Normophonic Speakers Research Articles

The Relationship between Traditional Acoustic Measures and Cepstral Analysis of Voice

Introduction: In this study, the correlations between traditional acoustic measures (TAMs) and cepstral analysis (CA) were explored in Persian. Methods: This investigation was a cross-sectional study including 179 dysphonic (n = 141) and normophonic (n = 38) speakers. The TAMs (jitter, shimmer, and noise-to-harmonic ratio) and CA (cepstral peak prominence and cepstral peak prominence smoothed) values were obtained during vowel prolongation, reading a standard sentence, and a nonstandard running speech sample using Praat software. The difference of acoustic measures between normophonic and dysphonic speakers and intercorrelation among acoustic measures and correlation between the acoustic measures and perceived dysphonia levels were analyzed with independent t test, Mann-Whitney U test, Pearson, Spearman, and Kendall’s Tau-b correlation tests using IBM SPSS Statistics. Results: The findings showed that dysphonic speakers had higher TAM values and lower CA values than normophonic speakers (p < 0.05). In dysphonic speakers, a large correlation was discovered among all acoustic measurements (r = 0.52–0.96; p < 0.05), while in various perceived dysphonic speakers, there was a correlation of varying strength (r = 0.25–0.97; p < 0.05). Ultimately, there was a significant small-to-large correlation between the acoustic measures and perceived dysphonia levels (r = 0.34–0.58; p < 0.05). Conclusion: This research demonstrated that Persian speakers with dysphonia experienced a rise in TAM and a corresponding reduction in CA. In the future, multi-parametric indices can be developed using both TAM and CA to include various aspects of vocal production and yield a single, comprehensive value.

Supraglottic Laryngeal Maneuvers in Adductor Laryngeal Dystonia During Connected Speech

ObjectiveAdductor laryngeal dystonia (AdLD) disrupts fine motor movements of vocal folds during speech, resulting in a strained, broken, and strangled voice. Laryngeal high-speed videoendoscopy (HSV) in connected speech enables the direct visualization of detailed laryngeal dynamics, hence, it can be effectively used to study AdLD. The current study utilizes HSV to investigate supraglottic laryngeal tissue maneuvers obstructing the view of the vocal folds, in AdLD and normophonic speakers during connected speech. Characterizing the laryngeal maneuvers in these groups can facilitate a deeper understanding of the normophonic voice physiology and AdLD voice pathophysiology. MethodsHSV data were obtained from six normophonic speakers and six patients with AdLD during production of connected speech. Three experienced raters visually analyzed the data to determine laryngeal tissues leading to obstructions of vocal folds in HSV images. The raters recorded the duration of each obstruction and indicated the specific tissue(s) leading to the obstruction After the completion of their individual visual analysis, the raters came to consensus about their observations and measurements. ResultsStatistical analysis indicated that AdLD patients exhibited higher occurrences of vocal fold obstructions and longer durations of obstructions compared to the normophonic group. Similar obstruction types were found in both groups, with the epiglottis being the primary site of obstruction for both. Participants with AdLD displayed significantly elevated occurrences of sphincteric compression resulting in vocal fold obstruction. ConclusionHSV can be used to study the movements of laryngeal tissues in detail during connected speech. The analysis of supraglottic laryngeal tissue dynamics in speech can help us characterize the AdLD pathophysiology. The study's findings regarding the tissues implicated in obstructions may potentially inform the development of patient-specific therapeutic strategies targeting individual control over specific laryngeal muscles during phonation and speech production.

Has the Prevalence of Creaky Voice Increased Among Finnish University Students From the 1990'S to the 2010'S?

