Perception of speech produced by native and nonnative talkers by listeners with normal hearing and listeners with cochlear implants

Abstract

PURPOSE The aim of this study was to evaluate the understanding of English sentences produced by native (English) and nonnative (Spanish) talkers by listeners with normal hearing (NH) and listeners with cochlear implants (CIs). METHOD Sentence recognition in noise was measured in adult subjects with CIs and subjects with NH, all of whom were native talkers of American English. Test sentences were from the Hearing in Noise Test (HINT) database and were produced in English by four native and eight nonnative talkers. Subjects also rated the intelligibility and accent for each talker. RESULTS The speech recognition thresholds in noise of subjects with CIs and subjects with NH were 4.23 dB and 1.32 dB poorer with nonnative talkers than with native talkers, respectively. Performance was significantly correlated with talker intelligibility and accent ratings for subjects with CIs but only correlated with talker intelligibility ratings for subjects with NH. For all subjects, performance with individual nonnative talkers was significantly correlated with talkers' number of years of residence in the United States. CONCLUSION CI users exhibited a larger deficit in speech understanding with nonnative talkers than did subjects with NH, relative to native talkers. Nonnative talkers' experience with native culture contributed strongly to speech understanding in noise, intelligibility ratings, and accent ratings of both listeners with NH and listeners with CIs.

Figure 1

Mean SRTs (across talkers) for individual CI subjects. The black bars show data for native talkers, the gray bars show data for non-native talkers. There error bars show the standard error.

Figure 2

SRTs (across subjects) for CI (left panel) and NH subjects (right panel). Data is shown for English (male and female) and Spanish (male and female) talkers. The solid line shows median performance, the dashed line shown mean performance; the error bars show the 10^th and 90^th percentile, and the circles show outliers.

Figure 3

Mean SRTs (across subjects) for each talker, for CI (top panel) and NH subject (right panel); mean performance for the English and Spanish talkers is shown at far right. The solid line shows median performance, the dashed line shown mean performance; the error bars show the 10^th and 90^th percentile, and the circles show outliers.

Figure 4

Mean SRTs as a function of mean talker intelligibility rating (black circles; bottom x-axis) and mean talker accent rating (white circles; top x-axis), for CI (left panel) and NH subjects (right panel). The solid lines show linear regressions between intelligibility ratings and SRTs, and the dashed lines show linear regressions between accent ratings and SRTs. r² and p values are shown for each correlation in the lower right corner of each plot.