Judgments Of Voice Quality Research Articles

A rough task: Defining a measure for rough voice quality.

Perceptual judgments of voice quality on a rating scale or a magnitude estimation task are highly context dependent, making it difficult to compare data from one experiment to another. In previous work, a matching task using a sawtooth wave mixed with speech‐shaped noise was found useful for quantifying breathiness in vowels [Patel et al., 2006, JASA, 119, 3340]. In the present experiment, we attempted to adapt this matching task for the estimation of roughness in vowels. Ten listeners participated in a matching task where listeners compared the roughness of a voice standard and the reference signal. A low‐pass filtered sawtooth wave mixed with speech‐shaped noise was used as the reference signal. The roughness of this signal was manipulated by amplitude modulating the waveform with a 40‐Hz square wave. The modulation depth at which the signal and standard were perceived to be equally rough was used as an index of vowel roughness. Preliminary results show that listeners are able to use the matching task to estimate roughness in vowels, particularly for moderately to severely roughness voices. However, voices with little or no roughness are difficult to match to the signal because of the inherent timbre of the sawtooth.

Voice assessment: updates on perceptual, acoustic, aerodynamic, and endoscopic imaging methods.

This paper describes recent advances in perceptual, acoustic, aerodynamic, and endoscopic imaging methods for assessing voice function. We review advances from four major areas. PERCEPTUAL ASSESSMENT: Speech-language pathologists are being encouraged to use the new consensus auditory-perceptual evaluation of voice inventory for auditory-perceptual assessment of voice quality, and recent studies have provided new insights into listener reliability issues that have plagued subjective perceptual judgments of voice quality. ACOUSTIC ASSESSMENT: Progress is being made on the development of algorithms that are more robust for analyzing disordered voices, including the capability to extract voice quality-related measures from running speech segments. AERODYNAMIC ASSESSMENT: New devices for measuring phonation threshold air pressures and air flows have the potential to serve as sensitive indices of glottal phonatory conditions, and recent developments in aeroacoustic theory may provide new insights into laryngeal sound production mechanisms. ENDOSCOPIC IMAGING: The increased light sensitivity of new ultra high-speed color digital video processors is enabling high-quality endoscopic imaging of vocal fold tissue motion at unprecedented image capture rates, which promises to provide new insights into the mechanisms of normal and disordered voice production. Some of the recent research advances in voice function assessment could be more readily adopted into clinical practice, whereas others will require further development.

Prospective trial of voice outcomes after thyroidectomy: Evaluation of patient-reported and clinician-determined voice assessments in identifying postthyroidectomy dysphonia

Reliable voice grading systems to identify postoperative voice dysfunction by surgeons are needed. To examine the utility of patient-reported and clinician-determined voice assessment in identifying postthyroidectomy voice dysfunction. Fifty patients enrolled in a prospective observational trial evaluating voice function perioperatively by patient-reported symptoms (Voice Case History [VCHx]) and perceived voice handicap (Voice Handicap Index [VHI]), clinician-determined judgment of voice quality (Consensus Auditory-Perceptual Evaluation--Voice [CAPE-V]), and laryngeal examination via video laryngoscopy (VLS). Voice dysfunction at first postoperative visit in symptomatic patients was defined by objective laryngeal abnormalities on VLS. Postoperative changes from baseline in voice parameters were compared between patients with and without voice dysfunction using the Wilcoxon rank sum test. Receiver operating characteristics were evaluated to determine area under the curve (AUC) for tested parameters. Eight (16%) had early transient and 1 (2%) had permanent postoperative voice dysfunction. VCHx symptoms had negative (NPV) and positive (PPV) predictive values of 96%-100% and 39%-53%, respectively for voice dysfunction. The rating of overall severity from the CAPE-V was highly predictive (AUC = 0.96), and a change in severity from preoperative baseline >or=20% at 1-2 weeks had a PPV of 86% and NPV of 95% for postoperative dysphonia. Patient-reported total VHI score was most predictive (AUC = 0.97) and a change in VHI from preoperative baseline >or=25 early postoperatively had a PPV of 88% and NPV of 97% for postoperative dysphonia. Patient self-assessment of voice handicap using the VHI reliably identifies voice dysfunction after thyroidectomy. Patients with a change in VHI >or=25 from preoperative baseline warrant early referral to speech pathology and laryngology.

