients (OQ1 and OQ2), Quasi-open quotient (QoQ), Closing quotient (ClQ), Amplitude quotient (AQ), Normalized Amplitude quotient (NAQ) and Speed quotients (SQ1 and SQ2).We included 39 patients. OQ2 and QoQ decreased significantly at Day1 and Month1. OQ1 and NAQ decreased significantly at Month1. ClQ remained stable at both post-operative assessments. AQ decrease was not significant at both dates. SQ1 increased at Day1 and Month1 but the change was not significant. SQ2 decreased significantly at both Day1 and Month1. OQ, QoQ AQ, NAQ and SQ2 did not recover at Month1. We noted that the decrease of SQ1 and SQ2 correlated significantly with the increase of the Voice Handicap Index-10 (VHI-10) at Month1. ConclusionGlottal acoustic features can be a reliable modality to detect vocal changes following thyroidectomy. Thyroidectomy was associated with a vocal dysfunction that was manifested by the decrease of open, amplitude, and speed quotients. Glottal features can present a potential tool to objectively assess the effect of thyroidectomy on vocal folds movements.

무후두 음성에 대한 성문 역 여과 분석의 유용성

The purpose of this study was to present basic data for voice rehabilitation by acoustically analyzing the voices of subjects who lost their voice due to laryngeal excision and used esophageal vocalization as an alternative method. We aimed to investigate the usefulness of esophageal speech analysis using open source software that can automatically run glottic inverse filtration (GIF) analysis and analyze various parameter values. GIF analysis was performed on 20 normal adults and 20 people with negative esophageal vocalization. Analysis variables included open quotient, speed quotient, closure quotient, amplitude quotient, normalized amplitude quotient, and semi-open quotient. As a result of glottal inverse filtration analysis of normal voice and esophageal vocalization, the values of esophageal vocalization were lower in all variables compared to normal vocalization, and the average score of esophageal vocalization was found to be 1/4 of that of normal vocalization. In this study, objective values for the glottal waveform of normal adults were obtained, and these parameter values were applied to esophageal voice to determine the extent to which they differ from normal voice, and the GIF value was used to determine the degree of voice progress in esophageal voice rehabilitation. It is believed that it can be used for prediction.

Acoustic Parameters in the Evaluation of Voice Quality of Choral Singers. Prototype of Mobile Application for Voice Quality Evaluation

Choral singers are among intensive voice users whose excessive vocal effort puts them at risk of developing voice disorders. The aim of the work was to assess voice quality for choral singers in the choir at the Polish-Japanese Academy of Information Technology. This evaluation was carried out using the acoustic parameters from the COVAREP (A Collaborative Voice Analysis Repository For Speech Technologies) repository. A prototype of a mobile application was also prepared to allow the calculation of these parameters. The study group comprised 6 male and 19 female choir singers. The control group consisted of healthy non-singing individuals, 50 men and 39 women. Auditory perceptual assessment (using the RBH scale) as well as acoustic analysis were used to test the voice quality of all the participants. The voice quality of the female choir singers proved to be normal in comparison with the control group. The male choir singers were found to have tense voice in comparison with the controls. The parameters which proved most effective for voice evaluation were Peak Slope and Normalized Amplitude Quotient.

Laryngeal and Acoustic Analysis of Chest and Head Registers Extended Across a Three-Octave Range: A Case Study.

Voice registers are assumed to be related to different laryngeal adjustments, but objective evidence has been insufficient. While chest register is usually associated with the lower pitch range, and head register with the higher pitch range, here we investigated a professional singer who claimed an ability to produce both these registers at every pitch, throughout her entire singing range. The singer performed separated phonations alternating between the two registers (further called chest-like and head-like) at all pitches from C3 (131 Hz) to C6 (1047 Hz). We monitored the vocal fold vibrations using high-speed video endoscopy and electroglottography. The microphone sound was recorded and used for blind listening tests performed by the three authors (insiders) and by six "naive" participants (outsiders). The outsiders correctly identified the registers in 64% of the cases, and the insiders in 89% of the cases. Objective analysis revealed larger closed quotient and vertical phase differences for the chest-like register within the lower range below G4 (<392 Hz), and also a larger closed quotient at the membranous glottis within the higher range above Bb4 (>466 Hz), but not between Ab4-A4 (415-440 Hz). The normalized amplitude quotient was consistently lower in the chest-like register throughout the entire range. The results indicate that that the singer employed subtle laryngeal control mechanisms for the chest-like and head-like phonations on top of the traditionally recognized low-pitched chest and high-pitched head register phenomena. Across all pitches, the chest-like register was produced with more rapid glottal closure that was usually, but not necessarily, accompanied also by stronger adduction of membranous glottis. These register changes were not always easily perceivable by listeners, however.

