Evidence for phonetic processing of cues to place of articulation: Perceived manner affects perceived place

Using stimuli that could be labeled either as stops [b,d] or as fricatives [f,v,θ,ð], we found that, for a given acoustic stimulus, perceived place of articulation was dependent on perceived manner. This effect appeared for modified natural syllables with a free-identification task and for a synthetic transition continuum with a forced-choice identification task. Since perceived place could be changed by changing manner labels with no change in the acoustic stimulus, it follows that the processing of the place feature depends on the value the listener assigns to the manner feature rather than directly on any of the acoustic cues to manner. We interpret these results as evidence that the identification of place of articulation involves phonetic processing and could not be purely auditor     

Invariants,specifiers, cues: An investigation of locus equations as information for place of articulation

This experiment explored the information for place of articulation provided bylocus equations— equations for a line relating the second formant (F2) of a vowel at midpoint toF2 of the formant at consonant-vowel (CV) syllable onset. Locus equations cue place indirectly by quantifying directly the degree of coarticulatory overlap (coarticulation resistance) between consonant and vowel. Coarticulation resistance is correlated with place, The experiment tested predictions that when coarticulation resistance varies due to properties of the consonant other than place of articulation (in particular due to manner of articulation), locus equations would not accurately reflect consonantal place of articulation. These predictions were confirmed. In addition, discriminant analyses, using locus equation variables as classifiers, were generally unsuccessful in classifying a set of consonants representing six different places of articulation. I conclude that locus equations are unlikely to provide useful place information to listeners.     

Auditory and phonetic processes in place perception for stops

Use of the selective adaptation procedure with speech stimuli has led to a number of theoretical positions with regard to the level or levels of processing affected by adaptation. Recent experiments (i.e., Sawusch & Jusczyk, 1981) have, however, yielded strong evidence that only auditory coding processes are affected by selective adaptation. In the present experiment, a test series that varied along the phonetic dimension of place of articulation for stops ([da]-[ga]) was used in conjunction with a [ska] syllable that shared the phonetic value of velar with the [ga] end of the test series but had a spectral structure that closely matched a stimulus from the [da] end of the series. As an adaptor, the [ska] and Ida] stimuli produced identical effects, whereas in a paired-comparison procedure, the [ska] produced effects consistent with its phonetic label. These results offer further support for the contention that selective adaptation affects only the auditory coding of speech, whereas the paired-comparison procedure affects only the phonetic coding of speech. On the basis of these results and previous place-adaptation results, a process model of speech perception is described.     

Acoustic cues for the perception of place of articulation in aphasia

Two experiments assessed the abilities of aphasic patients and nonaphasic controls to perceive place of articulation in stop consonants. Experiment I explored labeling and discrimination of [ba, da, ga] continua varying in formant transitions with or without an appropriate burst onset appended to the transitions. Results showed general difficulty in perceiving place of articulation for the aphasic patients. Regardless of diagnostic category or auditory language comprehension score, discrimination ability was independent of labeling ability, and discrimination functions were similar to normals even in the context of failure to reliably label the stimuli. Further there was less variability in performance for stimuli with bursts than without bursts. Experiment II measured the effects of lengthening the formant transitions on perception of place of articulation in stop consonants and on the perception of auditory analogs to the speech stimuli. Lengthening the transitions failed to improve performance for either the speech or nonspeech stimuli, and in some cases, reduced performance level. No correlation was observed between the patient's ability to perceive the speech and nonspeech stimuli.     

Auditory and linguistic processing of cues for place of articulation by infants

Two- and 3-month-old infants were found to discriminate the acoustic cues for the phonetic feature of place of articulation in a categorical manner; that is, evidence for the discriminability of two synthetic speech patterns was present only when the stimuli signaled a change in the phonetic feature of place. No evidence of discriminability was found when two stimuli, separated by the same acoustic difference, signaled acoustic variations of the same phonetic feature. Discrimination of the same acoustic cues in a nonspeech context was found, in contrast, to be noncategorical or continuous. The results were discussed in terms of infants’ ability to process acoustic events in either an auditory or a linguistic mode.     

