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PubMed1981

Auditory processing in aging listeners.

Many aspects of auditory processing in aging listeners are poorly understood. Methodological problems encountered with the aging population, ranging from ear canal collapse to a conservative criterion, have rarely been considered in past research. The relation between pure-tone thresholds and other aspects of auditory functions is unclear. There have been few studies of frequency and temporal analysis in aging listeners. There is disagreement on the effect of age on speech discrimination abilities in various listening conditions, and the cause of speech perception problems in aging listeners has not been adequately investigated. Areas of importance for clinical consideration and auditory research with aging listeners are discussed.

Acoustic Impedance Tests↗
PubMed2001

[Detection of loudness recruitment in patients with retrocochlear lesions using the "Würzburger Hörfeld" loudness scaling].

BACKGROUND: The pathogenesis of hearing loss caused by cerebellopontine angle tumors such as acoustic neuromas is unknown. The lack of loudness recruitment is thought to be one of the features of retrocochlear hearing impairment. In contrast to conventional suprathreshold tests, the categorial loudness scaling using the "Würzburger Hörfeld" is a valuable tool to describe the individual perception of sound. The aim of the present study was to analyze the loudness growth rate in patients with acoustic neuroma. PATIENTS AND METHOD: Pure tone and speech audiometry as well as auditory brainstem response and bilateral categorial loudness scaling were performed preoperatively in 54 patients with acoustic neuroma. Loudness scaling was done in free field switching off the contralateral ear by using an ear-plug. RESULTS: An abnormal rapid loudness growth function was found in 38 of the 54 patients (70.4%) at least at one frequency on the tumor side. The contralateral side was effected only in 57.4% of the patients. The incidence of a recruitment depended on the frequency with a maximum at 4 kHz. The slope of the loudness function showed a tendency to increase with increasing hearing loss. CONCLUSIONS: Loudness recruitment is not a rare phenomenon in patients with acoustic neuroma. The underlying cause (a preexisting hair cell damage, hair cell changes resulting from an obstruction of the cochlear blood supply or a disruption of the cochlear efferents) still remains unclear.

Adult↗
PubMed2002

[Influence of interaural time- and level differences on the binaural interaction components in normal adults].

BACKGROUND: Binaural interaction components of auditory brainstem responses have long been studied and its beta-wave has been shown to be correlated with directional hearing ability. As patients with auditory processing disorders such as patients with some sorts of learning disabilities frequently have difficulties with binaural processing it seems sensible to use binaural interaction components in the diagnosis of these disorders. METHODS: In order to obtain normal values and to investigate the influence of interaural time (ITD) and level differences (ILD) binaural interaction components were measured in 21 adults. Interaural time differences varied between 0 and 1.2 ms and interaural level differences between 0 and 30 dB. RESULTS: beta-latencies increased significantly as interaural time differences increased while beta-amplitudes did not change significantly. In measurements with higher interaural time differences detection of the beta-wave was only rarely possible. The effect of interaural level differences on beta-latencies was less pronounced and not significant as well as the influence of interaural level differences on beta-amplitudes. CONCLUSIONS: In the present study it could be shown that the beta-wave of the binaural interaction waveform is present in almost every normal hearing subject. As amplitudes show a considerable variation beta-latencies seem to be of higher diagnostic value than amplitudes.

Acoustic Stimulation↗
PubMed1996

[Recruitment detection--a comparison of category loudness scaling and classical supra-threshold audiometry].

BACKGROUND: The assessment and localization of hearing impairments require reliable and valid recruitment indicators. Although many diagnostic tests are available, which of these tests are most important is still the subject of controversy. METHOD: To compare the efficacy of various diagnostic audiometric tests, 51 subjects with monaural sensorineural hearing loss were submitted to the following tests at 500 and 2000 Hz: category loudness scaling of narrowband noise bursts, alternate binaural loudness balance (ABLB), intensity difference limen test, SISI test, fixed frequency Békésy audiometry, and contralateral determination of the acoustic reflex threshold for pure tones. RESULTS: Using the findings of the ABLB test as reference, the results of the present study revealed that category loudness scaling and acoustic reflex audiometry are reliable quantitative recruitment indicators. This holds for the intensity difference limen test to a lesser extend as well. However, the recruitment selectivity of the SISI test and Békésy audiometry turned out to be considerably poorer. CONCLUSIONS: Category loudness scaling has proven to be a valuable element in the conventional recruitment test battery particularly for patients with symmetrical hearing loss. Therefore, category loudness scaling, ABLB test (when feasible), acoustic reflex measurement, and to a lesser extend the intensity difference limen test should be given the highest priority when selecting appropriate diagnostic audiometric tests. The efficacy of the SISI test and Békésy audiometry should be comprehensively reevaluated on the basis of expanded data. Until such material is available and a final judgement of the clinical value is possible, both these tests should be used and interpreted carefully.

