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Biomedical subjects

C W Newman

Publications and source records attributed to C W Newman.

69 records · Page 4Linked to original sources
PubMed1983

Prolonged auditory processing time in the elderly: evidence from a backward recognition-masking paradigm.

The rate of processing pure-tone stimuli was measured in 10 elderly subjects and 10 young controls using an auditory backward recognition-masking paradigm. Experimental trials consisted of the presentation of either a 770- or 870-Hz target stimulus (TS) followed by an 820-Hz masking stimulus (MS), separated by a variable silent intertone interval (ITI). For both groups, the mean percent correct recognition scores for TS identification improved systematically with increases in ITIs, reaching an asymptote followed by an apparent plateau. The mean recognition scores at each ITI were lower for the elderly subjects than for the controls; however, equivalence between groups was observed at prolonged ITIs. The elderly group's mean asymptote was observed at a longer ITI (360 ms) relative to that of the controls (248 ms), a statistically significant difference. The findings suggest an age-associated slowing in auditory processing time.

Adult↗
PubMed1982

Recognition of time-compressed high- and low-predictability sentences by normal subjects.

Recall accuracy for time-compressed real sentences varying in contextual redundancy was documented on 12 normal-hearing young adults. Ss were required to identify the final word (key word) of uncompressed and 60% time-compressed high-predictability (HP) and low-predictability (LP) sentences of the SPIN test sentences. Time compression was more detrimental for the perception of LP sentences than for HP items, suggesting that especially under conditions of temporal stress normal Ss rely upon the linguistic and semantic information contained within real sentences.

Adult↗
PubMed1981

Synchronization of estrus in gilts with allyl trenbolone: fecundity after natural service and insemination with frozen semen.

The synthetic progestogen, allyl trenbolone, was fed daily to 60 gilts at 15 mg/gilt for 18 days. Sixty-eight gilts that came into estrus the same week as treated gilts served as controls. Gilts were checked for estrus twice daily and were artificially inseminated with frozen semen or bred by natural service. All but two treated gilts returned to estrus between 4 and 7 days after withdrawal of allyl trenbolone (mean = 5.6; SD = .82). The farrowing rate among gilts inseminated with frozen semen was significantly lower than that among gilts bred by natural service (52.5 vs 89.6%). The farrowing rate among synchronized gilts was similar to that among untreated gilts (70.7 vs 73.5%). Average total and live litter sizes at birth and litter size at weaning were significantly smaller for untreated gilts inseminated with frozen semen than for synchronized gilts inseminated with frozen semen or those of untreated gilts bred by natural service. Average litter size for synchronized gilts bred by natural service was not significantly larger than that for synchronized gilts inseminated with frozen semen or that of untreated gilts bred by natural service.

Animals↗
PubMedDate not supplied

Absence of rate-dependent BAEP P5 latency changes in patients with definite multiple sclerosis: possible physiological mechanisms.

Brain-stem auditory evoked potential (BAEP) rate studies have been incorporated into evoked potential protocols in an attempt to identify demyelinating lesions. A group of 9 patients with clinically definite MS are described who showed abnormal BAEP P1-P5 interwave latencies at slow repetition rates and failed to demonstrate a significant enhancement of this abnormality following rapid click presentation rates. The lack of rate-dependent P5 latency changes has been hypothesized to represent a less severe form of axonal demyelination. Thus, it may be possible to subclassify or subgroup patients with evidence of brain-stem demyelination based on the presence or absence of BAEP rate-dependent abnormalities.

Adult↗
PubMedDate not supplied

Eustachian tube efficiency of geriatric subjects.

The effects of age on Eustachian tube efficiency were examined using a tympanometric swallow procedure. Ten aged males and 10 young controls served as subjects. Tympanograms were examined for middle ear pressure and amplitude after a swallow maneuver and manipulation of external auditory meatus pressure. Statistical analysis of pressure peak findings revealed a significant interaction effect (age X tympanometric condition), which reflected less extreme pressure shifts obtained from geriatric subjects. Lack of shift and shift in the opposite direction from expectation among the geriatric subjects were both observed. The authors suggested that further exploration of possible hypofunction of the aged Eustachian tube relative to that of the young controls is warranted.

Acoustic Impedance Tests↗
PubMedDate not supplied

Reliability of a measure of eustachian tube function in normal subjects.

Short-term reliability of a tympanometric pressure-swallow technique for assessing eustachian tube (ET) ventilating efficiency was measured in 20 normals with intact tympanic membranes on otoadmittance and impedance instruments. Tympanograms were examined for middle ear pressure and amplitude after a swallow maneuver and manipulation of ear canal pressure in a repeated measures design. Test-retest correlations were examined for both pressure shift and amplitude. Poor reliability was obtained for pressure measures with otoadmittance, while high reliability was observed for pressure values on impedance trials and amplitude for both instruments. Findings suggested significant probability of misclassification of normals for repeated measures of ET efficiency, using the currently accepted criterion for minimum pressure shift.

Acoustic Impedance Tests↗
PubMedDate not supplied

Age-associated degeneration of backward masking task performance: evidence of declining temporal resolution abilities in normal listeners.

A backward masking paradigm was employed to investigate temporal resolution capabilities in normal-hearing subjects of increasing chronological age. Results have documented: (1) a 2-, 4-, 8-, and 11-fold decibel magnitude difference for averaged psychoacoustic functions when comparing data obtained from young adults to those of elderly listeners; (2) that backward masking function slopes become significantly steeper with age, especially at very short interstimulus intervals; (3) a significant interaction between age and target frequency; (4) a linear age-associated decrement in presumed temporal resolution abilities, and (5) no significant target frequency difference nor any ear differences existed. Both end organ and central nervous system mechanisms were considered in explaining these findings.

Acoustic Stimulation↗
PubMedDate not supplied

Relationships among psychoacoustic judgments, speech understanding ability and self-perceived handicap in tinnitus subjects.

Tinnitus is often a disturbing symptom which affects 6-20% of the population. Relationships among tinnitus pitch and loudness judgments, audiometric speech understanding measures and self-perceived handicap were evaluated in a sample of subjects with tinnitus and hearing loss (THL). Data obtained from the THL sample on the audiometric speech measures were compared to the performance of an age-matched hearing loss only (HL) group. Both groups had normal hearing through 1 kHz with a sloping configuration of < or = 20 dB/octave between 2-12 kHz. The THL subjects performed more poorly on the low predictability items of the Speech Perception in Noise Test, suggesting that tinnitus may interfere with the perception of speech signals having reduced linguistic redundancy. The THL subjects rated their tinnitus as annoying at relatively low sensation levels using the pitch-match frequency as the reference tone. Further, significant relationships were found between loudness judgment measures and self-rated annoyance. No predictable relationships were observed between the audiometric speech measures and perceived handicap using the Tinnitus Handicap Questionnaire. These findings support the use of self-report measures in tinnitus patients in that audiometric speech tests alone may be insufficient in describing an individual's reaction to his/her communication breakdowns.

Adult↗