Effects of consonant environment on vowel formant patterns

A significant body of evidence has accumulated indicating that vowel identi fication is influenced by spectral change patterns. For example, a large-sc ale study of vowel formant patterns showed substantial improvements in cate gory separability when a pattern classifier was trained on multiple samples of the formant pattern rather than a single sample at steady state [J. Hil lenbrand et Lll., J. Acoust. Sec. Am. 97, 3099-3111 (1995)]. However, in th e earlier study all utterances were recorded in a constant /hVd/ environmen t. The main purpose of the present study was to determine whether a close r elationship between vowel identity and spectral change patterns is maintain ed when the consonant environment is allowed to vary. Recordings were made of six men and six women producing eight vowels (/i,I,epsilon,ae,alpha ,U,u ,A/) in isolation and in CVC syllables. The CVC utterances consisted of all combinations of seven initial consonants (/h,b,d,g.p.t,k/) and six final c onsonants (/b,d,g,p,t,k/). Formant frequencies for F-1-F-3 were measured ev ery 5 ms during the vowel using an interactive editing tool. Results showed highly significant effects of phonetic environment. As with an earlier stu dy of this type, particularly large shifts in formant patterns were seen fo r rounded vowels in alveolar environments [K. Stevens and A. House, J. Spee ch Hear. Res. 6, 111-128 (1963)]. Despite these context effects, substantia l improvements in category separability were observed when a pattern classi fier incorporated spectral change information. Modeling work showed that ma ny aspects of listener behavior could be accounted for by a fairly simple p attern classifier incorporating F0, duration, and two discrete samples of t he formant pattern. (C) 2001 Acoustical Society of America.