PP512 - Speech Impressions and Speech Intelligibility of Deaf Talkers

Abstract:
Deaf talkers have reduced intelligibility (Freeman & Pisoni, 2017,) but the way normal-hearing listeners perceive the naturalness and likability of deaf speech is unknown. Moreover, normal-hearing listeners familiar with deaf speech rate it as more intelligible than unfamiliar listeners do (McGarr, 1983); however, the impact of such exposure on perceived naturalness and likability is not understood. In this study, normal-hearing participants with varying levels of experience with deaf speech rate speech produced by deaf talkers on these three factors. This study will investigate the relationship between these factors in deaf speech and the impact of listening experience.

Summary:
Rationale
Intelligibility is the degree to which the listener recovers the speaker’s intended message (Kent et al., 1989), while naturalness and likability are subjective impressions of speech. Previous research has established reduced intelligibility for deaf talkers (Freeman & Pisoni, 2017), likely due to wide-ranging differences in speech production (Hayat et al., 2022; Arias-Vergara et al., 2022), though this is mitigated when the listener has experience with deaf speech (McGarr, 1983). While the naturalness and likability of deaf talkers have not been investigated, research on other populations suggests that speech production differences can reduce perceived naturalness and likability (Euler et al., 2021; Parker & Borrie, 2018); however, it is unknown if it depends on the listener’s experience.

This study aims to test whether deaf speech intelligibility, naturalness, and likability are correlated; the secondary purpose is to assess whether the listener’s experience with deaf speech impacts their ratings of any of these factors.

Method
Participants. Participants are 18-60 year-old native English speakers from deaf or hearing families. Some will be from Gallaudet University, a school for deaf and hard-of-hearing, resulting in varied familiarity with deaf speech.

Procedure. Participants complete two tasks. First, they complete a background questionnaire to determine their familiarity with deaf speech. They then complete a rating task in PsychoPy, in which they listen to recordings of deaf talkers and rate them for intelligibility, likability, and naturalness. Data collection will be completed this fall.

Speech stimuli. Recordings are from the corpus of Mendel et al. (2017), which includes recordings from 30 deaf talkers (22 females) aged 16 to 77 years (mean = 50; SD=17) reading the grandfather passage.

Data analysis. To test the relationship between deaf speech intelligibility, naturalness, and likability, multiple correlation analysis in R (R Core Team, 2022) will be used. To find the impact of listening experience with deaf speech, a simple linear regression model will be run separately for intelligibility, naturalness, and likability.

Hypotheses and Importance
We hypothesize positive correlations between intelligibility, naturalness, and likability, with a stronger link between naturalness and likability. If intelligibility strongly correlates with the other variables, targeting it in therapy may reduce social stigma related to speech perceived as unnatural or unlikable. On the other hand, since consonants and vowel production heavily influence intelligibility (Ertmer, 2010), a weak correlation between intelligibility and naturalness or likability would imply that resonance, voice, or prosody may be more important for improving how “normal” speech sounds. We also hypothesize that listeners who are experienced with deaf speech will rate intelligibility higher than less experienced ones, but that naturalness and likability may not differ by the listener’s experience. However, if the experience with deaf speech does improve any of these factors, this would suggest that fostering interactions between hearing and deaf individuals could help reduce the social stigma experienced by deaf talkers.

Innovation
This study is the first to investigate the naturalness and likability of deaf speech, along with their relationship to intelligibility. Furthermore, it assesses the influence of listening experience.