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At least 1,531 records · Page 85Linked to original sources
PubMed1989

Influence of stimulus intensity on AEP components in the 80- to 200-millisecond latency range.

The influence of the intensity of passively perceived 1-kHz tones on the latencies and amplitudes of AEP components in the 80- to 200-ms latency range recorded from frontal, central and temporal electrode locations was investigated in healthy adult subjects. At stimulus intensities from 30 to 70 dB SL the latencies of the frontally and centrally recorded N100 and P175 waves decreased, their amplitudes increased. At stimulus intensities from 70 to 90 dB the latencies of N100 and P175 increased, N100 amplitude declined and P175 amplitude increased at a slower rate than between 30 and 70 dB. The latency of the N140 wave recorded at temporal electrode locations decreased markedly with increasing stimulus intensity.

Adult↗
PubMed1990

Brainstem auditory-evoked response in the rat. Normative studies, with observations concerning the effects of ossicular disruption.

Six young adult Sprague-Dawley rats were unilaterally cochleotomized, Brain-stem auditory-evoked responses (BAERs) to clicks and to 1-, 2-, 4-, 8- and 16-kHz tone bursts were obtained. In addition, response thresholds were estimated before and after ossicular disruption in the noncochleotomized ear of 4 animals. With increasing tone burst frequency, there was a decrease in BAER peak latencies as well as a decrease in threshold. With increasing click and tone burst intensity, there was a decrease in peak latencies and an increase in peak amplitudes. BAER peak latency/intensity functions to click stimuli ranged from -.013 to -.018 ms/dB. With increasing tone burst frequency there was a decrease in the slope of the latency/intensity function. Following ossicular disruption, BAER thresholds to clicks were elevated by an average of 49 dB. Threshold shifts to tone burst stimuli were smallest for 1- and 2-kHz tone bursts (35-36 dB) and increased with increasing frequency up to a maximum of 65 dB for 16-kHz tone bursts.

Animals↗
PubMed1991

Objective measures of sentence level with respect to loudness.

The best method for objectively measuring the level of running speech has not yet been established. In the present study, subjective and objective measures of the level of sentence pairs were compared. Psychoacoustic judgments of the loudness of ten sentence pairs were made by ten listeners. The level of the sentences was measured using four objective methods. The purpose was to determine which of the objective measures best matched the psychoacoustic data. The objective methods included: Sound level meter (SLM), percentile level, average power level (Leq) and the loudness calculation procedure according to ISO 532 B. There were no significant differences between the estimates using the SLM set on either 'Impulse', 'Fast' or 'Slow' settings, the Leq, the percentile level Lmax and the percentile loudness Nmax to N30 using conventional calculation techniques. The measures obtained using A-weighting on the SLM were not found to be superior to the unweighted measures. These findings have implications for the measurement of the level of sentences used in clinical audiology.

Adult↗
PubMed1991

Compound action potentials recorded from the intracranial portion of the auditory nerve in man: effects of stimulus intensity and polarity.

Compound action potentials (CAP) were recorded from the intracranial portion of the eighth nerve in patients with normal hearing who were undergoing neurosurgical operations for cranial nerve disorders (trigeminal neuralgia and hemifacial spasm). Brain-stem auditory-evoked potentials were recorded intraoperatively to ensure that no noticeable changes occurred in conduction in the auditory nerve as a result of surgical dissections. The CAP recorded from the middle portion of the exposed intracranial portion of the eighth nerve in response to clicks of high intensity (100-110 dB peak equivalent SPL, or pe SPL) had a triphasic shape, as is commonly seen in monopolar recordings from long nerves. A second negative peak (N2) could be identified in some patients. There was little difference in the waveform of the CAP in response to condensation and rarefaction clicks, and in some patients the waveform of the CAP remained the same over a range of stimulus intensities (from 105 to 75 dB pe SPL), whereas in others the negative peak of the CAP became much broader in response to stimuli with intensities of less than 85 dB. In some patients the N2 peak became dominant as the stimulus intensity was decreased. At low stimulus intensities, the response consisted of a single, broad negativity. The latency-intensity curves for the N1 peak had different slopes in different patients. In those individuals in whom there was a noticeable difference between the latency of the N1 peak in response to clicks of opposite polarity, the latency-intensity curves of the responses to rarefaction clicks were steeper than those of the responses to condensation clicks, and the latency of the N1 peak to condensation clicks became shorter than that to rarefaction clicks at intensities below 85-90 dB pe SPL. The latency-intensity curves for the N2 peak were usually less steep than those of the N1 peak, but in some patients the curves for these two peaks had similar slopes. The amplitude of the N1 peaks showed a steep increase in click intensities at 95 and 105 dB, and a much less steep course for intensities below 95 dB. The amplitudes of the N2 peak reached a plateau in the range 95-105 dB, and decreased more rapidly than the N1 peak below 95 dB.

