Hearing loss and the phonetic context effect

In order to gain a better understanding of how hearing loss influences speech perception, the influence of phonetic context on vowel identification was tested under simulated hearing loss conditions. Participants (n=17) were presented vowels along the /ε/ - /∧/ acoustic continuum in /bVb/ and /dVd/ contexts and instructed to indicate which vowel they heard in normal hearing, and mild and severe simulated hearing loss conditions. It was hypothesized that a phonetic context effect would be observed in the normal hearing condition, diminish in the mild hearing loss condition, and disappear in the severe hearing loss conditions. The percent of /ʌ/ responses were calculated and the categorical boundary was estimated for each context and compared for differences within and across conditions. Contrary to expectations, no context effect was found for the normal hearing and mild hearing loss conditions. However, an unexpected phonetic context effect was observed in the severe hearing loss condition. These results were difficult to interpret given the lack of a significant context effect in the normal hearing condition and suggested possible interference introduced by test or stimulus procedures. It should be noted, however, that 9 of the 17 participants did demonstrated the effect in the normal hearing condition, with many maintaining the effect across both hearing loss conditions