Abstract:

Based on factors in lexical competition such as usage frequency and similarity-neighborhood density, previous research has characterized words as ``easy'' or ``hard'' to identify. Lindblom [in W. Hardcastle and A. Marchal (Eds.), 403--439 (1990)] has proposed that talkers accommodate listeners' communicative needs by controlling the degree of reduction (hyper- and hypoarticulation) in different contextual conditions. This study examines the degree of centralization of vowels in 38 ``easy'' and 38 ``hard'' monosyllabic (CVC) words of equal familiarity spoken in isolation by ten talkers. Measurements of the first two vowel formants (F1, F2) are made at the point of maximal displacement in the vowel (excluding the initial and final 50 ms of the vowel). Centralization is measured by calculating the Euclidean distance from the center of a talker's F1--F2 vowel space. Three results emerge: (1) overall ``easy'' words were significantly more centralized than ``hard'' words; (2) peripheral vowels, such as /i/, /a/, /u/, showed the greatest effect; and (3) there was considerable between-talker variability both in overall vowel centralization and in the magnitude of the difference between vowels in ``easy'' and ``hard'' words. [Work supported by NIH Grant No. DC00012.]