Acoustic prediction of severity in commonly occurring voice problems

Voice Quality of Children With Cerebral Palsy

Purpose Many children with cerebral palsy (CP) are described as having altered vocal quality. The current study utilizes psychoacoustic measures, namely, low-amplitude (H1*-H2*) and high-amplitude (H1*-A2*) spectral tilt and cepstral peak prominence (CPP), to identify the vocal fold articulation characteristics in this population. Method Eight children with CP and eight typically developing (TD) peers produced vowel singletons [i, ɑ, u] and a story retell task with the same vowels in the words "beets, Bobby, boots." H1*-H2*, H1*-A2*, and CPP were extracted from each vowel. Results were analyzed with mixed linear models to identify the effect of Group (CP, TD), Task (vowel singleton, story retell), and Vowel [i, ɑ, u] on the dependent variables. Results Children with CP have lower spectral tilt values (H1*-H2* and H1*-A2*) and lower CPP values than their TD peers. For both groups, vowel singletons were associated with lower CPP values as compared to story retell. Finally, the vowel [ɑ] was associated with higher spectral tilt and higher CPP values as compared to [i, u]. Conclusions Children with CP have more constricted and creaky vocal quality due to lower spectral tilt and greater noise. Unlike adults, children demonstrate poorer vocal fold articulation when producing vowel singletons as compared to story retell. Finally, low vowels like [ɑ] seem to be produced with less constriction and noise as compared to high vowels.

Linking human male vocal parameters to perceptions, body morphology, strength and hormonal profiles in contexts of sexual selection

Sexual selection appears to have shaped the acoustic signals of diverse species, including humans. Deep, resonant vocalizations in particular may function in attracting mates and/or intimidating same-sex competitors. Evidence for these adaptive functions in human males derives predominantly from perception studies in which vocal acoustic parameters were manipulated using specialist software. This approach affords tight experimental control but provides little ecological validity, especially when the target acoustic parameters vary naturally with other parameters. Furthermore, such experimental studies provide no information about what acoustic variables indicate about the speaker-that is, why attention to vocal cues may be favored in intrasexual and intersexual contexts. Using voice recordings with high ecological validity from 160 male speakers and biomarkers of condition, including baseline cortisol and testosterone levels, body morphology and strength, we tested a series of pre-registered hypotheses relating to both perceptions and underlying condition of the speaker. We found negative curvilinear and negative linear relationships between male fundamental frequency (fo) and female perceptions of attractiveness and male perceptions of dominance. In addition, cortisol and testosterone negatively interacted in predicting fo, and strength and measures of body size negatively predicted formant frequencies (Pf). Meta-analyses of the present results and those from two previous samples confirmed that fonegatively predicted testosterone only among men with lower cortisol levels. This research offers empirical evidence of possible evolutionary functions for attention to men's vocal characteristics in contexts of sexual selection.

Vocal Indicators of Size, Shape and Body Composition in Polish Men

OBJECTIVES

From a human evolution perspective, identifying a link between physique and vocal quality could demonstrate dual signaling in terms of the health and biological condition of an individual. In this regard, this study investigates the relationship between men's body size, shape, and composition, and their vocal characteristics.

MATERIALS AND METHODS

Eleven anthropometric measurements, using seven indices, were carried out with 80 adult Polish male participants, while the speech analysis adopted a voice recording procedure that involved phonetically recording vowels /ɑː/, /ɛː/, /iː/, /ɔː/, /uː/ to define the voice acoustic components used in Praat software.

RESULTS

The relationship between voice parameters and body size/shape/composition was found. The analysis indicated that the formants and their derivatives were useful parameters for prediction of height, weight, neck, shoulder, waist, and hip circumferences. Fundamental frequency (F₀) was negatively correlated with neck circumference at Adam's apple level and body height. Moreover neck circumference and F₀ association was observed for the first time in this paper. The association between waist circumference and formant component showed a net effect. In addition, the formant parameters showed significant correlations with body shape, indicating a lower vocal timbre in men with a larger relative waist circumference.

DISCUSSION

Men with lower vocal pitch had wider necks, probably a result of larynx size. Furthermore, a greater waist circumference, presumably resulting from abdominal fat distribution in men, correlated with a lower vocal timbre. While these results are inconclusive, they highlight new directions for further research.

Impact of Subharmonic and Aperiodic Laryngeal Dynamics on the Phonatory Process Analyzed in Ex Vivo Rabbit Models

Normal voice is characterized by periodic oscillations of the vocal folds. On the other hand, disordered voice dynamics (e.g., subharmonic and aperiodic oscillations) are often associated with voice pathologies and dysphonia. Unfortunately, not all investigations may be conducted on human subjects; hence animal laryngeal studies have been performed for many years to better understand human phonation. The rabbit larynx has been shown to be a potential model of the human larynx. Despite this fact, only a few studies regarding the phonatory parameters of rabbit larynges have been performed. Further, to the best of our knowledge, no ex vivo study has systematically investigated phonatory parameters from high-speed, audio and subglottal pressure data with irregular oscillations. To remedy this, the present study analyzes experiments with sustained phonation in 11 ex vivo rabbit larynges for 51 conditions of disordered vocal fold dynamics. (1) The results of this study support previous findings on non-disordered data, that the stronger the glottal closure insufficiency is during phonation, the worse the phonatory characteristics are; (2) aperiodic oscillations showed worse phonatory results than subharmonic oscillations; (3) in the presence of both types of irregular vibrations, the voice quality (i.e., cepstral peak prominence) of the audio and subglottal signal greatly deteriorated compared to normal/periodic vibrations. In summary, our results suggest that the presence of both types of irregular vibration have a major impact on voice quality and should be considered along with glottal closure measures in medical diagnosis and treatment.

