Volume 106, Issue 3, September 1999
Index of content:
- SPEECH PERCEPTION 
106(1999); http://dx.doi.org/10.1121/1.427152View Description Hide Description
Among the world’s languages, syllable inventories allowing only initial consonants predominate over those allowing both initial and final consonants. Final consonants may be disfavored because they are less easy to identify and/or more difficult to produce than initial consonants. In this study, two perceptual confusion experiments were conducted in which subjects identified naturally produced consonant–vowel–consonant syllables in different frame sentences. Results indicated that initial consonants were significantly more identifiable than final consonants across all conditions. Acoustic analyses of the test syllables indicated that the relative identifiability of initial and final consonants might be explained in terms of production differences as indicated by the greater acoustic distinctiveness of initial consonants.
106(1999); http://dx.doi.org/10.1121/1.428035View Description Hide Description
In order to assess the relative importance of various signal processing algorithms and distortions on hearing-aid preference, male and female speech was manipulated in a number of ways and subsequently presented to normal-hearing and hearing-impaired subjects (the latter having a mild sensorineural high-frequency hearing loss). Signal manipulations were artificial (e.g., filtering, compression, peak clipping, or adding noise) or were actual dummy-head recordings of five different hearing aids. Listeners judged the sounds in a pairwise-comparison format. Their task was to indicate the “hearing aid” they would prefer assuming they had to wear it all day. The data were analyzed with multidimensional scaling techniques; Principal Components Analysis revealed that the first two dimensions on which preference judgments were based, can be interpreted as (1) intelligibility or clarity, and (2) distinction between signal distortion and added background distortion. Furthermore, the results showed that normal-hearing subjects generally preferred the original signal, whereas hearing-impaired subjects were inclined to choose the signals with a high-frequency emphasis. Severe band-pass filtering or low-frequency emphasis were disliked, as was to be expected. Surprisingly, however, a soft background noise (S/N ratio of 25 dB) was often among the least preferred of all signals. The differences in preference between the five hearing aids were small, but consistent. For hearing-impaired subjects, hearing-aid ordering could be accounted for by the amount of low-frequency cutoff; for normal-hearing subjects both high- and low-frequency cutoff played a role. Results of a retest experiment with normal-hearing subjects, about one year later, showed that subjects’ criteria remain remarkably stable.