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PubMed1994

[Effect of contralateral stimulation on otoacoustic evoked emissions in acute deafness].

23 patients with unilateral hearing loss and presence of TEOAE on both ears were examined with regard to the association between contralateral acoustic stimulation and evoked otoacoustic emissions. Contralateral white noise of 40 dB HL, 50 dB HL and 60 dB HL decreases the amplitude of TEOAE both at the ear with and without hearing loss. In comparison with a group of subjects with normal hearing, the decrease in the amplitude of TEOAE was less in the group of patients with hearing loss. Two paradoxical cases were found with an increase in the TEOAE amplitude in the ear with hearing loss during contralateral stimulation. It is assumed that impairment of the efferent synapses on the outer hair cells or of the decussated efferent nerve fibres at the floor of the fourth ventricle contributes to the pathogenesis of hearing loss. Impairment of the efferent system at brainstem level can explain the lower decrease in the amplitude both in the diseased ear and the normal ear. The behaviour of the normal ear during stimulation of the diseased ear can also be caused by disturbance of the afferent system.

Acoustic Stimulation↗
PubMed1992

[Evoked otoacoustic emissions and their modification by contralateral acoustic stimulation].

The active vibration of the basilar membrane as well as evoked otoacoustic emissions (EOAE) are probably based on the motile properties of cochlear outer hair cells (OHC). In the present study we examined the effects of contralateral acoustic stimulation on ipsilateral EOAE and thereby the active cochlear micromechanics. Contralateral white noise with intensities below 30 dB HL enhanced the EOAE amplitude, whereas higher sound levels reduced the evoked acoustic emissions. Similar effects of contralateral acoustic stimuli on ipsilateral EOAE were observed in patients with a conductive hearing loss. However, the required sound levels were higher compared to probands with normal hearing. In controls with unilateral deaf patients white noise up to 60 dB HL did not alter the EOAE amplitude. We concluded, that in patients with normal hearing or unilateral conductive hearing loss, effects of contralateral acoustic stimulation on evoked ipsilateral sound emissions may be due to the activation of crossed olivo-cochlear efferents reaching the OHCs.

Acoustic Stimulation↗
PubMed1992

[What improvements can be gained by additional boring in hearing aid fitting?].

In several investigations the authors tried to find a objective correlation to the subjective positive reactions after venting an earmold. There was no notable effect neither on insertion gain nor on speech intelligibility in different background noise situations. In this study the most comfortable hearing level has been used. This stimulus is influenced by the suprathreshold loudness growth. The measurement has been carried out with and without venting. Comparing the results there can be seen only a little effect of venting at all frequencies. Might be that patient's report about improvement after venting results from the direct input of low frequencies through the vent to the eardrum. These frequency region plays a special part of hearing comfort to reach a comfortable sound quality.

Adult↗
PubMed1992

[Effect of decreased and lost high frequency hearing on latency of acoustically evoked brain stem reaction].

The diagnosis of retrocochlear damage is supported by an increased latency difference between peak I and peak V. In case of high frequency hearing loss peak I is often hard to determine, and peak V latency may be shifted not only by neural delay, but also by missing basal hair cells. The amount of cochlear delay can be estimated by a procedure presented here. High frequency decay was simulated by steep high-pass noise masking. Peak V latency turned out to be established by the highest unaffected frequency components of the click stimulus. Thus, in case of a high frequency gap (with normalization towards higher frequencies) latency may be almost normal. In case of prolonged latency the amount ascribable to the cochlea may be rather precisely be estimated. If the whole lag is explained this way, unnecessary further diagnostics can be avoided.

Audiometry, Evoked Response↗
PubMed1992

[Various uncomfortable loudness thresholds, their correlation and use in general practice].

In the present study we examined the relationship of the loudness discomfort level LDL of different signals. We carried out measurements in 97 patients, all of whom suffered from a sensorineural hearing loss. The results showed almost no difference between the LDL of pure tones and narrow band noise. The LDL of broad band noise showed a good correlation to the LDL of 250 Hz. Only the LDL of monosyllables ranged at a higher SPL. For an up-to-date hearing aid fitting, all forms of LDL should be taken into consideration. This is especially necessary when using digital hearing aids.

