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PubMed1996

Recalibrating the perception of loudness: interaural transfer.

Previous research, using both magnitude-scaling and direct-comparison methods, has shown the perception of loudness to be contingent on the distribution of tonal stimuli varying in sound frequency as well as SPL: When a low-frequency signal, f1, is presented at low SPLs and a high-frequency signal, f2, at high SPLs, loudness at f1 is great relative that at f2; reversing the association of SPL with frequency reverses the loudness relation. These shifts in relative loudness, recently termed "recalibration" [Marks, J. Exp. Psychol: Hum. Percept. Perf. 20, 382-396 (1994)] [corrected], are consistent with the operation of frequency-specific, fatiguelike processes at f1 and f2. Experiment 1 combined both scaling (magnitude estimation) and matching (direct-comparison) methods and showed that exposing one ear to recalibrating stimuli (500 and 2500 Hz) led to substantial shifts not only in the ipsilateral ear but also in the contralateral ear (albeit smaller ones). Experiment 2 used a selective-exposure procedure and gave similar results. Thus the processes underlying recalibration of loudness appear to involve central mediation; consequently, it is possible that processes of auditory fatigue rely on central as well as peripheral mechanisms.

Female↗
PubMed2000

[Clinical comparison of a digital with an analog hearing aid].

The benefit of innovative hearing aid technology can be evaluated in clinical trials. The present study describes the comparison of a new digital hearing aid with an analogue device serving as a reference. The tests were carried out with 15 experienced hearing aid wearers. To prevent the influence of different fitting algorithms such as prescriptive or loudness-based the digital devices were not renewed fitted but their level- and frequency-depending gain was adjusted to that of the reference. Different tests concerning loudness perception (category loudness scaling) speech discrimination in noise (the Göttingen sentence test) and self-assessment of the benefit by questionnaires were performed. All tests yielded slightly better results for the digital hearing aid. The speech audiometric evaluation showed somewhat better discrimination for the test-device. The questionnaires yielded a marked preference for the digital device. Because the study was not blinded influences due to the knowledge of the subjects of testing a new technology generally can occur. On the other hand, the question arises whether present audiometric tests sufficiently consider signal processing of modern hearing systems. Furthermore, one has to take into account that only a few of the features of digital technology such as noise-reduction and feedback-cancellation were considered in this study to allow for a sensible comparison. Because of the large number of possibilities offered by digital technology additional benefit by the hearing aid can be expected.

Analog-Digital Conversion↗
PubMed2002

The non-classical auditory pathways are involved in hearing in children but not in adults.

Auditory information ascends through the brainstem to the cerebral cortices in two parallel pathways, known as the classical and the non-classical ascending auditory pathways. The importance of the non-classical auditory pathway for hearing in humans is unknown but its subcortical connection to limbic structures may be important in tinnitus. In this study we show evidence that non-classical pathways are involved in loudness perception in young individuals but not in adults. We used the fact that some neurons in the non-classical auditory pathways receive somatosensory input and we determined the effect on loudness perception of monaural sounds from electrical stimulation of the median nerve at the wrist. Stimulation of the somatosensory system had the greatest effect on loudness perception in the youngest children that we studied (7-8 years) and the effect was minimal for individuals above 20 years of age. The effect was an increase in loudness in 20 of the 40 individuals we studied and a decrease in 4 individuals; 16 experienced no noticeable change in loudness during somatosensory stimulation.

Adolescent↗
PubMed2000

Use of a loudness model for hearing aid fitting. IV. Fitting hearing aids with multi-channel compression so as to restore 'normal' loudness for speech at different levels.