Toward a cumulative science of vocal markers of autism: A cross-linguistic meta-analysis-based investigation of acoustic markers in American and Danish autistic children.

Acoustic atypicalities in speech production are argued to be potential markers of clinical features in autism spectrum disorder (ASD). A recent meta-analysis highlighted shortcomings in the field, in particular small sample sizes and study heterogeneity. We showcase a cumulative (i.e., explicitly building on previous studies both conceptually and statistically) yet self-correcting (i.e., critically assessing the impact of cumulative statistical techniques) approach to prosody in ASD to overcome these issues. We relied on the recommendations contained in the meta-analysis to build and analyze a cross-linguistic corpus of multiple speech productions in 77 autistic and 72 neurotypical children and adolescents (>1000 recordings in Danish and US English). We used meta-analytically informed and skeptical priors, with informed priors leading to more generalizable inference. We replicated findings of a minimal cross-linguistically reliable distinctive acoustic profile for ASD (higher pitch and longer pauses) with moderate effect sizes. We identified novel reliable differences between the two groups for normalized amplitude quotient, maxima dispersion quotient, and creakiness. However, the differences were small, and there is likely no one acoustic profile characterizing all autistic individuals. We identified reliable relations of acoustic features with individual differences (age, gender), and clinical features (speech rate and ADOS sub-scores). Besides cumulatively building our understanding of acoustic atypicalities in ASD, the study shows how to use systematic reviews and meta-analyses to guide the design and analysis of follow-up studies. We indicate future directions: larger and more diverse cross-linguistic datasets, focus on heterogeneity, self-critical cumulative approaches, and open science. LAY SUMMARY: Autistic individuals are reported to speak in distinctive ways. Distinctive vocal production can affect social interactions and social development and could represent a noninvasive way to support the assessment of autism spectrum disorder (ASD). We systematically checked whether acoustic atypicalities highlighted in previous articles could be actually found across multiple recordings and two languages. We find a minimal acoustic profile of ASD: higher pitch, longer pauses, increased hoarseness and creakiness of the voice. However, there is much individual variability (by age, sex, language, and clinical characteristics). This suggests that the search for one common "autistic voice" might be naive and more fine-grained approaches are needed.

Augmented visual-feedback of airflow: Immediate effects on voice-source characteristics of students of singing

Glottal adduction is a crucial aspect in voice education and vocal performance: it has major effects on phonatory airflow and, consequently, on voice timbre. As the voice is a non-visible musical instrument, controlling it could be facilitated by providing real-time visual feedback of phonatory airflow. Here, we test the usefulness of a flow ball (FB) training device, visualizing, in terms of the height of a polystyrene ball placed in a plastic basket, phonatory airflow during phonation. Audio and electroglottographic recordings of five postgraduate, classically trained singer students were made under three subsequent conditions: before, during, and after phonating into the FB. The calibrated audio signal was inverse-filtered, using an electroglottograph signal to guide the manual tuning of the inverse filters. Mean phonatory airflow, peak-to-peak pulse amplitude, and normalized amplitude quotient were extracted from the resulting flow glottograms. After the FB condition, increases of mean flow and peak-to-peak pulse amplitude were observed in four singers. In addition, the singers’ mean normalized amplitude quotient increased significantly. The findings, although exploratory, suggest that reduction of glottal adduction can be observed immediately after FB phonation.

Analysis of glottal inverse filtering in the presence of source-filter interaction

