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Biomedical subjects

J M Pickett

Publications and source records attributed to J M Pickett.

At least 19 recordsLinked to original sources
PubMed1991

VCVs vs CVCs for stop/fricative distinctions by hearing-impaired and normal-hearing listeners.

Moderately to profoundly hearing-impaired (n = 30) and normal-hearing (n = 6) listeners identified [p, k, t, f, theta, s] in [symbol; see text], and [symbol; see text]s tokens extracted from spoken sentences. The [symbol; see text]s were also identified in the sentences. The hearing-impaired group distinguished stop/fricative manner more poorly for [symbol; see text] in sentences than when extracted. Further, the group's performance for extracted [symbol; see text] was poorer than for extracted [symbol; see text] and [symbol; see text]. For the normal-hearing group, consonant identification was similar among the syllable and sentence contexts.

Audiometry, Pure-Tone↗
PubMed1991

Spectral cues to perception of /d, n, l/ by normal- and impaired-hearing listeners.

The alveolar consonants /d, n, l/ occur frequently in intervocalic position in conversational speech but have received little study for differences in their acoustic cues. Impaired- and normal-hearing listeners were investigated for use of consonant-segment versus transition-segment cues to recognition of /d, n, l/ in /aeCae/ tokens extracted from sentences. To examine the cues' contribution to /d, n, l/ recognition, the segments were degraded singly or in combinations in the tokens as follows: [aeC] or [Cae] transitions were replaced by adjacent pitch periods from the respective vowels; the consonant segments were replaced by silence or by a synthetic consonant approximating the summed low-frequency spectra of the /d, n, l/ murmurs. The results with normal-hearing listeners showed that the presence of any one of the three segments, [aeC] transition, [Cae] transition, or natural consonant segment, supported a moderate to high level of /d, n, l/ recognition, depending on the phoneme. In contrast, the severely hearing-impaired listeners' consonant recognition was poor on the basis of transition information, but better in the presence of the natural consonants. The /aeCae/'s with the synthetic consonant yielded chance level performance for the hearing-impaired listeners but good consonant recognition for the normal-hearing listeners--a further indication that cues in the transitions were quite useful for the normal-hearing group but not for the hearing-impaired group.

Adult↗
PubMed1987

Burst and transition cues to voicing perception for spoken initial stops by impaired- and normal-hearing listeners.

The use of cues to voicing perception of initial stop consonants in multiple spoken syllables was studied for moderately/severely hearing-impaired (n = 43) and normal-hearing listeners (n = 12). The test stimuli were ten utterances each of the syllables/baed, gaed, daed, paed, kaed, taed/. The utterances were analyzed acoustically to confirm the presence of certain cues to initial-stop voicing, namely, differences in voice onset time (VOT), aspiration, and vowel-onset values of the first formant and of fundamental frequency (fo). Test conditions were prepared in which different portions of the syllable onsets were either deleted or interchanged for voicing-cognate syllables. Also the fo contour was flattened for syllable pairs via analysis/synthesis using linear predictor code (LPC) processing. The results confirmed that VOT was a strong voicing cue for both the hearing-impaired and normal-hearing listeners. When the aspirations of the voiceless stops were inserted between the release and the vowel of the voiced-stop syllables, the normal-hearing listeners perceived voiceless stops predominantly. The transition portions of the vowel onsets in burstless /baed, gaed, daed/ contained strong cues for voicing perception of /b,g,d/. The hearing-impaired listeners seemed less sensitive than the normal-hearing listeners to the aspiration-presence and the vowel-onset cues. The fo difference at vowel onset appeared to have no cue value for either group of listeners.

Adult↗
PubMed1987

Speech-cue enhancement for the hearing impaired: amplification of burst/murmur cues for improved perception of final stop voicing.

A further study is reported from a program of research exploring the improvement of speech perception by hearing-impaired persons via enhancement of acoustic features of consonants (10,11). Enhancements were applied to certain acoustic segments of consonants, segments known to be useful in consonant perception by normal-hearing persons but often not for persons with severe/profound hearing losses. The consonants were /k/, /t/, /g/, and /d/ located as the final phoneme in /baeC/ words; the voicing feature difference of /k/ versus /g/ and /t/ versus /d/ was the focus of study. The results showed that stop voicing perception improved to at least 90 percent for 3/4 of the listeners when the voiced murmur segments during /d/ and /g/ and the release bursts of /t/ and /k/ were amplified above their natural levels. The audibility of the enhanced segments generally explained differences between the listeners who showed large versus minimal improvements. One training session for stop voicing perception with the cue-enhanced words seemed sufficient to effect maximum performance improvement.

Auditory Threshold↗
PubMed1986

Cations decrease specific [3H]-spiroperidol binding in human prefrontal cortex.

Ligand binding at many physiologically relevant receptors is regulated by divalent cations. To determine whether [3H]-spiroperidol binding sites in prefrontal cortex might be physiologically relevant receptors, we examined the effect of ions on the binding of this ligand in postmortem human prefrontal cortex. Our results indicate that several cations decreased [3H]-spiroperidol binding in a dose-dependent fashion. Of these, Cd++ and Zn++ were the most able to decrease [3H]-spiroperidol binding with IC50 of 5.5 +/- 2.4 X 10(-6)M and 5.6 +/- 1.1 X 10(-5)M respectively. These findings indicate that [3H]-spiroperidol may bind at physiologically relevant receptors in human prefrontal cortex.

