The Effects of Clear Speech on American English Listener Perception of Spanish-Accented and Native English Speech

Abstract

Purpose The purpose of this study was to explore (a) the effect of clear speech on intelligibility, ease of understanding, and accentedness in Spanish-accented and native English speakers of American English and (b) the extent to which accentedness predicts intelligibility and ease of understanding. Method Ten adult talkers, five native English speakers and five native Spanish speakers, read aloud 28 short sentences in habitual speech and clear speech. One hundred monolingual English listeners transcribed what they heard and rated ease of understanding using a 10-cm visual analog scale while hearing the sentences in six-talker babble. Then, accentedness (using a visual analog scale) was judged in quiet. Intelligibility was calculated as the number of words transcribed correctly for each sentence. Ten listeners with significant exposure to Spanish-accented speech rated each talker. Each listener heard only one talker, rating half the sentences in clear speech and half in habitual speech, so that no listener heard a sentence more than once for the intelligibility and ease of understanding assessments. Results Clear speech improved intelligibility and ease of understanding for both language groups, with greater improvement in nonnative talkers. Clear speech did not alter accentedness in nonnative talkers but did increase accentedness in native talkers. Accentedness did not strongly predict intelligibility but did predict ease of understanding, although the relationship was nonlinear. Conclusions Listeners who are experienced in hearing Spanish-accented speech derive significant benefits from clear speech. The difference in the predictability of accentedness for intelligibility and ease of understanding contributes further evidence to the difference in underlying cognitive processes for these two variables.