Audiometry, Pure-Tone↗
PubMed1993

[Value of in situ measurement for evaluating effective hearing aid amplification at high sound pressure levels].

A careful hearing aid fitting requires consideration of various characteristics of inner ear pathology. The recruitment phenomenon restricts the dynamic range of the impaired hearing and this increase the demands on the hearing aids for a satisfactory correction of the frequency characteristics as well as for an intensity reduction at higher sound pressure level SPL. For years data from coupler or KEMAR (Knowles Electronics Manikin of Acoustical Research) have served to estimate the real ear gain of a hearing aid at higher input levels. In previous papers we reported on some of the differences between coupler measurement and probe tube measurement. The object of this study was to investigate the differences between these two methods at higher input SPL. Therefore, we measured the real ear insertion gain as well as the output characteristics with a 2 cm3 coupler in 80 patients at input levels of 60 dB, 80 dB and 100 dB. The results show differences between the two methods up to 30 dB in both directions in the single patient. Furthermore, the highest compression rate was found in the middle and high frequency range which are crucial for speech discrimination. Consequently, probe tube measurement should be used not only to adjust the frequency characteristics of the hearing aid but also to characterise the real effect of Automatic Gain Control AGC and Peak Clipping PC on insertion gain at higher input SPL. Multichannel hearing aids should be used whenever possible to reduce the disturbances to speech discrimination at low frequencies.

Hearing Aids↗
PubMed1999

Temporal loudness integration and spectral loudness summation in normal-hearing and hearing-impaired listeners.

The aim of this study was to test for differences between normal-hearing and hearing-impaired listeners regarding two fundamental aspects of intensity perception: loudness integration and loudness summation. Loudness functions for three different stimuli were measured using categorical loudness scaling in 8 normal-hearing and 12 hearing-impaired subjects. The results indicated that temporal loudness integration, defined as the difference in SPL between 16.25-ms and 300-ms noise bursts of equal loudness, was larger in the hearing-impaired than in the normal-hearing listeners. Loudness summation, defined as the difference in SPL between a 300-ms, 1,600-Hz tone pip and a white noise burst of the same duration and loudness, did not differ between the two groups. Implications of these results for hearing aid fitting strategies based on loudness normalization are discussed.

Adult↗
PubMed1996

The illusion of increasing loudness in brief steady tones: variation with carrier frequency.

A brief tone of steady intensity is heard as growing louder; to be heard as steady, intensity must be decreasing. The present report concerns the influence of carrier frequency on this illusion. Stimuli each lasted 1.5 s, during which time intensity was increasing, decreasing, or remaining steady; the initial intensity was 40 dB SPL (sound pressure level relative to 0.0002 dynes/cm2). Carrier frequencies were between 0.0625 and 8.0 kHz. Four listeners made forced binary responses of "growing louder" or "growing softer" to stimuli. Values of changing intensity that elicited equal numbers of each type of response were computed. As expected, these values were negative. The illusion was most pronounced for the lowest and highest frequencies. In contrast to the results of a recent study, the findings were that sensitivity to changing intensity did not vary systematically with the size of the illusion. The illusion might arise because many sounds slowly decay in intensity and because of the importance of detecting approaching sound sources, analogous to "looming" in the visual modality. Overall loudness of the sound source should assist in altering the listener; the increase in the illusion at the extremities of the frequency range might compensate for the reduced overall loudness at such frequencies.

Adult↗
PubMedDate not supplied

Loudness and the acoustic reflex.

Fifteen subjects with unilateral sensorineural hypacusis were tested to determine the sound intensity eliciting the acoustic reflex in normal and impaired ears and the sound intensity in the normal ear which is equal in loudness to the intensity eliciting the acoustic reflex in the abnormal ear. Results suggest that loudness is not the mediating factor in the acoustic reflex, justifying the suggestion that low sensation level reflexes observed in hearing-impaired patients should not be considered an unequivocal indicant of recruitment.