Effects of Injection Laryngoplasty with Hyaluronic Acid in Patients with Vocal Fold Paralysis

Objectives

The purpose of this study was to explore the effects of injection laryngoplasty (IL) with hyaluronic acid in patients with vocal fold paralysis (VFP).

Methods

A total of 50 patients with VFP participated in this study. Pre- and post-IL assessments were performed, which included analyzing the sustained vowel /a/ phonation, and the patient reading 1 Korean sentence from the "Walk" passage that comprised 25 syllables in 10 words. To investigate the effect of IL on vocal fold function, acoustic analysis (acoustic voice quality index, cepstral peak prominence, maximum phonation time, speaking fundamental frequency) was conducted and auditory-perceptual (grade and overall severity), visual judgment (gap), and self-questionnaire (voice handicap index-10) assessments were performed.

Results

The patients with VFP showed statistically significant differences between pre-and post-IL assessments for acoustic and auditory-perception, visual judgment, and self-questionnaire assessments.

Conclusion

The patients with VFP showed positive change in vocal fold function between pre- and post-IL measurements. The findings showed that IL with hyaluronic acid is an effective method to improve vocal fold function in patients with VFP.

The Design and Assessment of a Multiparametric Model for the Dysphonia Severity Index for Persian-speaking Populations

OBJECTIVES

In instrumental voice assessment, multiparametric models reflect the multidimensional nature of voice and are therefore better than models that reflect only a single dimension of voice. The Dysphonia Severity Index (DSI) is one of the most common multiparametric models. In voice assessment, race, language, and structural and physiological features affect the acoustic, aerodynamic, and voice range profile measures. Given these differences, this study was conducted to design and evaluate a multiparametric and objective model for assessing the severity of dysphonia in Persian-speaking populations.

MATERIAL AND METHODS

This study examined 300 participants with several types of dysphonia (104 women and 196 men) and 100 healthy individuals (63 women and 37 men). Five acoustic parameters, three aerodynamic parameters, and seven voice range profile parameters were measured for designing the model. Perceptual evaluation was performed using the grade, roughness, breathiness, asthenia, strain scale. The logistic regression analysis was used to determine the factors affecting the DSI and each component's coefficient.

RESULTS

Of the 15 parameters assessed, shimmer, vital capacity, semitone range, and voice onset time of /pa/ remained in the model with their coefficients. This section presents the DSI model for the examined population. The discriminant analysis showed that this combination corresponds to 47.8 of the perceptual assessment: DSI = 0.289 (shimmer) + 0.0001 (VC) - 0.059 (STR) - 13.278 (VOT_Pa).

CONCLUSION

In this study, the DSI corresponded to the physiological, linguistic, and racial characteristics of the Persian-speaking population with or without voice disorder.

Influence of glottal closure on the phonatory process in ex vivo porcine larynges

Many cases of disturbed voice signals can be attributed to incomplete glottal closure, vocal fold oscillation asymmetries, and aperiodicity. Often these phenomena occur simultaneously and interact with each other, making a systematic, isolated investigation challenging. Therefore, ex vivo porcine experiments were performed which enable direct control of glottal configurations. Different pre-phonatory glottal gap sizes, adduction levels, and flow rates were adjusted. The resulting glottal closure types were identified in a post-processing step. Finally, the acoustic quality, aerodynamic parameters, and the characteristics of vocal fold oscillation were analyzed in reference to the glottal closure types. Results show that complete glottal closure stabilizes the phonation process indicated through a reduced left-right phase asymmetry, increased amplitude and time periodicity, and an increase in the acoustic quality. Although asymmetry and periodicity parameter variation covers only a small range of absolute values, these small variations have a remarkable influence on the acoustic quality. Due to the fact that these parameters cannot be influenced directly, the authors suggest that the (surgical) reduction of the glottal gap seems to be a promising method to stabilize the phonatory process, which has to be confirmed in future studies.

Is OperaVOX a clinically useful tool for the assessment of voice in a general ENT clinic?

Background

Objective acoustic analysis is a key component of multidimensional voice assessment. OperaVOX is an iOS app which has been shown to be comparable to Multi Dimensional Voice Program for most principal measures of vocal function. As a relatively cheap, portable and easily accessible form of acoustic analysis, OperaVOX may be more clinically useful than laboratory-based software in many situations. This study aims to determine whether correlation exists between acoustic measurements obtained using OperaVOX, and perceptual evaluation of voice.

Methods

Forty-four voices from the multidisciplinary voice clinic were examined. Each voice was assessed blindly by a single experienced voice therapist using the GRBAS scale, and analysed using OperaVOX. The Spearman rank correlation co-efficient was calculated between each element of the GRBAS scale and acoustic measurements obtained by OperaVOX.

Results

Significant correlations were identified between GRBAS scores and OperaVOX parameters. Grade correlated significantly with jitter (ρ = 0.495, p < 0.05), shimmer (ρ = 0.385, p < 0.05), noise-to-harmonic ratio (NHR; ρ = 0.526, p < 0.05) and maximum phonation time (MPT; ρ = −0.415, p < 0.05). Roughness did not correlate with any of the measured variables. Breathiness correlated significantly with jitter (ρ = 0.342, p < 0.05), NHR (ρ = 0.344, p < 0.05) and MPT (ρ = −0.336, p < 0.05). Aesthenia correlated with NHR (ρ = 0.413, p < 0.05) and MPT (ρ = −0.399, p < 0.05). Strain correlated with Jitter (ρ = 0.560, p < 0.05), NHR (ρ = 0.600, p < 0.05) and MPT (ρ = −0.356, p < 0.05).

Conclusions

OperaVOX provides objective acoustic analysis which has shown statistically significant correlation to perceptual evaluation using the GRBAS scale. The accessibility of the software package makes it possible for a wide range of health practitioners, e.g. general ENT surgeons, vascular surgeons, thyroid surgeons and cardiothoracic surgeons to objectively monitor outcomes and complications of surgical procedures that may affect vocal function. Given the increasing requirement for surgeons to monitor their outcomes as part of the move towards ‘surgeon reported outcomes’ this may become an invaluable tool towards that goal.

