Measures of Vocal Attack Time for Healthy Young Adults

Vowel onset measures and their reliability, sensitivity and specificity: A systematic literature review

OBJECTIVE

To systematically evaluate the evidence for the reliability, sensitivity and specificity of existing measures of vowel-initial voice onset.

METHODS

A literature search was conducted across electronic databases for published studies (MEDLINE, EMBASE, Scopus, Web of Science, CINAHL, PubMed Central, IEEE Xplore) and grey literature (ProQuest for unpublished dissertations) measuring vowel onset. Eligibility criteria included research of any study design type or context focused on measuring human voice onset on an initial vowel. Two independent reviewers were involved at each stage of title and abstract screening, data extraction and analysis. Data extracted included measures used, their reliability, sensitivity and specificity. Risk of bias and certainty of evidence was assessed using GRADE as the data of interest was extracted.

RESULTS

The search retrieved 6,983 records. Titles and abstracts were screened against the inclusion criteria by two independent reviewers, with a third reviewer responsible for conflict resolution. Thirty-five papers were included in the review, which identified five categories of voice onset measurement: auditory perceptual, acoustic, aerodynamic, physiological and visual imaging. Reliability was explored in 14 papers with varied reliability ratings, while sensitivity was rarely assessed, and no assessment of specificity was conducted across any of the included records. Certainty of evidence ranged from very low to moderate with high variability in methodology and voice onset measures used.

CONCLUSIONS

A range of vowel-initial voice onset measurements have been applied throughout the literature, however, there is a lack of evidence regarding their sensitivity, specificity and reliability in the detection and discrimination of voice onset types. Heterogeneity in study populations and methods used preclude conclusions on the most valid measures. There is a clear need for standardisation of research methodology, and for future studies to examine the practicality of these measures in research and clinical settings.

Evidence of Internal Consistency in the Spectrographic Analysis Protocol

OBJECTIVE

To verify the validity in the internal consistency in the spectrographic analysis protocol (SAP).

MATERIAL AND METHODS

Thirty-nine students of the Speech-Language Pathology graduate program and 38 speech-language pathologists, specialized in voice, participated in the study. The participants made visual inspections of 10 spectrograms and marked the items of the SAP. For analysis of the internal consistency in the SAP, the exploratory factor analysis (EFA) and confirmatory factor analysis were performed.

RESULTS

Most items showed corrected item-total correlation above 0.3, indicating that the items have a good relationship with each other and with the SAP as a whole. Six items presented values below the average, suggesting the exclusion of these from the construct. However, three of these were maintained because they were judged as important parameters in clinical practice, requiring the training of judges when using the SAP to properly understand the items. The EFA regrouped the previous domains of the SAP into three factors. All items presented a factor load above 0.4, suggesting the retention of all, except for the items previously indicated, for exclusion. The confirmatory factor analysis corroborated with the EFA and its indexes.

CONCLUSION

The SAP has good internal consistency. All items have a good degree of relationship with each other and contribute positively to the protocol as a whole. The final version of the SAP, at this stage, has 15 items (from the 25 items of the initial SAP version), distributed among three domains.

How Reliable Is the Auditory-Perceptual Evaluation of Phonation Onset Hardness?

BACKGROUND

Generally, phonation onset hardness has been similarly defined and categorized throughout literature. There are typically three categories: soft, breathy, and hard onset. Phonation onset hardness is relevant in both assessment and treatment of various voice disorders and is usually determined on an auditory-perceptual basis. However, as far as we know, reliability of clinical auditory-perceptual indications of phonation onset hardness has not been investigated yet. Therefore, this study aimed at evaluating intrarater as well as interrater reliability of auditory-perceptual assessment of phonation onset hardness by speech and language pathologists.

METHODS

After deidentification, the sentence-initial word [e.rst] was extracted from read text recordings of 20 subjects with various voice disorders and complaints. These 20 samples were purposefully selected to represent as much as possible the whole phonation onset hardness continuum. The auditory-perceptual rating protocol consisted of the paired comparison paradigm, in which all listeners were asked to perceptually compare phonation onset hardness of every fragment with the other 19 samples. This resulted in a ranking of the 20 samples, from hardest to softest phonation onset. Four speech and language pathologists agreed to compare phonation onset hardness according to this paradigm. The single-measures intraclass correlation coefficient (ICC) for absolute agreement was applied to determine the degree of reliability within as well as between raters.

RESULTS

Intrarater ICC's showed acceptable reliability for two raters, yet poor reliability for the other two raters. Interrater ICC's demonstrated low reliability in general. Zooming in on the ratings shows that three of four evaluators agreed on which sample had the softest phonation onset, and that only two raters agreed on which recording had the hardest phonation onset.