Adolescent↗
PubMedDate not supplied

Aging and auditory site of lesion.

The purpose of this study was to examine and quantify the functional auditory problems of presbycusis through a battery of recently developed diagnostic tests and to evaluate the usefulness of these tests with an elderly population. Diagnostic measures used were impedence measures, speech discrimination tests, synthetic sentence identification, compressed speech, two measures of tone decay, the short increment sensitivity index, a digit span test, and auditory brain stem response audiometry. Significant differences were found between scores for elderly subjects and those of young subjects who had similar audiograms. Use of the Metz test as an objective measure of recruitment yielded results suggesting a higher incidence of recruitment than evidenced by previous studies using loudness balancing procedures. The Olsen-Noffsinger procedure of quantifying tone decay revealed a greater difference between age groups than did the Suprathreshold Adaptation Test. Synthetic sentence identification revealed the most consistent age effect among the tests of central auditory function. Auditory brain stem response audiometry revealed several examples of abnormally long interpeak latencies. It is concluded that there is both behavioral and electrophysiological evidence of central and peripheral auditory disorder frequently accompanying senescence.

Aged↗
PubMedDate not supplied

Binaural interaction in auditory brain stem responses: parametric studies.

The effects of click stimulus presentation rate, spectrum, and polarity on binaural interaction in auditory brain stem responses (BI/ABR) were observed in guinea pigs and in normal-hearing human adults. The effects of repetition rate on the BI/ABR in both species were similar to those seen in ABRs. Six of 16 human subjects showed an unusual "early BI" only at high click intensity and high repetition rates; this is probably due to acoustic reflex effects. Animal data from stimulus spectrum experiments suggest a mid-to-high frequency dependence of the BI/ABR, while human data are less clear. Results are discussed relative to suggested recording strategies for the BI/ABR.

Acoustic Stimulation↗
PubMed1988

Loudness discomfort levels in children.

Loudness discomfort levels (LDLs) traditionally have been used to set the saturation sound pressure level (SSPL) or maximum output of a hearing aid. Many procedures have been used to obtain LDLs for adults; however, no systematic study has been conducted to determine if LDLs could be obtained reliably for children. In the present study, LDLs were measured on 20 hearing-impaired children aged 7 to 14 years using a modification of a procedure described by Hawkins, Walden, Montgomery, and Prosek (Ear Hear 1987; 8: 162-169). Test-retest reliability measures were obtained for 8 of the 20 children, and this modified procedure was found to provide reasonably reliable results. Data from the group of 20 children also were compared with similar data obtained from 20 hearing-impaired adults. These results revealed no systematic differences in LDLs between the two groups, suggesting no a priori reason to limit the maximum output of a hearing aid for a child in this age range below the levels that are appropriate for adults. Poor correlation between LDLs and hearing levels for both age groups indicate a need for determining LDLs on an individual basis whenever possible.

Adolescent↗
PubMed2000

Identification of neonatal hearing impairment: recruitment and follow-up.

OBJECTIVE: The purpose of this study is to describe the recruitment and retention strategies as well as the sample demographics for families with infants completing the neonatal examination and returning for follow-up. These data are compared to those infants inactivated from the study. DESIGN: This study was a prospective, randomized clinical study. All infants who were confined to the neonatal intensive care unit (NICU) and well babies with at least one risk indicator were targeted for behavioral audiometric follow-up testing. In addition, infants without risk factors from the well-baby nursery, but who failed a newborn test, were also followed. Several variables were evaluated to determine those factors, if any, that might predict which families returned for follow-up testing. RESULTS: Recruitment was achieved as per study design with 4911 high-risk infants and 2348 well-baby nursery infants (without risk indicators for hearing) enrolled. Of the 4911 high-risk infants enrolled, 64% were successfully recruited into the follow-up portion of the study. This was less than the projected rate of 80%. Factors predicting noncompliance with the study protocol for follow-up were predominantly sociodemographic and included nonwhite race, no insurance, substance abuse, young maternal age, more than two children at home, and late onset of prenatal care. CONCLUSIONS: Factors related to low socioeconomic status and increased social risk were the strongest predictors of poor study protocol compliance. Despite retention challenges, 64% of the targeted, high-risk infants subsequently returned for the 8-to 12-mo behavioral hearing assessment protocols for validation purposes.

