CUES FOR PERCEPTION OF SYNTHETIC AND NATURAL DIPHTHONGS IN EITHER NOISE OR REVERBERATION

The relationship between relative intensity of transition segments and identification of diphthongs has been investigated. In the first expe riment, synthesized /aI/ stimuli were used. The stimuli differed in th e amount of attenuation of the transition segment which ranged from 0 to 15 dB. It was expected that /a/ responses would be obtained for sti muli with attenuated transitions. The stimuli were tested in quiet, no ise, and reverberation with ten normal-hearing and seven hearing-impai red subjects. For the stimulus with the most attenuated transition, th e normal-hearing subjects gave no /a/ responses and the hearing-impair ed subjects gave only 20% /a/ responses in quiet. However, in noise, b oth groups of subjects gave 70% /a/ responses and in reverberation, th e normal-hearing subjects gave 95% and the hearing-impaired subjects g ave 90% /a/ responses. Generally, less transition attenuation was need ed for the hearing-impaired than for the normal-hearing subjects to gi ve /a/ responses. These findings indicated that identification errors in noise and reverberation for naturally produced diphthongs might be related to the intensity of their transition segments. In the second e xperiment, naturally produced diphthongs /aI,au,aI/ from the Nabelek e t al. [J. Acoust. Sec. Am. 92, 1228-1246 (1992)] study were spectrally analyzed. There were 30 different tokens for each diphthong. The resu lts of the analyses indicated significant correlations between the num ber of identification errors for these diphthongs made by either norma l-hearing or hearing-impaired subjects and the relative intensities of the F2 transition segment. In both noise and reverberation there were fewer errors for the diphthong tokens characterized by high intensity F2 transitions. (C) 1996 Acoustical Society of America.