DISCUSSION

It can be concluded that there is considerable variability within and across raters when asked to indicate the word with the hardest phonation onset. This is the first study to approach auditory interpretation of phonation onset hardness with the paired comparison task. Questions are raised about the clinical utility of phonation onset hardness perception, the potential role of training, and the importance of a more objective yet clinically feasible measurement tool.

Vocal Release Time of Mandarin Vowels at Different Pitch Levels

OBJECTIVE

To explore how vocal release time (VRT) varies when young adults articulate the three Chinese vertex vowels with increasingly higher pitch levels.

STUDY DESIGN

Sound pressure (SP) and electroglottographic (EGG) signals were recorded synchronously from 53 males and 53 females saying sustained /A/, /i/, /u/ at five equally spaced pitch heights, each being higher than the one before.

METHODS

About 3030 effective ST (semitone) and VRT measures were obtained. Statistical analyses of them were done by using SPSS 13.0 and Excel 2010.

FINDINGS

As mean STs increase linearly from pitch levels one to five, mean VRTs display a rise-fall pattern in a big group of subjects, but a fall-rise pattern in a small group of them. In both cases, pitch and VRT tend to present a curvilinear relationship, although VRT varies in opposite directions. And also, high vowels tend to have larger VRT than low vowels.

Research Note: Vocal Attack Time-Extended Analysis

Normative data for vocal attack time (VAT) have previously been presented, but descriptive statistics and assessments of statistical significance of differences have previously been based on a data corpus that included both negative- and positive-valued VATs. Negative VAT values denote a glottal vocal attack, but, at the present time, the signification of the magnitude of a negative VAT value is unknown. The magnitude of a positive VAT value, on the other hand, conveys useful information about glottal behavior at the time of voice onset and is much more likely to be of use, especially in the clinical domain. We present descriptive statistics for the set of positive-valued VATs and demonstrate that the VAT differences between genders and among tone categories in Cantonese remain valid.

Comparison Study of Vocal Attack Time in Patients With Cleft Palate With and Without Glottal Stop in Mandarin

Glottal stop (GS) is a typical compensatory articulation, which has a great impact on speech intelligibility in patients with cleft palate. It is usually detected by perceptual analysis. The aim of this study is to investigate the utility of vocal attack time (VAT) values in patients with cleft palate with and without GS, when unaspirated monosyllables are articulated in Mandarin, by using electroglottography. Unaspirated monosyllables /pa/ /pi/ /pu/ /ta/ /ti/ /tu/ /ka/ /ki/ /ku/ with tone one were analyzed. A total of 575 tokens were obtained from 42 patients with cleft palate, divided into a GS category (n = 312 tokens) and a nonglottal stop (NGS) category (n = 263 tokens), as assessed perceptually by three judges. Sound pressure and electroglottography recordings were also obtained from these tokens. The time lag of the cross-correlation function was used to gain VAT values. The results showed that the mean VAT values of tokens from the GS category (-0.25 ms) was significantly shorter than that of tokens in the NGS category (3.19 ms) (t = 7.326, P < 0.001). The results also showed that there was no significant difference in VAT values between the different combined monosyllables both in GS and in NGS group. The conclusion that can be drawn from this study is that the VAT value was sensitively decreased in cleft palate Mandarin speakers with GS comparing to those without GS.

Content evidence of a spectrographic analysis protocol

ABSTRACT Objective: to verify the content evidence of a spectrographic analysis protocol. Methods: a methodological study in which five speech therapists who assessed the clarity and the relevance of the protocol were selected. The Content Validity Index (CVI) was used to investigate the level of agreement among judges regarding overall aspects, items and domains of the protocol. Results: most judges considered the overall aspects of the protocol as comprehensive. As for clarity, 17 items showed an excellent content validity (CVI ≥ 0.78), three showed a good content validity (0.60 ≤ CVI ≤ 0.77) and two items were judged as poor (CVI ≤ 0.59). As for relevance, 19 items obtained an excellent content validity (CVI ≥ 0.78) and three had a good content validity (0.60 ≤ CVI ≤ 0.77). The judges suggested adding items related to vocal signal normality in all domains. After the analysis, 18 items required no reformulation, five items were added, three were reformulated and one was excluded. Conclusion: the proposed protocol was regarded as a comprehensive one. The items presented a good to excellent content validity as for clarity and relevance. After this validation step, the protocol ended up presenting 25 items distributed into five domains.

