Effects of Adventitious Acute Vocal Trauma: Relative Fundamental Frequency and Listener Perception

The Effect of Rating Method on Reliability of Judgments of Strain Across Populations

PURPOSE

Variability in auditory-perceptual ratings of voice limits their utility, with the poorest reliability often noted for vocal strain. The purpose of this study was to determine whether an experimental method, called visual sort and rate (VSR), promoted stronger rater reliability than visual analog scale (VAS), for ratings of strain in two clinical populations: adductor laryngeal dystonia (ADLD) and vocal hyperfunction (VH).

METHOD

Connected speech samples from speakers with ADLD and VH as well as age- and sex-matched controls were selected from a database. Fifteen inexperienced listeners rated strain for two speaker sets (25 ADLD speakers and five controls; 25 VH speakers and five controls) across four rating blocks: VAS-ADLD, VSR-ADLD, VAS-VH, and VSR-VH. For the VAS task, listeners rated each speaker for strain using a vertically oriented 100-mm VAS. For the VSR task, stimuli were distributed into sets of samples with a range of severities in each set. Listeners sorted and ranked samples for strain within each set, and final ratings were captured on a vertically oriented 100-mm VAS. Intrarater reliability (Pearson's r) and interrater variability (mean of the squared differences between a listener's ratings and group mean ratings) were compared across rating methods and populations using two repeated-measures analyses of variance.

RESULTS

Intrarater reliability of strain was significantly stronger when listeners used VSR compared to VAS; listeners also showed significantly better intrarater reliability in ADLD than VH. Listeners demonstrated significantly less interrater variability (better reliability) when using VSR compared to VAS. No significant effect of population or interactions was found between listeners for measures of interrater variability.

CONCLUSIONS

VSR increases intrarater reliability for ratings of vocal strain in speakers with VH and ADLD. VSR decreases variability of auditory-perceptual judgments of strain between inexperienced listeners in these clinical populations. Future research should determine whether benefits of VSR extend to voice clinicians and/or clinical settings.

Voice Acoustics and Vocal Effort in Mask-Wearing Healthcare Professionals: A Comparison Pre- and Post-Workday

OBJECTIVE

We evaluated voice acoustics and self-perceptual ratings in healthcare workers required to wear face masks throughout their workday.

METHODS

Eighteen subjects (11 cisgender female, 7 cisgender male; M = 33.72 years, SD = 8.30) completed self-perceptual ratings and acoustic recordings before and after a typical workday. Chosen measures were specific to vocal effort, dysphonia, and laryngeal tension. Mixed effects models were calculated to determine the impact of session, mask type, sex, and their interactions on the set of perceptual and acoustic measures.

RESULTS

The subjects self-reported a significant increase in vocal effort following the workday. These perceptual changes coincided with an increase in vocal intensity and harmonics-to-noise ratio, but decrease in relative fundamental frequency offset 10. As expected, men and women differed in measures related to fundamental frequency and vocal tract length.

CONCLUSION

Healthcare professionals wearing masks reported greater vocal symptoms post-workday compared to pre-workday. These symptoms coincided with acoustic changes previously related to vocal effort; however, the degree of change was considered mild. Further research is needed to determine whether vocal hygiene strategies may reduce vocal symptoms in mask-wearing workers.

Voice Onset Time in Children With and Without Vocal Fold Nodules

PURPOSE

Voice onset time (VOT) of voiceless consonants provides information on the coordination of the vocal and articulatory systems. This study examined whether vocal-articulatory coordination is affected by the presence of vocal fold nodules (VFNs) in children.

METHOD

The voices of children with VFNs (6-12 years) and age- and gender-matched vocally healthy controls were examined. VOT was calculated as the time between the voiceless stop consonant burst and the vocal onset of the vowel. Measures of the average VOT and VOT variability, defined as the coefficient of variation, were calculated. The acoustic measure of dysphonia, cepstral peak prominence (CPP), was also calculated. CPP provides information about the overall periodicity of the signal, with more dysphonic voices having lower CPP values.

RESULTS

There were no significant differences in either average VOT or VOT variability between the VFN and control groups. VOT variability and average VOT were both significantly predicted by the interaction between Group and CPP. There was a significant negative correlation between CPP and VOT variability in the VFN group, but no significant relationship was found in the control group.

CONCLUSIONS

Unlike previous studies with adults, there were no group differences in average VOT or VOT variability in this study. However, children with VFNs who were more dysphonic had increased VOT variability, suggestive of a relationship between dysphonia severity and control of vocal onset during speech production.

