An Auditory-Perceptual and Pupillometric Study of Vocal Strain and Listening Effort in Adductor Spasmodic Dysphonia

Abstract

This study evaluated ratings of vocal strain and perceived listening effort by normal hearing participants while listening to speech samples produced by talkers with adductor spasmodic dysphonia (AdSD). In addition, objective listening effort was measured through concurrent pupillometry to determine whether listening to disordered voices changed arousal as a result of emotional state or cognitive load. Recordings of the second sentence of the “Rainbow Passage” produced by talkers with varying degrees of AdSD served as speech stimuli. Twenty naïve young adult listeners perceptually evaluated these stimuli on the dimensions of vocal strain and listening effort using two separate visual analogue scales. While making the auditory-perceptual judgments, listeners’ pupil characteristics were objectively measured in synchrony with the presentation of each voice stimulus. Data analyses revealed moderate-to-high inter- and intra-rater reliability. A significant positive correlation was found between the ratings of vocal strain and listening effort. In addition, listeners displayed greater peak pupil dilation (PPD) when listening to more strained and effortful voice samples. Findings from this study suggest that when combined with an auditory-perceptual task, non-volitional physiologic changes in pupil response may serve as an indicator of listening and cognitive effort or arousal.

Eye movements decrease during effortful speech listening

“…Previous work differed in the specific threshold that was used. Some works used a velocity threshold of 5 (Engbert and Kliegl, 2003;Widmann et al, 2014), whereas others used a threshold of 15 (Kadem et al, 2020). A lower threshold leads to a higher number of data points that are considered a saccade/microsaccade.…”

“…Hence, we calculated analyses for both thresholds. A time course of saccade/microsaccade rate was calculated from the individual saccade/microsaccade times (Widmann et al, 2014;Kadem et al, 2020) by convolving each occurrence with a Gaussian function (standard deviation of 0.02 s; zero phase lag). We do not distinguish between saccades and microsaccades, because the definition depends on the velocity threshold and previous work suggests that the same mechanisms underlie saccades and microsaccades (Martinez-Conde et al, 2009;Martinez-Conde et al, 2013).…”

“…For four out of the 26 participants, the quality of the eye-tracking and pupil data was low. That is, over 30% of trials contained more than 40% of missing data (Kadem et al, 2020). Hence, data from twenty-two adults (median age: 23 years; age range: 18-30 years; 16 female, 6 male) were available for analyses of eye movements (N=26 for behavioral analysis).…”

“…Different SNRs were achieved by adjusting the sound level of the sentence, while keeping the babble level constant across trials (Ohlenforst et al, 2017;Kadem et al, 2020). This approach ensured that stimuli with different SNRs did not differ prior to sentence onset (Ohlenforst et al, 2017;Kadem et al, 2020). Assignment of SNR levels to specific sentences was randomized across participants.…”

“…Physiological measures provide an objective window onto listening effort that can remedy disadvantages of subjective ratings (Mackersie et al, 2015;Wöstmann et al, 2015;Dimitrijevic et al, 2017;Miles et al, 2017). Pupillometry -the measurement of pupil dilation -is the most used objective tool to assess listening effort Zekveld et al, 2018;Kadem et al, 2020). However, pupil dilation is sensitive to environmental changes in luminance (Knapen et al, 2016) and light spectrum (Suzuki et al, 2019;Thurman et al, 2021), and is therefore difficult to use outside of the laboratory.…”