An investigation of the relation between sibilant production and somatosensory and auditory acuity.

The relation between auditory acuity, somatosensory acuity and the magnitude of produced sibilant contrast was investigated with data from 18 participants. To measure auditory acuity, stimuli from a synthetic sibilant continuum ([s]-[ʃ]) were used in a four-interval, two-alternative forced choice adaptive-staircase discrimination task. To measure somatosensory acuity, small plastic domes with grooves of different spacing were pressed against each participant's tongue tip and the participant was asked to identify one of four possible orientations of the grooves.

Perception and production of /r/ allophones improve with hearing from a cochlear implant.

Tongue shape can vary greatly for allophones of /r/ produced in different phonetic contexts but the primary acoustic cue used by listeners, lowered F3, remains stable. For the current study, it was hypothesized that auditory feedback maintains the speech motor control mechanisms that are constraining acoustic variability of F3 in /r/; thus the listener's percept remains /r/ despite the range of articulatory configurations employed by the speaker. Given the potential importance of auditory feedback, postlingually deafened speakers should show larger acoustic variation in /r/ allophones than hearing controls, and auditory feedback from a cochlear implant could reduce that variation over time.

Effects of short- and long-term changes in auditory feedback on vowel and sibilant contrasts.

Purpose: To assess the effects of short- and long-term changes in auditory feedback on vowel and sibilant contrasts and to evaluate hypotheses arising from a model of speech motor planning.

Method: The perception and production of vowel and sibilant contrasts were measured in 8 postlingually deafened adults prior to activation of their cochlear implant speech processors, 1 month postactivation, and 1 year postactivation. Measures were taken postactivation both with and without auditory feedback.

Interactions of speaking condition and auditory feedback on vowel production in postlingually deaf adults with cochlear implants.

This study investigates the effects of speaking condition and auditory feedback on vowel production by postlingually deafened adults. Thirteen cochlear implant users produced repetitions of nine American English vowels prior to implantation, and at one month and one year after implantation. There were three speaking conditions (clear, normal, and fast), and two feedback conditions after implantation (implant processor turned on and off).

Time course of speech changes in response to unanticipated short-term changes in hearing state.

The timing of changes in parameters of speech production was investigated in six cochlear implant users by switching their implant microphones off and on a number of times in a single experimental session. The subjects repeated four short, two-word utterances, /dV1n#SV2d/ (S = /s/ or /S/), in quasi-random order. The changes between hearing and nonhearing states were introduced by a voice-activated switch at V1 onset.

On the structure of phoneme categories in listeners with cochlear implants.

Purpose: To describe cochlear implant users' phoneme labeling, discrimination, and prototypes for a vowel and a sibilant contrast, and to assess the effects of 1 year's experience with prosthetic hearing.

Method: Based on naturally produced clear examples of "boot," "beet," "said," and "shed" by 1 male and 1 female speaker, continua with 13 stimuli were synthesized for each contrast. Seven hearing controls labeled those stimuli and assigned them goodness ratings, as did 7 implant users at 1-month postimplant.

Effects of masking noise on vowel and sibilant contrasts in normal-hearing speakers and postlingually deafened cochlear implant users.

The role of auditory feedback in speech production was investigated by examining speakers' phonemic contrasts produced under increases in the noise to signal ratio (N/S). Seven cochlear implant users and seven normal-hearing controls pronounced utterances containing the vowels /i/, /u/, /e/ and /ae/ and the sibilants /s/ and /I/ while hearing their speech mixed with noise at seven equally spaced levels between their thresholds of detection and discomfort. Speakers' average vowel duration and SPL generally rose with increasing N/S.

Control of voice-onset time in the absence of hearing: a review.

The relation between partial or absent hearing and control of the voicing contrast has long been of interest to investigators, in part because speakers who are born deaf characteristically have great difficulty mastering the contrast and in part for the light it can cast on the role of hearing in the acquisition and maintenance of phonological contrasts in general. One of the phonetic characteristics that distinguish voiced from voiceless plosives in English (p/b, t/d, k/g) is voice onset time (VOT): the interval from plosive release to the onset of voicing of the following vowel. This article first reviews research on VOT anomalies in the speech production of prelingually and postlingually deaf speakers.

Effects of bite blocks and hearing status on vowel production.

This study explores the effects of hearing status and bite blocks on vowel production. Normal-hearing controls and postlingually deaf adults read elicitation lists of /hVd/ syllables with and without bite blocks and auditory feedback. Deaf participants' auditory feedback was provided by a cochlear prosthesis and interrupted by switching off their implant microphones.

Ethnicity, ethics, and the deaf-world.

This article is concerned with ethical aspects of the relations between language minorities using signed languages (called the Deaf-World) and the larger societies that engulf them. The article aims to show that such minorities have the properties of ethnic groups, and that an unsuitable construction of the Deaf-World as a disability group has led to programs of the majority that discourage Deaf children from acquiring the language and culture of the Deaf-World and that aim to reduce the number of Deaf births-programs that are unethical from an ethnic group perspective. Four reasons not to construe the Deaf-World as a disability group are advanced: Deaf people themselves do not believe they have a disability; the disability construction brings with it needless medical and surgical risks for the Deaf child; it also endangers the future of the Deaf-World; finally, the disability construction brings bad solutions to real problems because it is predicated on a misunderstanding.

The distinctness of speakers' /s/-/S/ contrast is related to their auditory discrimination and use of an articulatory saturation effect.

This study examines individual differences in producing the sibilant contrast in American English and the relation of those differences to 2 speaker characteristics: (a) use of a quantal biomechanical effect (called a "saturation effect") in producing the sibilants and (b) performance on a test of sibilant discrimination. Twenty participants produced the sibilants /s/ and /S/ in normal-, clear-, and fast-speaking conditions. The degree to which the participants used a saturation effect in producing /s/ and /S/ was assessed with a custom-made sensor that measured contact of the underside of the tongue tip with the lower alveolar ridge; such contact normally occurs during the production of /s/ but not /S/.

The distinctness of speakers' productions of vowel contrasts is related to their discrimination of the contrasts.

This study addresses the hypothesis that the more accurately a speaker discriminates a vowel contrast, the more distinctly the speaker produces that contrast. Measures of speech production and perception were collected from 19 young adult speakers of American English. In the production experiment, speakers repeated the words cod, cud, who'd, and hood in a carrier phrase at normal, clear, and fast rates.

Economy of effort in different speaking conditions. I. A preliminary study of intersubject differences and modeling issues.

This study explores the hypothesis that clear speech is produced with greater "articulatory effort" than normal speech. Kinematic and acoustic data were gathered from seven subjects as they pronounced multiple repetitions of utterances in different speaking conditions, including normal, fast, clear, and slow. Data were analyzed within a framework based on a dynamical model of single-axis frictionless movements, in which peak movement speed is used as a relative measure of articulatory effort (Nelson, 1983).

Ethical issues in cochlear implant surgery: an exploration into disease, disability, and the best interests of the child.

This paper examines ethical issues related to medical practices with children and adults who are members of a linguistic and cultural minority known as the DEAF-WORLD. Members of that culture characteristically have hearing parents and are treated by hearing professionals whose values, particularly concerning language, speech, and hearing, are typically quite different from their own. That disparity has long fueled a debate on several ethical issues, most recently the merits of cochlear implant surgery for DEAF children.