Everyday observations indicate that creaky voice has become common in Finland in recent years. Previous studies suggest that this trend is also occurring in other countries. This cross-sectional study investigates the use of creaky voice among Finnish university students from the 1990's to the 2010's. Material was obtained from a sound archive. It consisted of 200 samples from normophonic speakers (95 males, 105 females; mean age 23.7 years, SD 3.3 years, range 19-35 years). Normophonia was checked by two speech therapists in a preliminary perceptual analysis. Thereafter, two voice specialists rated the amount of creak and strain. A scale of 0-4 was used (0=none, 4=a lot). The inter- and intrarater reliability for the listening evaluations were satisfactory (for creaky phonation, rho=0.611, P < 0.001 for interrater reliability and rho=0.540, P < 0.001 for intrarater reliability; for strain, rho=0.463, P < 0.001 and rho=0.697, P < 0.001 for inter- and intrarater reliability, respectively). These results revealed a significant increase in the amount of perceived creak in females (from 1.04, SD 0.69 to 1.55, SD 1.06; P < 0.05, Mann-Whitney U test). In males, no significant change was found. However, the frequency of creaky voice use increased in both genders. No male speakers from the 1990's were rated as using "a lot" of creaky voice, but 2.3% of male speakers from the 2010's received this rating. Male speakers who were rated "quite a lot" increased from 5.9% in the 1990's to 18.1% in the 2010's. Female speakers rated "a lot" increased from 0% to 6%, and female speakers rated "quite a lot" increased from 7% to 25.8% over the studied time periods. Creaky phonation and strain correlated slightly in males (rho=0.24, P < 0.05) and moderately in females (rho=0.55, P < 0.001). Age did not correlate with the amount of creaky phonation (rho=0.005, P > 0.10 for males, rho=-0.011, P > 0.10 for females). It can be concluded that the prevalence of creaky voice has increased among young Finnish speakers, particularly females.

Voice Quality in Telephone Interviews: A preliminary Acoustic Investigation

To investigate the impact of standardized mobile phone recordings passed through a telecom channel on acoustic markers of voice quality and on its perception by voice experts in normophonic speakers. Continuous speech and a sustained vowel were recorded for fourteen female and ten male normophonic speakers. The recordings were done simultaneously with a head-mounted high-quality microphone and through the telephone network on a receiving smartphone. Twenty-two acoustic voice quality, breathiness and pitch-related measures were extracted from the recordings. Nine vocologists perceptually rated the G, R and B parameters of the GRBAS scale on each voice sample. The reproducibility, the recording type, the stimulus type and the gender effects, as well as the correlation between acoustic and perceptual measures were investigated. The sustained vowel samples are damped after one second. Only the frequencies between 100 and 3700Hz are passed through the telecom channel and the frequency response is characterized by peaks and troughs. The acoustic measures show a good reproducibility over the three repetitions. All measures significantly differ between the recording types, except for the local jitter, the harmonics-to-noise ratio by Dejonckere and Lebacq, the period standard deviation and all six pitch measures. The AVQI score is higher in telephone recordings, while the ABI score is lower. Significant differences between genders are also found for most of the measures; while the AVQI is similar in men and women, the ABI is higher in women in both recording types. For the perceptual assessment, the interrater agreement is rather low, while the reproducibility over the three repetitions is good. Few significant differences between recording types are observed, except for lower breathiness ratings on telephone recordings. G ratings are significantly more severe on the sustained vowel on both recording types, R ratings only on telephone recordings. While roughness is rated higher in men on telephone recordings by most experts, no gender effect is observed for breathiness on either recording types. Finally, neither the AVQI nor the ABI yield strong correlations with any of the perceptual parameters. Our results show that passing a voice signal through a telecom channel induces filter and noise effects that limit the use of common acoustic voice quality measures and indexes. The AVQI and ABI are both significantly impacted by the recording type. The most reliable acoustic measures seem to be pitch perturbation (local jitter and period standard deviation) as well as the harmonics-to-noise ratio from Dejonckere and Lebacq. Our results also underline that raters are not equally sensitive to the various factors, including the recording type, the stimulus type and the gender effects. Neither of the three perceptual parameters G, R and B seem to be reliably measurable on telephone recordings using the two investigated acoustic indexes. Future studies investigating the impact of voice quality in telephone conversations should thus focus on acoustic measures on continuous speech samples that are limited to the frequency response of the telecom channel and that are not too sensitive to environmental and additive noise.

