Volume 51, Issue 4

Three experiments used sine-wave replicas of speech sounds to explore some differences between speech perception and general auditory perception. The experiments compared patterns of behavior in categorization and discrimination tasks for listeners reporting either speech or nonspeech percepts of sine-wave replicas of speech. We hypothesized that the perception of speech sounds is automatized, while the perception of less familiar sounds is not. The first experiment was designed to investigate the perception of relatively long initial consonant transitions using a synthetic /wa/-/ya/ sine-wave analog continuum. Speech listeners perceived the continuum categorically, but nonspeech listeners could not consistently categorize the items in the continuum. In the second experiment, both speech and nonspeech listeners could consistently categorize stimuli having final glides (an /ay/-/aw/ sine-wave replica continuum), but differences between speech and nonspeech listeners were found in the slopes of the identification functions, in reaction times, and in the effect of context. These differences are consistent with the hypothesis that speech perception is automatized. In the third experiment, nonspeech listeners’ discrimination sensitivity was greater than speech listeners’. The observed pattern of results suggests that speech perception is accomplished by a fast, obligatory, and thus automatic perceptual mechanism.

Aerodynamic evidence indicates the existence of overlapped labial//velar sequences in Korean. Oral pressure readings for [ipku] show a brief rarefaction in oral pressure during the consonantal sequence, indicating that tongue retraction during a front-back vowel sequence occurs simultaneously with full closures at the labial and velar places of articulation. This confluence of phenomena results in the observed pressure rarefaction due to expansion of the sealed oral cavity. Similarly, pressure readings for [upki] show a brief, marked increase during the consonantal sequence, indicating that tongue advancement during a back-front vowel sequence temporally overlaps with full closures at both the labial and velar places of articulation. This results in a pressure increase due to contraction of the sealed oral cavity. To our knowledge, the present study is the first to demonstrate consonant coproduction in terms of oral pressure, and to report on coarticulatory effects involving four sequenced segments.

This study explored the extent to which the acoustic manifestation of a phonetic feature is influenced by the linguistic role that the feature plays in the sound inventory of the particular language. To this end, we investigated the acoustic property associated with the feature [strident] in the production of bilabial and labiodental fricatives in Ewe, and labiodental and alveolar fricatives in English, and explored whether the acoustic manifestation of the feature [strident] varied in the instantiation of [f] in Ewe and English. In Ewe, the feature [strident] plays a contrastive role distinguishing labiodental from bilabial fricatives, whereas in English the feature [strident] does not play a contrastive role. Results showed that a measure of turbulence noise was able to distinguish bilabial and labiodental fricatives in Ewe and labiodental and alveolar fricatives in English. Moreover, the range of values associated with defining the amplitude characteristics for [f] was similar in the two languages. Nevertheless, differences emerged in the acoustic fine structure of the noise amplitude for [f v] in the two languages, with the frequency distribution for the labiodental fricative in Ewe being skewed towards the high amplitude range relative to English. These results suggest that while the fundamental manifestation of the acoustic property is the same across languages, its instantiation may be influenced by the functional role that its associated feature plays in the language.