The Effect of Visual Sort and Rate Versus Visual Analog Scales on the Reliability of Judgments of Dysphonia

Purpose The reliability of auditory-perceptual judgments between listeners is a long-standing problem in the assessment of voice disorders. The purpose of this study was to determine whether a relatively novel experimental scaling method, called visual sort and rate (VSR), yielded stronger reliability than the more frequently used method of visual analog scales (VAS) for ratings of overall severity (OS) and breathiness (BR) in speakers with voicedisorders. Method Fifty speech samples were selected from a database of speakers with voice disorders. Twenty-two inexperienced listeners provided ratings of OS or BR in four rating blocks: VSR-OS, VSR-BR, VAS-OS, and VSR-BR. For the VAS task, listeners rated each speaker for BR or OS using a vertically oriented 100-mm VAS. For the VSR task, stimuli were distributed into sets of samples with a range of speaker severities in each set. Listeners sorted and ranked samples for OS or BR within each set, and final ratings were captured on a vertically oriented 100-mm VAS. Interrater variability, defined as the mean of the squared differences between a listener's ratings and group mean ratings, and intrarater reliability (Pearson r) were compared across rating tasks for OS and BR using paired t tests. Results Results showed that listeners had significantly less interrater variability (better reliability) when using VSR methods compared to VAS for judgments of both OS and BR. Intrarater reliability was high across rating tasks and dimensions; however, ratings of BR were significantly more consistent within individual listeners when using VAS than when using VSR. Conclusions VSR is an experimental method that decreases variability of auditory-perceptual judgments between inexperienced listeners when rating speakers with a range of dysphonic severities and disorders. Future research should determine whether a clinically viable tool may be developed based on VSR principles and whether such benefits extend to experienced listeners.

Perceptual and Acoustic Assessment of Strain Using Synthetically Modified Voice Samples

Purpose Assessment of strained voice quality is difficult due to the weak reliability of auditory-perceptual evaluation and lack of strong acoustic correlates. This study evaluated the contributions of relative fundamental frequency (RFF) and mid-to-high frequency noise to the perception of strain. Method Stimuli were created using recordings of speakers producing /ifi/ with a comfortable voice and with maximum vocal effort. RFF values of the comfortable voice samples were synthetically lowered, and RFF values of the maximum vocal effort samples were synthetically raised. Mid-to-high frequency noise was added to the samples. Twenty listeners rated strain in a visual sort-and-rate task. The effects of RFF modification and added noise on strain were assessed using an analysis of variance; intra- and interrater reliability were compared with and without noise. Results Lowering RFF in the comfortable voice samples increased their perceived strain, whereas raising RFF in the maximum vocal effort samples decreased their strain. Adding noise increased strain and decreased intra- and interrater reliability relative to samples without added noise. Conclusions Both RFF and mid-to-high frequency noise contribute to the perception of strain. The presence of dysphonia may decrease the reliability of auditory-perceptual evaluation of strain, which supports the need for complementary objective assessments. Supplemental Material https://doi.org/10.23641/asha.13172252.

Acoustic Model of Perceived Overall Severity of Dysphonia in Adductor-Type Laryngeal Dystonia

Purpose This study is a secondary analysis of existing data. The goal of the study was to construct an acoustic model of perceived overall severity of dysphonia in adductory laryngeal dystonia (AdLD). We predicted that acoustic measures (a) related to voice and pitch breaks and (b) related to vocal effort would form the primary elements of a model corresponding to auditory-perceptual ratings of overall severity of dysphonia. Method Twenty inexperienced listeners evaluated the overall severity of dysphonia of speech stimuli from 19 individuals with AdLD. Acoustic features related to primary signs of AdLD (hyperadduction resulting in pitch and voice breaks) and to a potential secondary symptom of AdLD (vocal effort, measures of relative fundamental frequency) were computed from the speech stimuli. Multiple linear regression analysis was applied to construct an acoustic model of the overall severity of dysphonia. Results The acoustic model included an acoustic feature related to pitch and voice breaks and three acoustic measures derived from relative fundamental frequency; it explained 84.9% of the variance in the auditory-perceptual ratings of overall severity of dysphonia in the speech samples. Conclusions Auditory-perceptual ratings of overall severity of dysphonia in AdLD were related to acoustic features of primary signs (pitch and voice breaks, hyperadduction associated with laryngeal spasms) and were also related to acoustic features of vocal effort. This suggests that compensatory vocal effort may be a secondary symptom in AdLD. Future work to generalize this acoustic model to a larger, independent data set is necessary before clinical translation is warranted.