Prevalence of arytenoid adduction asymmetry in normophonic speakers: a retrospective study.

This study aimed to assess the incidence and severity of arytenoid adduction asymmetry in normophonic speakers and to identify related demographic characteristics. A retrospective observational clinical study on normophonic patients was conducted. Videos of flexible laryngoscopy of the study group (aged 18 to 45 years) were reviewed. Arytenoid adduction asymmetry, if present, was graded as mild (grade 1), moderate (grade 2) and severe (grade 3). Video recordings of 347 normophonic patients were analysed. The total prevalence of arytenoid adduction asymmetry was 36.4 per cent, with a predominance in males and on the right side. Right-sided predominance was statistically significant (p < 0.01). A total of 60.3 per cent of patients with arytenoid adduction asymmetry had only mild asymmetry, whereas 34.9 per cent had moderate asymmetry. Only 4.8 per cent showed severe asymmetry. Arytenoid adduction asymmetry is found in more than one third of the normophonic population, has significant right-sided preponderance and was more common in males.

The effect of the auditory signal on videolaryngostroboscopy ratings and interpretation

ObjectiveThe primary aim of this study was to examine the effect of the videolaryngostroboscopic auditory signal on videolaryngostroboscopy (VLS) ratings and interpretation in normophonic and dysphonic speakers. Study DesignProspective repeated measures design MethodEight speech-language pathologists evaluated rigid VLS exams obtained from 12 dysphonic speakers with vocal fold pathology and 4 normophonic speakers with normal VLS exams. VLS exams were evaluated with the auditory signal present and absent with a washout period between rating sessions. VLS measures were obtained using the Voice-vibratory Assessment of Laryngeal Imaging (VALI) and a 100mm visual analog scale (VAS). The effects of the auditory signal and its interaction with voice quality severity on 9 VLS ratings, diagnostic billing codes, and treatment recommendations were examined. ResultsThere was no effect of auditory information on VLS measures or overall severity of laryngeal function evaluated using the VAS (ps > 0.05). There was a main effect of auditory information and a significant interaction with voice quality severity for only one VLS measure (non-vibrating portion-left) evaluated using the VALI (P = 0.05). Post-hoc analysis for this rating showed significant increases (t-test adjusted P < 0.05) when voice quality severity was moderate-severe (M = 4.8%; SD = 1.65%) and auditory information was present. Agreement in individual clinician's selection of diagnostic codes (73%) and treatment recommendations (65.6%) when auditory cues were present and absent was moderate to high. ConclusionThe presence of the videolaryngostroboscopic auditory signal had a minimal effect on VLS ratings, treatment recommendations, or diagnostic billing codes.

Does the Acoustic Voice Quality Index (AVQI) Correlate with Perceived Creak and Strain in Normophonic Young Adult Finnish Females?

Background: The Acoustic Voice Quality Index (AVQI) is a correlate of dysphonia. It has been found to differentiate between dysphonic and normophonic speakers and to indicate the effects of voice therapy. This study investigates how the AVQI reacts towards creak and strain, which are common in normophonic speakers. Methods: The material was obtained from an earlier study on 104 Finnish female university students (mean age 24.3 years, SD 6.3 years) with no known pathology of voice or hearing and a perceptually normal voice (G = 0 in GRBAS), who were recorded while reading aloud a standard text and sustaining the vowel [a:]. Perceptual analysis for the amount of creak and strain was carried out by 2 expert listeners. In this study, the AVQI v03.01 was analyzed and correlated with perceptual evaluations. Samples with low and high amounts of creak and strain were compared with t tests. Results: On average, the AVQI was below the threshold value of dysphonia in the Finnish population. The AVQI (ρ = 0.35, p = 0.000) and its subparameters, smoothed cepstral peak prominence (CPPS; ρ = –0.35, p = 0.000) and harmonics-to-noise ratio (HNR; ρ = –0.30, p = 0.002) showed low but significant correlations with creak. Strain had low but significant correlations with spectral Slope (ρ = 0.38, p = 0.000) and Tilt (ρ = –0.40, p = 0.009). The AVQI was lower (better) in samples that were evaluated as having a high amount of strain, but the difference was not significant. Only CPPS differentiated significantly between low and high amounts of creak. Conclusion: The AVQI does not seem to differentiate between high and low amounts of creak and strain in normophonic speakers.