The validity of glottal inverse filtering (GIF) to obtain a glottal flow waveform from radiated pressure signal in the presence and absence of source-filter interaction was studied systematically. A driven vocal fold surface model of vocal fold vibration was used to generate source signals. A one-dimensional wave reflection algorithm was used to solve for acoustic pressures in the vocal tract. Several test signals were generated with and without source-filter interaction at various fundamental frequencies and vowels. Linear Predictive Coding (LPC), Quasi Closed Phase (QCP), and Quadratic Programming (QPR) based algorithms, along with supraglottal impulse response, were used to inverse filter the radiated pressure signals to obtain the glottal flow pulses. The accuracy of each algorithm was tested for its recovery of maximum flow declination rate (MFDR), peak glottal flow, open phase ripple factor, closed phase ripple factor, and mean squared error. The algorithms were also tested for their absolute relative errors of the Normalized Amplitude Quotient, the Quasi-Open Quotient, and the Harmonic Richness Factor. The results indicated that the mean squared error decreased with increase in source-filter interaction level suggesting that the inverse filtering algorithms perform better in the presence of source-filter interaction. All glottal inverse filtering algorithms predicted the open phase ripple factor better than the closed phase ripple factor of a glottal flow waveform, irrespective of the source-filter interaction level. Major prediction errors occurred in the estimation of the closed phase ripple factor, MFDR, peak glottal flow, normalized amplitude quotient, and Quasi-Open Quotient. Feedback-related nonlinearity (source-filter interaction) affected the recovered signal primarily when fo was well below the first formant frequency of a vowel. The prediction error increased when fo was close to the first formant frequency due to the difficulty of estimating the precise value of resonance frequencies, which was exacerbated by nonlinear kinetic losses in the vocal tract.

Electroglottographic and acoustic analysis of voice in children with vocal nodules

PurposeVocal fold nodules are usually caused by voice overuse or vocal hyperfunction, and their symptoms include persistent hoarseness – a disturbance in the vocal fold vibrations which results in a turbulent passage of air in the glottis, manifested as a raspy, rough voice. The aim of the study was to present data concerning voice quality in patients with vocal nodules and to compare electroglottographic analysis (EGG) with acoustic analysis. MethodsThe study examined 57 children with vocal fold nodules (Group 1). Each patient underwent a phoniatric evaluation of the vocal tract, a videolaryngoscopic examination, and a voice quality assessment, employing electroglottographic and acoustic analyses. The control group consisted of 37 healthy children (Group 2). The following parameters were analyzed: Closed Quotient (EGG signal), Peak Slope, Normalized Amplitude Quotient and Cepstral Peak Prominence (acoustic signal - waveform). ResultsChanges in the EGG signal could be detected in 95% of the patients with vocal nodules, indicating the occurrence of vocal nodules and glottal insufficiency. The acoustic analysis confirmed breathy phonation in 63% of the patients. The Closed Quotient parameter proved to be more effective than Peak Slope. Closed Quotient, Peak Slope and Normalized Amplitude Quotient allowed for the differentiation of the EGG signal and the acoustic signal in groups 1 and 2 in a statistically significant way. ConclusionsThe results of electroglottographic and acoustic analysis show incorrect voice parameters in patients with vocal nodules with reference to the control group. At the same time, the EGG analysis proved to be more effective than the analysis of the acoustic signal.

Analysis of phonation onsets in vowel production, using information from glottal area and flow estimate

A multichannel dataset comprising high-speed videoendoscopy images, and electroglottography and free-field microphone signals, was used to investigate phonation onsets in vowel production. Use of the multichannel data enabled simultaneous analysis of the two main aspects of phonation, glottal area, extracted from the high-speed videoendoscopy images, and glottal flow, estimated from the microphone signal using glottal inverse filtering. Pulse-wise parameterization of the glottal area and glottal flow indicate that there is no single dominant way to initiate quasi-stable phonation. The trajectories of fundamental frequency and normalized amplitude quotient, extracted from glottal area and estimated flow, may differ markedly during onsets. The location and steepness of the amplitude envelopes of the two signals were observed to be closely related, and quantitative analysis supported the hypothesis that glottal area and flow do not carry essentially different amplitude information during vowel onsets. Linear models were used to predict the phonation onset times from the characteristics of the subsequent steady phonation. The phonation onset time of glottal area was found to have good predictability from a combination of the fundamental frequency and the normalized amplitude quotient of the glottal flow, as well as the gender of the speaker. For the phonation onset time of glottal flow, the best linear model was obtained using the fundamental frequency and the normalized amplitude quotient of the glottal flow as predictors.

Relation of RBH Auditory-Perceptual Scale to Acoustic and Electroglottographic Voice Analysis in Children With Vocal Nodules

The aim of this paper was to present an analysis of the feasibility of voice quality prediction on the roughness, breathiness, hoarseness (RBH) scale for children with vocal nodules on the basis of both acoustic parameters and electroglottographic (EGG) examination. The first step to achieve this goal involved the creation of a dedicated database, Voice Pathology Analysis Database (VPADB), containing voice recordings from patients, the EGG signal, medical diagnosis, and the classification of voice quality on the above-mentioned scale. The database also contains data concerning the patients' age and sex. The next step involved performing statistical analyses to test the relationship between the values of objective parameters, such as peak slope and normalized amplitude quotient, and the classification of voice quality. The study made use of voice recordings of 57 patients with vocal nodules and 37 healthy individuals. The RBH classification was carried out by two independent voice specialists. It was found that speech signal parameters can be used to predict expert evaluation with regard to roughness and hoarseness.