Relationship Between Acoustic Voice Onset and Offset and Selected Instances of Oscillatory Onset and Offset in Young Healthy Men and Women

OBJECTIVE

This study aimed to investigate the relationship between (1) onset of the acoustic signal (X_1a) and prephonatory phases associated with oscillatory onset and (2) offset of the acoustic signal (X_2a) with the postphonatory events associated with oscillatory offset across vocally healthy adults.

SUBJECTS AND METHODS

High-speed videoendoscopy was captured simultaneously with the acoustic signal during repeated production of /hi.hi.hi/ at typical pitch and loudness from 56 vocally healthy adults (aged 20-42 years; 21 men, 35 women). The relationships between the acoustic sound pressure signal and oscillatory onset and offset events from the glottal area waveforms (GAWs) were statistically investigated using a multivariate linear regression analysis.

RESULTS

The X_1a is a significant predictor of the onset of first oscillatory motion (X_1g) and onset of sustained oscillations (X_2g). X_1a as well as gender are significant predictors of the first medial contact of the vocal folds (X_1.5g). The X_2a is a significant predictor of the first instance of oscillatory offset (X_3g), first instance of incomplete glottal closure (X_3.5g), and complete cessation of (vocal fold) oscillatory motion (X_4g).

CONCLUSIONS

The acoustic signal onset is closely related to the X_1.5g, but the latency between these events is longer for women compared to men. The X_2a occurs immediately after incomplete glottal adduction. The emerging normative group latencies between the onset and offset of the acoustic and the GAW from this study appear promising for future investigations.

Effects of Volume, Pitch, and Phonation Type on Oscillation Initiation and Termination Phases Investigated With High-speed Videoendoscopy

OBJECTIVES

This study aimed to investigate the effects of varying volume, pitch, and phonation types on the initiation and termination phases of vocal fold oscillation using high-speed digital videoendoscopy. Specifically, it addressed the effects of the variation of volume, pitch, and phonation type (normal, pressed, and breathy) on the transient duration of the vibrating glottal length (length transient duration, T_len), the transient duration of the glottal area waveform (area transient duration, T_area), the time offset between the beginning (or the end) of the full-length vibration and the full-amplitude vibration, T_Δ, and the variation of the fundamental frequency during the vocal fold oscillation initiation and termination segments (pitch instability, %PI).

METHODS

A female subject with no voice problem produced voices with varying pitch and loudness, including comfortable pitch and comfortable loudness, normal pitch loud, high pitch and comfortable loudness, and high pitch and loud. Breathy and pressed phonations were also recorded. Each of the six phonation types was recorded six times, which resulted in 72 transient segments (each recording included both initiation and termination phases). Mixed model statistical analyses were employed to the five objective high-speed digital videoendoscopy parameters.

RESULTS

Preliminary findings demonstrated significant findings for voice type effects for the length and area transient durations for the oscillation initiation segment but not for the oscillation termination segment.

CONCLUSIONS

This study demonstrates that voice types appear to influence vibration initiation patterns more than the vibration termination patterns.

A Spatiotemporal Approach to the Objective Analysis of Initiation and Termination of Vocal-fold Oscillation With High-speed Videoendoscopy

High-speed videoendoscopy excels in the ability to observe the vocal-fold oscillatory patterns during voice initiation and termination. The initial and most critical step in the analysis of these transient regions is to identify the locations of these transient periods, that is, determining when the vocal-fold oscillation is absent and when the oscillation has reached its steady-state behavior. The latter is more challenging as the "steady" oscillation during sustained phonation is not truly steady and is expected to vary over time. This variation may cause unreliable identification of the transient periods, possibly resulting in less accurate or less reliable parameter measurements. An oscillation feature that is relatively consistent in the steady state is the glottal length, that is, the extent of the oscillation along vocal folds. This paper proposes an autonomous algorithm to estimate the vocal-fold oscillation length and its use to detect four transient events: oscillation onset and offset, and attainment and loss of full-length oscillation. The detected event markers are intended to be used to improve the transient parameter measurements. The autonomous algorithm manipulates the set of glottal width waveforms spatiotemporally to estimate the oscillation length. Examples with in vivo high-speed videoendoscopy recordings of both normal and pathological cases are included to show the efficacy of the proposed algorithm to identify the transient markers.

Acoustic Correlates of Compensatory Adjustments to the Glottic and Supraglottic Structures in Patients with Unilateral Vocal Fold Paralysis

The goal of this study was to analyse perceptually and acoustically the voices of patients with Unilateral Vocal Fold Paralysis (UVFP) and compare them to the voices of normal subjects. These voices were analysed perceptually with the GRBAS scale and acoustically using the following parameters: mean fundamental frequency (F0), standard-deviation of F0, jitter (ppq5), shimmer (apq11), mean harmonics-to-noise ratio (HNR), mean first (F1) and second (F2) formants frequency, and standard-deviation of F1 and F2 frequencies. Statistically significant differences were found in all of the perceptual parameters. Also the jitter, shimmer, HNR, standard-deviation of F0, and standard-deviation of the frequency of F2 were statistically different between groups, for both genders. In the male data differences were also found in F1 and F2 frequencies values and in the standard-deviation of the frequency of F1. This study allowed the documentation of the alterations resulting from UVFP and addressed the exploration of parameters with limited information for this pathology.