Cepstral Analysis of Voice in Patients With Thyroidectomy

Objectives

The vocal changes after a thyroidectomy are temporary and nonsevere, therefore, obtaining accurate analytical results on the pathological vocal characteristics following such a procedure is difficult. For a more objective acoustic analysis, this study used the cepstral analysis method to examine changes in the patients’ voices during the perioperative period regarding sustained vowel phonation.

Methods

The sustained phonation of the five vowels (i.e., /a/, /e/, /i/, /o/, and /u/) by 35 patients with thyroidectomy were recorded by using a Multi-Speech program. Of the 35 patients, 10 were men and 25 were women, with an average age of 51.5 years. Voice data were collected a total of 3 times (preoperatively, 5–7 days after the operation, and 6 weeks after the operation) and were edited according to each fragment (on-set, mid, and off-set) for cepstral analysis.

Results

The cepstral analysis on the patients’ voices revealed no significant differences between the examination periods of all vowel phonations. However, analysis of the on-set fragment of the vowel /i/ revealed pathological characteristics in which the cepstral measurements of the voice were significantly lower after the operation than before the operation, with the cepstral measurements of the voice increasing further 6 weeks following surgery.

Conclusion

The results of the acoustic analysis on the on-set fragment of the vowel /i/ will be important data for characterizing the vocal changes during the perioperative period. This study contributes to future research on the mechanisms underlying changes in the voice of patients with a history of thyroid or neck surgery.

Integrating voice evaluation: correlation between acoustic and audio-perceptual measures

OBJECTIVES/HYPOTHESIS

This article aims to establish correlations between acoustic and audio-perceptual measures using the GRBAS scale with respect to four different voice analysis software programs.

STUDY DESIGN

Exploratory, transversal.

METHODS

A total of 90 voice records were collected and analyzed with the Dr. Speech (Tiger Electronics, Seattle, WA), Multidimensional Voice Program (Kay Elemetrics, NJ, USA), PRAAT (University of Amsterdam, The Netherlands), and Voice Studio (Seegnal, Oporto, Portugal) software programs. The acoustic measures were correlated to the audio-perceptual parameters of the GRBAS and rated by 10 experts.

RESULTS

The predictive value of the acoustic measurements related to the audio-perceptual parameters exhibited magnitudes ranging from weak (R(2)a=0.17) to moderate (R(2)a=0.71). The parameter exhibiting the highest correlation magnitude is B (Breathiness), whereas the weaker correlation magnitudes were found to be for A (Asthenia) and S (Strain). The acoustic measures with stronger predictive values were local Shimmer, harmonics-to-noise ratio, APQ5 shimmer, and PPQ5 jitter, with different magnitudes for each one of the studied software programs.

CONCLUSIONS

Some acoustic measures are pointed as significant predictors of GRBAS parameters, but they differ among software programs. B (Breathiness) was the parameter exhibiting the highest correlation magnitude.

Nonlinear dynamic-based analysis of severe dysphonia in patients with vocal fold scar and sulcus vocalis

OBJECTIVE

The primary goal of this study was to evaluate a nonlinear dynamic approach to the acoustic analysis of dysphonia associated with vocal fold scar and sulcus vocalis.

STUDY DESIGN

Case-control study.

METHODS

Acoustic voice samples from scar/sulcus patients and age-/sex-matched controls were analyzed using correlation dimension (D2) and phase plots, time-domain based perturbation indices (jitter, shimmer, signal-to-noise ratio [SNR]), and an auditory-perceptual rating scheme. Signal typing was performed to identify samples with bifurcations and aperiodicity.

RESULTS

Type 2 and 3 acoustic signals were highly represented in the scar/sulcus patient group. When data were analyzed irrespective of signal type, all perceptual and acoustic indices successfully distinguished scar/sulcus patients from controls. Removal of type 2 and 3 signals eliminated the previously identified differences between experimental groups for all acoustic indices except D2. The strongest perceptual-acoustic correlation in our data set was observed for SNR and the weakest correlation was observed for D2.

CONCLUSIONS

These findings suggest that D2 is inferior to time-domain based perturbation measures for the analysis of dysphonia associated with scar/sulcus; however, time-domain based algorithms are inherently susceptible to inflation under highly aperiodic (ie, type 2 and 3) signal conditions. Auditory-perceptual analysis, unhindered by signal aperiodicity, is therefore a robust strategy for distinguishing scar/sulcus patient voices from normal voices. Future acoustic analysis research in this area should consider alternative (e.g., frequency- and quefrency-domain based) measures alongside additional nonlinear approaches.

The Acoustic Voice Quality Index: toward improved treatment outcomes assessment in voice disorders

Voice practitioners require an objective index of dysphonia severity as a means to reliably track treatment outcomes. To ensure ecological validity however, such a measure should survey both sustained vowels and continuous speech. In an earlier study, a multivariate acoustic model referred to as the Acoustic Voice Quality Index (AVQI), consisting of a weighted combination of 6 time-, frequency- and quefrency-domain metrics, was developed to measure dysphonia severity in both speaking tasks. In the current investigation, the generalizability and clinical utility of the AVQI are evaluated by first assessing its external cross-validity and then determining its sensitivity to change in dysphonia severity following surgical and/or behavioral voice treatment. The results, based upon a new set of normal and disordered voices compared favorably with outcomes reported earlier, indicating acceptable external validity. Furthermore, the AVQI was sensitive to treatment-related changes, validating its role as a potentially robust and objective voice treatment outcomes measure.