Many researchers have proposed that multi-channel compression hearing aids should process sounds so as to restore loudness perception to 'normal'. However, procedures for achieving this have generally been based on measurements or calculations using narrowband stimuli, and these procedures may not be accurate for broadband sounds such as speech. Here, a model for predicting loudness for people with cochlear hearing loss is used to calculate the frequency- and level-dependent gains that would be required to restore loudness perception to 'normal' for speech-like signals. The calculations are based entirely on the pure tone audiogram, and do not require measures of loudness growth. The model was applied to several different hypothetical hearing losses, varying in slope and severity. In each case, the model was used to calculate the insertion gains (IGs) that would be required as a function of frequency so that speech-shaped noise with a level of 65 dB SPL would evoke a specific loudness pattern matching that for a normal ear. A similar procedure was applied using speech-shaped noise with a level of 85 dB SPL (with the spectral characteristics of shouted speech). The results were used to derive functions relating the required IG to hearing loss for each audiometric frequency and each speech-shaped noise level. These functions were used in turn to derive compression ratios and gains for each channel of a multi-channel compression system. The derivations apply to systems with any number of channels. The outcome is a method than can be used for the initial fitting of multichannel compression hearing aids, so as to restore loudness perception to near 'normal' for broadband speech-like signals.

Acoustic Stimulation↗
PubMed1984

Acute exposure to methyl or ethyl alcohol alters auditory function in the rat.

Effects of alcohol on audition were studied in the rat by examining the modification of acoustic startle reflexes by pure tone pulses and by gaps in white noise. Systematic inhibition of the startle reflex by variation in pulse intensity provides an objective measure of loudness perception, while variation in gap duration assesses temporal acuity. Groups of rats (n = 8) received four injections of 0.0, 0.25, 1.00, and 2.00 g/kg of either methyl or ethyl alcohol in increasing order at 1-hr intervals. One-half hour after the administration of each dose, loudness perception or temporal acuity was measured. Blood alcohol levels (mM) for the two alcohols obtained in control animals were equivalent following the final dose. Alcohol produced a dose-dependent reduction in baseline startle amplitude that was greater during exposure to ethanol than during methanol. Loudness functions associated with pulse intensity were not diminished by alcohol; however, inhibition produced by a gap in noise was reduced following the highest dose of either alcohol. These data are consistent both with behavioral studies that have suggested that alcohol does not affect loudness perception, and with electrophysiological experiments which indicate that alcohol disrupts temporal relationships along the primary auditory pathway.

Acoustic Stimulation↗
PubMed2000

[Categorical loudness scaling within the scope of hearing aid management].

The loudness perception of patients with hearing aids was measured with a one-stage category loudness scaling procedure. Data were obtained from 102 ears and were studied primarily in older patients who represented the majority of patients with hearing disorders evaluated in our department. In all, 75% of the patients were older than 45 years and had a mean age of 58 years. The reduction of dynamics at high frequencies was considered to be typical for age-related hearing disorders and was easily quantified with loudness scaling. Findings demonstrated that prediction of recruitment was not possible from pure-tone thresholds or even together with uncomfortable loudness levels, since the slopes of the level-loudness functions revealed a high interindividual variability. In contrast, the desired compression ratio can be easily calculated with data from the loudness scaling. In this study the loudness perception of patients with mainly non-linear hearing aids fitted with customary procedures was evaluated. The benefit from the hearing aids was proven with the outcome from the loudness scaling, with testing also allowing for a better fitting of the aids.

Adult↗
PubMed2000

[Use of auditory field measurement in patients with otosclerosis].

BACKGROUND: Middle ear surgery sometimes leads to unpleasant auditory impressions such as distortion or hyperacusis that cannot be detected by conventional audiometric testing. METHOD: Sixty-one patients with conductive hearing loss caused by otosclerosis underwent audiological evaluation, which included a questionnaire followed by testing of the audiometric threshold, speech audiometry, and assessment and quantification of loudness perception with a commercial system (WESTRA). This investigation includes the postoperative measurement of hearing improvement and the patients' subjective impressions regarding hearing increase, distortion of speech, and hyperacusis. RESULTS: Hearing improved in 88% of the patients. A quantification of this hearing increase was possible with pure tone audiometry and the Freiburg speech discrimination test. Reduced hearing threshold and lack of improvement in speech discrimination was confirmed by conventional hearing measurements. However, the presence of hyperacusis and distortion of speech could be determined by conventional audiometry in only 50% of cases. It was interesting to note that the subjects who reported speech distortion and hyperacusis in the questionnaire were identified by their increased loudness perception using the categorical loudness scaling. CONCLUSION: Category loudness scaling appears to be a valuable additional clinical test to characterize postoperative phenomena as distortion of speech and hyperacusis in patients undergoing stapes surgery.

