Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Doctor of Philosophy

Program

Health and Rehabilitation Sciences

Supervisor

Doyle, Philip C.

2nd Supervisor

Parsa, Vijay

Co-Supervisor

Abstract

Background: This thesis reports the findings of three projects that included pupillometric and auditory-perceptual evaluation of three voice quality features (strain, roughness, and breathiness, respectively), and measurement of perceived listening effort. Methods: In the first study, speech samples from individuals with adductor spasmodic dysphonia (AdSD) were perceptually evaluated by both naïve and experienced listeners on the feature of vocal strain and listening effort. In the second project, speech samples of postlaryngectomy tracheoesophageal (TE) speakers were rated by two groups of naïve listeners on vocal roughness and listening effort; one group was provided with audio anchors, the other without. The final study focused on perceptual evaluation of breathiness and listening effort in talkers with vocal fold paralysis (VFP). The VFP speech samples were rated by two groups (with and without audio anchors). In all three studies, listeners’ pupillary responses also were collected (EyeLink 1000) while listening to and perceptually rating voice stimuli. Findings: Data obtained from the pupillary assessment, peak pupil dilation (PPD), may indicate a listener’s cognitive load when perceptually evaluating disordered voices. Results revealed high correlations between each of the voice dimensions and listening effort. Also, various degrees of correlations were observed between perceptual ratings and PPD. In the first study, high correlations were found between PPD and perceptual ratings for naïve listeners. A listener’s previous exposure and training evoked different pupillary behavior when compared to naïve listeners. In the second study, moderate correlations were found between perceptual dimensions and PPD values of the with–anchor group; extra cognitive load was attributed to the inclusion of anchors. Anchors also improved interrater reliability for this listener group. In the third project, again correlation was observed between perceptual ratings and PPD. The inclusion of anchor did not improve reliability over the no-anchor group. Similar to the second study, PPD measures of the with-anchor group were impacted by the use of anchors. 2 Conclusions: Overall, our data offer valuable insights into auditory- perceptual evaluation of voice quality, the influence of listener experience, previous exposure to dysphonic voices, inclusion/exclusion of audio anchors, and voice features and the potential physiological or cognitive responses to dysphonic voices.

Summary for Lay Audience

The purpose of the experiments reported in this thesis was to examine how people evaluate the voices of individuals diagnosed with different voice disorders. Voice disorders may happen due to different reasons such as neurological problems that influence the nerves controlling the muscles of the larynx or due to laryngeal cancer. Depending on the type and underlying cause of the voice disorder, changes in the sound or “quality” of the voice may vary and will differ from that which is considered normal. Such disorders impact many aspects of an individual’s life and many of them seek treatment. In order to assess the extent of the disorder at the time of diagnosis and to see how successful the treatment has been afterwards, voice quality is typically evaluated through various methods. One of the most commonly used measures is auditory-perceptual evaluation, a measure based on the judgments and impression of listeners. In addition to the individuals with voice disorder, it is interesting to evaluate how people who are in close contact with them such as family members, and care givers may be impacted by changes in their voices. As a result, these studies recruited participants to listen to samples from speakers with three types of voice disorders. Listeners were asked to rate the voices of each speaker on one of three dimensions, how strained, rough, or breathy they sounded. The listeners also were asked to indicate how much “work” they thought they needed to listen to those samples by rating a feature termed “listener effort”. In all three experiments, simultaneous data on each listener’s variations in pupil dilation in response to these abnormal voice samples were gathered. This measure was obtained with the assumption that changes in pupil dilation, namely, what is termed peak pupil diameter could be used as an indicator of listening and cognitive effort. Results revealed that listeners may require more cognitive work and attention when listening to some disordered voices. This listening demand or cognitive load also may decrease and listeners may habituate to voices with an abnormal quality as they get more exposure to such voices.

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