The interaction of lexical and phrasal prosody in whispered speech.

The production and perception of Dutch whispered boundary tones, i.e., phrasal prosody, was investigated as a function of characteristics of the tone-bearing word, i.e., lexical prosody. More specifically, the disyllabic tone-bearing word also carried a pitch accent, either on the same syllable as the boundary tone (clash condition), or on the directly adjacent syllable (no clash condition). In a statement/question classification task listeners showed moderate, but above-chance performance for both conditions in whisper, which, however, was much worse as well as slower than in normal speech. The syllabic rhymes of speakers' productions were investigated for acoustic correlates of boundary tones. Results showed mainly secondary cues to intonation, that is, cues that are present in whisper as in normal speech, but minimal compensatory cues, which would reflect speakers' efforts to enhance their whispered speech signal in some way. This suggests that multiple prosodic events in close proximity are challenging to perceive and produce in whispered speech. A moderate increase in classification performance was found when that acoustic cue was enhanced that whispering speakers seemed to employ in a compensatory way: changing the spectral tilt of the utterance-final syllable improved perception of especially the poorer speakers and of intonation on stressed syllables.

Perceptual development of phoneme contrasts: how sensitivity changes along acoustic dimensions that contrast phoneme categories.

Listeners discriminate acoustic differences between phoneme categories at a higher level than similarly sized differences within phoneme categories. The question this paper aims to answer is how this pattern in perceptual sensitivity develops along an acoustic dimension that contrasts two non-native speech sounds: through acquired distinctiveness, through acquired similarity, or through a combination of the two. A pretest-training-post-test experiment was designed to study perceptual development directly, i.e., by including (i) a discrimination task to measure perceptual sensitivity, (ii) a transfer test to ensure language learning instead of stimulus learning, and (iii) a control group to exclude task repetition as an explanation of improvement. It is shown that the typical peak in perceptual sensitivity near a phoneme boundary that native listeners show is not found in relatively inexperienced language learners, despite their ability to classify a continuum in a nativelike way after short laboratory training. Experiment II indicates that a discrimination peak may be achieved by language learners, but only after much more language experience than short-term laboratory training can offer. Furthermore, reasons are given why classification improvement in the laboratory should not be taken as evidence for (i) increased discrimination of the newly learned phonemes and (ii) learning of phoneme representations.