Description of the Features and Vibratory Behaviors of the Nyquist Plot Analyzed From Laryngeal High-Speed Videoendoscopy Images

Facilitative playback-based subjective measures offer a more reliable evaluation of the vocal fold vibration than those derived from direct inspection of video playback. One of the measures is a Nyquist plot, which presents the analyzed cycle-to-cycle vibratory information in a graphical form. While the potential is evident, the information of the features of the Nyquist plot, which the evaluation is based on, is still incomplete. The current identified features and their vibratory behaviors may be inadequate to guarantee accurate interpretation of the findings. The present study aims to address this issue by examining the features of the Nyquist plot and their vibratory behaviors. A total of 56 young normophonic speakers, that is, 20 males and 36 females were recruited as the participants. Each of them underwent laryngeal high-speed videoendoscopy to record the images of the vocal fold vibration, which were then analyzed to generate the Nyquist plots. The features were identified by inspecting the properties of the plot points forming the Nyquist plots. For each identified feature, its vibratory behaviors were examined. The results revealed four features: rim contour depicting the longitudinal phase difference; left edge shape signifying the glottal configuration, phase closure, and closed phase duration; rim width and rim pattern visualizing the regularity of glottal areas and the regularity of the intracycle variations, respectively. The findings present a more complete reference of the features and their vibratory behaviors that is pertinent for the Nyquist plot interpretation.

Acoustic Breathiness Index for the Japanese-Speaking Population: Validation Study and Exploration of Affecting Factors

Objectives The purposes of this study were to validate the Acoustic Breathiness Index (ABI) for the Japanese-speaking population and to determine whether it is independent of factors such as sex, age, and perceptual ratings of roughness. Method First, the concurrent validity of the ABI for perceptual breathiness was evaluated on the concatenations of continuous speech and sustained vowels from 288 patients with varying degrees of dysphonia. The diagnostic accuracy was examined on 343 samples with 55 additional normophonic speakers. Second, the validity related to responsiveness-to-change was estimated on 222 samples obtained before and after interventions for 111 voice-disordered patients. Third, the relationships between the ABI and other variables (i.e., perceptual hoarseness/breathiness/roughness, sex, and age) were explored using bivariate and multivariate analyses for the 288 patients. Results First, the concurrent validity and the responsiveness-to-change validity were confirmed by strong correlation coefficients of .890 and .878, respectively. Second, the receiver operating characteristic analysis showed the area under the curve to be 0.939, indicating excellent accuracy. The ABI of 3.44 exhibited a sensitivity of 76.3% and a specificity of 94.1%. Third, although bivariate analyses revealed a weak relationship between ABI and roughness and an ABI difference by age, multiple regression analyses showed a strong relation between only ABI and breathiness, without a meaningful contribution from roughness, sex, and age factors. Conclusion The study confirmed that the ABI is an accurate and specific tool to estimate breathiness levels in the Japanese-speaking population and neither roughness, sex, nor age significantly affects the ABI.

Intertext Variability of Smoothed Cepstral Peak Prominence, Methods to Control It, and Its Diagnostic Properties