Glottal Inverse Filtering Using Probabilistic Weighted Linear Prediction

Glottal inverse filtering is a noninvasive method for getting the glottal flow estimate from the speech. In this paper, we propose a method for glottal inverse filtering based on probabilistic weighted linear prediction PWLP in which the speech is assumed to be the output of an all-pole filter with glottal flow as an excitation. First, we introduce a probabilistic interpretation of the WLP, and we propose a probabilistic temporal weighting as convolution of a binary vector and a fixed window. We construct the posterior distribution based on the PWLP likelihood and a Gaussian prior on the filter coefficients. The parameters are estimated using the Gibbs sampling. The experiments are performed using the Lijencrants–Fant LF model based synthetic data, a physical model based synthetic data of different vowels and real speech data. Results demonstrate that the proposed method outperforms the best of the existing state-of-the-art methods in terms of the normalized amplitude quotient by 0.035 and 0.12 for the LF model and physical model based synthetic data, respectively. The results based on real speech data show that the glottal flow estimated by the proposed method in the closed phase is flatter and has less formant ripple compared to existing state-of-the-art methods. We also show two key features of the proposed method: first, the proposed method does not need prior detection of glottal closure or opening instants. The temporal weights are learnt in a data-driven manner, which is often found to be high near the closed phase of the glottal cycle, second, the Gaussian prior helps in estimating the filter coefficients when the closed phase duration is small.

How Much Loading Does Water Resistance Voice Therapy Impose on the Vocal Folds? An Experimental Human Study

Water resistance voice therapy applies phonation into water through a tube. This study investigates how strenuous this therapy can be for the vocal folds in terms of impact stress (IS). It further examines whether it is possible to estimate the IS using the contact quotient (CQ) and maximum derivative from an electroglottogram (EGG). Experimental study. A male participant sustained a rounded back vowel [u:] or [o:] at a comfortable speaking pitch and loudness, and phonated into a silicone "Lax Vox" tube submerged 2 cm in water. High-speed videolaryngoscopy was performed with a rigid scope. Oral air pressure (Poral) was registered in a mouthpiece through which an endoscope was inserted into the larynx. An EGG was recorded. The CQEGG from the EGG and the closed quotient from the glottal width (CQarea) increased, while the maximum glottal amplitude and absolute value of derivative minimum (dmin) and also the derivative maximum from the EGG decreased for phonation into water. Normalized amplitude quotient from the glottal width variation also decreased but the change was not significant. Based on the glottal area findings, water resistance therapy does not seem to increase vocal fold loading (in terms of increased IS) even if the increase of CQarea, and CQEGG suggest so. CQEGG may qualitatively correspond to that of area, but the reliability of CQ (from the glottal area or the EGG) and the maximum derivative from the EGG as estimates of IS in semiocclusion exercises warrant further studies.

Flow Glottogram and Subglottal Pressure Relationship in Singers and Untrained Voices

This article combines results from three earlier investigations of the glottal voice source during phonation at varying degrees of vocal loudness (1) in five classically trained baritone singers (Sundberg etal., 1999), (2) in 15 female and 14 male untrained voices (Sundberg etal., 2005), and (3) in voices rated as hyperfunctional by an expert panel (Millgård etal., 2015). Voice source data were obtained by inverse filtering. Associated subglottal pressures were estimated from oral pressure during the occlusion for the consonant /p/. Five flow glottogram parameters, (1) maximum flow declination rate (MFDR), (2) peak-to-peak pulse amplitude, (3) level difference between the first and the second harmonics of the voice source, (4) closed quotient, and (5) normalized amplitude quotient, were averaged across the singer subjects and related to associated MFDR values. Strong, quantitative relations, expressed as equations, are found between subglottal pressure and MFDR and between MFDR and each of the other flow glottogram parameters. The values for the untrained voices, as well as those for the voices rated as hyperfunctional, deviate systematically from the values derived from the equations.

