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Biomedical subjects

V C Tartter

Publications and source records attributed to V C Tartter.

9 recordsLinked to original sources
PubMed1992

Auditory perception changes after reimplantation in a child cochlear implant user.

The ability to remove cochlear implants from children and subsequently reimplant a more complex device in the same ear was the concern of this single case study. A postlinguistically deafened child, J.L., received a single-channel cochlear implant 1 yr after contracting meningitis and suffering a profound bilateral sensorineural hearing loss. After 3 yr of successful implant use, J.L. suffered an internal coil failure. She was then explanted and reimplanted with a multichannel cochlear implant in the same ear. This case report details her speech perception skills with her single-channel cochlear implant, a vibrotactile aid, and a multichannel cochlear implant. Results from auditory perceptual measures suggest that the explantation/reimplantation process was technically feasible with no adverse effects on J.L.'s ability to utilize a more sophisticated device and to exceed her previous performance levels.

Acoustic Stimulation↗
PubMed1992

Vowel perception strategies of normal-hearing subjects and patients using Nucleus multichannel and 3M/House cochlear implants.

Vowel perception strategies were assessed for two "average" and one "star" single-channel 3M/House and three "average" and one "star" Nucleus 22-channel cochlear implant patients and six normal-hearing control subjects. All subjects were tested by computer with real and synthetic speech versions of [symbol: see text], presented randomly. Duration, fundamental frequency, and first, second, and third formant frequency cues to the vowels were the vowels were systematically manipulated. Results showed high accuracy for the normal-hearing subjects in all conditions but that of the first formant alone. "Average" single-channel patients classified only real speech [hVd] syllables differently from synthetic steady state syllables. The "star" single-channel patient identified the vowels at much better than chance levels, with a results pattern suggesting effective use of first formant and duration information. Both "star" and "average" Nucleus users showed similar response patterns, performing better than chance in most conditions, and identifying the vowels using duration and some frequency information from all three formants.

Adolescent↗
PubMed1992

Speech changes following reimplantation from a single-channel to a multichannel cochlear implant.

The speech of a postlingually deafened preadolescent was recorded and analyzed while a single-electrode cochlear implant (3M/House) was in operation, on two occasions after it failed (1 day and 18 days) and on three occasions after stimulation of a multichannel cochlear implant (Nucleus 22) (1 day, 6 months, and 1 year). Listeners judged 3M/House tokens to be the most normal until the subject had one year's experience with the Nucleus device. Spectrograms showed less aspiration, better formant definition and longer final frication and closure duration post-Nucleus stimulation (6 MO. NUCLEUS and 1 YEAR NUCLEUS) relative to the 3M/House and no auditory feedback conditions. Acoustic measurements after loss of auditory feedback (1 DAY FAIL and 18 DAYS FAIL) indicated a constriction of vowel space. Appropriately higher fundamental frequency for stressed than unstressed syllables, an expansion of vowel space and improvement in some aspects of production of voicing, manner and place of articulation were noted one year post-Nucleus stimulation. Loss of auditory feedback results are related to the literature on the effects of postlingual deafness on speech. Nucleus and 3M/House effects on speech are discussed in terms of speech production studies of single-electrode and multichannel patients.

Child↗
PubMed1991

Identifiability of vowels and speakers from whispered syllables.

In the present experiments, the effect of whisper register on speech perception was measured. We assessed listeners' abilities to identify 10 vowels in [hVd] context pronounced by 3 male and 3 female speakers in normal and whisper registers. Results showed 82% average identification accuracy in whisper mode, approximately a 10% falloff in identification accuracy from normally phonated speech. In both modes, significant confusions of [o] for [a] occurred, with some additional significant confusions occurring in whisper mode among vowels adjacent in F1/F2 space. We also assessed listeners' abilities to match whispered syllables with normally phonated ones by the same speaker. Each trial contained the matching syllable and two foils whispered by speakers of the same sex as the speaker of the target. Identification performance was significantly better than chance across subjects, speakers, and vowels, with no listener achieving better than 96% performance. Acoustic analyses measured potential cues to speaker identity independent of register.

Adult↗
PubMed1989

The speech of a postlingually deafened teenager during the first year of use of a multichannel cochlear implant.

The speech of a profoundly postlingually deafened teenager was recorded before, immediately after, 3 months after, and 1 year after electrical stimulation with a Nucleus multichannel cochlear implant. Listener tests of target words revealed significant improvement in overall quality over the year. Spectrograms showed less aspiration and better definition of the lower formants. Acoustic measurements indicated immediate change in F0 and gradual changes in syllable duration and some aspects of voicing and manner of articulation. Vowel space shrank steadily over the year, with both first- and second-formant frequencies dropping. Prestimulation results are discussed relative to the literature on the speech of the congenitally hearing impaired. Effects of multichannel electrical stimulation on speech are compared with studies of single-electrode stimulation.

Adolescent↗
PubMed1989

What's in a whisper?

Whispering is a common, natural way of reducing speech perceptibility, but whether and how whispering affects consonant identification and the acoustic features presumed important for it in normal speech perception are unknown. In this experiment, untrained listeners identified 18 different whispered initial consonants significantly better than chance in nonsense syllables. The phonetic features of place and manner of articulation and, to a lesser extent, voicing, were correctly identified. Confusion matrix and acoustic analyses indicated preservation of resonance characteristics for place and manner of articulation and suggested the use of burst, aspiration, or frication duration and intensity, and/or first-formant cutback for voicing decisions.

Adult↗