This study aimed to estimate the intertext variability of smoothed cepstral peak prominence (CPPS), examine whether sound-processing techniques improved its variability and diagnostic capability, and evaluate the degree of intertext variability in detail with reference to the CPPS variabilities in sustained vowels. This was a retrospective study. Text readings of 58 Japanese syllables were recorded from 210 speakers with different diagnoses and varying degrees of dysphonia, and were divided into six passages. Applying the sound-processing techniques to those passages, we prepared three sample types: (1) nonprocessed, (2) only-loud, and (3) only-voiced samples. The intertext CPPS variability and diagnostic properties were compared across the passages and sample types. For detailed analysis, we subsequently extracted 63 normophonic speakers who maintained constant quality in their vowel utterances to evaluate the degree of intertext CPPS variability in relation to the variabilities between repeated identical vowels and across different vowels. Although several combinations of passages showed moderate-to-large CPPS variabilities, those variabilities were decreased by either technique, especially the deletion of silent segments, which resulted in the best diagnostic accuracy. The degree of intertext CPPS variability for the only-voiced samples was comparable to that of the CPPS variabilities in sustained vowels. The sound-processing technique removing silent segments should be applied to enhance the diagnostic properties of CPPS. The additional technique of deleting unvoiced segments is worth adopting if clinicians and researchers seek to attenuate the influence of text differences in calculating CPPS values.

Does the Accuracy of Medical Diagnoses Affect Novice Listeners' Auditory-Perceptual Judgments of Dysphonia Severity?

To determine whether the presence and accuracy of a laryngeal medical diagnosis affects novice listeners' judgments of dysphonia. Prospective, within subjects, modified factorial experimental design. Twenty-six speakers with dysphonia and four normophonic speakers provided speech recordings. Forty novice clinicians evaluated speech samples for roughness and breathiness using 100-mm visual analog scales in two conditions. First, speech samples were presented without diagnostic information. In the second condition, 50% of the speech samples were presented with the accurate laryngeal medical diagnosis, while the other 50% of samples were presented with an inaccurate (alternative) diagnosis. Results showed that judgments of dysphonia were affected by the presence of both accurate and inaccurate diagnoses. As expected, when compared to no known diagnosis, judgments of roughness significantly increased in severity when an accurate diagnostic label of vocal fold lesions was presented. Likewise, in comparison to no known diagnosis, judgments of breathiness trended toward an increase in severity when an accurate diagnostic label of vocal fold paralysis/paresis was presented. Interestingly, increases in perceived severity of dysphonia were also observed with the presentation of inaccurate diagnoses, with the overall effect of inaccurate diagnostic information being greater than accurate diagnoses. Specifically, increases in perceived roughness and breathiness were observed when inaccurate diagnoses included benign vocal fold lesion(s) and vocal fold paralysis/paresis. In contrast, inaccurate diagnostic labels indicating "clear larynx" or diagnoses other than benign vocal fold lesion(s) or paralysis/paresis resulted in decreased perceived roughness and breathiness severity. The magnitude of the differences in perceived severity between conditions was overall reduced for breathiness compared to roughness. Sources of bias such as knowledge and accuracy of medical diagnoses should be considered when novice clinicians use auditory-perceptual measures to evaluate dysphonia and measure treatment outcomes.

Assessment of disordered voices based on an optimized glottal source model

In this paper, a method for the assessment of disordered voices is proposed. A feature named mean opening quotient (MOQ) obtained from the glottal source estimation is used as an acoustic cue to summarize the degree of severity of the voice disorder. The analysis method uses the empirical mode decomposition algorithm to estimate the glottal source excitation signal from the speech signal. The logarithm of the magnitude spectrum of the speech signal is decomposed into oscillatory modes, called intrinsic mode functions, that are clustered into two classes, the spectral envelope and the harmonic component. The exploitation of the phase information jointly with the estimated harmonic component enables the estimation of the glottal source signal. An appropriate parametric model is fitted to the estimated glottal source excitation signal. The optimal parameters of the glottal source excitation model from which the MOQ is defined are obtained by using a genetic algorithm. The presented method is tested on a corpus of natural speech including the vowel [a] uttered by 22 normophonic speakers and 229 speakers with different degrees of dysphonia. Experimental results show that the proposed method is very effective for assessing the degree of severity of the voice disorder.

