Spectral Form and Duration as Cues in the Recognition of English and German Vowels

Pairs of short and long vowels, such as English / / and /3: / as in shut vs. shirt, differ from each other in both spectral form and duration. Experiments were carried out on two such pairs of English vowels and two pairs of German vowels, using synthetic speech, in order to assess the relative importance of the two cues in the discrimination of the vowels. The results confirmed the hypothesis that the importance of the duration cue is inversely proportional to the distance between the qualities of a given pair of vowels. The results showed in addition that spectral form is in general more important than duration in vowel recognition in both English and German, since it is only when two vowels are very close in quality that the duration cue is more important for their discrimination. To examine the possibility that the different linguistic background of speakers of English and German might influence the amount of attention they devote to spectral form and duration, English and German subjects were presented with a test in which they had to discriminate a pair of back, unrounded vowels, and :, that occur neither in English nor in German. For the English subjects the duration cue was slightly more important than the spectral form cue. The Germans, on the other hand, discriminated the vowels largely on the basis of the spectral form cue. These results are in accordance with predictions that might be made from consideration of the phonological systems of the two languages.