LEARNING OUTCOMES

Readers will be able to: (1) explain methodological issues surrounding the development of voice treatment outcomes measures (such as external cross-validity and responsiveness to change), (2) appreciate the relevance of measuring dysphonia severity in both sustained vowels and connected speech, (3) describe the method of obtaining the Acoustic Voice Quality Index (AVQI), (4) appreciate differences among a variety of estimates of diagnostic accuracy, and (5) discuss the AVQI as a clinically valid treatment outcomes measure.

Acoustic measurement of overall voice quality: a meta-analysis

Over the past several decades, many acoustic markers have been proposed to be sensitive to and measure overall voice quality. This meta-analysis presents a retrospective appraisal of scientific reports, which evaluated the relation between perceived overall voice quality and several acoustic-phonetic correlates. Twenty-five studies met the inclusion criteria and were evaluated using meta-analytic techniques. Correlation coefficients between perceptual judgments and acoustic measures were computed. Where more than one correlation coefficient for a specific acoustic marker was available, a weighted average correlation coefficient was calculated. This was the case in 36 acoustic measures on sustained vowels and in 3 measures on continuous speech. Acoustic measures were ranked according to the strength of the correlation with perceptual voice quality ratings. Acoustic markers with more than one correlation value available in literature and yielding a homogeneous weighted r of 0.60 or above were considered to be superior. The meta-analysis identified four measures that met these criteria in sustained vowels and three measures in continuous speech. Although acoustic measures are routinely utilized in clinical voice examinations, the results of this meta-analysis suggest that caution is warranted regarding the concurrent validity and thus the clinical utility of many of these measures.

Beta-adrenergic blockade and voice: a double-blind, placebo-controlled trial

This study investigated the effects of laboratory-induced stress and beta-adrenergic blockade on acoustic and aerodynamic voice measures. In a double-blind, placebo-controlled trial, 12 participants, six males and six females, underwent cold pressor-induced sympathetic activation followed by placebo or treatment with 40 mg propranolol. Aerodynamic and acoustic parameters of voice were collected at baseline, during cold pressor and after treatment with propranolol or placebo. Fundamental frequency, jitter, shimmer, maximum airflow declination rate, voice onset time, speaking rate, and subglottal pressure were measured at baseline, during cold pressor-induced stress, and after treatment with propranolol or placebo. Cardiovascular measures served as indicators of sympathetic nervous system (SNS) activation by cold pressor and antagonism by propranolol, and were collected during all conditions. Cold pressor appeared to adequately agonize the SNS as indicated by significant increases in resting systolic and diastolic blood pressure and heart rate. Propranolol appeared to adequately antagonize the SNS for the participants. Jitter ratio demonstrated a statistically significant increase in the participants treated with propranolol. Speaking rate demonstrated a small but significant increase in the placebo control group during cold pressor. Gender differences were observed in a few measures. Cold pressor adequately agonized and propranolol adequately antagonized the SNS. No statistically significant differences across subjects were observed in the voice parameters during cold pressor-induced stress before treatment. Jitter ratio increased significantly during propranolol treatment and cold pressor. Speaking rate demonstrated a statistically significant increase during cold pressor in the placebo control group. Gender differences were observed, but were few.

Toward a more quantitative measure to assess severity of dysphonia: preliminary observations

Rating scales to determine the severity of dysphonia have shown considerable inter-rater variability. The objective of this study, therefore, was to investigate a more quantitative measure to perceptually rate the severity of dysphonia. The study was conducted on 10 participants with abuse-related dysphonia in two conditions, spontaneous speech, and paragraph reading. Four speech-language pathologists, who had experience with voice disorders, and one trained student counted the frequency of the nondysphonic syllables during the above two conditions. The voice samples were both recorded and transcribed for simultaneous analysis. All the recordings were randomized when presented to the raters. The raters circled the nondysphonic syllables while listening to each participant's recording. The nondysphonic syllables were counted, and a percentage of dysphonic severity was calculated for each participant to obtain a dysphonic severity percentage. Specific characteristics (eg, breathiness, noise, strain) were not specifically addressed, as they were components of the percentage of dysphonia obtained. The Cronbach's alpha revealed very high inter-rater reliability and high correlations among the raters for both spontaneous speech and paragraph reading, indicating reduced variability in raters' perceptions. This method appeared to be a more quantitative measure of perceptual ratings than current scales, which use general gradations of dysphonic severity. In addition, a naïve rater was successfully trained to use this method. This technique has the potential to be used in both pre- and posttherapy analysis, as well as during therapy, to determine progress.

Intonation and Phonation in Young Adults with Down Syndrome

This paper investigates various aspects of intonation and phonation in young adults with Down syndrome. The speech of nine speakers with Down syndrome was analyzed acoustically for different aspects of intonation and phonation. The results of these analyses were compared to similar speech samples of nine typical speakers of Standard British English. The controls were matched for age and gender. Different aspects of speakers' individual pitch framework were analyzed, ie, organic and linguistic pitch ranges, voice compass, and declination. Phonation was investigated acoustically as maximum phonation time, jitter, and shimmer. The results suggest that speakers with Down syndrome exhibit normal respiratory capacity, a reduced organic pitch range, and a somewhat reduced linguistic pitch range. In terms of the melodic variation in the intonation patterns, a higher mean speaking fundamental frequency was found with generally a less melodious rendering of the intonation contours and a shallower declination. The analysis of phonation indicated reduced jitter, while shimmer did not deviate significantly from the control group. Although the observed deviations in the Down syndrome speakers are suggestive of lack of laryngeal control at the physiological level, it cannot be excluded at this stage that they may also reflect personality characteristics or the use of different linguistic strategies in implementing intonation patterns.

Voice outcomes after radiotherapy treatment for early glottic cancer: assessment using multidimensional tools

BACKGROUND

This is the first prospective study to use instrumental and both clinician- and client-rated auditory-perceptual measures to examine voice and voice-related quality of life changes in patients after curative radiotherapy for early glottic cancer.

