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Biomedical subjects

A C Neuman

Publications and source records attributed to A C Neuman.

7 recordsLinked to original sources
PubMed1991

Evaluation of a dereverberation technique.

A two-microphone dereverberation technique was evaluated by obtaining speech recognition measures and preference judgments from normal-hearing and hearing-impaired listeners. Monaural speech recognition performance was measured for two reverberation conditions (0.4 second and 1.2 seconds) with and without processing. Binaural speech recognition performance was also measured for the unprocessed conditions. In addition, paired-comparison judgments of preference were obtained for all combinations of the processed and unprocessed monaural stimuli. For both groups of subjects, scores at the shorter reverberation time were significantly higher than scores for the longer reverberation time. For the normal-hearing subjects, processing to dereverberate had no significant effect on speech recognition performance. Binaural presentation of the unprocessed signal yielded significantly higher scores. For the hearing-impaired subjects, performance was significantly better in the unprocessed condition than the processed condition, but was not significantly different from the binaural condition. Paired-comparison judgments revealed differences in patterns of preference between normal-hearing and hearing-impaired listeners.

Adult↗
PubMed1991

Evaluation of orthogonal polynomial compression.

In orthogonal polynomial compression, the short-term speech spectrum is first approximated by a family of orthogonal polynomials. The coefficients of each polynomial, which vary over time, are then adjusted in terms of their average value and range of variation. These adjustments can be used to compress (or expand) temporal variations in the average level, slope, and various forms of curvature of the short-term speech spectrum. The analysis and reconstruction of the short-term speech spectrum using orthogonal polynomials was implemented using a digital master hearing aid. This method of compression was evaluated on eight sensorineurally hearing-impaired listeners. Speech recognition scores were obtained for a range of compression conditions and input levels with and without frequency shaping. The results showed significant advantages over conventional linear amplification when temporal variations in the average level of the short-term spectrum were compressed, a result comparable to that obtained with conventional amplitude compression. A subset of the subjects showed further improvement when temporal variations in spectrum slope were compressed, but these subjects also showed similar improvements when frequency shaping was combined with level-only compression. None of the subjects showed improved speech recognition scores when variations in quadratic curvature were compressed in addition to level and slope compression.

Adult↗
PubMed1987

An evaluation of three adaptive hearing aid selection strategies.

Paired-comparison judgments of intelligibility of speech in noise were obtained from eight hearing-impaired subjects on a large number of hearing aids simulated by a digital master hearing aid. The hearing aids which comprised a 5 X 5 matrix differed systematically in the amount of low-frequency and high-frequency gain provided. A comparison of three adaptive strategies for determining optimum hearing aid frequency-gain characteristics (an iterative round robin, a double elimination tournament, and a modified simplex procedure) revealed convergence on the same or similar hearing aids for most subjects. Analysis revealed that subjects for whom all three procedures converged on the same hearing aid showed a single pronounced peak in the response surface, while a broader peak was evident for the subjects for whom the three procedures identified similar hearing aids. The modified simplex procedure was found to be most efficient and the iterative round robin least efficient.

Adult↗
PubMed1987

Experiments with a programmable master hearing aid.

A series of experiments is described tracing the development and application of adaptive paired-comparison testing to the prescriptive fitting of hearing aids. The equipment needed to implement the test procedures became progressively more complex with each new experiment, leading to the development of a digital master hearing aid.

Adult↗
PubMed1983

Children's perception of speech in reverberation.

Recordings of nonsense syllables (VCV construction) were presented to groups of children aged 5, 7, 9, 11, and 13 years and young adults under monaural (reverberation time = 0.6s) and binaural (reverberation times = 0, 0.4, and 0.6 s) conditions of reverberation. Phoneme identification performance was affected by age, reverberation, and mode of presentation (monaural versus binaural). The major findings were (1) phoneme identification scores in reverberant conditions improved with increasing age and decreased with increased reverberation time; (2) children's performance in reverberant conditions did not reach asymptote until age 13; (3) binaural performance was consistently better than monaural performance for all age groups, with 5-year-olds showing the largest binaural advantage.

Adolescent↗