Biomedical subjects

J M Festen

Publications and source records attributed to J M Festen.

At least 19 recordsLinked to original sources

PubMed2000

Method for the selection of sentence materials for efficient measurement of the speech reception threshold.

A method is described to select sentence materials for efficient measurement of the speech reception threshold (SRT). The first part of the paper addresses the creation of the sentence materials, the recording procedure, and a listening experiment to evaluate the new speech materials. The result is a set of 1272 sentences, where every sentence has been uttered by two male and two female speakers. In the second part of the paper, a method is described to select subsets with properties that are desired for an efficient measurement of the SRT. For two speakers, this method has been applied to obtain two subsets for measurement of the SRT in stationary noise with the long-term average spectrum of speech. Lastly, a listening experiment has been conducted where the two subsets (each comprising 39 lists of 13 sentences each) are directly compared to the existing sets of Plomp and Mimpen [Audiology 18, 43-52 (1979)] and Smoorenburg [J. Acoust. Soc. Am. 91, 421-437 (1992)]. One of the outcomes is that the newly developed sets can be considered as equivalent to these existing sets.

Adolescent↗

PubMed2000

Measuring the threshold for speech reception by adaptive variation of the signal bandwidth. II. Hearing-impaired listeners.

In a previous study [Noordhoek et al., J. Acoust. Soc. Am. 105, 2895-2902 (1999)], an adaptive test was developed to determine the speech-reception bandwidth threshold (SRBT), i.e., the width of a speech band around 1 kHz required for a 50% intelligibility score. In this test, the band-filtered speech is presented in complementary bandstop-filtered noise. In the present study, the performance of 34 hearing-impaired listeners was measured on this SRBT test and on more common SRT (speech-reception threshold) tests, namely the SRT in quiet, the standard SRT in noise (standard speech spectrum), and the spectrally adapted SRT in noise (fitted to the individual's dynamic range). The aim was to investigate to what extent the performance on these tests could be explained simply from audibility, as estimated with the SII (speech intelligibility index) model, or require the assumption of suprathreshold deficits. For most listeners, an elevated SRT in quiet or an elevated standard SRT in noise could be explained on the basis of audibility. For the spectrally adapted SRT in noise, and especially for the SRBT, the data of most listeners could not be explained from audibility, suggesting that the effects of suprathreshold deficits may be present. Possibly, such a deficit is an increased downward spread of masking.

Adult↗

PubMed1999

Intensity discrimination of Gaussian-windowed tones: indications for the shape of the auditory frequency-time window.

The just-noticeable difference in intensity jnd(I) was measured for 1-kHz tones with a Gaussian-shaped envelope as a function of their spectro-temporal shape. The stimuli, with constant energy and a constant product of bandwidth and duration, ranged from a long-duration narrow-band "tone" to a short-duration broadband "click." The jnd(I) was measured in three normal-hearing listeners at sensation levels of 0, 10, 20, and 30 dB in 35 dB(A) SPL pink noise. At intermediate sensation levels, jnd(I) depends on the spectro-temporal shape: at the extreme shapes (tones and clicks), intensity discrimination performance is best, whereas at intermediate shapes the jnd(I) is larger. Similar results are observed at a higher overall sound level, and at a higher carrier frequency. The maximum jnd(I) is observed for stimuli with an effective bandwidth of about 1/3 octave and an effective duration of 4 ms at 1 kHz (1 ms at 4 kHz). A generalized multiple-window model is proposed that assumes that the spectro-temporal domain is partitioned into "internal" auditory frequency-time windows. The model predicts that intensity discrimination thresholds depend upon the number of windows excited by a signal: jnd(I) is largest for stimuli covering one window.

Adult↗

PubMed1999

Measuring the threshold for speech reception by adaptive variation of the signal bandwidth. I. Normal-hearing listeners.

An adaptive test has been developed to determine the minimum bandwidth of speech that a listener needs to reach 50% intelligibility. Measuring this speech-reception bandwidth threshold (SRBT), in addition to the more common speech-reception threshold (SRT) in noise, may be useful in investigating the factors underlying impaired suprathreshold speech perception. Speech was bandpass filtered (center frequency: 1 kHz) and complementary bandstop filtered noise was added. To obtain reference values, the SRBT was measured in 12 normal-hearing listeners at four sound-pressure levels, in combination with three overall spectral tilts. Plotting SRBT as a function of sound-pressure level resulted in U-shaped curves. The most narrow SRBT (1.4 octave) was obtained at an A-weighted sound-pressure level of 55 dB. The required bandwidth increases with increasing level, probably due to upward spread of masking. At a lower level (40 dBA) listeners also need a broader band, because parts of the speech signal will be below threshold. The SII (Speech Intelligibility Index) model reasonably predicts the data, although it seems to underestimate upward spread of masking.