Relative Fundamental Frequency in Children With and Without Vocal Fold Nodules

Purpose Relative fundamental frequency (RFF) is an acoustic measure that is sensitive to functional voice differences in adults. The aim of the current study was to evaluate RFF in children, as there are known structural and functional differences between the pediatric and adult vocal mechanisms. Method RFF was analyzed in 28 children with vocal fold nodules (CwVN, M = 9.0 years) and 28 children with typical voices (CwTV, M = 8.9 years). RFF is the instantaneous fundamental frequency (f ₀) of the 10 vocalic cycles during devoicing (vocal offset) and 10 vocalic cycles during the revoicing (vocal onset) of the vowels that surround a voiceless consonant. Each cycle's f ₀ was normalized to a steady-state portion of the vowel. RFF values for the cycles closest to the voiceless consonant, that is, Offset Cycle 10 and Onset Cycle 1, were examined. Results Average RFF values for Offset Cycle 10 and Onset Cycle 1 did not differ between CwVN and CwTV; however, within-subject variability of Offset Cycle 10 was decreased in CwVN. Across both groups, male children had lower Offset Cycle 10 RFF values as compared to female children. Additionally, Onset Cycle 1 values were decreased in younger children as compared to those of older children. Conclusions Unlike previous work with adults, CwVN did not have significantly different RFF values than CwTV. Younger children had lower RFF values for Onset Cycle 1 than older children, suggesting that vocal onset f ₀ may provide information on the maturity of the laryngeal motor system.

Test-Retest Reliability of Relative Fundamental Frequency and Conventional Acoustic, Aerodynamic, and Perceptual Measures in Individuals With Healthy Voices

Purpose Recent studies have shown that an acoustic measure, relative fundamental frequency (RFF), has potential for the assessment of excessive laryngeal tension and vocal effort associated with functional and neurological voice disorders. This study presents an analysis of the test-retest reliability of RFF in individuals with healthy voices and a comparison of reliability between RFF and conventional measures of voice. Method Acoustic and aerodynamic measurements and Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V) were performed on 28 individuals with healthy voices on 5 consecutive days. Participants produced RFF stimuli, a sustained /ɑ/, and a reading passage to allow for extraction of acoustic measures and CAPE-V ratings; /pa/ trains were produced to allow for extraction of aerodynamic measures. Results Moderate reliabilities (intraclass correlation coefficient [ICC] = .64-.71) were found for RFF values. Mean vocal fundamental frequency, smoothed cepstral peak prominence, shimmer, harmonics-to-noise ratio, and mean airflow rate exhibited good-to-excellent reliabilities (ICC = .76-.99). ICCs for jitter and phonation threshold pressure were moderately reliable (ICC = .67-.74). ICCs for subglottal pressure estimates and all CAPE-V parameters showed poor reliabilities (ICC = .31-.58). Conclusion RFF has comparable reliability to conventional measures of voice. This expands the potential for clinical application of RFF. Supplemental Material https://doi.org/10.23641/asha.8233376.

The relationship between acoustical and perceptual measures of vocal effort

Excessive vocal effort is a common clinical voice symptom, yet the acoustical manifestation of vocal effort and how that is perceived by speakers and listeners has not been fully elucidated. Here, 26 vocally healthy adults increased vocal effort during the production of the utterance /ifi/, followed by self-ratings of effort on a 100 mm visual analog scale. Twenty inexperienced listeners assessed the speakers' vocal effort using the visual sort-and-rate method. Previously proposed acoustical correlates of vocal effort were calculated, including: mean sound pressure level (SPL), mean fundamental frequency (f o), relative fundamental frequency (RFF) offset cycle 10 and onset cycle 1, harmonics-to-noise ratio (HNR), cepstral peak prominence and its standard deviation (SD), and low-to-high (L/H) spectral ratio and its SD. Two separate mixed-effects regression models yielded mean SPL, L/H ratio, and HNR as significant predictors of both speaker and listener ratings of vocal effort. RFF offset cycle 10 and mean f o were significant predictors of listener ratings only. Therefore, speakers and listeners attended to similar acoustical cues when making judgments of vocal effort, but listeners also used additional time-based information. Further work is needed to determine how vocal effort manifests in the speech signal in speakers with voice disorders.