Adult↗
PubMedDate not supplied

[Automatic regulation in the auditory analyzer and the phenomenon of accelerated growth of loudness].

Physical analysis of the ear periphery structure and the data on loudness perception have been used to develop a model of loudness measurement and self-control in the hearing analyzer. The experimental results obtained recently by different researchers are shown to confirm that the basic ideas of this model are reasonable, and the model is of considerable heuristic importance. The author provides treatment of the main hearing "paradox", that is the existence of a wide dynamic range of loudness perception for a narrow range of afferent pulsation in auricular nerve fibers. A simple explanation is found for the so-called adaptation phenomenon. The explanation of the phenomenon of loudness increase acceleration typical for many forms of neurosensory hypoacousis opens up new perspectives in the diagnostics and treatment of these diseases.

Adaptation, Physiological↗
PubMed1984

The perception of control in loud noise.

Perception of control is known to affect performance under stress. Two experiments are reported the object of which was to find out how loud noise during a contingency assessment task influences perceived control. Subjects were required to choose one of two responses, note one of two results, and then provide an overall percentage estimation of the degree of contingency present after 40 trials. Subjects made these judgments for one of three levels of objective contingency (25%, 50%, 75%), either in quiet (55 dBA) or in loud noise (95 dBA) conditions. The first experiment involved a series of randomly chosen, preprogrammed outcomes for noncontingent trials. An unexpected effect of noise was that subjects improved their successes in predicting events, and could only have done so by finding sequential structure in the preprogrammed alternations. They also overestimated control relative to contingency data actually received, at the 25% objective contingency level, but the result could have been dependent on different base levels of data actually received. A second experiment, with a random generation of outcomes for noncontingent trials, resulted in no differences in success levels, but confirmed that noise is associated with the overestimation of contingency at the 25% objective contingency level and demonstrated the same effect for the 50% level. The results are discussed in the context of the 'illusion of control'.

Association↗
PubMed1987

A method for relating loudness-matching and intensity-discrimination data.

A method that allows direct comparisons between pure-tone loudness-matching and intensity-discrimination data in normal and hearing-impaired listeners is described. This method makes a minimal number of assumptions about the relations between loudness perception and intensity-discrimination performance. Loudness is considered to be related to overall, perceived stimulus magnitude and intensity-discrimination performance is considered to reflect the accuracy with which a loudness judgment can be made. Because pure-tone intensity-discrimination performance varies as a function of stimulus level in normal ears, the standard level required to produce a particular difference limen in an impaired ear can be inferred from normal-ear intensity-discrimination data. Thus, plotting standard levels yielding normal difference limens as a function of standard levels yielding the equivalent sized difference limens from a threshold-shifted ear produces a function directly comparable to loudness recruitment functions. If loudness-growth and intensity-difference limens were tightly coupled in threshold-shifted ears, then stimuli that yield equal size difference limens would be equally loud. This relation was tested by obtaining loudness-matching and intensity-discrimination data from normal-hearing listeners with thresholds shifted by a wideband noise and hearing-impaired listeners with cochlear-type hearing losses. The results from these listeners show similarities between the traditional loudness-recruitment functions and "intensity-recruitment" functions derived from the assumed relation between the two measures. The primary difference between the functions is at low and moderate sensation levels where loudness grows at a more rapid rate than the difference limen.

Audiometry, Pure-Tone↗
PubMed1977

Intensity perception. VIII. Loudness comparisons between different types of stimuli.

In this paper, we describe an extension of our preliminary theory of intensity resolution [Durlach and Braida, J. Acoust. Soc. Am. 46, 372-383 (1969)] to include loudness comparisons among different types of stimuli. The extended theory relates mean loudness matches to discrimination and provides a framework for the interpretation of results on the intrasubject variability of loudness comparisons. The predicted relation between mean loudness matches and discrimination is essentially the same as that proposed by Riesz [J. Acoust. Soc. Am. 5, 211-216 (1933)]. With regard to the variability of loudness comparisons, the extended model is essentially the same as the preliminary model except that a new term is included in the trace-mode memory variance to account for the dissimilarity of the stimuli being compared. The model is compared to some published data on loudness matching and discrimination and to some new data of our own on the variability of loudness comparisons obtained in a two-interval, roving-level, loudness-discrimination experiment.