Performance of wavelet analysis and neural networks for pathological voices identification

Within the medical environment, diverse techniques exist to assess the state of the voice of the patient. The inspection technique is inconvenient for a number of reasons, such as its high cost, the duration of the inspection, and above all, the fact that it is an invasive technique. This study focuses on a robust, rapid and accurate system for automatic identification of pathological voices. This system employs non-invasive, non-expensive and fully automated method based on hybrid approach: wavelet transform analysis and neural network classifier. First, we present the results obtained in our previous study while using classic feature parameters. These results allow visual identification of pathological voices. Second, quantified parameters drifting from the wavelet analysis are proposed to characterise the speech sample. On the other hand, a system of multilayer neural networks (MNNs) has been developed which carries out the automatic detection of pathological voices. The developed method was evaluated using voice database composed of recorded voice samples (continuous speech) from normophonic or dysphonic speakers. The dysphonic speakers were patients of a National Hospital ‘RABTA’ of Tunis Tunisia and a University Hospital in Brussels, Belgium. Experimental results indicate a success rate ranging between 75% and 98.61% for discrimination of normal and pathological voices using the proposed parameters and neural network classifier. We also compared the average classification rate based on the MNN, Gaussian mixture model and support vector machines.

Visualizing Phase Relations of the Vocal Folds by Means of High-Speed Videoendoscopy

To present a method called Fourier image (FI) for analyzing high-speed videoendoscopy recordings. These false-color images visualize functional vocal fold properties and allow the quantification of phase relations. Furthermore, reference data for phase asymmetries in normophonic speakers as assessed with this method are provided. Prospective study. Phase relations between parts of the vocal folds were assessed using Fourier analysis of the grayscale fluctuations of corresponding pixel within the endoscopic high-speed videos. This phase information was displayed by means of colors and can thus be used to quantify left-right or anterior-posterior phase asymmetries. These phase relations were assessed in 11 normophonic speakers. Several instructive examples are given, which demonstrate how the FIs can be interpreted. From the cohort of clinically normophonic speakers, all but one displayed at least some extent of phase asymmetry. The method presented herein can be used to display functional vocal fold properties including the absence of oscillation, glottal insufficiency, and phase relations within one single image. The reference data showed that phase asymmetries seem to be frequent even in normophonic speakers.

Phase Asymmetries in Normophonic Speakers: Visual Judgments and Objective Findings

To ascertain the amount of phase asymmetry of the vocal fold vibration in normophonic speakers via visualization techniques and compare findings for habitual and pressed phonations. Fifty-two normophonic speakers underwent stroboscopy and high-speed videoendoscopy (HSV). The HSV images were further processed into 4 visual displays: HSV playbacks, digital kymography (DKG) playbacks, mucosal wave kymography playbacks, and static kymographic images of the medial line from the DKG playback. Two types of phase asymmetries, left-right and anterior-posterior, were rated on a scale from 1 to 5. Objective measures of left-right phase asymmetry were obtained. The majority of normophonic speakers (81%) were noted to display anterior-posterior asymmetry; however, 66% of those were characterized as mild. Seventy-nine percent of participants were noted to display left-right asymmetry; however, 72% of those were mild. A moderate relationship between the objective measures and subjective ratings was found. Most normophonic speakers exhibit mild left-right and anterior-posterior asymmetries for both habitual and pressed phonations. Asymmetries were noted more often during habitual than pressed phonations, and when visualized by HSV and kymography than stroboscopy. Differences between objective measures and visual judgments support the need to quantify vocal fold vibratory features.

Vocal fold mucus aggregation in vocally normal speakers

Vocal fold mucus aggregation is common in persons with voice disorders. The normality of vocal fold mucus aggregation in vocally normal speakers is not known. The purpose of this study was to preliminarily ascertain the presence, type, thickness, location, and pooling of mucus aggregation in vocally normal speakers. An additional aim was to evaluate whether the features of mucus aggregation are more easily identified using stroboscopy or high-speed videoendoscopy (HSV). These aims were accomplished by visually rating a systematically collected database of stroboscopy and HSV recordings from 52 normophonic speakers. Results revealed 97% of normophonic speakers presented with visible mucus aggregation. Statistically significant differences were found for judgments of HSV compared to stroboscopy on the parameters of type 1 mucus, not apparent and mild thickness, not apparent pooling, and all three locations. Two main conclusions can be drawn from this study: 1) normophonic speakers commonly have mucus aggregation and 2) mucus aggregation is identified more often through stroboscopy than HSV.

