Recognition of spoken words by native and non-native listeners: talker-, listener-, and item-related factors

Abstract

In order to gain insight into the interplay between the talker-, listener-, and item-related factors that influence speech perception, a large multi-talker database of digitally recorded spoken words was developed, and was then submitted to intelligibility tests with multiple listeners. Ten talkers produced two lists of words at three speaking rates. One list contained lexically "easy" words (words with few phonetically similar sounding "neighbors" with which they could be confused), and the other list contained lexically "hard" words (words with many phonetically similar sounding "neighbors"). An analysis of the intelligibility data obtained with native speakers of English (experiment 1) showed a strong effect of lexical similarity. Easy words had higher intelligibility scores than hard words. A strong effect of speaking rate was also found whereby slow and medium rate words had higher intelligibility scores than fast rate words. Finally, a relationship was also observed between the various stimulus factors whereby the perceptual difficulties imposed by one factor, such as a hard word spoken at a fast rate, could be overcome by the advantage gained through the listener's experience and familiarity with the speech of a particular talker. In experiment 2, the investigation was extended to another listener population, namely, non-native listeners. Results showed that the ability to take advantage of surface phonetic information, such as a consistent talker across items, is a perceptual skill that transfers easily from first to second language perception. However, non-native listeners had particular difficulty with lexically hard words even when familiarity with the items was controlled, suggesting that non-native word recognition may be compromised when fine phonetic discrimination at the segmental level is required. Taken together, the results of this study provide insight into the signal-dependent and signal-independent factors that influence spoken language processing in native and non-native listeners.

FIG. 1

Mean transcription accuracy scores across all talkers and listeners for the easy and hard words at the slow, medium, and fast speaking rates. The error bars represent the standard error of the mean.

FIG. 2

Mean transcription accuracy scores across all talkers and listeners for the easy and hard words in the first and fourth quartiles at the slow, medium, and fast speaking rates, and averaged across all three speaking rates. The error bars represent the standard error of the mean.

FIG. 3

Mean transcription accuracy scores for the easy and hard words in the single and multiple talker conditions for the control subjects (left panel), the non-native subjects (middle panel), and only the items of high familiarity to the non-native subjects (right panel). The error bars represent the standard error of the mean.

FIG. 4

Mean familiarity ratings for the control and non-native subjects on words of previously determined low, medium, and high familiarity (left panel), and the easy and hard words used in the present word recognition tests (right panel). The error bars represent the standard error of the mean.