PubMed Health⌕ Search

Biomedical subjects

K R Kluender

Publications and source records attributed to K R Kluender.

9 recordsLinked to original sources
PubMed1992

Amplitude rise time and the perception of the voiceless affricate/fricative distinction.

Variation of amplitude envelope at stimulus onset has been considered to be of primary importance for distinguishing voiceless affricates from fricatives (e.g., [symbol: see text]). In earlier perceptual experiments, however, variation in amplitude rise time was confounded with variation in frication duration. In two experiments, these variables were independently manipulated, and their individual and combined effects for perception of magnitude of [symbol: see text] were examined. Variation in amplitude rise time alone was not sufficient to signal the voiceless affricate/fricative contrast in these experiments, but variation in frication duration alone was sufficient.

Humans↗
PubMed1992

Effects of glide slope, noise intensity, and noise duration on the extrapolation of FM glides through noise.

Listeners are quite adept at maintaining integrated perceptual events in environments that are frequently noisy. Three experiments were conducted to assess the mechanisms by which listeners maintain continuity for upward sinusoidal glides that are interrupted by a period of broadband noise. The first two experiments used stimulus complexes consisting of three parts: prenoise glide, broadband noise interval, and postnoise glide. For a given prenoise glide and noise interval, the subject's task was to adjust the onset frequency of a same-slope postnoise glide so that, together with the prenoise glide and noise, the complex sounded as "smooth and continuous as possible." The slope of the glides (1.67, 3.33, 5, and 6.67 Bark/sec) as well as the duration (50, 200, and 350 msec) and relative level of the interrupting noise (0, -6, and -12 dB S/N) were varied. For all but the shallowest glides, subjects consistently adjusted the offset portion of the glide to frequencies lower than predicted by accurate interpolation of the prenoise portion. Curiously, for the shallowest glides, subjects consistently selected postnoise glide onset-frequency values higher than predicted by accurate extrapolation of the prenoise glide. There was no effect of noise level on subjects' adjustments in the first two experiments. The third experiment used a signal detection task to measure the phenomenal experience of continuity through the noise. Frequency glides were either present or absent during the noise for stimuli like those use in the first two experiments as well as for stimuli that had no prenoise or postnoise glides. Subjects were more likely to report the presence of glides in the noise when none occurred (false positives) when noise was shorter or of greater relative level and when glides were present adjacent to the noise.

Adult↗
PubMed1991

On the interpretability of speech/nonspeech comparisons: a reply to Fowler.

Fowler [J. Acoust. Soc. Am. 88, 1236-1249 (1990)] makes a set of claims on the basis of which she denies the general interpretability of experiments that compare the perception of speech sounds to the perception of acoustically analogous nonspeech sound. She also challenges a specific auditory hypothesis offered by Diehl and Walsh [J. Acoust. Soc. Am. 85, 2154-2164 (1989)] to explain the stimulus-length effect in the perception of stops and glides. It will be argued that her conclusions are unwarranted.

Auditory Perception↗
PubMed1991

A composite model of the auditory periphery for the processing of speech based on the filter response functions of single auditory-nerve fibers.

A composite model of the auditory periphery, based upon a unique analysis technique for deriving filter response characteristics from cat auditory-nerve fibers, is presented. The model is distinctive in its ability to capture a significant broadening of auditory-nerve fiber frequency selectivity as a function of increasing sound-pressure level within a computationally tractable time-invariant structure. The output of the model shows the tonotopic distribution of synchrony activity of single fibers in response to the steady-state vowel [e] presented over a 40-dB range of sound-pressure levels and is compared with the population-response data of Young and Sachs (1979). The model, while limited by its time invariance, accurately captures most of the place-synchrony response patterns reported by the Johns Hopkins group. In both the physiology and in the model, auditory-nerve fibers spanning a broad tonotopic range synchronize to the first formant (F1), with the proportion of units phase-locked to F1 increasing appreciably at moderate to high sound-pressure levels. A smaller proportion of fibers maintain phase locking to the second and third formants across the same intensity range. At sound-pressure levels of 60 dB and above, the vast majority of fibers with characteristic frequencies greater than 3 kHz synchronize to F1 (512 Hz), rather than to frequencies in the most sensitive portion of their response range. On the basis of these response patterns it is suggested that neural synchrony is the dominant auditory-nerve representation of formant information under "normal" listening conditions in which speech signals occur across a wide range of intensities and against a background of unpredictable and frequently intense acoustic interference.

Animals↗
PubMed1991

Effects of first formant onset properties on voicing judgments result from processes not specific to humans.

Both first formant (F1) transition duration and F1 onset frequency have been proposed to be perceptually significant in categorization of voiced and voiceless syllable-initial stops. Transition duration per se may not, however, explain the fact that, for longer transitions, longer F1 cutback is required in order to perceive a stop as voiceless. Longer transitions result in lower F1 onsets at any duration of cutback greater than zero, and it is possible that the major effect of F1 is determined by its frequency at onset. In this study, F1-transition duration, onset frequency, and slope were varied across four types of F1 transition in which one of the three variables (onset frequency, duration, slope) was held constant while the other two were allowed to vary. Each of the four F1 types was used in syllables with higher formants appropriate for labial, alveolar, and velar places of articulation. By far, the best predictor of identification of these stimuli by human listeners was F1 onset frequency. F1 duration, F1 slope, and place of articulation had little or no effect on labeling boundaries. In a second experiment using Japanese quail (Coturnix coturnix japonica), birds were trained to respond differentially to voiced versus voiceless stops. The differential effects of F1 onset frequency on the "labeling" behavior of these birds was strikingly similar to that of humans listening to the same stimuli. These results are taken to provide strong evidence that F1 onset frequency is the primary determinant of shifts in voicing boundaries across place of articulation, and that general mechanisms not unique to humans appear adequate to account for the effects of F1 onset frequency on perception of voicing for syllable-initial stops.

Adult↗
PubMed1987

Japanese quail can learn phonetic categories.

Japanese quail (Coturnix coturnix) learned a category for syllable-initial [d] followed by a dozen different vowels. After learning to categorize syllables consisting of [d], [b], or [g] followed by four different vowels, quail correctly categorized syllables in which the same consonants preceded eight novel vowels. Acoustic analysis of the categorized syllables revealed no single feature or pattern of features that could support generalization, suggesting that the quail adopted a more complex mapping of stimuli into categories. These results challenge theories of speech sound classification that posit uniquely human capacities.

Animals↗
PubMed1985

Are selective adaptation and contrast effects really distinct?

Although there is evidence that selective adaptation and contrast effects in speech perception are produced by the same mechanisms, Sawusch and Jusczyk (1981) reported a dissociation between the effects and concluded that adaptation and contrast occur at separate processing levels. They found that an ambiguous test stimulus was more likely to be labeled b following adaptation with [pha] and more likely to be labeled p following adaptation with [ba] or [spa] (the latter consisting of [ba] preceded by [s] noise). In the contrast session, where a single context stimulus occurred with a single test item, the [ba] and [pha] contexts had contrastive effects similar to those of the [ba] and [pha] adaptors, but the [spa] context produced an increase in b responses to the test stimulus, an effect opposite to that of the [spa] adaptor. One interpretation of this difference is that the rapid presentation of the [spa] adaptor gave rise to "streaming," whereby the [s] was perceptually segregated from the [ba]. In our experiment, we essentially replicated the results of Sawusch and Jusczyk (1981), using procedures similar to theirs. Next, we increased the interadaptor interval to remove the likelihood of stream segregation and found that the adaptation and contrast effects converged.

Adaptation, Physiological↗