Butyrophenones↗
PubMed1986

Speech cue enhancement for the hearing impaired: I. Altered vowel durations for perception of final fricative voicing.

Hearing-impaired persons with reduced voicing perception for final fricatives were studied for improvement in perception via training or enhancement of the vowel duration cue. Ten utterances each of the syllables /baef, baes, baev, baez/ composed three stimulus sets that were graded for the magnitude of the vowel duration cue. These sets were used differentially among 25 hearing-impaired listeners to train and test voicing perception. When enhanced, the vowels of the utterances were lengthened before voiced fricatives and shortened before voiceless fricatives. Training for the utterances with unmodified vowels yielded a small performance improvement for a subgroup of 14 listeners. In comparison, this subgroup showed considerably more improvement for the utterances with vowel duration enhancements. Another subgroup of 5 listeners displayed good fricative voicing perception independent of training or the vowel duration enhancements. A remaining subgroup of 6 listeners manifested poor use of the maximum unmodified vowel duration cues, even subsequent to training. This group showed a significant improvement in perception only for the voiced fricatives when extra duration enhancement and further training were used. This subgroup also demonstrated the poorest performance for a measure of vowel duration discrimination. Among the auditory variables examined, the listeners' tone thresholds at 250 Hz showed the highest relation to perception of fricative voicing.

Auditory Threshold↗
PubMed1986

Speech communication for the deaf: visual, tactile, and cochlear-implant.

A review is given of current research and development on electronic devices to aid speech communication for the deaf. Visual and tactile displays are compared with stimulation of hearing via electrodes implanted in the cochlea. Specific comparative performance data are given for cochlear electrical implants versus tactile aids.

Audiovisual Aids↗
PubMed1986

Some rehabilitative considerations for future speech-processing hearing aids.

Improvements in speech-recognition and speech-processing technology promise eventual ways of assisting the hearing impaired by automatically enhancing the audibility of critical speech segments or distinctive features. Some results of applying enhancement techniques are summarized and procedures are proposed for selecting the speech sounds requiring enhancement, the degree of amplification, and the training that hearing-impaired listeners might need.

Computer-Assisted Instruction↗
PubMed1985

Auditory implants and tactile aids for the profoundly deaf.

This paper reviews data on speech perception via implanted electrodes and via tactile aids. The two approaches are compared in terms of amount and types of aid provided to communication. Related issues discussed are the performance levels with multi-versus single-channel implants, promontory electrical stimulators versus implants, use of minimal residual hearing, implants for children, and the possible design of complementary systems combining auditory implant and tactile information. The diversity of the test methods and subjects used in implant versus tactile research precludes definitive comparisons of speech perception performance. However, it appears from the available data that, at present and for the foreseeable future, neither approach can provide more than a modest aid to lipreading. Speech reception test results from multichannel-implanted subjects are better, on the average, than for single-channel subjects. However, the best single-channel results are comparable to the best multichannel in tests using simple sentences. There is great variation among subjects with the same implant. Tactile aid performance by highly practiced subjects seems comparable to that of the better implant subjects.

Adolescent↗
PubMed1985

Perceptual cues to the voiced-voiceless distinction of final fricatives for listeners with impaired or with normal hearing.

Cues to the voicing distinction for final /f,s,v,z/ were assessed for 24 impaired- and 11 normal-hearing listeners. In base-line tests the listeners identified the consonants in recorded /d circumflex C/ syllables. To assess the importance of various cues, tests were conducted of the syllables altered by deletion and/or temporal adjustment of segments containing acoustic patterns related to the voicing distinction for the fricatives. The results showed that decreasing the duration of /circumflex/ preceding /v/ or /z/, and lengthening the /circumflex/ preceding /f/ or /s/, considerably reduced the correctness of voicing perception for the hearing-impaired group, while showing no effect for the normal-hearing group. For the normals, voicing perception deteriorated for /f/ and /s/ when the frications were deleted from the syllables, and for /v/ and /z/ when the vowel offsets were removed from the syllables with duration-adjusted vowels and deleted frications. We conclude that some hearing-impaired listeners rely to a greater extent on vowel duration as a voicing cue than do normal-hearing listeners.

Auditory Threshold↗
PubMed1976

Gels in soap stabilized emulsions.

In some soap stabilized liquid paraffin emulsions a correlation has been found between emulsion type and the contact angle of the soap gel (the stabilizing agent) at the o/w interface. Two unrelated series of emulsions have been prepared, one series being stabilized by magnesium oleate gels and the other series by ammonium oleate gels. The soap gels were prepared by double decomposition and suppression of ionization respectively. Unlike the magnesium oleate system no inversion to w/o emulsions occurred with the ammonium oleate series. This dissimilarity is predicted from differences in the contact angles of the soap gels at the o/w interface.

Chemical Phenomena↗