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Biomedical subjects

R Plomp

Publications and source records attributed to R Plomp.

At least 55 records · Page 3Linked to original sources
PubMed1986

Spectral analysis of sung vowels. III. Characteristics of singers and modes of singing.

The 1/3-oct spectra of nine different vowels, sung by 14 professional male and female singers in nine different modes of singing, were analyzed to reveal spectral characteristics of individual singers and modes of singing. The main spectral differences between singers could be described in two dimensions characterizing, respectively, differences among male and among female singers. Spectral characteristics of these dimensions suggested that interindividual differences among males, like the average difference between males and females, arise mainly from differences in vocal tract dimensions, whereas interindividual differences among females may have a glottal basis. The spectral characteristics of the modes of singing could be represented for each vowel in two dimensions. Differences among the soft (pianissimo), light, neutral, free, straight, extra vibrato, and loud (fortissimo) modes were mainly due to the spectral effect of vocal effort, which constituted a very dominant first spectral dimension. This dimension essentially reflected the slope of the spectrum. The second dimension mainly described the spectral differences between the dark and pressed modes of singing. A possible explanation of the results in terms of glottal and supraglottal morphological variation is discussed.

Female↗
PubMed1986

Speech-reception threshold in noise with one and two hearing aids.

The binaural free-field speech-reception threshold (SRT) in 70-dBA noise was measured with conversational sentences for 24 hearing-impaired subjects without hearing aids, with a hearing aid left, right, and left plus right, respectively. The sentences were always presented in front of the listener and the interfering noise, with a spectrum equal to the long-term average spectrum of the sentences, was presented either frontally, from the right, or from the left side. For subjects with only moderate hearing loss, PTA (average air-conduction hearing level at 500, 1000, and 2000 Hz) less than 50 dB, the SRT in 70-dBA noise in both ears is determined by the signal-to-noise ratio even if only one hearing aid is used. For larger hearing losses the SRT appears to be partly determined by the absolute threshold. In conditions with a high noise level relative to the absolute threshold, in which case for both ears the SRT is determined by the signal-to-noise ratio, a second hearing aid, just as a monaural hearing aid, generally does not improve the SRT. However, in the case of a high hearing level, or a low noise level, in which a monaural hearing aid is profitable, the use of two hearing aids is even more profitable. In a separate experiment, acoustic head shadow was measured at the entrance of the ear canal and at the microphone location of a hearing aid. It appeared that, for a lateral noise source and speech frontal, the microphone position of behind-the-ear hearing aids has a negative effect on the signal-to-noise ratio of 2-3 dB.

Adult↗
PubMed1986

Speechreading supplemented with auditorily presented speech parameters.

Results are reported from two experiments in which the benefit of supplementing speechreading with auditorily presented information about the speech signal was investigated. In experiment I, speechreading was supplemented with information about the prosody of the speech signal. For ten normal-hearing subjects with no experience in speechreading, the intelligibility score for sentences increased significantly when speechreading was supplemented with information about the overall amplitude of the speech signal, information about the fundamental frequency, or both. Binary information about voicing appeared not to be a significant supplement. In experiment II, the best-scoring supplements of experiment I were compared with two supplementary signals from our previous studies, i.e., information about the sound-pressure levels in two 1-oct filter bands centered at 500 and 3160 Hz, or information about the frequencies of the first and second formants from voiced speech segments. Sentence-intelligibility scores were measured for 24 normal-hearing subjects with no experience in speechreading, and for 12 normal-hearing experienced speechreaders. For the inexperienced speechreaders, the sound-pressure levels appeared to be the best supplement (87.1% correct syllables). For the experienced speechreaders, the formant-frequency information (88.6% correct), and the fundamental-frequency plus amplitude information (86.0% correct), were equally efficient supplements as the sound-pressure information (86.1% correct). Discrimination of phonemes (both consonants and vowels) was measured for the group of 24 inexperienced speechreaders. Percentage correct responses, confusion among phonemes, and the percentage of transmitted information about different types of manner and place of articulation and about the feature voicing are presented.

Adolescent↗
PubMed1985

Speechreading supplemented with formant-frequency information from voiced speech.

The benefit of supplementing speechreading with information about the frequencies of the first and second formants from the voiced sections of the speech signal was studied by presenting short sentences to 18 normal-hearing listeners under the following three conditions: (a) speechreading combined with listening to the formant-frequency information, (b) speechreading only, and (c) formant-frequency information only. The formant frequencies were presented either as pure tones or as a complex speechlike signal, obtained by filtering a periodic pulse sequence of 250 Hz by a cascade of four second-order bandpass filters (with constant bandwidth); the center frequencies of two of these filters followed the frequencies of the first and second formants, whereas the frequencies of the others remained constant. The percentage of correctly identified syllables increased from 22.8 in the case of speechreading only to 82.0 in the case of speechreading while listening to the complex speechlike signal. Listening to the formant information only scored 33.2% correct. However, comparison with the best-scoring condition of our previous study [Breeuwer and Plomp, J. Acoust. Soc. Am. 76, 686-691 (1984)] indicates that information about the sound-pressure levels in two one-octave filter bands with center frequencies of 500 and 3160 Hz is a more effective supplement to speechreading than the formant-frequency information.

Acoustic Stimulation↗
PubMed1985

The effect of competing melodies on melody recognition by hearing-impaired and normal-hearing listeners.

