Place Cues Research Articles

Acoustic-perceptual factors in nasal place assimilation.

Phonologically, nasal consonants often assimilate to the place of a following oral stop. While the source of this assimilation is generally taken to be anticipatory coarticulation, this study examines the possibility that acoustic-perceptual factors are partially or even primarily responsible. Two American English speakers produced /zV́NCschwa/ tokens (V=/i/, /æ/, /schwa /;NC=/mb/, /nd/, /hooked en g/). Stimuli were split into /zVN/ and /Cschwa/ portions. /zVN/ portions whose final N was identified with at least 97% accuracy (four judges) were cross-spliced with /Cschwa/ portions to yield all possible N–C pairings. Listeners identified N and C of the cross-spliced /zV́NCschwa/ stimuli. Homorganic clusters were correctly identified 95% of the time (preliminary results with eight listeners). Listeners varied in accuracy of N identification in nonhomorganic clusters, but across subjects one-third of nonhomorganic nasals were misidentified, with homorganic responses comprising 80% of these errors. Although different places of articulation showed different response patterns, overall results indicate that place cues for nasals may be overridden by those of a following oral stop. Even nasals whose place is unambiguous in final position may shift perceptually before heterosyllabic oral stops.

Infant memory for place information

The present studies were designed to examine the role of place cues in memory retrieval during early infancy. Three-month-old infants were trained to move a mobile by kicking. Two weeks later, memory retrieval was disrupted if they were reminded in a location or place different from where they had been trained, but not if they were reminded in the same place (Experiment 1A). The same result was obtained even though highly salient cues in their immediate visual surround remained unchanged during reminding (Experiments 1B and 1C). No disruption was seen, however, when retrieval was cued in a different place after only 1 day (Experiment 2). These findings unequivocally demonstrate that infants as young as 3 months encode incidental information about the place where an event occurs and suggest that early memories are buffered against retrieval in potentially inappropriate contexts over the long term.

Dynamic spectral shape features as acoustic correlates for initial stop consonants

A comprehensive investigation of two acoustic feature sets for English stop consonants spoken in syllable initial position was conducted to determine the relative invariance of the features that cue place and voicing. The features evaluated were overall spectral shape, encoded as the cosine transform coefficients of the nonlinearly scaled amplitude spectrum, and formants. In addition, features were computed both for the static case, i.e., from one 25-ms frame starting at the burst, and for the dynamic case, i.e., as parameter trajectories over several frames of speech data. All features were evaluated with speaker-independent automatic classification experiments using the data from 15 speakers to train the classifier and the data from 15 different speakers for testing. The primary conclusions from these experiments, as measured via automatic recognition rates, are as follows: (1) spectral shape features are superior to both formants, and formants plus amplitudes; (2) features extracted from the dynamic spectrum are superior to features extracted from the static spectrum; and (3) features extracted from the speech signal beginning with the burst onset are superior to features extracted from the speech signal beginning with the vowel transition. Dynamic features extracted from the smoothed spectra over a 60-ms interval timed to begin with the burst onset appear to account for the primary vowel context effects. Automatic recognition results for the 6 stops (93.7%) based on 20 features was better than the rates obtained with human listeners for a 50-ms segment (89.9%) and only slightly worse than the rates obtained by human listeners for a 100-ms interval (96.6%). Thus the basic conclusion from our work is that dynamic spectral shape features are acoustically invariant cues for both place and voicing in initial stop consonants.

Cross-language speech perception in adults: Phonemic, phonetic, and acoustic contributions

Cross-language studies have shown that foreign consonant contrasts vary in the degree of perceptual difficulty which they present adult non-native listeners. Phonemic, phonetic, and acoustic factors have been considered important in accounting for this variability. These factors were examined by comparing English listeners' perception of the Hindi retroflex versus dental place-of-articulation contrast in four different voicing contexts: voiceless unaspirated, breathy voiced, voiceless aspirated, and prevoiced. Differences in perceptual difficulty of the four contrasts were predicted based on (1) phonemic status (the functional status of the contrast in the listeners' native phonology), (2) phonetic experience (as allophones or free variants), and (3) differences in acoustic salience related to voicing. Performance was not "nativelike" for any of the four contrasts; however, significant differences in perceptual difficulty among the four contrasts were evident. Perceptual differences were correlated with both acoustic salience of place cues and subjects' descriptions of their assimilation strategies.

Analysis of aversively conditioned learning and memory in rats recovered from pyrithiamine-induced thiamine deficiency.