METHOD

Thirty patients undergoing curative radiotherapy treatment for early glottic cancer completed the following: 3 voice tasks for acoustic, aerodynamic, and auditory-perceptual voice measures (therapist-rated); a patient self-report rating of voice quality; and a voice-related quality of life assessment before and 12 months after radiotherapy.

RESULTS

Patients' perceptions of their voice quality and their voice-related quality of life significantly improved posttreatment, as did acoustic, aerodynamic, and auditory-perceptual voice measures. Mean speaking fundamental frequency did not change significantly, although breathiness and strain in the voice recordings were demonstrably reduced.

CONCLUSION

In describing postradiotherapy voices in this study, pertinent measures of voice outcomes have been established, setting the benchmark for comparison in future cohort studies.

Objective Voice Analysis in Dysphonic Patients: New Data Including Nonlinear Measurements

OBJECTIVES/HYPOTHESIS

This report describes a comparative study of objective voice evaluation using a multiparametric protocol including aerodynamic parameters and linear and nonlinear acoustic parameters recorded on an EVA(R) workstation and perceptual voice analysis by a jury.

STUDY DESIGN

A total of 449 samples were retrospectively selected including 391 patients with pathological voices (308 women and 141 men) and 58 controls with normal voices (38 women and 20 men). A prospective complementary study concerning 43 female patients and 3 controls is presented.

METHODS

Objective measures included fundamental frequency (Fo), intensity, jitter, signal-to-noise ratio (SNR), Lyapunov coefficient (Lya), oral airflow (OAF), estimated subglottic pressure (ESGP), maximum phonatory time (MPT) and vocal range. A jury of 4 experienced listeners was instructed to classify voice samples (continuous speech) according to the G (overall dysphonia) component of the GRBAS score on a Visual Analogue Scale (VAS) secondarily transformed in a scale ranging from 0 for normal to 3 for severe dysphonia.

RESULTS

It was shown that a nonlinear combination of only 7 parameters in women (vocal range, Lya, ESGP, MPT, OAF, SNR, and Fo) and 6 parameters in men (vocal range, Lya, OAF, ESGP, Fo, SNR) allowed classification of 81% voice samples in the same grade as the jury in women and 84% in men. In the prospective study, 80.5% were correctly classified with the same set of objective measurements.

DISCUSSION

The relative importance of the different objective parameters in this type of discriminant analysis is dealt with. Special emphasis is placed on Lya.

Acoustic and Aerodynamic Measurement of Speech Production after Supracricoid Partial Laryngectomy

BACKGROUND

Supracricoid partial laryngectomy (SCPL) results in laryngeal preservation in more than 95% of patients with T2 glottic carcinoma. After surgery, glottis function is characterized by an absence of vocal cords and poor glottis closure. Voice is an important postSCPL quality of life factor.

OBJECTIVE

Enhance postSCPL vocal function. Obtain postsurgical acoustic and aerodynamic measurements and correlate multiple objective parameters with perceptual results.

METHOD

Continuous speech voice samples from 61 patients who had undergone SCPL more than 1 year before were scored according to the global, roughness, breathiness, asthenia, and strain (GRBAS) scale by a jury of listeners. Acoustic and aerodynamic parameters were recorded: fundamental frequency (F0), intensity, jitter, shimmer, signal-to-noise ratio (SNR), signal-to-noise ratio greater than 1 kHz (SNR>1), oral airflow (OAF), maximum phonation time (MPT), and estimated subglottic pressure (ESGP). Nonparametric tests and logistic regression analysis were used to compare objective measurements and perceptual evaluations.

RESULTS

All patients had various degrees of dysphonia: grade 1, 4.9%; grade 2, 55.7%; and grade 3, 39.4%. Correlations between perceptual grades and objective parameters were obtained for jitter, shimmer, SNR, SNR>1, ESGP, and OAF. No correlations were obtained between the different parameters and age, number of arytenoids, and time elapsed since surgery (TESS). Logistic regression analysis of jitter, SNR, ESGP, and OAF parameters revealed 92.6% agreement with the perceptual evaluation results.

Suitability of Acoustic Perturbation Measures in Analysing Periodic and Nearly Periodic Voice Signals

In recent years, acoustic perturbation measurement has gained clinical and research popularity due to the ease of availability of commercial acoustic analysing software packages in the market. However, because the measurement itself depends critically on the accuracy of frequency tracking from the voice signal, researchers argue that perturbation measures are not suitable for analysing dysphonic voice samples, which are aperiodic in nature. This study compares the fundamental frequency, relative amplitude perturbation, shimmer percent and noise-to-harmonic ratio between a group of dysphonic and non-dysphonic subjects. One hundred and twelve dysphonic subjects (93 females and 19 males) and 41 non-dysphonic subjects (35 females and 6 males) participated in the study. All the 153 voice samples were categorized into type I (periodic or nearly periodic), type II (signals with subharmonic frequencies that approach the fundamental frequency) and type III (aperiodic) signals. Only the type I (periodic and nearly periodic) voice signals were acoustically analysed for perturbation measures. Results revealed that the dysphonic female group presented significantly lower fundamental frequency, significantly higher relative amplitude perturbation and shimmer percent values than the non-dysphonic female group. However, none of these three perturbation measures were able to differentiate between male dysphonic and male non-dysphonic subjects. The noise-to-harmonic ratio failed to differentiate between the dysphonic and non-dysphonic voices for both gender groups. These results question the sensitivity of acoustic perturbation measures in detecting dysphonia and suggest that contemporary acoustic perturbation measures are not suitable for analysing dysphonic voice signals, which are even nearly periodic.

Prediction of Laryngeal Aspiration Using Voice Analysis

OBJECTIVE

To determine the diagnostic value of voice analysis to screen for patients with high risk of clinically significant aspiration.