For a group of 30 hearing-impaired subjects and a matched group of 15 normal-hearing subjects (age range 13-17) the following data were collected: the tone audiogram, the auditory bandwidth at 1000 Hz, and the recognition threshold of a short melody presented simultaneously with two other melodies, lower and higher in frequency, respectively. The threshold was defined as the frequency distance required to recognize the test melody. It was found that, whereas the mean recognition threshold for the normal-hearing subjects was five semitones, it was, on the average, 27 semitones for the hearing-impaired subjects. Although the interindividual spread for the latter group was large, it did not correlate with the subjects' auditory bandwidth, nor with their musical experience or education.

Acoustics↗
PubMed1985

Relations between psychophysical data and speech perception for hearing-impaired subjects. II.

Twenty-one sensorineurally hearing-impaired adolescents were studied with an extensive battery of tone-perception, phoneme-perception, and speech-perception tests. Tests on loudness perception, frequency selectivity, and temporal resolution at the test frequencies of 500, 1000, and 2000 Hz were included. The mean values and the gradient across frequencies were used in further analysis. Phoneme-perception data were gathered by means of similarity judgments and phonemic confusions. Speech-reception thresholds were determined in quiet and in noise for unfiltered speech material, and with additional low-pass and high-pass filtering in noise. The results show that hearing loss for speech is related to both the frequency resolving power and temporal processing by the ear. Phoneme-perception parameters proved to be more related to the filtered-speech thresholds than to the thresholds for unfiltered speech. This finding may indicate that phoneme-perception parameters play only a secondary role, and for that reason their bridging function between tone perception and speech perception is only limited.

Acoustic Stimulation↗
PubMed1984

Spectral analysis of sung vowels. I. Variation due to differences between vowels, singers, and modes of singing.

Average 1/3-oct filter spectra of vowels, sung by seven professional male and seven professional female singers , were measured. The material consisted of nine different vowels, sung at six fundamental frequencies (F0, ranging from 98 up to 880 Hz). For each vowel the singers were requested to sing in the following nine modes: neutral, light, dark, pressed, free, loud, soft, straight, and extra vibrato . To study origins of spectral variation, the quantity of spectral variance, based on band filter sound levels, was used. For each fundamental frequency and separately for males and females, portions of total spectral variance associated with the main effects and the interactions of the factors "vowels," " singers ," and "modes of singing," were computed. A considerable decrease in total spectral variance was found when F0 rose from 98 to 880 Hz, mostly due to the reduced spectral variance between vowels. Above about F0 = 660 Hz spectral variation was dominated by differences related to singers and modes of singing. Additional analyses revealed that for all F0 values vowel spectra of the tenor and the soprano singers varied more than those of the bass and the alto singers , there was only a slight dependence of spectral differences between vowels on the mode of singing, and the amount of spectral variation in a vowel, sung by different singers with different modes of singing, was vowel dependent.

Female↗
PubMed1984

Speechreading supplemented with frequency-selective sound-pressure information.

The benefit of supplementing speechreading with frequency-selective sound-pressure information was studied by auditorily presenting this information to normal-hearing listeners. The sound-pressure levels in one or two frequency bands of the speech signal with center frequencies of 500, 1600, and 3160 Hz, respectively, and with 1- or 1/3-oct bandwidth were used to amplitude-modulate pure-tone carriers with frequencies equal to the center frequencies of the filter bands. Short sentences were presented to 18 normal-hearing listeners under the conditions of speechreading-only and speechreading combined with the sound-pressure information. The mean number of correctly perceived syllables increased from 22.8% for speechreading-only to 65.7% when sound-pressure information was supplied in a single 1-oct band at 500 Hz and to 86.7% with two 1-oct bands at 500 and 3160 Hz, respectively. The latter signal scored only 26.7% correct syllables without accompanying visual information.

Adolescent↗
PubMed1983

Relations between auditory functions in impaired hearing.

Relations between auditory functions, as expressed by coefficients of correlation, were studied for a group of 22 sensorineurally hearing-impaired subjects with moderate losses. In addition to the audiogram, we measured frequency resolution, temporal resolution, and speech reception in quiet and in noise. Frequency resolution was derived from masking with comb-filtered noise and from the psychophysical tuning curve, for both paradigms in simultaneous and in nonsimultaneous masking. The critical ratio was also determined. Temporal resolution was determined with intensity-modulated noise and from backward and forward masking. All tests were performed at 1000 Hz. Correlations among tests were gathered in a matrix and subjected to a principal-components analysis. It turned out that tests on frequency resolution form a cluster, and are approximately independent of audiometric loss. Furthermore, hearing loss for speech in noise is closely allied to frequency resolution, whereas hearing loss for speech in quiet is governed by audiometric loss.

Adult↗
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↗
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↗
PubMed1981

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↗
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

Relation between psychophysical data and speech perception for hearing-impaired subjects. I.

In heterogeneous group of ten hearing-impaired adolescents, relations are studied between several psychophysical test results and speech reception thresholds in quiet and noise. To examine the results, data-reduction techniques were used to extract the most relevant parameters. High correlations were found between the intelligibility of speech in noise on the one side, and vowel-perception parameters resulting from INDSCAL analysis (frequency resolution parameters, critical bandwidth and critical ratio) and audiogram parameters on the other.

Adolescent↗
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↗
PubMed1979

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↗