Adult↗

PubMed1999

Compression and expansion of the temporal envelope: evaluation of speech intelligibility and sound quality.

Sensorineural hearing loss is accompanied by loudness recruitment, a steeper-than-normal rise of perceived loudness with presentation level. To compensate for this abnormality, amplitude compression is often applied (e.g., in a hearing aid). Alternatively, since speech intelligibility has been modeled as the perception of fast energy fluctuations, enlarging these (by means of expansion) may improve speech intelligibility. Still, even if these signal-processing techniques prove useful in terms of speech intelligibility, practical application might be hindered by unacceptably low sound quality. Therefore, both speech intelligibility and sound quality were evaluated for syllabic compression and expansion of the temporal envelope. Speech intelligibility was evaluated with an adaptive procedure, based on short everyday sentences either in noise or with a competing speaker. Sound quality was measured by means of a rating-scale procedure, for both speech and music. In a systematic setup, both the ratio of compression or expansion and the number of independent processing bands were varied. Individual hearing thresholds were compensated for by a listener-specific filter and amplification. Both listeners with normal hearing and listeners with sensorineural hearing impairment participated as paid volunteers. The results show that, on average, both compression and expansion fail to show better speech intelligibility or sound quality than linear amplification.

Adult↗

PubMed1999

Preference judgments of artificial processed and hearing-aid transduced speech.

In order to assess the relative importance of various signal processing algorithms and distortions on hearing-aid preference, male and female speech was manipulated in a number of ways and subsequently presented to normal-hearing and hearing-impaired subjects (the latter having a mild sensorineural high-frequency hearing loss). Signal manipulations were artificial (e.g., filtering, compression, peak clipping, or adding noise) or were actual dummy-head recordings of five different hearing aids. Listeners judged the sounds in a pairwise-comparison format. Their task was to indicate the "hearing aid" they would prefer assuming they had to wear it all day. The data were analyzed with multidimensional scaling techniques; Principal Components Analysis revealed that the first two dimensions on which preference judgments were based, can be interpreted as (1) intelligibility or clarity, and (2) distinction between signal distortion and added background distortion. Furthermore, the results showed that normal-hearing subjects generally preferred the original signal, whereas hearing-impaired subjects were inclined to choose the signals with a high-frequency emphasis. Severe band-pass filtering or low-frequency emphasis were disliked, as was to be expected. Surprisingly, however, a soft background noise (S/N ratio of 25 dB) was often among the least preferred of all signals. The differences in preference between the five hearing aids were small, but consistent. For hearing-impaired subjects, hearing-aid ordering could be accounted for by the amount of low-frequency cutoff; for normal-hearing subjects both high- and low-frequency cutoff played a role. Results of a retest experiment with normal-hearing subjects, about one year later, showed that subjects' criteria remain remarkably stable.

Adolescent↗

PubMed1997

Quantitative analysis of voice quality in early glottic laryngeal carcinomas treated with radiotherapy.

The quality of voice after radiotherapy is generally considered to be better than that after surgery for early glottic (T1a and T1b) carcinomas. Studies concerning voice quality after radiotherapy are scarce, and results have been contradictory concerning actual normalization of voice following therapy. This study was designed to compare several voice parameters of patients successfully treated 1-12 years previously with radiotherapy (5750-7000 cGy) for early glottic carcinoma. Parameters involved an age- and sex-matched control group. Results showed that voice quality following radiotherapy was less than normal for maximum vocal intensity, dynamic vocal intensity range, jitter, and mean fundamental frequency. These findings showed that voice following radiotherapy could not be considered normal.

Aged↗

PubMed1996

Peaks in the frequency response of hearing aids: evaluation of the effects on speech intelligibility and sound quality.

In a series of experiments, we introduced peaks of 10, 20, and 30 dB, in various combinations, onto a smooth reference frequency response. For each of the conditions, we evaluated speech intelligibility in noise, using a test as developed by Plomp and Mimpen (1979), and sound quality (for both speech and music), using a rating-scale procedure. We performed the experiments with 26 listeners with sensorineurally impaired hearing and 10 listeners with normal hearing. Signal processing was accomplished digitally; for each listener, the stimuli were filtered and subsequently amplified so that the average speech spectrum was well above the threshold of hearing at all frequencies. The results show that, as a result of the introduction of peaks onto the frequency response, speech intelligibility is affected more for the listeners with impaired hearing than for those with normal hearing. Sound-quality judgments tend to be less different between the listener groups. Conditions with 30-dB peaks especially show serious effects on both speech intelligibility and sound quality.