Simple and contingent adaptation effects for place of articulation in stop consonants

Experiments on selective adaptation have shown that the locus of the phonetic category boundary between two segments shifts after repetitive listening to an adapting stimulus. Theoretical interpretations of these results have proposed that adaptation occurs either entirely at an auditory level of processing or at both auditory and more abstract phonetic levels. The present experiment employed two alternating stimuli as adaptors in an attempt to distinguish between these two possible explanations. Two alternating stimuli were used as adaptors in order to test for the presence of contingent effects and to compare these results to simple adaptation using only a single adaptor. Two synthetic CV series with different vowels that varied the place of articulation of the consonant were employed. When two alternating adaptors were used, contingent adaptation effects were observed for the two stimulus series. The direction of the shifts in each series was governed by the vowel context of the adapting syllables. Using the single adaptor data, a comparison was made between the additive effects of the single adaptors and their combined effects when presented in alternating pairs. With voiced adaptors, only within-series adaptation effects were found, and these data were consistent with a on,level model of selective adaptation. However, for the voiceless adaptors, both within- and cross-series adaptation effects were found, suggesting the possible presence of two levels of adaptation to place of articulation. Further, the contingent adaptation effects with the voiceless adaptors seemed to be the result of the additive effects of the two alternating adaptors. This result indicates that previously reported contingent adaptation results may also reflect the net vowel specific adaptation effects after cancellation of other, nonvowel dependent effects and that caution is needed in interpreting such results.     

Integral processing of visual place and auditory voicing information during phonetic perception.

Results of auditory speech experiments show that reaction times (RTs) for place classification in a test condition in which stimuli vary along the dimensions of both place and voicing are longer than RTs in a control condition in which stimuli vary only in place. Similar results are obtained when subjects are asked to classify the stimuli along the voicing dimension. By taking advantage of the "McGurk" effect (McGurk & MacDonald, 1976), the present study investigated whether a similar pattern of interference extends to situations in which variation along the place dimension occurs in the visual modality. The results showed that RTs for classifying phonetic features in the test condition were significantly longer than in the control condition for the place and voicing dimensions. These results indicate a mutual and symmetric interference exists in the classification of the two dimensions, even when the variation along the dimensions occurs in separate modalities.     

Phonetic disintegration in aphasia: Acoustic analysis of spectral characteristics for place of articulation

In this study, we attempted to determine whether phonetic disintegration of speech in Broca's aphasia affects the spectral characteristics of speech sounds as has been shown for the temporal characteristics of speech. To this end, we investigated the production of place of articulation in Broca's aphasics. Acoustic analysis of the spectral characteristics for stop consonants were conducted. Results indicated that the static aspects of speech production were preserved, as Broca's aphasics seemed to be able to reach the articulatory configuration for the appropriate place of articulation. However, the dynamic aspects of speech production seemed to be impaired, as their productions reflected problems with the source characteristics of speech sounds and with the integration of articulatory movements in the vocal tract. Listener perceptions of the aphasics' productions were compared with acoustic analyses for these same productions. The two measures were related; that is, the spectral characteristics of the utterances provided salient cues for place of articulation perception. An analysis of the occurrences of errors along the dimensions of voicing and place showed that aphasics rarely produce utterances containing both voice and place substitutions.     

Extending formant transitions may not improve aphasics'' perception of stop consonant place of articulation

Synthetic speech stimuli were used to investigate whether aphasics' ability to perceive stop consonant place of articulation was enhanced by the extension of initial formant transitions in CV syllables. Phoneme identification and discrimination tests were administered to 12 aphasic patients, 5 fluent and 7 nonfluent. There were no significant differences in performance due to the extended transitions, and no systematic pattern of performance due to aphasia type. In both groups, discrimination was generally high and significantly better than identification, demonstrating that auditory capacity was retained, while phonetic perception was impaired; this result is consistent with repeated demonstrations that auditory and phonetic processes may be dissociated in normal listeners. Moreover, significant rank order correlations between performances on the Token Test and on both perceptual tasks suggest that impairment on these tests may reflect a general cognitive rather than a language-specific deficit.     

Further analysis of stuttering as a phonetic transition defect

This article presents a further analysis of stuttering as a phonetic transition defect. Three types of phonetic transitions are identified. Two of these occur within words and represent sites where stutterings are readily detectable. The third transition involves movement from the end of one word to the beginning of the next. Spectrographic evidence is provided to show that stuttering also occurs at points of transition of this type. The same data are interpreted relative to their implications for stuttering theory, research, and therapy.     