Demography↗
PubMed2007

Electrode independence in intraneural cochlear nerve stimulation.

OBJECTIVES/HYPOTHESIS: We have previously reported feline electrophysiological and anatomical studies focused on the development of an intraneural auditory neuroprosthesis. Because only the tips of the electrodes implanted in the cochlear nerve are the stimulating elements that abut the nerve axons, we hypothesize that intraneural stimulation will be highly focal in nature. In this article, we report the electrophysiological characterization of the selective activation of subpopulations of cochlear nerve fibers via electrodes implanted in feline cochlear nerve. STUDY DESIGN: We have used a forward-masking paradigm to estimate the extent of stimulation overlap produced by pairs of electrodes implanted into the cochlear nerve. METHODS: The technique uses sequential stimulation via masking and probe electrodes and monitoring of the electrically evoked auditory brain stem response as an index of cochlear nerve fiber recruitment. We investigated overlap in all possible electrode pair combinations. RESULTS AND CONCLUSION: Many electrode pairs manifest virtually no overlap in the subpopulations of fibers excited by perithreshold stimuli, whereas most had considerable overlap at higher stimulation levels. However, we also noted that our measured overlap was similar across electrodes possibly because of lack of specificity of the whole nerve electrically evoked auditory brain stem response as an assay for this parameter. These findings indicate that direct cochlear nerve stimulation via intraneural electrodes provides selective excitation of small subpopulations of cochlear nerve fibers, and suggest that cochlear nerve stimulation may selectively evoke narrow-band frequency percepts.

Animals↗
PubMed1979

Temporary threshold shift, loudness, and auditory evoked potentials.

TTS2 of 20dB was produced in a group of subjects using a 1000 Hz pure tone. All TTS and related measurements were made at 1500 Hz. The recovery of TTS, and of TLS or 'temporary loudness shift' (measured against a reference tone at 20db, 40dB and 60dB SL in the opposite ear), as well as N1-P2 amplitude of the Vertex potential, were plotted. There was an orderly recovery of both TLS and TTS although the rate of recovery of the latter was noticeably more rapid. Recovery of N1-P2 amplitude was much less orderly, although it did recover in much the same way. When the amplitudes were measured at 40dB SL the recovery was more orderly and followed the course of TTS more closely. It was concluded that any relation between N1-P2 amplitude and growth of loudness was indirect.

Acoustic Stimulation↗
PubMed1992

Audiogenic seizure susceptibility and auditory brainstem responses in rats prenatally exposed to alcohol.

Rats prenatally exposed to alcohol (0%, 17.5%, or 35% ethanol-derived calories) were tested for audiogenic seizure susceptibility on one of postnatal days 18 to 23, then retested 5 days later. Prenatal alcohol exposure did not influence audiogenic seizure susceptibility or severity. There was, however, a significant increase in seizure incidence on the retest day for all groups, suggesting a priming effect. Auditory brainstem response (ABR) data suggested that prenatal alcohol exposure and acoustic trauma (i.e., exposure to an alarm bell used for eliciting audiogenic seizures) induced measurable sensorineural hearing loss, and that the combined exposure to alcohol and acoustic trauma interacted additively to produce greater hearing loss than either alone.

Animals↗
PubMed2002

Spectral loudness summation as a function of duration.

Loudness was measured as a function of signal bandwidth for 10-, 100-, and 1000-ms-long signals. The test and reference signals were bandpass-filtered noise spectrally centered at 2 kHz. The bandwidth of the test signal was varied from 200 to 6400 Hz. The reference signal had a bandwidth of 3200 Hz. The reference levels were 45, 55, and 65 dB SPL. The level to produce equal loudness was measured with an adaptive, two-interval, two-alternative forced-choice procedure. A loudness matching procedure was used, where the tracks for all signal pairs to be compared were interleaved. Mean results for nine normal-hearing subjects showed that the magnitude of spectral loudness summation depends on signal duration. For all reference levels, a 6- to 8-dB larger level difference between equally loud signals with the smallest (delta f = 200 Hz) and largest (delta f = 6400 Hz) bandwidth is found for 10-ms-long signals than for the 1000-ms-long signals. The duration effect slightly decreases with increasing reference loudness. As a consequence, loudness models should include a duration-dependent compression stage. Alternatively, if a fixed loudness ratio between signals of different duration is assumed, this loudness ratio should depend on the signal spectrum.

Adult↗