Hearing Aids↗

PubMed1996

Effect of temporal modulation reduction on spectral contrasts in speech.

In this paper the effect of temporal modulation reduction on spectral contrasts is investigated. First, a spectral modulation transfer function (SMTF) is presented as a method to measure the transfer of spectral ripples (sinusoidal periods/oct) in the short-time spectral envelope by comparing the spectral modulation depth of original and processed speech fragments. Measuring the SMTF for speech subjected to uniform reduction of the temporal modulation depth (i.e., modulation-frequency-independent reduction) in 24 1/4-oct bands showed an almost equal uniform reduction of the spectral modulations. Furthermore, the SMTF was used to measure the reduction of spectral contrasts associated with low-pass and high-pass temporal-envelope filtering [Drullman et al., J. Acoust. Soc. Am.95, 1053-1064 and 2670-2680 (1994a, b)]. For a perceptual evaluation, sentences were processed to reduce spectral contrasts and the speech-reception threshold (SRT) in noise was measured with ten normal-hearing subjects. Comparison of the results with those obtained previously after temporal-envelope filtering revealed that the SRT-effect of temporal high-pass filtering can be completely accounted for by the associated reduction of spectral contrasts. However, this relationship cannot be demonstrated conclusively in the case of temporal low-pass filtering.

Adolescent↗

PubMed1996

[Hearing impairment in quietude and noise; 2 different forms of expression of presbyacusis].

Many elderly persons have problems in understanding speech in the presence of voice babble, music, etc. Fitting a hearing aid often does not improve their speech intelligibility. For a better insight, we should distinguish between two different modes of presbyacusis. The first mode expresses itself in attenuation of all incoming sounds, which can be compensated successfully by the hearing-aid's electronic amplification. The second mode has to do with a reduced capacity of the ear to separate simultaneous sounds. As the hearing aid amplifies both the wanted and the unwanted sounds, its effect is in this case nihil. Extensive investigations have indicated the extent to which each of the two modes is actually present in the elderly. The data have confirmed that the amplification of the hearing aid cannot solve the hearing problems of the majority of the elderly. They need primarily a hearing aid that would help to separate simultaneous sounds. At the moment, the most promising solution of this difficult technical challenge is improving the directional sensitivity.

Aged↗

PubMed1995

Evaluation of a wide range of amplitude-frequency responses for the hearing impaired.

The long-term average frequency spectrum of speech was modified to 25 target frequency spectra in order to determine the effect of each of these spectra on speech intelligibility in noise and on sound quality. Speech intelligibility was evaluated using the test as developed by Plomp and Mimpen (1979), whereas sound quality was examined through judgments of loudness, sharpness, clearness, and pleasantness of speech fragments. Subjects had different degrees of sensorineural hearing loss and sloping audiograms, but not all of them were hearing aid users. The 25 frequency spectra were defined such that the entire dynamic range of each listener, from 5 dB above threshold to 5 dB below UCL, was covered. Frequency shaping of the speech was carried out on-line by means of Finite Impulse Response (FIR) filters. The tests on speech reception in noise indicated that the Speech-Reception Thresholds (SRTs) did not differ significantly for the majority of spectra. Spectra with high levels, especially at low frequencies (probably causing significant upward spread of masking), and also those with steep negative slopes resulted in significantly higher SRTs. Sound quality judgments led to conclusions virtually identical to those from the SRT data: frequency spectra with an unacceptably low sound quality were in most of the cases significantly worse on the SRT test as well. Because the SRT did not vary significantly among the majority of frequency spectra, it was concluded that a wide range of spectra between the threshold and UCL levels of listeners with hearing losses is suitable for the presentation of speech energy. This is very useful in everyday listening, where the frequency spectrum of speech may vary considerably.

Adult↗

PubMed1995

Acute myocardial infarction while using the nicotine patch.

A 39-year-old man developed an acute myocardial infarction 20 days after starting treatment with nicotine patches. He had not smoked while using the patches. He recovered without complications. Coronary angiography did not reveal coronary stenoses. He had no history of myocardial infarction, hypertension, or diabetes mellitus. Although coincidence cannot be excluded, it is recommended that all patients should be strongly advised not to smoke while using the nicotine patch and to consult a physician if chest pain develops.

