Christine Szostak

Rate dependent speech processing can be speech specific: Evidence from the perceptual disappearance of words under changes in context speech rate.

The perception of reduced syllables, including function words, produced in casual speech can be made to disappear by slowing the rate at which surrounding words are spoken (Dilley & Pitt, Psychological Science, 21(11), 1664–1670. doi: 10.1177/0956797610384743, 2010). The current study explored the domain generality of this speech-rate effect, asking whether it is induced by temporal information found only in speech. Stimuli were short word sequences (e.g., minor or child) appended to precursors that were clear speech, degraded speech (low-pass filtered or sinewave), or tone sequences, presented at a spoken rate and a slowed rate. Across three experiments, only precursors heard as intelligible speech generated a speech-rate effect (fewer reports of function words with a slowed context), suggesting that rate-dependent speech processing can be domain specific.

A lexically biased attentional set compensates for variable speech quality caused by pronunciation variation

Words are pronounced in multiple ways in casual speech, which from the perspective of information transmission can be viewed as distortions that the listener must overcome to recognise the word intended by the talker. Two experiments explored the proposal that the recognition of pronunciation variants is facilitated by a lexically biased attentional set, which listeners adopt to compensate for fluctuations in signal reliability. Lexical decision responses were collected to multi-syllabic words in which a phoneme in one of four positions was gradually altered to make it a nonword. In Experiment 1, attention was manipulated through instruction. In Experiment 2, a lexically biased attentional set was induced by altering the design of Experiment 1. Results suggest that attention modulates lexical acceptability, damping lexical influences when attention is focused on perceiving the speech signal veridically (i.e., as pronounced), and maximising lexical biases when attention is focused on ensuring successful message transfer (i.e., perceiving the intended word).

The influence of amplitude envelope information on resolving lexically ambiguous spoken words

Prior studies exploring the contribution of amplitude envelope information to spoken word recognition are mixed with regard to the question of whether amplitude envelope alone, without spectral detail, can aid isolated word recognition. Three experiments show that the amplitude envelope will aid word identification only if two conditions are met: (1) It is not the only information available to the listener and (2) lexical ambiguity is not present. Implications for lexical processing are discussed.

Word segmentation of American English /s/ in semi‐spontaneous speech.

To comprehend spoken language, listeners need to find words from a continuous stream of speech sounds. Little work has explored whether there are reliable acoustic cues to word boundaries in conversational speech, which is highly reduced and under‐articulated, potentially creating ambiguities at word boundaries. Segmentation may be even more difficult when the same segment repeats at a word boundary, ending the preceding word and beginning the following word (e.g., gas station). Segmentation in this environment was investigated by examining the production and perception of fricative /s/ in semi‐spontaneous speech. Twenty talkers produced sentences containing ambiguous two‐word sequences with /s/ between the two words. All sequences are interpretable in three ways (e.g., grow snails, gross snails, and gross nails) depending on how the frication is segmented. Acoustic analyses of the production data examined whether there are acoustic cues distinguishing the three versions of the ambiguous sequences. Listen...