The role of vowel length and glottalization in German learners' perception of the English coda stop voicing contrast

In German, the voicing contrast in word-final stops is neutralized towards the voiceless sound. We tested how German learners of English use in perception two phonetic cues to this contrast in English: the duration of the vowel preceding the stop and the partial glottalization of this vowel. While a longer vowel cues the voiced sound of the contrast, glottalization enhances the voiceless sound, which should be ‘easy’ for learners as word-finally it is the default in German. We asked whether cueing the ‘easy’ sound would nevertheless affect learners’ word identification. Learners categorized two English minimal pairs along vowel duration continua with either a fully modal vowel or the last 25% of the vowel glottalized. Learners gave more voiced-stop responses as vowel duration increased. They also used glottalization by giving fewer voiced-stop responses for the glottalized continua. A second experiment demonstrated that the glottalization was not merely perceived as a change in the vowel+closure duration ratio. When the glottalized portion of the vowels was set to silence learners gave even fewer voiced-stop responses than in the glottalized condition. Results suggest that learners can use a phonetic cue to a second language sound contrast even if it enhances the familiar ‘easy’ sound.