Administration, Cutaneous↗

PubMed1994

Effect of temporal envelope smearing on speech reception.

The effect of smearing the temporal envelope on the speech-reception threshold (SRT) for sentences in noise and on phoneme identification was investigated for normal-hearing listeners. For this purpose, the speech signal was split up into a series of frequency bands (width of 1/4, 1/2, or 1 oct) and the amplitude envelope for each band was low-pass filtered at cutoff frequencies of 0, 1/2, 1, 2, 4, 8, 16, 32, or 64 Hz. Results for 36 subjects show (1) a severe reduction in sentence intelligibility for narrow processing bands at low cutoff frequencies (0-2 Hz); and (2) a marginal contribution of modulation frequencies above 16 Hz to the intelligibility of sentences (provided that lower modulation frequencies are completely present). For cutoff frequencies above 4 Hz, the SRT appears to be independent of the frequency bandwidth upon which envelope filtering takes place. Vowel and consonant identification with nonsense syllables were studied for cutoff frequencies of 0, 2, 4, 8, or 16 Hz in 1/4-oct bands. Results for 24 subjects indicate that consonants are more affected than vowels. Errors in vowel identification mainly consist of reduced recognition of diphthongs and of confusions between long and short vowels. In case of consonant recognition, stops appear to suffer most, with confusion patterns depending on the position in the syllable (initial, medial, or final).

Acoustic Stimulation↗

PubMed1994

Effect of reducing slow temporal modulations on speech reception.

The effect of reducing low-frequency modulations in the temporal envelope on the speech-reception threshold (SRT) for sentences in noise and on phoneme identification was investigated. For this purpose, speech was split up into a series of frequency bands (1/4, 1/2, or 1 oct wide) and the amplitude envelope for each band was high-pass filtered at cutoff frequencies of 1, 2, 4, 8, 16, 32, 64, or 128 Hz, or infinity (completely flattened). Results for 42 normal-hearing listeners show: (1) A clear reduction in sentence intelligibility with narrow-band processing for cutoff frequencies above 64 Hz; and (2) no reduction of sentence intelligibility when only amplitude variations below 4 Hz are reduced. Based on the modulation transfer function of some conditions, it is concluded that fast multichannel dynamic compression leads to an insignificant change in masked SRT. Combining these results with previous data on low-pass envelope filtering (temporal smearing) [Drullman et al., J. Acoust. Soc. Am. 95, 1053-1064 (1994)] shows that at 8-10 Hz the temporal modulation spectrum is divided into two equally important parts. Vowel and consonant identification with nonsense syllables were studied for cutoff frequencies of 2, 8, 32, 128 Hz, and infinity, processed in 1/4-oct bands. Results for 12 subjects indicate that, just as for low-pass envelope filtering, consonants are more affected than vowels. Errors in vowel identification mainly consist of reduced recognition of diphthongs and of durational confusions. For the consonants there are no clear confusion patterns, but stops appear to suffer least. In most cases, the responses tend to fall into the correct category (stop, fricative, or vowel-like).

Acoustic Stimulation↗

PubMed1993

Effect of spectral envelope smearing on speech reception. II.

This paper describes two experiments on the effect of reduced spectral contrast on the speech-reception threshold (SRT) for sentences in a background of interfering sound. Signal processing is performed by smoothing the envelope of the squared short-time fast Fourier transform by a convolution with a Gaussian-shaped filter, and overlapping additions to reconstruct a continuous signal. In the first experiment the effect of reduced spectral contrast on the SRT for male speech is investigated and compared with previously obtained results for female speech [ter Keurs et al., J. Acoust. Soc. Am. 91, 2872-2880 (1992)]. Spectral energy is smeared over bandwidths of 1/8, 1/4, 1/3, 1/2, 1, 2, and 4 oct. The results show that, despite the differences in spectral pattern between male and female voices, the SRT in noise increases similarly for both voices for smearing bandwidths over 1/3 oct. In terms of the ripple density of the spectral envelope the results indicate that the range of lower spectral modulations, up to a limit of about 1.5 periods/oct, is sufficient for the intelligibility of speech in interfering sounds. In the second experiment the extent of the threshold difference between a speech masker and a noise masker is investigated for spectral smearing bandwidths of 1/2, 1, and 2 oct. The release from masking found for the speech masker relative to the (steady-state) noise masker decreases with spectral envelope smearing.

