Biomedical subjects

A J Duquesnoy

Publications and source records attributed to A J Duquesnoy.

6 recordsLinked to original sources

PubMed1983

The effect of a hearing aid on the speech-reception threshold of hearing-impaired listeners in quiet and in noise.

The monaural free-field speech-reception threshold (SRT) without and with a hearing aid was investigated for conversational sentences presented to 50 hearing-impaired listeners. SRT without a hearing aid was measured in quiet and in noise levels of 40, 55, 70, and 85 dBA. SRT with a hearing aid was obtained in quiet and at noise levels of 25, 40, 55, and 70 dBA. The noise had a long-term average spectrum equal to that of the sentences. The 50 subjects were equally distributed over five degrees of pure-tone hearing loss and five types of hearing impairment (sensorineural high-frequency losses, with or without recruitment; flat audiogram of a sensorineural, mixed, or conductive origin). It is shown that a model of SRT as a function of noise level, developed by Plomp [J. Acoust. Soc. Am. 63, 533-549 (1978)] gives a good description of the SRT values measured, both without and with a hearing aid. The data illustrate that, generally, current hearing aids do not improve speech intelligibility in noise beyond, roughly, 60 dBA.

Adult↗

PubMed1983

Effect of a single interfering noise or speech source upon the binaural sentence intelligibility of aged persons.

The free-field speech-reception threshold (SRT) for sentences was investigated in quiet and under nine conditions involving noise or competing speech for a group of 20 elderly subjects (ten male, age 75-85; ten female, age 76-88) and a reference group of ten young normal-hearing subjects. The noise source had the same long-term average spectrum as the competing speech. The interfering signals were presented at a constant level of 55 dBA. All elderly subjects had moderate, nearly symmetrical pure-tone hearing losses with an average loss at 500, 1000, and 2000 Hz of between 9 and 40 dB re: ISO-389. The main results are (1) the SRT values in noise and competing speech are about equal, whereas the normal-hearing subjects showed a lower SRT (7 dB lower for the condition that both sound sources are in front) in competing speech than in noise; apparently, the elderly subjects do not benefit from the relatively silent periods in competing speech; (2) the gain obtained by moving the interfering noise source from the front to the lateral position is only 2.5 dB, in contrast to a gain of 9.6 dB for the young subjects; apparently, the elderly are unable to make full use of the spatial divergence between primary speaker and noise source.

Age Factors↗

PubMed1983

The intelligibility of sentences in quiet and in noise in aged listeners.

The monaural speech-reception threshold (SRT) for sentences was investigated in quiet and under four noise conditions for 80 male subjects (age 60-90) and 30 female subjects (age 71-89). The noise levels used were 28, 43, 58, and 73 dBA. The noise had the long-term average spectrum of speech. It is shown that a model developed by Plomp [J. Acoust. Soc. Am. 63, 533-549 (1978)], which interprets any hearing loss for speech (SHL) as a combination of a loss of class A (attenuation of both speech and noise) and a loss of class D (distortion of the sound signals), enables one to make an accurate description of the SRT values measured. Fitting this model, for each individual, to the SRT data yielded values for SHL in quiet (= A + D) and in noise (= D). These individual SHL values were studied in relation to one another and in relation to such parameters as the pure-tone average (PTA), the Fletcher Index (FI), and the increment in intelligibility score per dB near SRT. It was found that (1) subjects with the same SHL in quiet may differ considerably in their SHL in noise; (2) for an individual, PTA and FI are inaccurate measures for predicting SHL in quiet and in noise, and (3) the higher an individual's SHL in noise, the lower is the increase per dB of the intelligibility score for sentences in noise.

Adult↗

PubMed1982

A model for the speech-reception threshold in noise without and with a hearing aid.

This paper presents a summary of the main results of our current research programme on the speech-reception threshold for sentences as a function of the sound-pressure level of interfering noise. The experimental results agree with a simple quantitative model in which every hearing loss for speech is interpreted as the sum of a class-A loss (attenuation), characterized by a reduction in the levels of both speech signal and noise, and a class-D loss (distortion), comparable to a reduction in S/N ratio. The experiments confirm the model's prediction that a hearing aid can compensate for class-A hearing losses but, generally, not for class-D hearing losses. The implies that the problem of having difficulties in understanding speech in a noisy environment, which is the primary handicap of hearing-impaired subjects, is not solved by the hearing aid.

Audiometry, Speech↗

PubMed1980

Effect of reverberation and noise on the intelligibility of sentences in cases of presbyacusis.

For 80 male subjects (age 60--90) and 30 female subjects (age 71--89) the monaural Speech-Reception Threshold (SRT) for sentences was investigated under five reverberation conditions at a constant noise level. The reverberation times used were between 0 and 2.3 s. The noise, with the long-term average speech spectrum, had a level of 52.5 dBA. Each subject was assigned to one of several subgroups formed on the basis of the maximum reverberation time at which the subject was still able to understand the sentences correctly The mean SRTs and the standard deviations are given, per subgroup, as a function of reverberation time. It is shown that, for each subgroup, the SRT in different reverberant sound fields can be expressed as a single number, namely the required Speech Transmission Index (STI) as introduced in room acoustics by Houtgast and Steeneken [Acustica 28, 66--73 (1973)]. Furthermore, it is shown that a model of SRT as a function of noise level, developed by Plomp [J. Acoust. Soc. Am. 63, 533--549 (1978)], can be combined with the STI model and can thus include the effect of reverberation.

Acoustics↗

PubMed1980

Room acoustics for the aged.

This article deals with the combined effects of noise and reverberation on the speech-reception threshold for sentences. It is based on a series of current investigations on: (1) the modulation-transfer function as a measure of speech intelligibility in rooms, (2) the applicability of this concept to hearing-impaired persons, and (3) hearing loss for speech in quiet and in noise as a function of age. It is shown that, generally, in auditoria, classrooms, etc. the reverberation time T, acceptable for normal-hearing listeners, has to be reduced to (0.75)DT in order to be acceptable for elderly subjects with a hearing loss of D dB for speech in noise; for listening conditions as in lounges, restaurants, etc. the corresponding value is (0.82)DT.

Acoustics↗