Abstract
Background: Many factors influence listener perception of dysarthric speech. Final consensus on the role of gender and listener experience is still to be reached. The speaker's perception of his/her speech has largely been ignored.
Aims: (1) To compare speaker and listener perception of the intelligibility of dysarthric speech; (2) to explore the role of gender and listener experience in speech perception; and (3) to examine the relationship between speaker perceptions of intelligibility and formal clinical intelligibility ratings.
Methods & Procedures: Study 1 examines listener perception of intelligibility of dysarthric speech. Twenty people with acquired dysarthria, ten speech language therapists (SLTs) and 20 naïve listeners heard audio recordings of dysarthric speech and used direct magnitude estimation (DME) to rate perceptions of speech intelligibility. Differences in perception across gender and listener experience (SLTs versus naïve listeners) were examined. Study 2 tackles the speaker's perception of his/her own speech intelligibility. Using the same groups of participants and DME, speakers rated their own speech intelligibility. SLTs and naïve listeners then rated their perception of the speakers' intelligibility. Differences in perceptions between speakers and listeners were compared. Further analysis examined differences across gender and listener experience. Finally, ratings of speakers' perception of their own intelligibility were compared with intelligibility scores on the Assessment of Intelligibility of Dysarthric Speech (ASSIDS) (1981).
Outcomes & Results: Study 1 showed no statistically significant differences in perception of intelligibility across the three listener groups, although results suggest that speakers rate perceptions of intelligibility differently to SLTs and naïve listeners. Despite some individual differences in ratings between speakers and listeners in Study 2, overall there are no significant group differences and methodological limitations to this section of the study are highlighted. In Studies 1 and 2 there are no statistically significant differences across gender and listener experience, although SLTs are less consistent in their ratings of speech when compared with naïve listeners. There is no statistically significant relationship between formal intelligibility assessment scores and the speakers' perception of intelligibility.
Conclusions: This study contributes to an understanding of perceptions of dysarthric speech. The lack of gender differences in listener perception supports earlier findings in other areas of SLT. The strong relationship between SLT and naïve listeners' perceptions suggests that SLTs are not more critical of dysarthric speech. The discrepancy between formal assessment measures and speakers' perceptions of intelligibility has implications for clinical practice. The need for further research in the area is highlighted.
Notes
1. These judges comprised one naïve listener, one SLT student, and one SLT who did not participate further in the study.
2. Numerical values are not always supplied. Listeners can supply their own numerical values. This is known as a free modulus situation. Southwood (personal communication, 1998) advises on supplying a numerical value not only for ease of calculation, but also because studies (Schiavetti et al.Citation1983, Southwood and Flege Citation1999) have shown that there are no differences between responses when a numerical value has been supplied and a free modulus situation.