Relationship between identification errors and spectral details of naturally produced diphthongs

In an earlier study [A. K. Nabelek etal., J. Acoust. Soc. Am. 92, 1228–1246 (1992)], identification errors were collected for 15 English vowels, monophthongs, and diphthongs. The vowels were produced in a /b–t/ context by six male talkers who uttered five tokens of each vowel. There were 20 normal-hearing and 20 hearing-impaired subjects. Listening conditions were quiet, noise, and reverberation. Large differences in number of errors were observed among the 30 tokens of each vowels. The goal of the current study was to determine relationships between the spectral details of the diphthongs /open ayei, open ohi, open ayeu/ and identification errors. Spectral analyses indicated that all three diphthongs had two distinct segments. In the first segment F1 and F2 were relatively steady state and in the second segment F2 changed over time. For each token of each diphthong, frequencies and levels of F1 and F2 were traced along the duration of the diphthong. The results of this analysis seem to indicate a relationship between the number of identification errors for these diphthongs and the relative levels of the F2 transition segment. Examples of highly identifiable and high confusable diphthongs will be shown. [This work was supported by NIDCD.]