Adolescent↗
PubMed1997

[Contralateral modification of transitory evoked otoacoustic emissions].

BACKGROUND: In recent publications the influence of contralateral white noise on transient evoked otoacoustic emissions (TEOAE) is discussed with regard on contributions of the efferent auditory system. METHODS: In the present study the effects have been investigated with regards to middle-ear muscles, efferents and cross hearing. TEOAE to monaural 40-80 dB SPL clicks were recorded in normal-hearing adults under simultaneous presentation of 20-60 dB SPL broadband noise to the contralateral ear. Control runs were performed before, during a short break of, and after contralateral stimulation. The control run before contralateral stimulation was used as a reference. RESULTS: Decrease in TEOAE, and increase in accompanying noise floor, were found to follow the contralateral stimulation. In particular a 1-3 dB decrease was found for contralateral noise levels of 40 and 60 dB SPL, even though the readings at 60 dB only were statistically significant (paired-samples t test, p = 0.05). For both TEOAE and noise floor no systematic dependence on click intensity was seen. The control runs during temporary break and after contralateral noise revealed an increase in both TEOAE and noise floor. As a rule, the TEOAE adapted to the reference within 2-3 min following the cessation of contralateral stimulation, whereas the increased noise floor level was still noted after 10 min. CONCLUSIONS: Traditionally, suppressing effects of contralateral stimulation on TEOAE have been attributed to cochlear efferents (CEs). Occasionally, the middle-ear muscle and cross hearing involvement have been considered as well. Substantially, the present results and findings of other workers are inconsistent with the basic knowledge of CE functioning: (I) The decrease in TEOAE under contralateral stimulation is in conflict with an increase in cochlear microphonics and summating potentials observed during activation of CEs: (II) contralateral suppression of TEOAE exhibited no significant dependence on the test-stimulus level while the CEs are known to be efficient in the range of the low signal intensities only, and (III) acoustic activation of the CEs can hardly be expected to reach levels sufficient to influence the TEOAE mechanism. The present findings, i.e. decrease in TEOAE and increase in noise floor level, can more reasonably be explained as being mainly attributable to activation of the middle-ear muscles.

Adult↗
PubMed1997

[Reference curves for hearing surface scaling in clinical use].

METHODS: A commercially available system for the purpose of categorial loudness rating (WHF, WESTRA ELECTRONIC GmbH, Wertingen) was applied with 57 subjects with normal hearing to evaluate reference loudness level functions for 1/3-octave bandpass filtered noise and octave bandpass filtered environmental sounds. RESULTS: The procedure can be carried out with high reproducibility without effects of training due to repetition and only slight influence of subject sex, whereas the labeling of input device and temporal structure of the environmental sounds influence results, as does the center frequency. CONCLUSIONS: Our results showed deviations compared with the reference functions displayed in the WHF system.

Adolescent↗
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↗
PubMed1996

[In situ sound pressure measurement in a professional violinist with bilateral tinnitus].

BACKGROUND: A case of a professional violinist suffering from a bilateral tinnitus is presented. The musician reported the tinnitus to be louder and more straining when playing his Vuillaume violin (France 1840) as compared with his Carcassi violin (Italy 1763). CASE REPORT: In the 42-year-old musician, audiometry revealed a normal hearing threshold in the right ear and a slight hearing loss in the left ear of up to 20 dB between 2 kHz and 8 kHz. Transitory evoked otoacoustic emissions could only be measured in the right ear. The tinnitus could be masked (distance type); residual inhibition was only seen in the right ear. By sound intensity measurements in both external auditory canals, the different sound spectra of both violins could be demonstrated. When playing with "forte" intensity, sound pressure reached peaks of over 90 dB. The tinnitus was ameliorated by lidocaine infusions. DISCUSSION AND CONCLUSIONS: The different sound spectra of both violins may be the reason for the enhancement of the musician's tinnitus. Interference of air and bone-conducted sound could lead to a cochlear overlap and thus influence the tinnitus although such a phenomenon can not be verified. It was previously reported that high-pitched instruments may cause tinnitus sensations in performing musicians. A review of the literature surprisingly reveals that although professional musicians are exposed to sound pressure levels that may cause hearing impairment, only very few do develop one. This fact has to be taken into account whenever an occupational disease is suspected.

