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A M Liberman

Publications and source records attributed to A M Liberman.

17 recordsLinked to original sources
PubMed1989

A specialization for speech perception.

The processes that underlie perception of consonants and vowels are specifically phonetic, distinct from those that localize sources and assign auditory qualities to the sound from each source. This specialization, or module, increases the rate of information flow, establishes the parity between sender and receiver that every communication system must have, and provides for the natural development of phonetic structures in the species and in the individual. The phonetic module has certain properties in common with modules that are "closed" (for example, sound localization or echo ranging in bats) and, like other members of this class, is so placed in the architecture of the auditory system as to preempt information that is relevant to its special function. Accordingly, this information is not available to such "open" modules as those for pitch, loudness, and timbre.

Animals↗
PubMed1987

Speech perception takes precedence over nonspeech perception.

Some components of a speech signal, when made more intense, are heard simultaneously as speech and nonspeech--a form of duplex perception. At lower intensities, the speech alone is heard. Such intensity-dependent duplexity implies the existence of a phonetic mode of perception that takes precedence over auditory modes.

Adult↗
PubMed1979

Some experiments on the sound of silence in phonetic perception.

The results of several experiments demonstrate that silence is an important cue for the perception of stop-consonant and affricate manner. In some circumstances, silence is necessary; in others, it is sufficient. But silence is not the only cue to these manners. There are other cues that are more or less equivalent in their perceptual effects, though they are quite different acoustically. Finally, silence is effective as a cue when it separates utterances produced by male and female speakers. These findings are taken to imply that, in these instances, perception is constrained as if by some abstract conception of what vocal tracts do when they make linguistically significant gestures.

Cues↗
PubMed1978

Perceptual integration of acoustic cues for stop, fricative, and affricate manner.

Introducing a short interval of silence between the words SAY and SHOP causes listeners to hear SAY CHOP. Another cue for the fricative-affricate distinction is the duration of the fricative noise in SHOP (CHOP). Now, varying both these temporal cues orthogonally in a sentence context, we find that, within limits, they are perceived in relation to each other: The shorter the duration of the noise, the shorter the silence necessary to convert the fricative into an affricate. On the other hand, when the rate of articulation of the sentence frame is increased while holding noise duration constant, a longer silent interval is needed to hear an affricate, as if the noise duration, but not the silence duration, were effectively longer in the faster sentence. In a second experiment, varying noise and silence durations in GRAY SHIP, we find that given sufficient silence, listeners report GRAY CHIP when the noise is short but GREAT SHIP when it is long. Thus, the long noise in the second syllable disposes listeners to displace the stop to the first syllable, so that they hear not a syllable-initial affricate (i.e., stop-initiated fricative) but a syllable-final stop (followed by a syllable-initial fricative). Repeating the experiment with GREAT SHIP as the original utterance, we obtain the same pattern of results, together with only a moderate increase in GREAT responses. In all such cases, the listeners integrate a numerous, diverse, and temporally distributed set of acoustic cues into a unitary phonetic percept. These several cues have in common only that they are the products of a unitary articulatory act. In effect, then, it is the articulatory act that is perceived.

Cues↗
PubMed1976

Discussion paper.

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Acoustics↗