Rats that had recovered from pyrithiamine-induced thiamine deficiency (PTD) were trained on tasks motivated by escape from mild footshock. On postmortem examination, the PTD model showed two consistent lesions: a bilaterally symmetrical lesion of the medial thalamus, which was centered on the internal medullary lamina (IML), and a lesion centered on the medial mammillary nuclei. PTD rats with IML lesions were impaired in learning a spatial nonmatching-to-sample (NMTS) task that was mastered without error by controls and PTD animals without IML lesions. These same animals were able to perform as well as controls on discrimination tasks based on either place or visual (light-dark) cues, although they made more errors than controls in reaching criterion in the initial place discrimination problem. These findings are consistent with findings from appetitively motivated tasks that PTD rats with IML lesions have an impaired capacity for working memory but not for reference memory.

The representation in memory of morphine’s unconditioned motivational effects depends on the nature of the conditioned stimulus

In conditioning paradigms, morphine has both rewarding and aversive motivational properties. The rewarding motivational property is preferentially associated with places, whereas the aversive property is preferentially associated with tastes. We used this preferential associability of stimuli in combination with a higher order conditioning procedure to ask how the motivational effects of morphine are represented in memory. First-order conditioning involved the pairing of a novel taste or distinct place with an intraperitoneal injection of morphine (15 mg/kg) in two separate groups of rats. As expected, conditioned taste aversions developed in one group and conditioned place preferences developed in the other. Second-order conditioning involved pairing the firstorder taste conditioned stimulus (CS) with a distinct place CS in the absence of morphine in one group and pairing the first-order place CS with a distinct taste CS in the absence of morphine in the other group. If the first-order taste CS, for example, elicits from memory a representation of the entire motivational spectrum of morphine, then the second-order place cues might be expected to reveal conditioned place preferences on the basis of differential associability findings. However, if the first-order taste CS calls up only a representation of morphine’s aversive effects, then second-order conditioned place aversions would be expected. We found that the first-order taste CS produced second-order conditioned place aversions. Similarly, in the other group, the first-order place CS produced second-order taste preferences. In other words, only conditioning within one motivational system was observed. We propose that the first-order stimulus conditioned to morphine represents in memory only that single motivational effect of morphine to which the first-order conditioned stimulus is preferentially associable.

Are F2‐ and F3‐onset frequencies equal cues for place of articulation

This study reevaluated F2‐ and F3‐onset frequencies as cues for place of articulation. Seven levels of F2‐onset frequency, ranging from 600 to 1800 Hz, were factorially combined with eight levels of F3‐onset frequency, ranging from 1400 to 4200 Hz, to create 56 synthetic syllables. Subjects were asked to classify each initial phoneme of the syllable into/ba/, /da/,/ga/, or/others/. A canonical correlation analysis was conducted to recover the relationship between the percentage of each response category and the values of F2‐ and F3‐onset frequencies. The canonical correlation structure shows that F2‐onset frequency has a high negative correlation with the /ba/ category, and a positive correlation with the/da/ category, while both F2‐ and F3‐onset frequencies are moderately correlated with the /ga/ category. This result suggests that F2‐onset frequency is an adequate cue to distinguish /ba/ from /da/. However, both F2‐ and F3‐onset frequencies are interacted to cue /da/ and /ga/ distinction. This result is in contrast to claims that either F2‐ or F3‐onset frequency is a strong cue for three place categories.

Perception of Hindi retroflex versus dental stops by monolingual speakers of American English

Cross‐language studies have shown that foreign consonant contrasts vary in the degree of perceptual difficulty that they present adult non‐native listeners. Phonemic, phonetic, and acoustic factors have been considered important in accounting for this variability. These factors were examined by comparing English listeners' perception of the Hindi retroflex versus dental place‐of‐articulation contrast in four different voicing contexts: prevoiced, voiceless aspirated, voiceless unaspirated, and breathy voiced. Differences in the perceptual difficulty of the four Hindi contrasts were predicted based on: (1) phonemic status (the functional status of the contrast in listeners' native phonology), (2) phonetic familiarity (as allophones or free variants), (3) differences in acoustic salience related to voicing, and (4) assimilation strategies. Differences in performance in a categorial AX discrimination task were ordered from most to least errors: prevoiced, voiceless aspirated, breathy‐voiced, and voiceless unaspirated. Perceptual differences were correlated with both acoustic salience of place cues and subjects' descriptions of their assimilation strategies. [Work supported by NICHD and NINCDS.]