Vocal Attack Time of Different Pitch Levels and Vowels in Mandarin

The purpose of this study was to investigate how vocal attack time (VAT) varies when young adults articulate the three vertex vowels in Mandarin Chinese at five linguistically unconstrained pitch levels. Sound pressure and electroglottographic signals were recorded simultaneously from 53 male and 53 female subjects saying sustained /A/, /i/, and /u/ at five equally spaced pitch heights, each being higher than the preceding one. Then analyses of means, variance, and correlation were performed to explore the relationships of VAT/pitch levels and VAT/vowels. Findings were As mean STs (semitone) increase linearly from levels 1 to 5, mean VATs decrease nonlinearly in a big group of subjects but increase nonlinearly in a small group of them. Based on the body-cover model of F0 control, data here lead to the guess that different people incline to use different strategies in increasing pitch height. When males, females, and males plus females are considered as a whole, average STs and VATs tend to be positively correlated among the three vertex vowels.

Effect of Voice Onset Type on Vocal Attack Time

Vocal attack time (VAT) is the time lag between the growth of sound pressure (SP) and electroglottographic (EGG) signals at vocal initiation. The characteristics of voice initiation are associated with issues of vocal hygiene, efficiency, and quality. Vocal onsets have commonly been qualitatively characterized into three types: hard, simultaneous, and breathy. This study examines the effect of voice onset type on VAT values in normal speakers. SP and EGG recordings were obtained for 55 female and 57 male subjects while producing multiple tokens of three tasks (sustained /ɑ/ and "always" as unaspirated onsets, and "hallways" as an aspirated onset). Results revealed a significant effect of onset type on VAT, with the mean VAT for the "hallways" (aspirated) task greater than the mean VAT for the sustained /ɑ/ and "always" (unaspirated) tasks. There was no significant VAT difference between the sustained /ɑ/ and "always" tasks. Findings confirm the sensitivity of the VAT measure to vocal onset type and suggest its potential application as an objective and quantitative clinical measure of the type of vocal onset.

Effect of fundamental frequency at voice onset on vocal attack time

OBJECTIVE

To examine vocal attack time (VAT) values associated with the production of low, mid, and high rates of vocal fold vibration in normal speakers.

STUDY DESIGN

Sound pressure (SP) and electroglottographic (EGG) recordings were obtained for eight female and five male subjects while producing multiple tokens of the sustained vowels /ɑ/, /i/, and /u/ at comfortable loudness and at mid, low (-3 semitones), and high (+6 semitones) rates of vocal fold vibration.

METHODS

Generalized sinusoidal models of the SP and EGG signals were computed to compare rates of amplitude change. VAT was computed from the time lag of the cross-correlation function.

RESULTS

Adjusted mean VAT for the high frequency condition was smaller than the adjusted mean VAT values for the low- and mid-frequency conditions. There was no significant difference between the mid and low frequency conditions.

CONCLUSIONS

Findings reveal an association of the VAT measure with increases in vocal fold tension associated with the production of high rates of vocal fold vibration.

Vocal release time: a quantification of vocal offset

OBJECTIVE

To determine the vocal release time (VRT) for linguistically unconstrained voice offsets in a healthy young adult population.

STUDY DESIGN

Sound pressure (SP) and electroglottographic (EGG) recordings were obtained for 57 female and 55 male subjects while producing multiple tokens of three tasks (sustained /ɑ:/, "always," and "hallways") at comfortable pitch and loudness.

METHODS

SP and EGG signals were digitally time reversed and generalized sinusoidal models of the SP and EGG signals were obtained to compare rates of amplitude change. VRT was computed from the time lag of the cross-correlation function.

RESULTS

Adjusted mean VRT values were significantly greater for females than for males. There was no systematic effect of age on VRT. However, 25-29-year old and >40 year old females showed shorter VRT values than the youngest female age group.

CONCLUSIONS

Normative data are presented for a new measure of the duration of vocal offset, VRT. Acquisition of this measure requires little user intervention, thereby minimizing effects of subjective decision making. Comparison with previously reported vocal attack time (VAT) values for the same population suggests phenomenological differences between linguistically and physiologically constrained voice onsets and unconstrained voice offsets.