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B H Repp

Publications and source records attributed to B H Repp.

At least 73 records · Page 4Linked to original sources
PubMed1981

Influence of preceding fricative on stop consonant perception.

The effect of a preceding fricative on the perceived place of stop consonant articulation was investigated in a series of experiments. In experiment 1, we preceded synthetic syllables from two [tV]--[kV] continua with fricative noises appropriate to [integral of] or [s] and showed that more velar stops are perceived in the context of [s]. Experiment 1 also demonstrated a decrease in the magnitude of this perceptual context effect with increased temporal separation of fricative noise and CV portion, and with introduction of a vowel before the noise, which permitted a subjective syllable boundary after the fricative. Experiment 2 showed that although the effect of the fricative on stop perception declines initially with temporal separation, it may persist in reduced form over intervals as long as 375 ms. Experiment 3 replicated the basic fricative context effect using improved stimuli, but failed to replicate the reduction with an intervening syllable boundary obtained in experiment 1, which presumably was due to the vowel preceding the fricative. Experiments 4 and 5 revealed that the fricative context effect depends both on the phonetic category assigned to the fricative and on the specific spectral properties of the fricative noise. Experiment 5 also revealed a reciprocal effect of the stop consonant on fricative identification. We hypothesize that these perceptual effects serve to compensate for coarticulatory dependencies between stop consonants and preceding fricatives.

Adult↗
PubMed1981

Perceptual assessment of fricative--stop coarticulation.

The perceptual dependence of stop consonants on preceding fricatives [Mann and Repp, J. Acoust. Soc. Am. 69, 548--558 (1981)] was further investigated in two experiments employing both natural and synthetic speech. These experiments consistently replicated our original finding that listeners, report velar stops following [s]. In addition, our data confirmed earlier reports that natural fricative noises (excerpted from utterances of [st alpha], [sk alpha], [(formula: see text)k alpha]) contain cues to the following stop consonants; this was revealed in subjects' identifications of stops from isolated fricative noises and from stimuli consisting of these noises followed by synthetic CV portions drawn from a [t alpha]--[k alpha] continuum. However, these cues in the noise portion could not account for the contextual effect of fricative identity ([formula: see text] versus [sp) on stop perception (more "k" responses following [s]). Rather, this effect seems to be related to a coarticulatory influence of a preceding fricative on stop production; Subjects' responses to excised natural CV portions (with bursts and aspiration removed) were biased towards a relatively more forward place of stop articulation when the CVs had originally been preceded by [s]; and the identification of a preceding ambiguous fricative was biased in the direction of the original fricative context in which a given CV portion had been produced. These findings support an articulatory explanation for the effect of preceding fricatives on stop consonant perception.

Humans↗
PubMed1981

On levels of description in speech research.

Many researchers are linguistic category names (consonants, vowels, syllables) to refer to observations and measurements made in records of the acoustic speech signal. The present paper serves as a remainder that linguistic categories are abstract and have no physical properties, and that, therefore, their physical correlates in the speech wave are appropriately described in acoustic terms only.

Acoustics↗
PubMed1980

Stimulus dominance in fused dichotic syllables: trouble for the category goodness hypothesis.

Repp [J. Acoust. Soc. Am. 60, 456-469 (1976)] hypothesized that dichotic stimulus dominance relationships between fused speech sounds reflect the relative category goodness of the competing stimuli, i.e., their relative perceptual distances from the listener's linguistic category prototypes. In experiment I, 15 synthetic syllables from a /bae/-/dae/-/gae) continuum were dichotically fused with three selected stimuli from the same continuum and presented to listeners for identification. Stimuli in the vicinity of phonetic category boundaries were found to make weaker dichotic competitors than stimuli from well within a phonetic category, as predicted. However, some systematic deviations from the predictions and large individual differences were noted. In experiment II, synthetic syllables from a /ba/-/da/-/ga/ continuum were paired with either of the two endpoint stimuli (/ba/,/ga/) in dichotic or mixed presentation. The resulting fused hybrid stimuli were presented in identification and AXB discrimination tests. The hybrids were perceived quite categorically, and there was little difference between dichotic and mixed modes of presentation. These results did not replicate earlier data [Repp, Haskins SR-45/46, 123-139 (1976)] that had suggested that discrimination of dichotic hybrid stimuli might be based on a level of representation preceding phonetic categorization. The category goodness hypothesis, which implies such a level, was neither supported nor contradicted. In experiment III, the prediction was tested that increasing the aspiration amplitude of a /ta/ syllable, and thus its category goodness, would increase the perceptual dominance of this stimulus over a /da/ simultaneously presented to the other ear. This hypothesis was not supported by the data. Rather, the response pattern suggested that a listener's success in perceptually integrating the aspiration noise (of /ta/) with the fused vocalic portion (of /da/ and /ta/) into a single phonetic percept depended on the perceived spatial locations of these stimulus portions. Taken together, the results of the three experiments cast doubt on the category goodness hypothesis and suggest that dichotic stimulus dominance in fused speech sounds is determined by psychoacoustic factors, some as yet undefined.

Acoustic Stimulation↗
PubMed1979

Categories and context in the perception of isolated steady-state vowels.

The noncategorical perception of isolated vowels has been attributed to the availability of auditory memory in discrimination. In our first experiment, using vowels from an /i/-/I/epsilon) continuum in a same-different (AX) task and comparing the results with predictions derived from a separate identification test, we demonstrated that vowels are perceived more nearly categorically if auditory memory is degraded by extending the interstimulus interval and/or filling it with irrelevant vowel sounds. In a second experiment, we used a similar paradigm, but in addition to presenting a separate identification test, we elicited labeling responses to the AX pairs used in the discrimination task. We found that AX labeling responses predicted discrimination performance quite well, regardless of whether auditory memory was available, whereas the predictions from the separate identification test were more poorly matched by the obtained data. The AX labeling reponses showed large contrast effects (both proactive and retroactive) that were greatly reduced when auditory memory was interfered with. We conclude from the presence of these contrast effects that vowels are not perceived categorically (that is, absolutely). However, it seems that by taking the effects of context into account properly, discrimination performance can be quite accurately predicted from labeling data, suggesting that vowel discrimination, like consonant discrimination, may be mediated by phonetic labels.

Adult↗
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↗