Perceptual cues for place of articulation for the voiced pharyngeal and uvular consonants

A series of perceptual experiments was conducted to investigate the perceptual cues for place of articulation for the voiced pharyngeal /// and the voiced uvular /3/ consonants in Arabic. Synthetic consonant–vowel stimuli, in which the vowel was the long vowel /aa/ of Arabic, were used in the experiments. In the first experiment, stimulus continua were constructed by systematically varying the trajectories of the first and second formant frequencies (F1 and F2) independently between the values appropriate for the two consonants. In the second experiment, the bandwidth of F2 for the pharyngeal stimuli and the bandwidth of F1 for the uvular stimuli were manipulated. Results of the first experiment show that the onset value of F1(F1o) is essential in discriminating between the two consonants, while that of F2 is not. Results of the second experiment show that widening the bandwidth of F1 increases the percent of uvular responses and enhances the naturalness of the uvular stimuli, whereas it decreases substantially the number of pharyngeal responses. Increasing the bandwidth of F2 had no effect on either the percent identification of the pharyngeal or the naturalness of the synthetic stimuli.

Aversive conditioning properties of caffeine in rats

Four experiments tested the conditioning effects of caffeine. Flavor and place cues were paired with IP caffeine injections and followed by tests for cue preference. In Experiment 1A, saccharin was paired with 1.25, 5 or 20 mg/kg of caffeine. In Experiment 1B, caffeine was delivered 30 min before, 5 min before, or 30 min after saccharin. Dose- and time-dependent conditioned taste aversions were produced. In Experiment 2, a place and taste cue were paired simultaneously with 5 or 20 mg/kg of caffeine. Conditioned place and taste aversions developed at 20, but not at 5 mg/kg. In Experiment 3, a place cue alone was paired with 0, 5, or 20 mg/kg of caffeine; dose-dependent conditioned place aversions developed. In Experiment 4, place and taste cues were paired with control treatments: pH-buffered caffeine, purine or vehicle. Caffeine produced taste aversions whereas the purine and vehicle did not. These aversive conditioning effects of caffeine across a variety of situations, doses and temporal arrangements stand in contrast to results obtained with other psychoactive drugs, such as amphetamine and alcohol.

Individual differences in the perception of cues for initial stop place and voicing contrasts

Fifteen normal‐hearing adults were tested on their ability to identify synthesized stimuli from three initial stop contrasts. Two place contrasts, BAIT‐DATE and DATE‐GATE, were presented in three conditions. In the “full‐cue” condition, the place contrast was signaled by changes in burst frequency and F2/F3 transition. In the two “reduced‐cue” conditions, the contrasts were signaled by only one of these two cues. A voicing contrast, GATE‐KATE, was presented in two conditions: a “full‐cue” condition, in which the contrast was marked by changes in VOT and F1 onset; and a “VOT cue” condition in which the F1 onset was flat. Group results show significant variance across conditions, both in terms of the phoneme boundaries and identification function gradients obtained. In addition, individual differences were found in the labeling of reduced‐cue conditions. Some subjects showed little difference between the labeling of the full‐cue and the reduced‐cue conditions of the BAIT‐DATE and GATE‐KATE contrasts, while ...

Invariant acoustic cues in stop consonants: A cross‐language study using the Wignet distribution

Acoustic invariance was investigated in 200 unaspirated stops from English, Telugu, and French, using the Wigner distribution. The bilabials were characterized either by absence of any noticeable burst, or by an energy concentration in the low‐frequency region during the burst, when present. The burst of alveolars was mostly diffuse in nature, but sometimes became compact, especially when it was followed by a back vowel. The burst of velars had a compact spectrum centered near F2 of the vowel, when followed by back vowels, but was most often diffuse when followed by a front vowel. The burst of all dental from Telugu was found to be diffuse. When the burst of alveolars was compact, or that of velars diffuse, the duration from the start of the burst to the start of the vowel and F2 of the vowel were found to be reliable cues for place of articulation. The diffuse nature of bilabials and alveolars, reported by Lahiri et al. [J. Acoust. Soc. Am. 76, 391–404 (1984)] and by the authors referenced therein, can be partly attributed to the temporal averaging of the burst spectrum and the diffuse vowel spectrum, which is inevitable in Fourier‐type analyses [Garudadri et al., J. Acoust. Soc. Am. Suppl. 1 79, S94 (1986)]. Unlike in other investigations, no apparent pattern could be found for the tokens wrongly classified. [Work supported, in part, by NSERC, Canada.]