Period and Glottal Width Irregularities in Vocally Normal Speakers

Vocal fold vibratory irregularities can be caused by multiple factors. The underlying mechanism for irregularities is a difference in the mass or tension of the vibratory portion of the left versus the right vocal fold. The purpose of this study is to preliminarily investigate the prevalence of vocal fold vibratory irregularities in vocally normal speakers via high-speed videoendoscopy (HSV). Two aspects of irregularity, glottal width and period irregularity, were investigated in 52 vocally normal speakers undergoing videostroboscopy and HSV. The videostroboscopy and HSV recordings were processed and visually rated for glottal width and period irregularities. These ratings were also accomplished through the use of the novel digital kymography playback and from still kymographic images of the medial line of the vocal folds (mDKG). Objective measures of glottal width and period irregularities from the mDKG, and jitter and shimmer measures of the synchronously recorded acoustic waveforms, were also studied. The results suggest that period irregularities are less frequent in normophonic speakers than glottal width irregularities. However, more participants revealed acoustic jitter rather than acoustic shimmer above normal limits. Thus, speculation regarding the physiological source of these clinically used acoustic parameters continues. The lack of confidence in rating irregularity through stroboscopy and the discrepancies between visual ratings and objective measures requires future research efforts.

Mucosal Wave: A Normophonic Study Across Visualization Techniques

Visualization of vocal fold vibration is essential for accurate diagnoses and optimal treatment of persons with voice disorders. Recently, scientific and anecdotal reports have evidenced an increased amount of variation in the diagnostically relevant features of extent and symmetry of mucosal wave magnitude in normophonic speakers. The objectives of this study were to preliminarily ascertain the variation in mucosal wave magnitude and symmetry for normophonic speakers as assessed via standard and novel techniques, and compare findings across modal and pressed phonations. A correlational design with a multiple baseline across visualization methods approach was used. Mucosal wave presence, magnitude, and symmetry from 52 normophonic speakers were judged via stroboscopy, high-speed videoendoscopy (HSV) playback, mucosal wave playback, and mucosal wave kymography playback. Results demonstrate a prevalence of atypical magnitude and symmetry of mucosal wave during modal and pressed phonations by normophonic persons, differences across techniques, and a relationship between judgments and habitual fundamental frequency. Given the prevalence of mucosal wave magnitude and symmetry variations in the normophonic population, overdiagnosis may be possible without caution. The various visualization techniques provided unique information suggesting that it may be beneficial to use both full view and kymographic visualization techniques in combination. A major restriction of the current commercial HSV systems is the frame rate, typically limited to 2000 frames per second, which appears insufficient for most female habitual phonations.

Decomposition of Vocal Cycle Length Perturbations into Vocal Jitter and Vocal Microtremor, and Comparison of Their Size in Normophonic Speakers

Summary: A statistical method that enables raw vocal cycle length perturbations to be decomposed into perturbations ascribed to vocal jitter and vocal tremor is presented, together with a comparison of the size of jitter and tremor. The method is based on a time series model that splits the vocal cycle length perturbations into uncorrelated cycle-to-cycle perturbations ascribed to vocal jitter and supra-cycle perturbations ascribed to vocal tremor. The corpus was composed of 114 vocal cycle length time series for sustained vowels [a], [i], and [u] produced by 22 male and 16 female normophonic speakers. The results were the following. First, 100 out of 114 time series were decomposed successfully by means of the time series model. Second, vocal perturbations ascribed to tremor were significantly larger than perturbations ascribed to jitter. Third, the correlation between vocal jitter and vocal tremor was moderate, but statistically significant. Fourth, small but statistically significant differences were observed among the three vowel timbres in the relative jitter and the arithmetic difference of jitter and tremor. Fifth, the differences between male and female speakers were not statistically significant in the relative raw perturbations, the relative jitter, or the modulation level owing to tremor.