Acoustic Stimulation↗
PubMed1991

Application of phase-induced lateralization to the Stenger test.

The Stenger test was employed to estimate the genuine hearing thresholds in normally hearing volunteer subjects simulating a total unilateral loss. The test was carried out in its standard form and in a modified form in which a phase shift was introduced between the signal delivered to the two ears, set to produce phase-induced lateralization towards the 'poor' ear. The standard test estimated the thresholds at a mean of 13.5 dB above the true thresholds at five frequencies from 250 Hz to 4 kHz. Thresholds at the different frequencies were compared, and although thresholds were lower for the higher frequencies, the apparent effect of frequency was not statistically significant. The modified test, using a 90 degrees phase shift, was found to enhance the test at 250 and 500 Hz (thresholds estimated at about 7 dB above true values), but not significantly at 1 kHz.

Adult↗
PubMed1993

Loudness adaptation in children.

Simple loudness adaptation was measured for a steady tone presented alone at 10 dB SL; contralaterally induced adaptation was measured for a steady tone in one ear accompanied by an intermittent tone in the contralateral ear; ipsilaterally induced adaptation was measured for a tone increased intermittently by 15 dB. The method of successive magnitude estimation revealed no differences between 12 adults and 36 children from 9 to 14 years of age in the amounts of adaptation over a 3-min exposure. A second set of experiments with a new group of 20 adults and 20 children used a Békésy tracking procedure to reach similar results. Unlike Kärjä [Acta Oto-Laryngol 1968; (suppl)241:1-56], who found significant adaptation in only 5 of 29 children and much adaptation in most adults, we found considerable adaptation in children as well as in adults.

Acoustic Stimulation↗
PubMedDate not supplied

Azimuth estimates by human subjects under free-field and headphone conditions.

Estimates of sound source directions in the horizontal plane (azimuth) were made by human subjects under acoustic free-field (loudspeaker) and dichotic stimulus conditions (headphones). The functional relationship between the binaural cues, interaural time and intensity differences (ITDs and IIDs) and azimuth angle approximately follow a quarter of a full sine wave between 0 degrees straight ahead and the maximum at 90 degrees for ITDs and, depending on frequency for IIDs, at 60-90 degrees lateral (frontal quadrant). Under free-field conditions, these physically determined, interaural difference cues are correctly translated into azimuth angles by all listeners: estimated angles correspond to presented sound directions. In contrast, when providing dichotic stimuli containing ITDs/IIDs, so that sounds come from virtual azimuth angles, only 8% of the listeners estimated according to the expected transfer function of a quarter of a sine wave. However, about 60% of the listeners ranged azimuth directly proportionally to the binaural differences introduced, systematically overestimating virtual angles by up to 20 degrees. The remaining 32% of the listeners systematically overestimated virtual small and midrange sound directions even more. Virtual 40 degrees (corresponding to 12- to 14-dB and/or 450- to 550-microseconds differences) was often estimated as almost 90 degrees. Without corrective feedback, a reduction of the systematic errors was never observed. Central neural mechanisms and conceptual strategies to accomplish the expected transfer from virtual back to free-field directions are proposed to explain the large systematic overestimates: in contrast to our lifelong 'free-acoustic field' experience, we are unable, under dichotic conditions (hence in the absence of complete pinna cues and possibly room acoustics), to use the either innate or, more likely, acquired quarter of a sine interaural difference function necessary to accomplish the correct transfer.

Adult↗
PubMedDate not supplied

Confirmation of transiently evoked otoacoustic emissions based on user-independent criteria.

Transiently evoked otoacoustic emissions (TEOAEs) were recorded from 525 ears (children, 3-11 years). Based on visual evaluation, the recordings were classified as TEOAEs present, absent or uncertain. Within each group the distribution of response level and reproducibility as well as of four derived parameters were calculated. The latter comprised: (1) corrected response level (difference between response level and approximated noise), (2) weighted response level (product of response level and correlation), (3) weighted sound pressure of the response (product of sound pressure and correlation) and (4) level of the weighted sound pressure of the response (weighted sound pressure of the response transformed to decibels). Based on these distributions, criteria to separate recordings with TEOAEs from recordings without TEOAEs were established. In this study the cutoff point is the parameter value where the amount of incorrectly identified recordings with TEOAEs is equal to the amount of correctly identified recordings without TEOAEs. The corresponding limiting values are: (a) response level 7.3 dB with 7.6% incorrect identifications for each group, (b) reproducibility 56% with 4.2% incorrect identifications, (c) corrected response level 2.4 dB with 5% incorrect identifications, (d) weighted response level 3.7 dB with 3.2% of incorrect identifications, (e) sound pressure of the response 0.027 mPa with 2% incorrect identifications and (f) level of the weighted sound pressure of the response 1.22 dB with 2% incorrect identifications.