Phonatory Strategies of Male Vocalists in Singing Diatonic Scales With Various Dynamic Shapings

This work aimed to investigate glottal adduction in the case of the singing of diatonic D major ascending scales with different dynamic shapings on vowel [a:] by 10 classically trained male singers. The parameters obtained by inverse filtering-closed quotient (CQ), normalized amplitude quotient (NAQ), and the level difference between the first two partials of the glottal flow waveform spectrum (H1-H2)-all indicated statistically significant systematic changes when singers sang (1) with habitual dynamics without intentional dynamic changes; (2) with sempre crescendo from piano to forte; and (3) with sempre diminuendo from forte to piano. Adduction on average was lower if the tone with the same pitch was sung piano compared with when it was sung forte. The piano tones with the limit of one and the same dynamic task were sung with lower adduction on average compared with one octave higher or lower tones sung forte, although here the agreement between different parameters was poorer and the individual variability was greater. There was only a moderate negative correlation between CQ and NAQ (r = -0.41) but a strong negative correlation between CQ and H1-H2 (r = -0.8). CQ showed a moderate positive correlation with sound level but no significant correlation with pitch. NAQ showed a strong and significant positive correlation with pitch but not with sound level (except when it was calculated only at constant pitch). Some of the most experienced singers used quite high glottal adduction levels, questioning the concept of whether flow phonation is always the favorite classical style.

Physical task stress and speaker variability in voice quality

The presence of physical task stress induces changes in the speech production system which in turn produces changes in speaking behavior. This results in measurable acoustic correlates including changes to formant center frequencies, breath pause placement, and fundamental frequency. Many of these changes are due to the subject’s internal competition between speaking and breathing during the performance of the physical task, which has a corresponding impact on muscle control and airflow within the glottal excitation structure as well as vocal tract articulatory structure. This study considers the effect of physical task stress on voice quality. Three signal processing-based values which include (i) the normalized amplitude quotient (NAQ), (ii) the harmonic richness factor (HRF), and (iii) the fundamental frequency are used to measure voice quality. The effects of physical stress on voice quality depend on the speaker as well as the specific task. While some speakers do not exhibit changes in voice quality, a subset exhibits changes in NAQ and HRF measures of similar magnitude to those observed in studies of soft, loud, and pressed speech. For those speakers demonstrating voice quality changes, the observed changes tend toward breathy or soft voicing as observed in other studies. The effect of physical stress on the fundamental frequency is correlated with the effect of physical stress on the HRF (r = −0.34) and the NAQ (r = −0.53). Also, the inter-speaker variation in baseline NAQ is significantly higher than the variation in NAQ induced by physical task stress. The results illustrate systematic changes in speech production under physical task stress, which in theory will impact subsequent speech technology such as speech recognition, speaker recognition, and voice diarization systems.

Flow Glottogram Characteristics and Perceived Degree of Phonatory Pressedness

Phonatory pressedness is a clinically relevant aspect of voice, which generally is analyzed by auditory perception. The present investigation aimed at identifying voice source and formant characteristics related to experts' ratings of phonatory pressedness. Experimental study of the relations between visual analog scale ratings of phonatory pressedness and voice source parameters in healthy voices. Audio, electroglottogram, and subglottal pressure, estimated from oral pressure during /p/ occlusion, were recorded from five female and six male subjects, each of whom deliberately varied phonation type between neutral, flow, and pressed in the syllable /pae/, produced at three loudness levels and three pitches. Speech-language pathologists rated, along a visual analog scale, the degree of perceived phonatory pressedness in these samples. The samples were analyzed by means of inverse filtering with regard to closed quotient, dominance of the voice source fundamental, normalized amplitude quotient, peak-to-peak flow amplitude, as well as formant frequencies and the alpha ratio of spectrum energy above and below 1000Hz. The results were compared with the rating data, which showed that the ratings were closely related to voice source parameters. Approximately, 70% of the variance of the ratings could be explained by the voice source parameters. A multiple linear regression analysis suggested that perceived phonatory pressedness is related most closely to subglottal pressure, closed quotient, and the two lowest formants.

