An acoustic study of real and imagined foreigner-directed speech

Foreigner-directed speech is a much cited speech style, but its acoustic properties are surprisingly under-studied, and many existing studies evoke imagined interlocutors to elicit foreigner-directed speech. This study provides an acoustic comparison of foreigner-directed and native-directed speech in real and imaginary conditions. Ten native English speakers described the path between landmarks on a map to each of two confederate listeners (one native English speaker and one native Mandarin speaker) and to two imagined listeners (one described as a native English speaker and the other as a non-native speaker). Vowel duration, rate of speech, and vowel centralization were examined across native-foreigner and real-imagined conditions in 22 target words. Stressed vowels were longer and rate of speech was slower in foreigner-directed than in native-directed speech. Additionally, /ae/ was more peripheral in the vowel space in the foreigner-directed condition. These effects were consistent across real and imaginary conditions; however, vowels were longer, rate of speech was slower, and /ae/ was more peripheral in the imaginary than in the real condition. In other words, speakers made acoustic-phonetic adjustments in foreigner-directed speech that are consistent with those seen in listener-directed clear speech, and these accommodations were greater when the listener was imagined rather than real.