Child↗
PubMedDate not supplied

Electrocochleographic analysis of the suppression of tinnitus by electrical promontory stimulation.

To investigate the origin, and evaluate the mechanism by which tinnitus is suppressed we performed electrical promontory stimulation (EPS) in 56 patients with tinnitus, and measured the compound action potential (CAP) using electrocochleography before and after EPS. In the group of patients in whom tinnitus was suppressed, the CAP amplitudes increased significantly, whereas the latencies showed no remarkable change. In the group of patients in whom tinnitus was not suppressed, both the CAP amplitudes and latencies exhibited no significant change. These data indicate that the effect on the cochlear nerve plays an important role in the suppression of tinnitus by EPS. The CAP reflects the number of the auditory nerve fibers which discharge synchronously. It is speculated that an increase of the CAP amplitudes is caused by synchronizing discharges of the auditory nerve fibers, and that the mechanism by which EPS suppresses tinnitus may be related to synchronizing these discharges.

Adult↗
PubMedDate not supplied

Assessing aspects of auditory handicap by means of pupil dilatation.

The demand on extra effort and concentration during listening are notorious handicapping effects of hearing impairment as is shown by self-assessment studies. In an attempt to explore new ways of assessing hearing handicap, the present study focuses on an objective measure of mental effort during listening. Pupil dilatation is used as the index of mental effort. Results for 14 hearing-impaired and 14 normal hearing listeners show a relation between pupil dilatation and difficulty in speech reception in noise, as manipulated by the speech-to-noise ratio. In addition the study shows that, with regard to effort and concentration, hearing-impaired subjects benefit less than normals from easier listening situations (e.g. at 5 dB above the individual speech-reception threshold). The results show a significant correlation between self-rated handicap and pupil dilatation.

Adult↗
PubMedDate not supplied

The 40 Hz modulation-following response: prediction of low-frequency uncomfortable loudness levels in normally hearing adults.

Preliminary investigations have been made in normally hearing alert adults to establish whether the 40 Hz modulation-following response (MFR) can be used to predict 400 Hz uncomfortable loudness levels (ULLs). The MFR stimulus was a 400 Hz carrier, amplitude- and frequency-modulated by a 40 Hz sine function. Subjective ULLs were obtained using standard procedures. Objective ULLs were obtained from MFR parameter intensity functions using rms amplitude, phase angle and magnitude-squared coherence (40 Hz components). The best predictions of the subjective ULL were made using objective ULLs calculated from the gradients of linear best-fit lines for individual phase-intensity functions (80 per cent predicted within 10 dB of the subjective ULL; maximum deviation=16 dB). Poorest predictions were based on inter-subject average rms amplitude-intensity functions, where as few as 14 per cent were within 10 dB of the subjective value. The best predictions were considered sufficiently accurate to warrant further investigation using a variety of modulation and carrier frequencies in different age groups and with varying degrees of hearing loss.

Adult↗
PubMedDate not supplied

The relationship between the uncomfortable loudness level and the acoustic reflex threshold for pure tones in normally-hearing and impaired listeners--a meta-analysis.

The objective of this study was to determine the potential of the acoustic reflex threshold (ART) as a predictor of the uncomfortable level (ULL) and to identify related areas for investigations in the future. Eleven studies reporting data from 141 normally-hearing and 240 impaired hearing subjects have been reviewed, focusing on methods, test conditions and subjects. Results and conclusions are discussed and new calculations have been performed on the reported data. The median difference between ART and ULL across studies and frequencies was 5 dB both in normally-hearing and impaired subjects. Some authors argue, that although a close relationship of mean values of the two measurements may exist, prediction of the ULL based on ART measurement will be inaccurate because of high inter-subject variability. A statistically significant correlation exists between the mean HTL, the mean ART and the mean ULL in impaired hearing, while a relationship between the mean ART and the mean ULL does not exist in normal hearing. Based on pooled data across frequencies from the reviewed studies the mean ULL= (0.64 x mean ART+38) dB HL. The discrepancies between the results found in the reviewed studies may be explained by different instructions and stimulus presentation orders when assessing the ULL, difficulty in assessing the sound pressure level in the ear canal, influence of varying background noise levels and different admission criteria. It is recommended that the relationship between different loudness levels and the ART be investigated in normally-hearing subjects and in subjects with different levels of impairment, using standardized instructions. To further provide uniformity of the test material groups should be selected according to history of middle ear diseases and the use of hearing aids.

