On the perception of similarity among talkers.

A listener who recognizes a talker notices characteristic attributes of the talker's speech despite the novelty of each utterance. Accounts of talker perception have often presumed that consistent aspects of an individual's speech, termed indexical properties, are ascribable to a talker's unique anatomy or consistent vocal posture distinct from acoustic correlates of phonetic contrasts. Accordingly, the perception of a talker is acknowledged to occur independently of the perception of a linguistic message. Alternatively, some studies suggest that attention to attributes of a talker includes indexical linguistic attributes conveyed in the articulation of consonants and vowels. This investigation sought direct evidence of attention to phonetic attributes of speech in perceiving talkers. Natural samples and sinewave replicas derived from them were used in three experiments assessing the perceptual properties of natural and sine-wave sentences; of temporally veridical and reversed natural and sine-wave sentences; and of an acoustic correlate of vocal tract scale to judgments of sine-wave talker similarity. The results revealed that the subjective similarity of individual talkers is preserved in the absence of natural vocal quality; and that local phonetic segmental attributes as well as global characteristics of speech can be exploited when listeners notice characteristics of talkers.

Analysis and analogy in the perception of vowels.

In two experiments, we investigated the creation of conceptual analogies to a contrast between vowels. An ordering procedure was used to determine the reliability of simple sensory and abstract analogies to vowel contrasts composed by naive volunteers. The results indicate that test subjects compose stable and consistent analogies to a meaningless segmental linguistic contrast, some invoking simple and complex relational properties. Although in the literature of psychophysics such facility has been explained as an effect of sensory analysis, the present studies indicate the action of a far subtler and more versatile cognitive function akin to the creation of meaning in figurative language.

Learning to recognize talkers from natural, sinewave, and reversed speech samples.

In 5 experiments, the authors investigated how listeners learn to recognize unfamiliar talkers and how experience with specific utterances generalizes to novel instances. Listeners were trained over several days to identify 10 talkers from natural, sinewave, or reversed speech sentences. The sinewave signals preserved phonetic and some suprasegmental properties while eliminating natural vocal quality. In contrast, the reversed speech signals preserved vocal quality while distorting temporally based phonetic properties. The training results indicate that listeners learned to identify talkers even from acoustic signals lacking natural vocal quality. Generalization performance varied across the different signals and depended on the salience of phonetic information. The results suggest similarities in the phonetic attributes underlying talker recognition and phonetic perception.

Multimodal perceptual organization of speech: Evidence from tone analogs of spoken utterances.

Theoretical and practical motives alike have prompted recent investigations of multimodal speech perception. Theoretically, multimodal studies have extended the conceptualization of perceptual organization beyond the familiar modality-bound accounts deriving from Gestalt psychology. Practically, such investigations have been driven by a need to understand the proficiency of multimodal speech perception using an electrocochlear prosthesis for hearing. In each domain, studies have shown that perceptual organization of speech can occur even when the perceiver's auditory experience departs from natural speech qualities. Accordingly, our research examined auditor-visual multimodal integration of videotaped faces and selected acoustic constituents of speech signals, each realized as a single sinewave tone accompanying a video image of an articulating face. The single tone reproduced the frequency and amplitude of the phonatory cycle or of one of the lower three oral formants. Our results showed a distinct advantage for the condition pairing the video image of the face with a sinewave replicating the second formant, despite its unnatural timbre and its presentation in acoustic isolation from the rest of the speech signal. Perceptual coherence of multimodal speech in these circumstances is established when the two modalities concurrently specify the same underlying phonetic attributes.