Analysis and perception of sibilant fricatives: Shona data

In addition to the commonly found [s,z] and [∫ȝ], the Shona language has a third pair of sibilants [s,zw w] usually described as labialized alveolar fricatives and sometimes called “whistling” fricatives. Analysis of all these sibilants revealed that the location of the main frequency peak was typically 3 Bark higher for [s,z] than for the remaining four fricatives which did not differ significantly in this respect. Durational differences were slight throughout, and seemed unlikely to contribute as place cues. A likelier possibility for cueing the place distinction, we hypothesized, was an interaction of peak location with the gradient of the high‐ and low‐frequency slopes adjacent to the peak, together perhaps with contributions from the VCV transitions. Experimental manipulation of these variables in synthetic versions of the three voiceless sibilants yielded listener identifications suggesting that (1) a flat HF slope cued [s] overridingly, irrespective of the peak location, but (2) peak location becam...

Speech perception and language acquisition

Voice onset time (VOT) and first-formant (F1) transition characteristics are both important phonetic cues for voicing categorization of pretonic stops in English. These cues also covary with place of articulation in production, such that bilabials are produced with shorter VOT values, and velars are produced with longer VOT values. This study investigated the effects of place of articulation and F1transition pattern on voicing categorization of VOT continua. Listeners categorized for voicing and place of articulation the stop consonant in VCV and CV stimuli for which the variables F1transition pattern, place of articulation (bilabial, alveolar, and velar), and VOT were fully crossed. A logistic regression analysis shows that bilabial and alveolar stimuli were more likely than velar stimuli to be classified as voiceless, largely independent of F1transition pattern. Increasing F1onset frequency and shortening transition duration also made voiceless judgments more likely. The magnitude of theF1 transition effects was considerably larger than the place of articulation effect. The results are inconsistent with models of consonant classification in which acoustic–phonetic cues for place of articulation are not involved in the perception of the voicing contrast. However, the observed perceptual interaction between place of articulation and voicing may be consistent with either a feature- or segment-based model of consonant classification.

Discrete representation of perceptual structure underlying consonant confusions.

The perceptual representation of speech is generally assumed to be discrete rather than continuous, pointing to the need for general discrete analytic models to represent observed perceptual similarities among speech sounds. The INDCLUS (INdividual Differences CLUStering) model and algorithm [J.D. Carroll and P. Arabie, Psychometrika 48, 157-169 (1983)] can provide this generality, representing symmetric three-way similarity data (stimuli X stimuli X conditions) as an additive combination of overlapping, and generally not hierarchial, clusters whose weights (which are numerical values gauging the importance of the clusters) vary both as a function of the cluster and condition being considered. INDCLUS was used to obtain a discrete representation of underlying perceptual structure in the Miller and Nicely consonant confusion data [G.A. Miller and P.E. Nicely, J. Acoust. Soc. Am. 27, 338-352 (1955)]. A 14-cluster solution accounted for 82.9% of total variance across the 17 listening conditions. The cluster composition and the variations in cluster weights as a function of stimulus degradation were interpreted in terms of the common and unique perceptual attributes of the consonants within each cluster. Low-pass filtering and noise masking selectively degraded unique attributes, especially the cues for place of articulation, while high-pass filtering degraded both unique and common attributes. The clustering results revealed that perceptual similarities among consonants are accurately modeled by additive combinations of their specific and discrete acoustic attributes whose weights are determined by the nature of the stimulus degradation.

Frequency and Rate Discrimination by Menière Patients

Discrimination tests were conducted for each ear of 6 patients with unilateral Menière's disease. Differential sensitivity to changes in pure-tone frequency (presumably containing temporal and place cues) was compared to differential sensitivity to changes in rate of sinusoidally amplitude-modulated noise (presumably containing only a temporal cue) at common low frequencies and modulation rates (less than 400 Hz). An adaptive forced-choice psychophysical procedure was used. The better-ear results for the Menière patients generally were similar to findings for normally hearing listeners. For the impaired ears, pure-tone frequency discrimination typically was impaired relatively more than was the rate discrimination up to 200 Hz. However, rate discrimination was difficult or impossible above 250-300 Hz. Absolute frequency difference limens (DLs) were, on average, smaller than or at least equivalent to absolute rate DLs. Moreover, frequency discrimination always was possible for the Menière patients.