DESIGN

A total of 93 patients referred for a videofluoroscopic swallowing study were included in the study. Voice analyses were performed before and after videofluoroscopic swallowing study, and five acoustic variables were measured, including average fundamental frequency, relative average perturbation, shimmer percentage, noise-to-harmonic ratio, and voice turbulence index. The patients were divided into two groups based on the results of the videofluoroscopic swallowing study: a high-risk group with patients who had the ingested materials on or below the vocal cords and a low-risk group with patients who did not have the ingested materials on or below the vocal cords. The changes of each acoustic variable before and after the videofluoroscopic swallowing study were compared between the two groups.

RESULTS

Relative average perturbation, shimmer percentage, noise-to-harmonic ratio, and voice turbulence index were significantly increased after videofluoroscopic swallowing study in the high-risk group as compared with the low-risk group (P < 0.05). The change of average fundamental frequency, however, was not significantly different between the two groups (P > 0.05). According to the receiver operating characteristics curve, the sensitivity of these acoustic variables in detecting aspiration or penetration ranged from 68.9% to 91.1% and specificity ranged from 68.8% to 97.9%. Relative average perturbation was the most accurate variable, with a sensitivity of 91.1% and a specificity of 97.9% in predicting aspiration or penetration. The combination of relative average perturbation and noise-to-harmonic ratio increased the sensitivity to 100% but reduced the specificity to 77.1%.

CONCLUSION

Voice analysis is a safe, noninvasive, and reliable screening tool for patients with dysphagia and can detect patients at high risk of clinically significant aspiration, thereby augmenting clinical bedside examination.

Evaluación perceptual de la disfonía: correlación con los parámetros acústicos y fiabilidad

The perceptual GRBAS scale for analysis of voice quality is quite important clinically in voices that cannot be effectively analyzed with a voicing parameter method like vocalizations with strong subharmonics and modulations and in chaotic or random voices. In the present study, two experiments were performed: Firstly, GRBAS/acoustical correlations were investigated in 107 pathological voices. Secondly, the GRBAS interrater and intrarater agreement. The severity of dysphonia was assesed better by breath related parameters and low fundamental frequencies. The presence of subharmonics in the power spectrum had not a significant relationship with the degree of roughness. A (asthenic) and S (strain) scales. The results of this study show that GRBAS test-retest reliability and intrerrater agreement is high.

Cepstral peak prominence: a more reliable measure of dysphonia

Quantification of perceptual voice characteristics allows the assessment of voice changes. Acoustic measures of jitter, shimmer, and noise-to-harmonic ratio (NHR) are often unreliable. Measures of cepstral peak prominence (CPP) may be more reliable predictors of dysphonia. Trained listeners analyzed voice samples from 281 patients. The NHR, amplitude perturbation quotient, smoothed pitch perturbation quotient, percent jitter, and CPP were obtained from sustained vowel phonation, and the CPP was obtained from running speech. For the first time, normal and abnormal values of CPP were defined, and they were compared with other acoustic measures used to predict dysphonia. The CPP for running speech is a good predictor and a more reliable measure of dysphonia than are acoustic measures of jitter, shimmer, and NHR.

Analysis of voice and quantitative measurement of glottal gap after thyroplasty type I in the treatment of unilateral vocal paralysis

Thyroplasty type I is one of several surgical treatments in which improving the voice of unilateral vocal fold paralysis is the ultimate objective. The goal of the surgery is the medialization of the paralyzed vocal fold. The purpose of this study is to evaluate the effectiveness of thyroplasty type I through acoustical analysis, aerodynamic measures, and quantitative videostroboscopic measurements. We report on 20 patients with unilateral vocal cord paralysis who underwent thyroplasty type I. We performed preoperative and postoperative video image analysis (normalized glottal gap area) and computer-assisted voice analysis (fundamental frequency, jitter, shimmer, noise-to-harmonic ratio, mean phonation time, mean flow rate, mean subglottic pressure) in all patients. The glottal gap was significantly reduced after thyroplasty type I. Postoperative voice quality was characterized by an improved pitch and amplitude pertubation (jitter and shimmer), phonation time (mean phonation time), and subglottic pressure (mean subglottic pressure). Thyroplasty type I is an effective method for regaining glottal closure and vocal function.

The relationship between cepstral peak prominence and selected parameters of dysphonia

Traditional measures of dysphonia vary in their reliability and in their correlations with perceptions of grade. Measurements of cepstral peak prominence (CPP) have been shown to correlate well with perceptions of breathiness. Because it is a measure of periodicity, CPP should also predict roughness. The ability of CPP and other acoustic measures to predict overall dysphonia and the subcategories of breathiness and roughness in pathological voice samples is explored. Preoperative and postoperative speech samples from 19 patients with unilateral recurrent laryngeal nerve paralysis who underwent operative intervention were analyzed by trained listeners and by measures of smoothed CPP (CPPS), noise-to-harmonic ratio (NHR), amplitude perturbation quotient (APQ), relative average perturbation (RAP), and smoothed pitch perturbation quotient (sPPQ). The data were analyzed with bivariate Pearson correlation statistics. Grade of dysphonia and breathiness ratings correlated better with measurements of CPPS than with the other measures. CPPS from samples of connected speech (CPPS-s) best predicted overall dysphonia. None of the measures were useful in predicting roughness.

