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Biomedical subjects

R Plomp

Publications and source records attributed to R Plomp.

54 records · Page 3Linked to original sources

Relations between auditory functions in normal hearing.

The relations among a number of auditory functions were studied by concentration on small interindividual differences in these functions. For this purpose a battery of 12 tests was applied to 50 normal-hearing subjects. The tests included absolute threshold, auditory bandwidth measured with comb-filtered noise in direct and in forward masking, psychophysical tuning curve both in direct and in forward masking, temporal integration measured with intensity-modulated noise, forward- and backward-masking curves, cubic-difference-tone strength, and lateral suppression. In all cases the test frequency was 1000 Hz. Among the relations found, are (1) a positive correlation between the shift of the steep edge of the tuning curve, away from the probe frequency, and the width of the auditory filter as measured with comb-filtered noise, (2) an inverse relation between the width of the tuning curve and the width of the temporal window, and (3) a positive correlation between the width of the auditory filter and the strength of the cubic difference tone. Low correlations among tests were not caused by poor test reliability.

Acoustic Stimulation

Speech-reception threshold for sentences as a function of age and noise level.

For 140 male subjects (20 per decade between the ages 20 and 89) and 72 female subjects (20 per decade between 60 and 89, and 12 for the age interval 90-96), the monaural speech-reception threshold (SRT) for sentences was investigated in quiet and at four noise levels (22.2, 37.5, 52.5, and 67.5 dBA noise with long-term average speech spectra). The median SRT as well as the quartiles are given as a function of age. The data are described in terms of a model published earlier [J. Acoust. Soc. Am. 63, 533-549 (1978)]. According to this model every hearing loss for speech (SHL) is interpreted as the sum of a loss class A (attenuation), characterized by a reduction of the levels of both speech signal and noise, and a loss class D (distortion), comparable with a decrease in signal-to-noise ratio. Both SHLA+D (hearing loss in quiet) and SHLD (hearing loss at high noise levels) increase progressively above the age of 50 (reaching typical values of 30 and 6 dB, respectively, at age 85). The spread of SHLD as a function of SHLA+D for the individual ears is so large (sigma = 2.7 dB) that subjects with the same hearing loss for speech in quiet may differ considerably in their ability to understand speech in noise. The data confirm that the hearing handicap of many elderly subjects manifests itself primarily in a noisy environment. Acceptable noise levels in rooms used by the aged must be 5 to 10 dB lower than those for normal-hearing subjects.

Adult

Auditory handicap of hearing impairment and the limited benefit of hearing aids.

The aim of this article is to promote a better understanding of hearing impairment as a communicative handicap, primarily in noisy environments, and to explain by means of a quantitative model the essentially limited applicability of hearing aids. After data on the prevalence of hearing impairment and of auditory handicap have been reviewed, it is explained that every hearing loss for speech can be interpreted as the sum of a loss class A (attenuation), characterized by a reduction of the levels of both speech signal and noise, and a loss D (distortion), comparable with a decrease in speech-to-noise ratio. On the average, the hearing loss of class D (hearing loss in noise) appears to be about one-third (in decibels) of the total hearing loss (A + D, hearing loss in quiet). A hearing aid can compensate for class-A-hearing losses, giving difficulties primarily in quiet, but not for class-D hearing losses, giving difficulties primarily in noise. The latter class represents the first stage of auditory handicap, beginning at an average hearing loss of about 24 dB.

Adolescent

Improving the reliability of testing the speech reception threshold for sentences.

An accurate test for measuring the speech reception threshold (SRT) for sentences in quiet or in noise has been developed. It is shown that with ten carefully selected lists of only 13 sentences each, a high test-retest reliability can be obtained. The standard deviation of SRT measured with the different lists is approximately 1 dB.

Humans