Differential sensitivity to tonal frequency and to the rate of amplitude modulation of broadband noise by normally hearing listeners.

Differential sensitivities for tones which varied in frequency (containing cues for place and periodicity) and for broadband noise which varied in the rate of sinusoidal amplitude modulation (presumably containing only a periodicity cue) were measured at common frequencies and modulation rates of the stimulus for four normally hearing listeners. A forced-choice adaptive psychophysical procedure was used in all measurements. Through 60 Hz, tonal-frequency and rate discrimination were similar (on average, 2.5-3.0 Hz) across listeners. From 80-400 Hz, differential sensitivity for tones was between 1.0 and 2.0 Hz, whereas values for rate discrimination increased almost linearly from about 3.6 to 122.0 Hz. Apparently, differential sensitivities for both tonal frequency and modulation rate are mediated similarly, presumably by the same (periodicity) mechanism, through 60 Hz. Above 60 Hz, the listener is more sensitive to differences in tonal frequency than modulation rate. Detection thresholds for sinusoidal amplitude modulation of noise also were measured for these listeners. An average modulation threshold function was obtained and a half-power frequency was estimated for the function at 60 Hz; from this value a time constant of 2.65 ms may be derived, which is consistent with time constants measured by other psychophysical methods. These data further point to some change in perceptual quality above about 60 Hz, that frequency above which we found tonal-frequency and rate discrimination functions to separate.

Duration of frication noise as a perceptual cue

Natural speech CV syllables ([f, s, š, ō, v, z, ð] in the environment of [i, u, a]) were computer edited to include 20–70 ms of frication noise as measured from its onset in 10‐ms steps, as well as the entire frication noise. These stimuli were presented to 12 subjects for consonant identification. Results showed high recognition scores (>75%) for all fricatives but [ō, ð] in the longer conditions (60 and 70 ms and the full frication noise). In the remaining conditions scores, although lower, were still significantly above chance. Perception of manner of articulation seemed to be minimally affected by a decrease in frication duration, with 86% correct scores in the 20‐ms condition. Perception of place of articulation was somewhat more affected by duration of the stimuli, with correct identification falling to 60% in the 20‐ms condition. Results suggest that while a minimum duration of about 20 ms is required for perception of manner of articulation, frication duration is not an important perceptual cue to either place or manner. Instead, spectral rather than temporal properties provide the major cues for place and manner of articulation for consonants.

Perceptual assessment of the intervocalic formant transition place cues of /s/ in /sɪsi/ and /sɪsɑ/

This is an extension of the investigator's previous work [J. Acoust. Soc. Am. Suppl. 1 71, S105; and 72, S16 (1982)]. A series of spoken /sɪsi,sisɑ/ tokens was modified using a PCM speech editor. The /s/‐noise segments were excised. The original intervocalic /ɪ‐i,ɪ‐ɑ/ contexts and the /ɪ,i,ɑ/ vowels in isolation were assembled into a perceptual identification test and low‐pass filtered at 3 kHz with an attenuation slope of 48 dB/oct. As a consequence, the noise and transient energy coextensive in time but higher in frequency than the vocalic formant structures was removed more completely than before. Subjects identified the consonants heard adjacent to the vocalic segments. There was better agreement as to the labial stop frequently heard in the intervocalic /ɪ‐i/ context than previously. As before, dental‐alveolar stops were frequency heard in /ɪ‐ɑ/. These results reflect perceptual integration over the arresting and releasing transition and silent interval duration cues. [Haskins Laboratories provided valuable assistance in the preparation of stimuli on NIGHD Contract No. NIH‐71‐2420.]

Perceptual integration of the murmur and formant transitions for place of articulation in nasal consonants.

This study reassessed the role of the nasal murmur and formant transitions as perceptual cues for place of articulation in nasal consonants across a number of vowel environments. Five types of computer-edited stimuli were generated from natural utterances consisting of [m n] followed by [i e a o u]: (1) full murmurs; (2) transitions plus vowel segments; (3) the last six pulses of the murmur; (4) the six pulses starting from the beginning of the formant transitions; and (5) the six pulses surrounding the nasal release (three pulses before and three pulses after). Results showed that the murmur provided as much information for the perception of place of articulation as did the transitions. Moreover, the highest performance scores for place of articulation were obtained in the six-pulse condition containing both murmur and transition information. The data support the view that it is the combination of nasal murmur plus formant transitions which forms an integrated property for the perception of place of articulation.