Language and Speech

The present paper examines the issue of how speech sounds may be treated by infants as special signals relative to other kinds of acoustic stimuli. Consideration is given to the view that the mechanisms underlying the infant's perception of speech are specialized for this purpose. Some of the difficulties of providing definitive evidence for or against this position are noted. Then the thesis is advanced that special processing of speech may lie in the inherent salience which such sounds have for infants. in particular, it is suggested that the development of speech perception follows the course of an innately guided learning process. One key assumption of this view is that speech sounds may be more apt to attract attention or have a higher priority for further processing than other types of acoustic signals. Recent evidence from a number of new paradigms for studying infant speech perception is reviewed in light of this position. The paper concludes with a discussion of how findings concerning the development of speech perception during the first year of life fit with the innately guided learning view.

This paper reviews the various applications of the concepts of integration and segregation in speech perception research. These applications are illustrated with selected examples from the literature. After laying out some conceptual issues and basic assumptions, the review discusses auditory temporal and spectral integration, integration of phonetic information in its various forms, auditory temporal, spatial, and spectral segregation, segregation of linguistic from paralinguistic information, and segregation of intertwined linguistic information. It is concluded that the concepts of integration and segregation are necessary ingredients of a theory of speech perception.

The perception and production of voice onset time (VOT) was investigated in a Thai patient with an adventitious, profound sensorineural heating loss. Thai exhibits a three-category voicing distinction for bilabial (/b, p, p^h/) and alveolar (/d, t, t^h/) stops, and a two-category distinction for velar (/k, k^h/) stops. VOT perception was measured in labeling responses to synthetic speech continua differing in VOT; VOT production was measured in word-initial stops of words produced in isolation. These measurements were compared with previously published VOT data for normal-hearing Thai speakers. The results of acoustic analyses of this subject's productions suggested only minor articulatory perturbations, and the target phonemes were generally identified accurately by normal listeners.

The durations of syllabic intervals in sentences with different rhythmic structure were examined. Rhythmic structure was defined as the organization of stressed and unstressed syllables into metrical feet — in this case, iambs and anapests. Each sentence contained three metrical feet, and each foot could be either an iamb or an anapest; hence, there were eight sentences of different rhythm types. Six. native speakers of American English each read 24 versions of each of the 8 rhythm types (192 sentences). The utterances were recorded and the durations of each syllable of each foot were measured from sound spectrograms. Statistical analysis indicated that the durations of some syllables were affected by the structure of the foot that contained them. There was also, in most cases, a significant shortening of the stressed syllable of a foot when the following foot was an anapest rather than an iamb. The results were interpreted as indicating that the process by which speech is produced is not strictly concatenative but involves planning which extends to at least two metrical feet at a time.