Objective voice analysis for dysphonic patients: a multiparametric protocol including acoustic and aerodynamic measurements

The purpose was to determine the clinical value of a multiparametric objective voice evaluation protocol including acoustic and aerodynamic parameters measured mainly on a sustained /a/. This was done by comparison with perceptual analysis of continuous speech by a jury composed of 6 experienced listeners. Voice samples (continuous speech) from 63 male patients with dysphonia and 21 control subjects with normal voices were recorded and assesed by a jury of listeners. The jury was instructed to classify voice samples according to the G (overall dysphonia) component of the GRBAS score on a 4-point scale ranging from 0 for normal to 3 for severe dysphonia. Objective parameters were recorded on an EVA workstation. As usual with this type of system, parameters were measured mainly on a sustained /a/. Measured parameters included fundamental frequency (F0), intensity, jitter, shimmer, signal-to-noise ratio, Lyapunov coefficient (LC), oral airflow (OAF), maximum phonatory time (MPT), and vocal range (range). Estimated subglottic pressure (ESGP) was determined on a series of /pa/. Discriminant analysis was performed to detect correlation between jury classification and combinations of parameters. Results showed that a nonlinear combination of only six parameters (range, LC, ESGP, MPT, signal-to-noise ratio, and F0) allowed 86% concordance with jury classification. Discussion deals with the relative importance of the different objective parameters for discriminant analysis. Special emphasis is placed on two measurements rarely made in routine clinical workup, i.e., estimated subglottic pressure and Lyapunov coefficient.

Acoustic discrimination of pathological voice: sustained vowels versus continuous speech

We investigated the ability of acoustic measures to discriminate between normal and pathological talkers. Two groups of measures were compared: (a) those extracted from sustained vowels and (b) those based on continuous speech samples. Nine acoustic measures, which include fundamental frequency and amplitude perturbation measures, long term average spectral measures, and glottal noise measures were extracted from both sustained vowel and continuous speech samples. Our experiments were performed on a published database of 53 normal talkers and 175 talkers with a pathological voice. The classification performance of the nine acoustic measures was quantified using linear discriminant analysis and receiver operating characteristic (ROC) curve analysis. When individual measures were considered in isolation, classification was more accurate for measures extracted from sustained vowels than for those based on continuous speech samples. Classification accuracy improved when combinations of acoustic parameters were considered. For such combinations of measures, classification results were comparable for measures extracted from continuous speech samples and for those based on sustained vowels.

The dysphonia severity index: an objective measure of vocal quality based on a multiparameter approach

The vocal quality of a patient is modeled by means of a Dysphonia Severity Index (DSI), which is designed to establish an objective and quantitative correlate of the perceived vocal quality. The DSI is based on the weighted combination of the following selected set of voice measurements: highest frequency (F(0)-High in Hz), lowest intensity (I-Low in dB), maximum phonation time (MPT in s), and jitter (%). The DSI is derived from a multivariate analysis of 387 subjects with the goal of describing, purely based on objective measures, the perceived voice quality. It is constructed as DSI = 0.13 x MPT + 0.0053 x F(0)-High - 0.26 x I-Low - 1.18 x Jitter (%) + 12.4. The DSI for perceptually normal voices equals +5 and for severely dysphonic voices -5. The more negative the patient's index, the worse is his or her vocal quality. As such, the DSI is especially useful to evaluate therapeutic evolution of dysphonic patients. Additionally, there is a high correlation between the DSI and the Voice Handicap Index score.

Identification of pathological voices using glottal noise measures

We investigated the abilities of four fundamental frequency (F0)-dependent and two F0-independent measures to quantify vocal noise. Two of the F0-dependent measures were computed in the time domain, and two were computed using spectral information from the vowel. The F0-independent measures were based on the linear prediction (LP) modeling of vowel samples. Tests using a database of sustained vowel samples, collected from 53 normal and 175 pathological talkers, showed that measures based on the LP model were much superior to the other measures. A classification rate of 96.5% was achieved by a parameter that quantifies the spectral flatness of the unmodeled component of the vowel sample.

Relationship between subjective voice complaints and acoustic parameters in female teachers' voices

The aim of the study was to identify the acoustic correlates of female teachers' subjective voice complaints by recording their voices in their working environment. The subjects made recordings during lessons (N = 10) and breaks (N = 11). The subjects were divided into 2 groups: those with few voice complaints (FC group) and those with many voice complaints (MC group). The speech sample made in the breaks was maximally sustained /a/, from which fundamental frequency (F0), jitter, and shimmer were analyzed. The classroom samples were analyzed for F0, sound pressure level (SPL), and F0 time (the active vibration time of the vocal folds). Additionally, an index for assessing voice loading is presented. The results revealed a tendency of the MC group to have higher F0 and lower SPL and perturbation values than the FC group. The index values correlated moderately with the subjective vocal complaints.

Objective aerodynamic and acoustic measurement of voice improvement after phonosurgery

HYPOTHESIS

Objective analysis of the outcome of phonosurgery is needed to allow comparison of different surgical techniques or indications, or both. We tried to demonstrate that measurement of mean oral airflow during the production of a sustained vowel could be used in combination with acoustic measurements such as jitter or shimmer for assessment of voice improvement after phonosurgery.

STUDY DESIGN

This prospective study included 27 consecutive patients who underwent phonosurgery during a 3-month period.

METHOD

Perceptual analysis served as the "gold standard." Objective measurements (oral airflow, jitter, shimmer) on the most stable portion of a sustained vowel /a/ were made using the EVA system (SQ-Lab, Aix-en-Provence, France).

RESULTS

Oral airflow was significantly greater in patients with poor perceptual results than in patients with good perceptual results. Jitter and shimmer were not significantly different because of the dispersion of the values. Discriminant factorial analysis showed that a combination of jitter, shimmer, and oral airflow was able to identify patients with good or poor perceptual results in 77% of cases.

CONCLUSIONS

Oral airflow allows simple, quick, and reliable assessment of the outcome of phonosurgery and can be used in everyday clinical practice.