Comparison of consonantal and vocalic cues in selective adaptation

The acoustic cues to the phonetic identity of diphthongs normally include both spectral quality and dynamic change. This fact was exploited in a series of selective adaptation experiments examining the possibility of mutual adaptive effects between these two types of acoustic cues. One continuum of syllables varying from [εi] to [εd] and another varying from [ε] to [εi] were synthesized; endpoint stimuli of both series used as adaptors caused identification boundaries to be shifted. Cross-series adaptation was also attempted on the [ε?εi] stimuli, using [?], [∞], and [ai]. Only [ai] proved effective as an adaptor, suggesting the mediation of a rather abstract auditory level of similarity. The results argue strongly against interpretations in terms of feature detectors, but appear compatible with an “auditory contrast” explanation, which might in turn be incorporated within adaptation level theory in the form recently discussed by Restle (1978). The cross-series results further suggest that selective adaptation might be used to quantify the perceptual distance between auditory cues in speech.     

Pronouncing novel graphemes: The role of consonantal context

In three experiments, we examined how readers learn and generalize new pronunciations for vowel graphemes. Children ages 6 1/2 to 9 (n = 97) and college students (n = 21) were taught a nonword that included a novel vowel pronunciation in the middle position (e.g., zuop is pronounced /zup/). They were then asked to pronounce other nonwords that contained the same vowel grapheme. Participants were more likely to use the taught pronunciation when the target item and the training item shared a consonant as well as a vowel than when they shared only the vowel. The new pronunciation was not significantly more likely to appear when the target shared the vowel and final consonant (rime) of the training stimulus than when it shared the initial consonant and vowel. We discuss implications for views of reading and its development.     

Fundamental frequency as a cue to postvocalic consonantal voicing: Some data from speech perception and production

Several recent studies by Lehiste have reported that changes in fundamental frequency (F0) can serve as a cue to perceived vowel length and, furthermore, that the perceived lengthening of the vowel can influence perception of the voicing feature of stop consonants in syllable-final position. In Experiment 1, we replicated Lehiste’s basic results for stop consonants in final position. Experiment 2 extended these results to postvocalic fricatives. The final consonant in syllables of intermediate vowel duration was more often perceived as voiced when F0 was falling than when F0 was monotone. In Experiment 3, we examined the F0 contours produced by eight talkers before postvocalic stop consonants and fricatives in natural speech for minimal pairs of words differing in voicing. The amount of change of F0 over the vowel was no greater before voiced than voiceless consonants, suggesting that the earlier perceptual effects cannot be explained by appealing to regularities observed in the production of F0 contours in vowels preceding postvocalic consonants.     

Recurrence of phonetic responding

This study determined if previously reinforced academic responding recurred when alternative responses were differentially reinforced and subsequently placed on extinction, and whether the magnitude of resurgence was related to the rate of differential reinforcement for the alternative behavior. Three kindergarten students read Greek letters aloud as arbitrary consonant–vowel blends. Resurgence was reliably demonstrated within and across participants, and the magnitude of resurgence was related to the prior rate of differential reinforcement of alternative behavior.     

Situation-Behavior Profiles as a Locus of Consistency in Personality

Traditional approaches have long considered situations as "noise" or "error" that obscures the consistency of personality and its invariance. Therefore, it has been customary to average the individual's behavior on any given dimension (e.g., conscientiousness) across different situations. Contradicting this assumption and practice, recent studies have demonstrated that by incorporating the situation into the search for consistency, a new locus of stability is found. Namely, people are characterized not only by stable individual differences in their overall levels of behavior, but also by distinctive and stable patterns of situation-behavior relations (e.g., she does X when A but Y when B ). These if . . . then . . . profiles constitute behavioral "signatures" that provide potential windows into the individual's underlying dynamics. Processing models that can account for such signatures provide a new route for studying personality types in terms of their shared dynamics and characteristic defining profiles.     

Overlap of phonetic features as a determinant of the between-stream phonological similarity effect

Serial recall from working memory is known to be impaired by the presence of irrelevant background speech, but several prior studies have concluded that the magnitude of the impairment is independent of the phonological relationship between to-be-remembered (TBR) and to-be-ignored (TBI) sources of information. In the present study, we examined the influence of between-stream phonological similarity in serial recall while attending to a heretofore uncontrolled variable, the phonetic feature. We found that TBI items sharing many phonetic features with TBR items produced significantly stronger working-memory impairments than TBI items with minimal phonetic feature overlap. In addition, participants were more likely to report remembering incorrect items that incorporated phonological characteristics of the TBI stream in the high-overlap condition. These findings provide evidence for subphonemic between-stream interactions and suggest that multiple parallel processes contribute to the irrelevant speech effect. We propose that a 2-component model, which combines the assumptions of process- and content-based accounts for the irrelevant speech effect, offers the best explanation for these findings.