Acoustic Stimulation↗

PubMed1993

Contributions of comodulation masking release and temporal resolution to the speech-reception threshold masked by an interfering voice.

Two experiments are presented to explain the difference in speech-reception threshold (SRT) between conditions with a steady-state noise masker or an interfering voice. Literature shows for normal hearing a masking release of 6-8 dB with an interfering voice and a substantial reduction of this release with hearing impairment. In experiment I the possible role of comodulation masking release (CMR) is investigated by manipulating the comodulation in the interfering voice by the introduction of temporal shift among filter bands of various width. The spectral spread of masking from the manipulated interfering voice was controlled by interleaving the mutually shifted speech bands with 1/3-octave bands of noise. Although comodulation in the interfering speech appears to be very important for the low SRT, the contribution of across-frequency processing of masker fluctuations--commonly considered as the origin of CMR--is only 1.3 dB. In experiment II the level dependence of masking release with an interfering voice is investigated. The data fit in with the hypothesis by Festen and Plomp [J. Acoust. Soc. Am. 88, 1725-1736 (1990)] that the release from masking with an interfering voice is limited by forward masking. It appears that up to about 55 dBA the release from masking increases with level up to about 7 dB. Above 55 dBA the difference in SRT obtained with a noise masker or an interfering voice is constant due to the limited average modulation depth of speech.

Acoustic Stimulation↗

PubMed1993

Limited resolution of spectral contrast and hearing loss for speech in noise.

This paper examines the relations among the spectral contrast needed for speech intelligibility, hearing loss for speech in noise, and auditory filter bandwidth. Fifteen hearing-impaired listeners with relatively flat, mild-to-moderate sensorineural losses and eight normal-hearing listeners participated in the study. The spectral contrast needed for speech intelligibility was determined by reducing spectral contrast in the speech signal and measuring the reduction in contrast beyond which the speech-reception threshold (SRT) for sentences in noise increases. Reduction of spectral contrast was accomplished by smearing the envelope of the squared short-time fast Fourier transform by a convolution with a Gaussian-shaped filter, and overlapping additions to reconstruct a continuous signal. Auditory filter bandwidth was determined by estimating auditory filter shapes at center frequencies of 0.8, 1.6, and 3.2 kHz, using a notched-noise masking paradigm. The results show that limited resolution of spectral contrast is only loosely associated with hearing loss for speech in noise. Moreover, the correlations between the SRT for unsmeared speech and the auditory filter bandwidth at various frequencies were weak.

Acoustic Stimulation↗

PubMed1993

The efficacy of a multichannel hearing aid in which the gain is controlled by the minima in the temporal signal envelope.

A multichannel signal-processing hearing aid in which the gain is controlled by the level of the minima in the sound envelope [outlined by Festen et al., 1990] was evaluated with hearing-impaired listeners. This evaluation is an extension to the work reported by van Dijkhuizen et al. (1990). A first experiment focused on the speech-reception threshold (SRT), i.e. the S/N ratio for 50% intelligibility. The greatest benefit in terms of the SRT from frequency-dependent control of the amplification is expected in conditions where the spectrum of noise exceeds strongly that of the speech in a limited frequency region. In these conditions frequency-dependent amplification may reduce upward spread of masking. We investigated the upper limit of this benefit in conditions of intense frequency-limited interfering noise. Speech and noise were both spectrally shaped according to the line bisecting the listener's dynamic range; however, the level of the noise in one octave band (0.25-0.5 or 0.5-1 kHz) was increased by 20 dB. The results show that frequency-selective attenuation of the signal in the octave band with the 20-dB increase of noise is more beneficial than wide-band gain control, and gives a decrease in SRT of up to 4 dB relative to a condition without gain control. In a subsequent experiment we investigated, for several very common interfering sounds, the effect of controlling the gain by the minima in the signal envelope on both the SRT and the perceived noisiness. Results show that the condition with gain control does not affect the SRT for sentences in the presence of everyday interfering sounds having spectra that are roughly comparable to that of the speech signal; however, it substantially reduces the perceived noisiness. In line with our expectations, the effect of the gain control on the signal was very small for a single voice, and it was greatest in case of sounds with a more or less continuous character (e.g. stationary noise, music). For these last sounds it was found that the growth in perceived noisiness with the increase of input level is equivalent to the growth produced by only about one-fifth of the increase in input level (in decibels) in a condition without gain control.

Acoustic Stimulation↗