Jody K. Layer

Categorical perception of nonspeech chirps and bleats

Mattingly, Liberman, Syrdal, and Halwes, (1971) claimed to demonstrate that subjects cannot classify nonspeech chirp and bleat continua, but that they can classify into three categories a syllable place continuum whose variation is physically identical to the nonspeech chirp and bleat continua. This finding for F2 transitions, as well as similar findings for F3 transitions, has been cited as one source of support for theories that different modes or modules underlie the perception of speech and nonspeech acoustic stimuli. However, this pattern of finding for speech and nonspeech continua may be the result of research methods rather than a true difference in subject ability. Using tonal stimuli based on the nonspeech stimuli of Mattingly et al., we found that subjects, with appropriate practice, could classify nonspeech chirp, short bleat, and bleat continua with boundaries equivalent to the syllable place continuum of Mattingly et al. With the possible exception of the higher frequency boundary for both our bleats and the Mattingly syllables, ABX discrimination peaks were clearly present and corresponded in location to the given labeling boundary.

Temporal order identification for tone/noise stimuli with onset transitions

Temporal order of onset identification boundaries and difference thresholds (DLs) were measured for stimuli modeled after two formant speech stimuli that varied in voice onset time (VOT). The stimuli had dynamic onset transitions and consisted of a tone pair that varied in onset relative to a noise whose center frequency matched the higher frequency tone. DLs were measured relative to 0- and 7-msec onset delays (as well as 49- and 56-msec onset delays) by using a method of constant stimuli with a two-interval temporal forced choice psychophysical procedure. Discrete thresholds were found for noise lead conditions, but tone lead conditions were very difficult for most subjects. With rising-onset stimuli, evidence was found for long DLs based upon a fixed threshold location at 32–38 msec, and thus independent of the standard stimulus. With falling-onset stimuli, the short (5- to 20-msec) DLs were roughly proportional to the standard (0- or 7-msec) onset difference, although there was evidence for an additional fixed perceptual boundary at a longer (30- to 40-msec) onset difference. A noise burst at stimulus onset seemed to act as a type of masking stimulus, causing a shift in temporal order threshold to longer onset differences. The 30- to 40-msec fixed threshold location is similar in magnitude to those typical of VOT voicing boundaries for stop consonants of English.

The influence of orthographic information on the identification of an auditory speech event

It has been shown that the identification of an auditory or visual speech event can be influenced by information from the other modality when the information is perceived to arise from the same event. Employing a selective attention task, Logan et al. (1990) demonstrated an influence of an auditory speech event on the identification of orthographic characters over a range of stimulus onset differences. The current research investigates the influence of orthographic information on the identification of the initial phoneme of an auditory speech event. The stimuli were nonword CVC syllables. The stimuli were edited natural speech and orthographic representations of these stimuli plus a set that was neutral with respect to the auditory set. A range of stimulus onset differences was employed. The results show that when the auditory and visual information agree, there is faster responding for the identification of the initial auditory phoneme. When the information is discrepent, responding is slowed. These resu...

Duration effects revisited: Labeling of tone analogs to voicing contrasts

Our previous research described at the last Acoustical Society Meeting [Pastore et al., J. Acoust. Soc. Am. Suppl. 1 77, S27 (1985)] investigated duration effects in the perception of tone analogs to the delayed F1 onset cue for voicelessness. Two groups of psychophysically experienced subjects exhibited statistically significant dependencies on stimulus duration, with longer stimuli resulting in shorter delayed onset boundaries. This pattern of results is opposite to those reported for voicing contrast boundaries as a function of target stimulus duration. The second group of subjects now has replicated this statistically significant reversed duration dependency for equivalent stimuli with added harmonic structure. Naive subjects with the identical task and stimuli exhibit a statistically significant dependency on duration consistent with published findings for synthetic speech, and thus opposite to that found for our experienced subjects. The results are discussed in terms of the role of perceptual learning in the perception of voicing cues. [Research supported, in part, by National Science Foundation grant 8302873.]

Duration effects on labeling of tonal analogs to F1‐cutback continua

F1 cutback has been demonstrated to be at least a contributing cue, and very possibly a major cue, for the perception of voicing contrasts. In an attempt to evaluate the feasibility of there existing an acoustic basis for the role of F1‐cutback cues in the perception of voicing stimuli, our recent research has focused on comparing stimulus cue dependencies for voicing boundaries with similar stimulus changes in analogous tonal stimuli varying in complexity. An earlier paper [Pastore et al., J. Acoust. Soc. Am. 75, S65 (1984)], described parallel labeling boundaries as a function of tonal analogs to F1 frequency and F2 transitions, but no stimulus duration. We now have identified conditions under which our F1‐cutback analog stimuli exhibit both labeling boundary locations, and changes as a function of duration, which are characteristic of voicing boundaries for speech stimuli. [Supported in part by NSF.]

