When speaking clearly does not enhance comprehension: Comparing intelligibility of hard-of-hearing- and non-native-directed speech for native and non-native listeners

Abstract

While clear speech is more intelligible than casual speech, some prior work indicates that the clear speech benefit is reduced for non-native listeners. It is unclear, however, how intelligibility for native and non-native listeners might differ across clear styles directed towards different imagined interlocutor types. If clear speech enhancements benefit the intended listeners, then (1) for non-native listeners, non-native-directed speech should be more intelligible than hard-of-hearing-directed speech; (2) native and non-native listeners should benefit equally from non-native-directed speech, while the advantage of hard-of-hearing-directed speech should be greater for native listeners. Native English speakers were recorded producing casual, hard-of-hearing, and non-native-directed speech to imagined interlocutors. Results from a speech-perception-in-noise task indicate that (1) native listeners had higher transcription accuracy than non-native listeners; (2) hard-of-hearing-directed speech was more intelligible than both non-native-directed and casual speech; (3) non-native-directed and casual speech did not differ in intelligibility; and (4) native and non-native listeners did not differ in the relative benefit of hard-of-hearing-directed speech. Contra our hypothesis, non-native-directed speech did not benefit non-native listeners despite being hyper-articulated compared to casual speech. This study highlights that speakers’ expectations of what will be helpful for listeners do not always provide the intended benefit.