Contact Quotient Versus Closed Quotient: A Comparative Study on Professional Male Singers

The term "closed quotient" is frequently used for data derived both from inverse filtering and from electroglottography. In the former case, it is defined as the ratio between the closed phase and the period, as measured in flow glottograms (FLOGG), whereas in the latter case, it is defined as the time interval between the falling and rising parts of the electroglottogram (EGG), measured at some percentage of the peak-to-peak amplitude. The study aims at analyzing differences between EGG- and FLOGG-based closed quotients and their relationships with voice source parameters. Comparative study. FLOGG- and EGG-based measures collected from five professional male singers were compared, under different pitch and loudness conditions. Compared with the FLOGG-based quotient, the EGG-based quotient (i) varied more between subjects, (ii) presented greater values, (iii) varied less with subglottal pressure, (iv) varied less with the normalized amplitude quotient (ie, the ratio between the flow pulse amplitude and the product of period and maximum flow declination rate), and (v) varied less with the relative amplitude of the voice source fundamental. Although positively related, FLOGG- and EGG-based closed quotients differ and must not be confused.

Formant and Voice Source Properties in Two Male Kunqu Opera Roles: A Pilot Study

Objective: This investigation analyzes flow glottogram and electroglottogram (EGG) parameters as well as the relationship between formant frequencies and partials in two male Kunqu Opera roles, Colorful face (CF) and Old man (OM). Participants and Methods: Four male professional Kunqu Opera singers volunteered as participants, 2 singers for each role. Using inverse filtering of the audio signal flow glottogram parameters and formant frequencies were measured in each note of scales. Two EGG parameters, contact quotient (CoQ) and speed quotient, were measured. Results: Formant tuning was observed only in 1 of the OM singers and appeared in a pitch range lower than the passaggio range of Western male opera singers. Both the CF and the OM role singers showed high CoQ values and low values of the normalized amplitude quotient in singing. For 3 of the 4 singers CoQ and the level difference between the first and second partials showed a positive and a negative correlation with fundamental frequency (F0), respectively. Conclusions: Formant tuning may be applied by a singer of the OM role, and both CF and OM role singers may use a rather pressed type of phonation, CF singers more than OM singers in the lower part of the pitch range. Most singers increased glottal adduction with rising F0.

Pregnancy and the Singing Voice: Reports From a Case Study

Significant changes in body tissues occur during pregnancy; however, literature concerning the effects of pregnancy on the voice is sparse, especially concerning the professional classically trained voice. Hormonal variations and associated bodily changes during pregnancy affect phonatory conditions, such as vocal fold motility and glottal adduction. Longitudinal case study with a semiprofessional classically trained singer. Audio, electrolaryngograph, oral pressure, and air flow signals were recorded once a week during the last 12 weeks of pregnancy, 48 hours after birth and during the following consecutive 11 weeks. Vocal tasks included diminuendo sequences of the syllable /pae/ sung at various pitches, and performing a Lied. Phonation threshold pressures (PTPs) and collision threshold pressures (CTPs), normalized amplitude quotient (NAQ), alpha ratio, and the dominance of the voice source fundamental were determined. Concentrations of sex female steroid hormones were measured on three occasions. A listening test of timbral brightness and vocal fatigue was carried out. Results demonstrated significantly elevated concentrations of estrogen and progesterone during pregnancy, which were considerably reduced after birth. During pregnancy, CTPs and PTPs were high; and NAQ, alpha ratio, and dominance of the voice source fundamental suggested elevated glottal adduction. In addition, a perceptible decrease of vocal brightness was noted. The elevated CTPs and PTPs during pregnancy suggest reduced vocal fold motility and increased glottal adduction. These changes are compatible with expected effects of elevated concentrations of estrogen and progesterone on tissue viscosity and water retention.

Some Phonatory and Resonatory Characteristics of the Rock, Pop, Soul, and Swedish Dance Band Styles of Singing

This investigation aims at describing voice function of four nonclassical styles of singing, Rock, Pop, Soul, and Swedish Dance Band. A male singer, professionally experienced in performing in these genres, sang representative tunes, both with their original lyrics and on the syllable /pae/. In addition, he sang tones in a triad pattern ranging from the pitch Bb2 to the pitch C4 on the syllable /pae/ in pressed and neutral phonation. An expert panel was successful in classifying the samples, thus suggesting that the samples were representative of the various styles. Subglottal pressure was estimated from oral pressure during the occlusion for the consonant [p]. Flow glottograms were obtained from inverse filtering. The four lowest formant frequencies differed between the styles. The mean of the subglottal pressure and the mean of the normalized amplitude quotient (NAQ), that is, the ratio between the flow pulse amplitude and the product of period and maximum flow declination rate, were plotted against the mean of fundamental frequency. In these graphs, Rock and Swedish Dance Band assumed opposite extreme positions with respect to subglottal pressure and mean phonation frequency, whereas the mean NAQ values differed less between the styles.