Self-organizing map for the classification of normal and disordered female voices

The goal of this research was to train a self-organizing map (SOM) on various acoustic measures (amplitude perturbation quotient, degree of voice breaks, rahmonic amplitude, soft phonation index, standard deviation of the fundamental frequency, and peak amplitude variation) of the sustained vowel /a/ to enhance visualization of the multidimensional nonlinear regularities inherent in the input data space. The SOM was trained using 30 spasmodic dysphonia exemplars, 30 pretreatment functional dysphonia exemplars, 30 post-treatment functional dysphonia exemplars, and 30 normal voice exemplars. After training, the classification performance of the SOM was evaluated. The results indicated that the SOM had better classification performance than that of a stepwise discriminant analysis over the original data. Analysis of the weight values across the SOM, by means of stepwise discriminant analysis, revealed the relative importance of the acoustic measures in classification of the various groups. The SOM provided both an easy way to visualize multidimensional data, and enhanced statistical predictability at distinguishing between the various groups (over that conducted on the original data set). We regard the results of this study as a promising initial step into the use of SOMs with multiple acoustic measures to assess phonatory function.

A study of the effectiveness of voice therapy in the treatment of 45 patients with nonorganic dysphonia

Forty-five patients diagnosed as having nonorganic dysphonia were assigned in rotation to 1 of 3 groups. Patients in group 1 received no treatment and acted as a control group. Patients in groups 2 and 3 received a program of indirect therapy and direct with indirect therapy, respectively. A range of qualitative and quantitative measures were carried out on all patients before and after treatment to evaluate change in voice quality over time. Results revealed a significant difference between the 3 treatment groups in the amount of change for the voice severity, electrolaryngograph, and shimmer measurements and on ratings provided by a patient questionnaire (P<0.05). However, other measures failed to show significant differences between the 3 groups. Most of the patients (86%) in group 1 showed no significant change on any of the measures. Some patients in treatment group 2 (46%) showed significant change in voice quality. Fourteen out of 15 patients (93%) in treatment group showed significant changes in voice quality.

Acoustic and perceptual evaluation of laryngeal reinnervation by ansa cervicalis transfer

OBJECTIVES/HYPOTHESIS

To evaluate the acoustic and perceptual results of laryngeal reinnervation with ansa cervicalis to recurrent laryngeal nerve anastomosis.

STUDY DESIGN

Retrospective study of voice samples from 12 patients with unilateral recurrent laryngeal nerve paralysis, treated with ansa cervicalis to recurrent laryngeal nerve anastomosis. Samples were recorded before surgery and at least 8 months after surgery.

METHODS

The samples were subjected to several acoustic analyses sensitive to paralytic dysphonia, including cepstral peak prominence, noise-to-harmonics ratio, and measures of frequency and amplitude perturbation. The voice samples from the patients were randomized with age- and sex-matched samples from normal subjects and judged by trained listeners for overall dysphonia, roughness, breathiness, asthenia, and strain. The preoperative and postoperative results were compared statistically, and the postoperative results were compared with the matched normal subjects.

RESULTS

As a group, the patients showed improvement (P < .05) in cepstral peak prominence, frequency perturbation, and perceptual judgments of overall dysphonia, breathiness, and asthenia. The best results occurred in patients with isolated vocal fold paralysis. The postoperative group as a whole did not improve to the level seen in matched normals. Suboptimal results were seen primarily in patients with untreated laryngeal or extralaryngeal pathology beyond the laryngeal paralysis.

CONCLUSIONS

These data suggest that laryngeal reinnervation has the potential to bring about a return to normal or near-normal voice in patients with isolated unilateral vocal fold paralysis.

Effects of perceptual training based upon synthesized voice signals

28 undergraduate students participated in a perceptual voice experiment to assess the effects of training utilizing synthesized voice signals. An instructional strategy based upon synthesized examples of a three-part classification system: "breathy," "rough," and "hoarse," was employed. Training samples were synthesized with varying amounts of jitter (cycle-to-cycle deviation in pitch period) and harmonic-to-noise ratios to represent these qualities. Before training, listeners categorized 60 pathological voices into "breathy," "rough," and "hoarse," largely on the basis of fundamental frequency. After training, categorizations were influenced by harmonic-to-noise ratios as well as fundamental frequency, suggesting that listeners were more aware of spectral differences in pathological voices associated with commonly occurring laryngeal conditions. 40% of the pathological voice samples remained unclassified following training.

Comparison of voice analysis systems for perturbation measurement

Dysphonic voices are often analyzed using automated voice analysis software. However, the reliability of acoustic measures obtained from these programs remains unknown, particularly when they are applied to pathological voices. This study compared perturbation measures from CSpeech, Computerized Speech Laboratory, SoundScope, and a hand marking voice analysis system. Sustained vowels from 29 male and 21 female speakers with mild to severe dysphonia were digitized, and fundamental frequency (F0), jitter, shimmer, and harmonics- or signal-to-noise ratios were computed. Commercially available acoustical analysis programs agreed well, but not perfectly, in their measures of F0. Measures of perturbation in the various analysis packages use different algorithms, provide results in different units, and often yield values for voices that violate the assumption of quasi-periodicity. As a result, poor rank order correlations between programs using similar measures of perturbation were noted. Because measures of aperiodicity apparently cannot be reliably applied to voices that are even mildly aperiodic, we question their utility in quantifying vocal quality, especially in pathological voices.

Pathologic voice type and the acoustic prediction of severity

We hypothesized that acoustic measures would predict dysphonic severity with differential results for pathological voice types. An instructional program based upon synthesized voice signals was developed to facilitate an awareness of prototypical voice types. Eighty phonatory samples representing normal subjects as well as patients with unilateral vocal fold paralysis, vocal nodules, and functional dysphonia were analyzed acoustically on the basis of four measures: average fundamental frequency (F0), jitter, shimmer, and harmonic/noise ratio (H/N ratio). Following training, 29 listeners classified 62% of the phonatory samples on the basis of breathy, hoarse, rough, and normal. Dysphonic severity of rough voices was predicted more successfully by H/N ratio (r2 = .73) than by shimmer (r2 = .43). Dysphonic severity of breathy voices was predicted only by the combined features of less jitter, more shimmer, and lower H/N ratio (r2 = .74). No combination of acoustic variables was successful in the prediction of the hoarse voice type.