Information conveyed by voices

Two approaches for dealing with interrater variability in voice quality judgments have recently been proposed. The first [Shrivastav et al., J. Speech Lang. Hear. Res. 48, 323–335 (2005)] advocates reducing rating errors after data collection by averaging many ratings of each voice by each rater and then standardizing the resulting means. The second [Gerratt and Kreiman, J. Acoust. Soc. Am. 110, 2560–2566 (2001)] controls rating error at the source by applying a method-of-adjustment task, which controls variability due to attention, variable internal standards, etc. Using this second method, we accounted for 87% of the variance in listeners perception of noise level for 40 voices. This low level of residual variance (errors) raises the following question: Does averaging ratings reduce the information within listeners responses along with measurement errors? To address this question, 20 listeners provided 10 breathiness ratings for 40 voices. The likelihood of exact listener agreement was calculated and compared to data from the method-of-adjustment task. We also compared amounts of variance accounted for by differences between voices in quality (a metric of information captured). We hypothesized that the averaging and standardizing approach would produce both lower interrater agreement and lower amounts of variance accounted for than the method of adjustment technique. [Work supported by the NIH/NIDCD.]

The Effect of Perceptual Training on Inexperienced Listeners' Judgments of Dysphonic Voice

The purpose of this study was (1) to determine whether changes in intra- and interrater reliability occur for inexperienced listeners' judgments of overall severity, roughness, and breathiness in dysphonic and normal speakers after 2 hours of listener training; and (2) to determine the acoustic bases of inexperienced listeners' judgments before and after training. Prospective, single group, pre- and postdesign. Thirty adult dysphonic and six normal speaker samples were selected from a database. Samples included 21 test stimuli and 15 training stimuli of both sustained vowels and connected speech. Sixteen inexperienced listeners judged all samples for overall severity, roughness, and breathiness using visual analog scales. Each listener provided pretraining ratings at baseline. Listeners were then trained using 15 anchor voice samples and 15 training stimuli. During training, listeners were provided with definitions of rating dimensions, accuracy feedback, and anchor samples. Listeners then judged test stimuli in a posttraining session. Speaker samples also were analyzed acoustically. Intrarater reliability was least variable for judgments of overall severity, but improved further with training. Listener judgments of roughness and breathiness in vowels were least reliable at baseline, but they significantly improved between listeners after training. Finally, measures of cepstral peak prominence significantly predicted all voice quality judgments except roughness in vowels, which was predicted by shimmer. The acoustic bases of group perceptual judgments did not seem to change with training. These findings have implications for developing training programs in perceptual evaluation and mapping relationships between acoustic and perceptual characteristics of voice disorders.

The effect of acoustic context and scale resolution on judgments of voice quality

Anchored protocols (in which listeners match test stimuli to fixed examples of different scale levels) control response variability in voice-quality judgment tasks, and may be clinically applicable because they are also easy to use. Successful application requires that two conditions hold. First, listeners must be able to isolate the target quality in the natural pathologic voice and match the level of that quality to levels present in a different acoustic context (the anchors). Second, the anchored scales resolution must be sufficient for listeners to make consistent judgments about stimuli that fall between anchors. To examine these issues, listeners judged noise levels for 40 test voices in four tasks. Two were anchored tasks (limited-scale resolution), in which the synthetic anchor voices matched the test voice (matched acoustic environment) in one condition and differed from the test voice environment in a second condition (traditional approach). Tasks three and four used the method of adjustment (fine-scale resolution). Listeners adjusted the noise level of a synthetic voice to match either that of an identical test voice, or that of a voice that differed from the test stimulus. Implications for theory and clinical practice will be discussed. [Research supported by NIDCD.]

Perceptual Analyses of Spasmodic Dysphonia Before and After Treatment

To evaluate expert listeners' perceptions of voice and fluency in persons with adductor spasmodic dysphonia (ADSD) before and after treatment with botulinum toxin type A (Botox), as a function of initial severity of the disorder (while controlling for patients' age at injection). Simple before-and-after trial with blinded randomized listener judgments. Ambulatory care clinic at a single medical center. Forty-two consecutive patients with ADSD who underwent examination, with a 3- to 6-week follow-up, after initial botulinum toxin type A injection. There were also 42 age- and sex-matched healthy control subjects. Injections of botulinum toxin type A into the thyroarytenoid muscle(s). Computer-implemented visual analog scaling judgments of voice quality and speech fluency made by expert listeners under psychoacoustically controlled conditions. Response to botulinum toxin type A varied markedly as a function of pretreatment severity of ADSD. More severe initial symptoms exhibited greater magnitudes of improvement. Patients with mild dysphonia did not exhibit pretreatment to posttreatment change. Following treatment, voice and fluency remained significantly (P<.05) poorer in ADSD than in healthy speakers. Older patients exhibited less improvement than younger patients when the effect of initial severity was statistically controlled. Voice quality and fluency improved for most patients following treatment, but older patients and those with milder dysphonia exhibited the least optimal responses to the procedure. Patients who were profoundly impaired demonstrated the greatest amount of improvement. Computer-implemented visual analog scaling provided a reliable clinical tool for determining treatment-related changes in those with ADSD.

