UT PSY 394U - Speech perception by the chinchilla

Unformatted text preview:

Speech perception by the chinchilla: Identification functions for synthetic VOT stimuliPatrica K. Kuhl & James D. MillerJASIntroductionQuestions about the dichotomySolutionPrevious AnalysesGoalsExperiment ISubjectsApparatusDiscriminating trainingGeneralization testingResults-Experiment IExperiment IIResults –Experiment IIExperiment IIIExperiment IVResults-Experiment IVStatistical AnalysesDiscussionDiscussionDiscussionSpeech perception by the chinchilla: Identification functions for synthetic VOT stimuliPatrica K. Kuhl & James D. MillerJASA (1977)Introduction• To account for the data in speech experiment, it is useful to distinguish between auditory levels of processing and phonetic levels of processing.• The evidence supporting a dichotomy between the two levels:-a lack of acoustic invariance between the acoustic cues and our percepts (Liberman et al., 1967)-the discovery of perceptual behaviors like categorical perception-evidence from studies of selective adaptationQuestions about the dichotomy• Invariant cues for stop consonants may be found in the dynamic configurations of spectral energy over time (Fant(1973), Stevens (1975)).• Perceptual behaviors have been demonstrated for complex nonspeech signals (Pisoni, 1977)• The effects of selective adaptation, thought to provide evidence for phonetic feature detectors now appear to be attributed to auditory.Solution• A direct test of the distinction between auditory and phonetic levels of processing-using animal listener who has no phonetic resources.• The rationale for this comparative approach is to tease out the perceptual effects from those that are unique to speech-sound processing.Previous Analyses• Liberman et al.(1967): categorical perception is considered unique to the processing of speech sounds • For nonspeech stimuli: Cutting and Rosner (1974) - “plucked” or “bowed”,Pisoni(1977) • Eimas (1974b) : Infants perceives the stimuli in a linguistic mode and may categorically discriminate voicing contrasts that are not phonemic in the infant’s linguistic environment.• Kuhl (1978) : While the infant’s perceptual proclivities are linguistically relevant, their origins may reflect constraints that are psychoacoustic rather than specifically linguistic.Goals• In an attempt to differentiate perceptual effects that are attributable to “auditory” and “phonetic” levels of processing in speech perception, Kuhl & Moller(1977) undertook a series of experiments with animal listener• The results obtained with alveolar stimuli are reported in experiment I; results obtained with labial and velar stimuli are reported in experiments II and III.• Experiment IV is a report of results obtained when the stimuli from all three continua were used.Experiment IA. Stimuli• The speech sounds were synthesized at the Haskins Laboratories on the parallel-resonance synthesizer. • For a specified VOT, the upper two formants were excited with thermal noise for the duration of the interval; at the end of this interval, the two formants were excited with periodic pulses. • The first formant was off throughout the VOT interval.5ms for b/p and d/t, 20ms for g/k stimuli• VOT’s from 0 to 80ms in 10-ms steps, was recorded on a full-track tape recorder and then re-recorded onto a disk pack of RAP.Subjects• Four chinchillas, each about two years of age• Two of the four animals had been previously trained to categorize naturally produced alveolar tokens as either /d/ or /t/ syllables. • The other two animals had never been trained • Four English-speaking-adultsApparatus• A double-grille cage with a loudspeaker in a sound-treated booth.• The cage divided by a midline barrier and having a door buzzer at one end. • Presentation of a speech sound was initiated by the experimenter and controlled by punched paper tape and a high-speed paper-tape reader. • The punched tape was prepared according to the randomization speifications.Discriminating training• On positive trials, the animal had to cross the midline barrier to avoid a mild shock and the surrounding of the buzzer.• On negative trials, the animal could remain at the drinking tube. If the animal successfully inhibited the crossing response, it was rewarded with free water. • At the end of that experiment, two animals had learned to classify correctly the voiced and voiceless CV syllables produced by eight different talkers in six different vowel context.• Randomization of positive and negative trials by computer-punched paper tapesGeneralization testing• On half of the trials: the endpoint stimuli, 0 and +80 ms VOT • On the other half of trials: the stimuli between these endpoints, +10 to +70 ms VOT• During generalization testing, shock was never presented and all feedback was arranged to tell the animal he was always correct. • Testing human subjects: -Four human subjects with the same sound-treated booth -the same trial structure- instructed to label the stimuli as /da/ or /ta/.Results-Experiment I• Location of the phonetic boundaries:-The phonetic boundaries of the fitted curves: 35.2 ms VOT for English-speaking adults, 33.3 ms VOT for chinchillas-The boundary value range: 29.9 ms -42.0 ms for humans, 26.7 ms -36 ms for chinchilla-Exposure to natural speech had no effect on the location of the boundarya. the two animals trained- 31.4 ms VOTb. the two animals having no training-32.8 ms VOTExperiment II• Subjects: -Two of the four chinchillas used in experiment I served as subject. -One had originally been trained on natural speech while the other had been trained only on the synthetic tokens.-The same four English-speaking adultsResults –Experiment II1. Transfer from the alveolar stimuli to the stimuli with a labial place of articulation2. Location of the phonetic boundaries:phonetic boundaries of the fitted curves are 26.8 ms VOT for English-speaking adults and 23.3 ms for chinchillas.3. Boundary width: Each subject’s fitted curve was matched at the 50%.Experiment III• Subject: same subjects in experiment II.• Procedurea. Discrimination trainingb. Generalization testing•Resultsa. Transfer to stimuli with a velar place of articulationb. The 50% points of the fitted curves: 42.3 ms VOT for English-speaking adults, 42.5 ms VOT for chinchillasc. Each subject’s fitted curve was matched at the 50% point.Experiment IV• Stimuli: The labial, alveolar and velar stimuli previously described were used•


View Full Document

UT PSY 394U - Speech perception by the chinchilla

Documents in this Course
Roadmap

Roadmap

6 pages

Load more
Download Speech perception by the chinchilla
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Speech perception by the chinchilla and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Speech perception by the chinchilla 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?