Discrimination of duration ratios by native English and Estonian listeners

Abstract

It has been suggested that Estonian has a three-way quantity distinction among disyllabic word structures in terms of the ratio of the duration of first syllable compared to the duration of the second syllable. The present study examines the ability of Estonian speakers and American English speakers to discriminate among a set of duration ratios independent of other phonetic factors such as fundamental frequency or segmental variations. Subjects were required to discriminate among pairs of noise bursts whose durations were in the ratios of 1 : 2, 2: 3, 3: 2 and 2 : 1. In half the noise sequences the combined duration of noise 1 + noise 2 was 350ms, in the other half the combined duration was 450 ms. The results obtained show that both groups of listeners clearly recognized only two contrastive patterns: 1 : 2 and 2 : 3 vs. 3 : 2 and 2 : 1. In addition, overall sequence duration had a significant effect upon duration ratio discrimination. In terms of a language group difference, the Estonian and English groups differed only in terms of responses to very different ratios (e.g. 1 : 2 vs. 2 : 1; 2 : 3 vs. 2 : 1), in particular, the Estonian group produced fewer errors. The data support a reanalysis of the three-way quantity contrast into two distinct binary decisions: one based on quantity (short–long vs. long–short disyllabic structures) and one possibly based on fundamental frequency differences.