Acoustic Stimulation↗
PubMed1996

Perceptual consequences of cochlear hearing loss and their implications for the design of hearing aids.

This paper provides an overview of changes in the perception of sound that result from cochlear damage. It starts with a brief introduction to the physiology of the cochlea, emphasizing the role of the "active mechanism" and describing how cochlear function is altered by cochlear damage. Then the effects of cochlear damage on various aspects of perception are described, including absolute sensitivity, frequency selectivity, loudness perception and intensity discrimination, temporal resolution, temporal integration, pitch perception and frequency discrimination, and sound localization and other aspects of binaural and spatial hearing. The possible role of each of these aspects of auditory perception in the ability to understand speech in quiet and in noise is discussed and evaluated. It is concluded that, for losses up to about 45 dB, audibility is the single most important factor. However, for greater losses, poor discrimination of suprathreshold (audible) stimuli is also of major importance. The final section of the paper describes applications of the findings to hearing aid design. It is concluded that linear amplification can be of only limited benefit in compensating for the effects of cochlear damage. Hearing aids incorporating compression can help to compensate for the effects of reduced dynamic range. Digital signal processing to enhance spectral contrast may be of some help in compensating for the effects of reduced frequency selectivity.

Cochlea↗
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↗
PubMed1997

Effects of test procedure on individual loudness functions.

OBJECTIVE: To determine if measurement procedure effects occur for loudness perception data measured using a categorical rating scale. DESIGN: Loudness data were obtained from 40 normal-hearing adult volunteers, using 30 levels of pure tones at four frequencies (500, 1000, 2000, and 4000 Hz), with judgments made on a 9-point categorical scale. Two presentation orders, random and sequential, were compared within subjects. Subjects were divided into two groups: one group heard only a single tone on every trial, whereas the other group was presented with a maximum level reference tone at the start of each trial. RESULTS: A significant difference was found between loudness function exponents measured with the random and sequential presentation order of stimulus level. A significant difference was found between loudness function exponents measured when a high-level referent was presented at the start of each trial. The sequential presentation order was further subdivided into ascending and descending runs, and the loudness function exponents for each run were examined separately. The results showed a significant interaction between sequence (ascending versus descending) and group. CONCLUSIONS: For normal-hearing listeners, the procedure used to measure loudness has an effect on the loudness function exponent obtained. These results appear to be related to stimulus context effects. Loudness function exponents are smaller when the stimulus is preceded by a stimulus level greater than the level of the test tone. This occurred when a high-level referent was presented at the start of each trial or when the stimulus level from the previous trial was greater than the test level, as in a descending run. It seems likely that the difference between loudness function exponents obtained with a random and sequential presentation of level can be explained by the same phenomenon. The significance of these results for hearing aid fittings in which loudness normalization is the goal is discussed.

Auditory Threshold↗
PubMed2003

Use of a loudness model for hearing aid fitting. V. On-line gain control in a digital hearing aid.

Many researchers have proposed that hearing aids should process sounds so as to restore loudness perception to 'normal'. We describe how a model for predicting loudness for people with cochlear hearing loss can be implemented in a digital hearing aid so as to calculate the frequency-dependent gains that would be required to achieve that goal. It is assumed that the input signal is processed using brief segments or 'frames'. For each frame, the spectrum is calculated, usually via a fast Fourier transform (FFT). From the spectrum, an excitation pattern is calculated for a normal car and for the impaired ear of the patient. The loudness model is then used to calculate the gain required at the centre frequency of each channel in the aid, so as to match the specific loudness in the normal and impaired ears. The whole process is repeated for each successive frame, with overlap of frames and with smoothing of the gain changes across frames. We describe both an 'exact' model, which prescribes a 'curvilinear' compression characteristic at each frequency, and an approximation using 'straight' compression, which is computationally less intensive. Limitations of the present approach are described, and the approach is compared with more traditional approaches using multichannel compression, and with previous approaches using loudness models for fitting hearing aids.

Acoustic Stimulation↗