Temporal change in memory of human voice

This study investigates the extent to which human subjects accurately retain memory of speaker individuality and voice quality of utterances without receiving instruction to memorize them. Experiments constituted three phases. In phase one, 27 subjects listened to two target utterances in a paired-comparison test that required only a similarity judgment of voice quality. The target utterances were one sentence read by two males with average and characteristic voice quality, respectively, who were selected from 109 males. In phase two, performed 21 days after phase one, the same subjects evaluated Japanese expressions of voice quality [Proc. ICSLP-98, No. 1005] of the two previous target utterances based on memory only and judged with a degree of confidence whether each of seven speech stimuli (two targets and five additional speakers’ utterances) was identical to one of the two targets. In the final phase, conducted immediately after phase two, the subjects repeated the same phase-two task but after listening to the two target utterances. Data processing based on the signal detection theory revealed that temporal change in memory of speaker individuality and voice quality was relatively small over a period of 21 days. Experiments over a longer period of time are now underway.

Health status and voice outcome after treatment for T1a glottic carcinoma.

Radiotherapy as well as endoscopic laser surgery as the most widely used treatment modalities for T1a glottic carcinoma cause minor morbidity and negligible mortality and result in more or less comparable, excellent cure and larynx preservation rates. Therefore, other outcome measures such as voice-related problems and health status are important factors in the choice of treatment for T1a glottic cancer. The present study focuses on voice-related problems in the daily life of patients treated by radiotherapy or endoscopic laser surgery for T1a glottic cancer. Self ratings on health status assessed by means of COOP/WONCA health status charts and voice problems evaluated with a validated voice-specific questionnaire (the Voice Handicap Index) and overall judgment on voice quality were obtained. A total of 102 patients (56 treated by endoscopic laser surgery and 46 treated by radiotherapy) with at least 1-year follow-up were included. Response scores were high: 52 (93%) patients after endoscopic laser surgery versus 40 (87%) patients after radiation therapy completed and returned the questionnaires. A high percentage of patients reported voice problems in daily life: 58% of the patients following radiotherapy and 40% of the patients following endoscopic treatment had abnormal VHI scores. The difference between both treatment modalities proved to be significant. No significant differences were found concerning health status or overall judgment of voice quality. Moderate correlations were found between total VHI score and voice quality judgment and the COOP/WONCA social activities chart. This study reveals that treatment for T1a glottic cancer often does result in voice problems in daily life, negatively influencing patients social activities. Patients selected for endoscopic laser surgery on average report fewer voice-related problems than those who underwent radiotherapy.

Telehealth: voice therapy using telecommunications technology.

Telehealth offers the potential to meet the needs of underserved populations in remote regions. The purpose of this study was a proof-of-concept to determine whether voice therapy can be delivered effectively remotely. Treatment outcomes were evaluated for a vocal rehabilitation protocol delivered under 2 conditions: with the patient and clinician interacting within the same room (conventional group) and with the patient and clinician in separate rooms, interacting in real time via a hard-wired video camera and monitor (video teleconference group). Seventy-two patients with voice disorders served as participants. Based on evaluation by otolaryngologists, 31 participants were diagnosed with vocal nodules, 29 were diagnosed with edema, 9 were diagnosed with unilateral vocal fold paralysis, and 3 presented with vocal hyperfunction with no laryngeal pathology. Fifty-one participants (71%) completed the vocal rehabilitation protocol. Outcome measures included perceptual judgments of voice quality, acoustic analyses of voice, patient satisfaction ratings, and fiber-optic laryngoscopy. There were no differences in outcome measures between the conventional group and the remote video teleconference group. Participants in both groups showed positive changes on all outcome measures after completing the vocal rehabilitation protocol. Reasons for participants discontinuing therapy prematurely provided support for the telehealth model of service delivery.

Is the reliability of a visual analog scale higher than an ordinal scale? An experiment with the GRBAS scale for the perceptual evaluation of dysphonia.

