Identification and Discrimination of Rounded and Unrounded Vowels

The aim of this experiment was to examine the identification and discrimination of a series of rounded and unrounded vowels by a group of listeners (Swedish) who were familiar with both types of vowels. The following groups of stimuli were assembled using the Stockholm OVE II speech synthesizer, and were arranged in the form of identification tests and ABX discrimination tests: (1) a series of thirteen vowels in which the first three formants varied in approximately equal logarithmic steps through three unrounded vowels (roughly /i/, /ɪ/, and /ɛ/); (2) a similar series in which the second and third formants varied in approximately equal logarithmic steps from the unrounded /i/ through the rounded /y/ to the rounded /u/; and (3) a series of thirteen vowels constructed by taking /i/ as a center and then including the first six steps along the unrounded continuum and the first six steps along the rounded continuum. The discrimination functions showed small peaks near the phoneme boundaries; i.e., discriminat...