Categorization of nonspeech stimuli

A number of studies have claimed that a continuum consisting solely of auditory chirps or bleats produces uniform chance labeling and discrimination performance. However, when these auditory continua are added to an appropriate syllable base, they produce a categorically perceived place continuum. The current study demonstrates that practice allows subjects to categorically perceive these auditory continua in a manner equivalent to that reported for speech place continua. Three sets of 16 sinusoidal stimuli were synthesized with 40‐ms initial transitions that were analogous to the second formants of syllables. The starting frequency of the transitions varied in 15 equal steps from 1140 to 2420 Hz. The duration of the final steady‐state portion of the stimuli was 190, 40, or 0 ms [bleats, short bleats, and chirps] with total duration of 230, 80, or 40 ms, respectively. The study consisted of 4 practice days with initial testing on each day, and followed by 2 days of reevaluation of labeling performance. [W...

Identification of onset order for two‐tone components: Implications for voicing perception

A general account of voicing perception for initial position stop consonants varying in VOT has been offered based on the identification of onset order of component events. Pisoni [J. Acoust. Soc. Am. 61, 1352–1361 (1977)] reported categorical perception for nonspeech tonal stimuli, although the exact boundary locations differed from VOT speech boundaries. The current research replicates and extends the Pisoni study. Labeling task boundaries were in agreement with Pisoni, and a two‐interval, forced‐choice (2IFC) task yielded boundaries even shorter than those for the labeling task. Most synthetic speech stimuli varying in VOT employ an initial burst at onset. Adding a noise burst to the beginning of the tone stimulus shifted the temporal‐order labeling boundaries to significantly longer onset asynchronies that are consistent with those reported for VOT. Implications for temporal‐order processing and speech perception will be discussed. [Work supported by NSF.]

An evaluation of psychophysical trading relations and perceptual cues

Trading relations have been the empirical and theoretical focus of a number of research studies over the last decade. This paper provides a careful examination of the concept of a cue, the concept of a trading relation between cues for a given perceptual contrast, and published claims for empirical demonstrations of trading relations. While true trading relations should be expected for most types of perceptual phenomena, it was discovered that many studies claiming to find a trading relation have only demonstrated the effects of a single cue. Furthermore, some aspects of trading relations may be based upon a failure to adequately consider critical underlying assumptions about the nature of the continuum along which the dependent variable is defined. The theoretical implications of trading relations will be discussed. [Research supported in part by a NSF grant to the first author.]

Some auditory‐visual interactions are post‐categorical

The McGurk effect recently has been variously conjectured to be based upon a precategorical interaction or integration of information from the auditory and visual representation of the linguistic event. The conjecture of precategorical interactions, which rejects the original notion of post‐categorical interactions, may be in the form of a specialized module for speech or language, or may contribute to a logic‐decision process, either of which leads to a relatively discrete perception of speech. While not disputing such precategorical interactions for language, the research to be described demonstrates post‐categorical interaction of auditory and visual representations of phonemes. The stimuli are nonword CVC syllables. The set of auditory stimuli is edited from natural speech, while the set of visual stimuli includes the orthographic representations of the auditory stimuli syllables. Evidence for interactions in identification of initial phonemes is based upon both error rates and reaction times. [Research supported in part by an NSF grant to the first author.]The McGurk effect recently has been variously conjectured to be based upon a precategorical interaction or integration of information from the auditory and visual representation of the linguistic event. The conjecture of precategorical interactions, which rejects the original notion of post‐categorical interactions, may be in the form of a specialized module for speech or language, or may contribute to a logic‐decision process, either of which leads to a relatively discrete perception of speech. While not disputing such precategorical interactions for language, the research to be described demonstrates post‐categorical interaction of auditory and visual representations of phonemes. The stimuli are nonword CVC syllables. The set of auditory stimuli is edited from natural speech, while the set of visual stimuli includes the orthographic representations of the auditory stimuli syllables. Evidence for interactions in identification of initial phonemes is based upon both error rates and reaction times. [Resear...

Release burst masking effects for temporal order identification

Nearly three decades ago, Hirsh [J. Acoust. Soc. Am. 31, 759–761 (1959)] found that the threshold for identification of temporal order of onset is significantly longer than the threshold for detection of onset asynchrony, and proposed that the order identification threshold might serve as a basis for the contrast between voiced and unvoiced aspirated stop consonants in initial position. In the last decade, a number of researchers have argued that temporal order identification threshold does not play a significant role in voicing contrast. One basis for this argument against a phonetic perception role is that the 15‐ to 20‐ms range of typical order identification thresholds for simple stimuli are significantly shorter than VOT boundaries typical for synthetic stop consonants which include an initial release burst. The current research investigated the possible contribution of an initial noise burst analog as a masking stimulus. The initial noise burst shifts temporal order identification thresholds to sign...