Perceptual evaluation of 14 pathological voices was performed by 29 listeners using the GRBAS scale. To evaluate scale effects on the judgments, 2 versions of the scale were presented: the original 4-point scale and a visual analog scale. Each listener used the same voice samples for both versions of the scale with an interval of 2 weeks. Agreement was found to be higher with the original 4-point scale than with the visual analog version for all scale items G, R, B, A and S. Although a visual analog scale seems to enable a finer judgment of voice quality, this study showed that, with increased freedom of judgment, the interrater agreement decreased considerably. Therefore, we recommend the use of the original 4-point version of the GRBAS scale.

Relating objective measurements to expert evaluation of voice quality in Western classical singing: critical perceptual parameters.

Communication between voice pedagogues and voice scientists is often impeded by reliance on colorful and sometimes seemingly contradictory descriptions of vocal production and voice quality. A recent study identified perceptual criteria which are generally used by voice experts for the assessment of voice quality in classical singing. In the present study, performances by singers of various voice types and levels of accomplishment were rated by panels of expert voice teachers according to four perceptual criteria: "resonance/ring," "color/warmth," "clarity/focus," and "appropriate vibrato." Subjective ratings were related to objective measurements taken from acoustic analysis of the voice signal. Possible acoustic correlates of critical perceptual parameters influencing judgments of voice quality were thus identified. Results could help bridge the terminology gap between vocal artists and scientists, and help to promote understanding of the way in which acoustic stimuli influence perception of voice quality.

Tracking change in dysphonia: A case study

This longitudinal case study of a woman with nodules examines the relationship between clinical and acoustic measures of change. Relative changes in voice quality, vocal fold condition, and patient symptoms were compared to measures of mean fundamental frequency (MFF), jitter, and fundamental frequency range (FFR). Seven assessments were performed over a 2-year period. The findings indicated that voice quality judgments tended to relate to changes in degree of vocal fold pathology and patient report of vocal function. However, acoustic measures of MFF, FFR, and jitter did not relate to measures of clinical change. The discussion focuses on explanations for the acoustic findings, the need for using connected speech samples for perceptual and acoustic analysis, and a suggestion for future study.

Estimating the reliability of voice quality judgments: Comparing scales and statistics

Because perceptual measures are the primary means of assessing voice quality in the clinic, the reliability of listeners' judgments is of central importance. However, there is no consensus regarding the stability of trained listeners' judgments under conditions that mimic actual clinical practice, or as to the best method for estimating the reliability of such judgments. The present research compares the reliability of experts' estimates of vocal roughness gathered using equal appearing interval and visual analog scales, in order to determine (1) whether one scale type is inherently more reliable than the other; (2) the most appropriate methods for estimating the reliability of voice rating data; and (3) how reliable listeners actually are when they rate voices using these scales. The advantages and drawbacks of the many statistics used to evaluate reliability data will be discussed, and recommendations for standardizing perceptual measurement procedures will be presented.

Judgments of voice quality and preference: Acoustic interpretations

Summary Previous studies have shown that trained listeners are highly reliable in making perceptual judgments of several parameters of normal and pathologic voices. This study investigated objective measures of acoustic characteristics of high and low preference voices as determined by previous perceptual study. Four acoustic parameters were measured including harmonics-to-noise ratio, autocorrelation function, average jitter, and the standard deviation of the fundamental frequency. Useful correlations between perceptual and measured results were identified. Normal voices differ from pathologic voices in terms of the acoustic-perceptual relationships.

Some relations between voice quality judgments and derived acoustic measurements

The use of extracted acoustic features as descriptors of abnormal voice quality was explored by correlating voice quality ratings with the measurements. Sixteen talkers with no history of speech problems and 52 talkers with documented laryngeal pathologies recorded the vowel /ɑ/ using their typical pitch and loudness. Estimates of the excitation for each vowel were obtained using the linear prediction technique of inverse filtering, and the acoustic measurements, known as residue features, were calculated from this waveform. Voice quality estimates were obtained from a panel of judges who rated each vowel on 11 voice quality scales that have been described in the literature. The residue features were used as predictors of average voice quality rating in multiple linear regression analyses. The results are discussed in terms of the voice quality scales that were used most reliably by the judges and the ability of the features to distinguish among various voice quality categories.

Adult voice screening.

Voice screening by means of recordings was conducted on 428 adults going through a series of tests at a multiphasic health-screening unit. Judgments of voice quality made by a trained listener were compared with judgments made by the participant. Laryngeal examinations were obtained on selected cases. Between 5 and 10% had some type of laryngeal or nasopharyngeal pathology that produced a deviant voice quality, indicating that a health-screening program which includes voice screening can identify a significant segment of the affected adult population early enough to prevent the development of more serious laryngeal lesions.

Consistency of judgments of voice quality

Consistency of judgments of voice quality