Adolescent↗
PubMedDate not supplied

First audiometric results with the Vibrant soundbridge, a semi-implantable hearing device for sensorineural hearing loss.

The Vibrant soundbridge is a semi-implantable hearing device. The implanted electromagnetic transducer is attached to the incus and it is linked by telemetry to the externally worn audio processor. In Nijmegen, this device has been applied to seven patients with moderate or severe sensorineural hearing loss (PTA between 43 and 71 dB HL) who could not tolerate ear moulds. As the amplification of the device depends on the input level (amplifier with wide dynamic range compression), loudness scaling measurements were performed. The gain as a function of input level was determined from aided and unaided loudness growth curves. The mean gain was 21 dB at an input level of 40 dB SPL. The mean gain decreased to 5 dB at an input level of 90 dB SPL. Measured gain values were lower than target values prescribed by the FIG6 method, mainly however for the low-frequency range and for low-level sounds. It was concluded that this device is very promising for patients who cannot tolerate an ear mould.

Adult↗
PubMed1989

Loudness scales from loudness processes: a multivariate approach.

Five subjects were required to judge the loudness of pure tones that varied in intensity and duration (Experiment 1), in intensity and frequency (Experiment 2), or in duration and frequency (Experiment 3). Results of all three experiments were consistent with the respective models of sensory integration expected to underlie the various judgmental tasks (multiplicative for the first experiment, unidimensional for the latter two). Despite the use of common stimulus values across experiments and instructions to judge solely loudness, different loudness scales emerged. This outcome supports a task dependent, multirepresentative scheme for loudness.

Adult↗
PubMed1978

Clinical critical band estimation.

A modified version of the method of loudness summation, developed for clinical critical band estimation, is presented. The stimuli are noise bands centred around 1 kHz. The standard procedure includes 1) determination of the "sensitivity curve": the loudness difference between broad band noise and narrow band noise as a function of the level. For clinical use this function is necessary for evaluation of the level with the most rapid growth of loudness with bandwidth, i.e. the optimum level for sharp determination of the critical bandwidth. 2) Determination of the critical band function, i.e. the difference in sound pressure level required for equal loudness of the test noise band and the reference as a function of the bandwidth. This determination is performed at a level with maximum growth of loudness, evaluated by the sensitivity curve. 3) Critical band estimation by a mathematical model, described in another work (Bonding et al., 1978) from the data obtained. The method is analysed regarding feasibility and reproducibility.

Adult↗
PubMed1978

Comparison of unaided MCLs and use-gain of hearing aids.

Unaided MCLs for narrow bands of noise centered at 1 000, 2 000, 3 000 and 4 000 Hz were compared with the use-gain of hearing aids worn by 10 subjects with sensorineural hearing loss. In addition, for eight subjects, MCLs measured at the time of the hearing aid evaluation were compared with MCLs observed at the time of hearing aid follow-up. Results of the study suggest that (1) hearing aid use-gain can be accurately predicted on the basis of the MCLs for the narrow bands of noise, and (2) the hearing-impaired subjects were highly consistent in their MCL judgments for narrow-band noise.

Consumer Behavior↗
PubMed1980

Preferred listening levels for bands of speech in relation to hearing aid selection.

The Most Comfortable Loudness Level (MCL) was measured for 24 normal-hearing subjects, using narrow bands of speech having centre frequencies of 0.25, 0.5, 1.2 and 4kHz. MCL's were equivalent for octave band and one-third octave band stimuli. The sensation levels (SL) for various frequencies closely matched the SL of the 60 phon equal loudness contour for pure tones. It was concluded, for levels around MCL, sounds which are equally comfortable are equally loud and that equal loudness contours for pure tones are also applicable to narrow bands of speech. Some implications for hearing aid selection are discussed. However, this investigation was primarily a preliminary to other studies more directly related to hearing aid selection issues.

Adolescent↗
PubMed1981

Response factors in the choice of reference ear in ABLB.

Response patterns and the limits of loudness judgement accuracy were explored in a clinical presentation of the alternate binaural loudness balance (ABLB) procedure, and compared across the two methodological alternatives of using the better or poorer ear as reference ear. It was found: 1) that in the range of judgement uncertainty, responses were strongly influenced by stimulus presentation order; 2) that the magnitude of the range of uncertainty was similar across both methodologies. A suggested clinical procedure which controls for these effects is presented as an Appendix.

Acoustic Stimulation↗