Adult↗
PubMed1995

[Effect size on resonance of the outer ear canal by simulation of middle ear lesions using a temporal bone preparation].

By means of a model of the external and the middle ear it is possible to simulate various, exactly defined pathological conditions of the middle ear and to describe their influence on ear canal resonance. Starting point of the investigations are fresh postmortem preparations of 8 human temporal bones with an intact ear drum and a retained skin of the ear canal. The compliance of the middle ear does not significantly differ from the clinical data of probands with healthy ears. After antrotomy it is possible to simulate pathological conditions of the middle ear one after the other at the same temporal bone. The influence of the changed middle ear conditions on ear drum compliance, ear canal volume and on the resonance curve of the external ear canal was investigated. For example, the middle ear was filled with water to create approximately the same conditions as in acute serous otitis media. In this middle ear condition a significant increase of the sound pressure amplification was found, on an average by 4 decibels compared to the unchanged temporal bone model. A small increase in resonance frequency was also measured. The advantages of this model are the approximately physiological conditions and the constant dimensions of the external and middle ear.

Acoustic Impedance Tests↗
PubMed1995

[Effect of contralateral noise exposure on otoacoustic distortion product emissions in man].

The influence of contralateral white noise with levels of 50 and 60 dBnHL on the amplitude of distortion-product otoacoustic emissions (DPOAE) was measured. Thirty ears of normally hearing adults (17 women, 13 men, mean age 26.5 +/- 5.3 years) were examined. Two representative DPOAE frequencies 2f1-f2 = 1342 Hz and 6341 Hz were compared. The lower DPOAE frequency was placed in the frequency region where middle-ear pressure has a strong influence on DPOAE amplitudes, the higher DPOAE frequency respectively in the region where lesser influence is exerted by middle-ear pressure. During the application of contralateral white noise a statistically significant total of 85% of DPOAE amplitudes was reduced, although there was some variation in the individual behaviour of DPOAE amplitudes. In general the higher DPOAE frequency (6341 Hz) was reduced distinctly less than the lower DPOAE frequency (1342 Hz). The reaction of DPOAE amplitude depended closely on the time course of the contralateral stimulus and amplitude reductions were present over 10 minutes without adaptation or fatigue. It is not possible to differentiate between middle-ear or inner-ear mediate effects but the middle ear is at least involved. Based on the presence of those DPOAE amplitude reductions over ten minutes without adaptation or fatigue and the fact that lower frequencies are influenced much more than higher frequencies a synergistic effect--middle-ear and efferent mediated--is suggested.

Adult↗
PubMed1995

[Clinical aspects of coping with tinnitus].

Forty-two patients suffering form chronic tinnitus participated in our psychologically oriented treatment last year. The following study presents the results of the psychological management of chronic tinnitus combining counselling with relaxation training. Furthermore individual therapy is compared with group therapy. The therapeutical efficiency can be tested using visual analog scales. The individual estimated loudness and annoyance of tinnitus are registered. A quantitative assessment of complaints is made via questionnaires (adapted to Back Depression Inventory). In most cases a reduction of tinnitus loudness and annoyance after individual and group therapy is seen directly. But a constant therapeutical effect is only found is individual therapy. In group therapy, many of our patients reported an increase in the pretherapeutical estimation of tinnitus loudness and annoyance. We believe that permanent confrontation with the tinnitus problem may advance the psychological conflict in many cases. Therefore, psychological management of tinnitus should be concentrated on temporary limited support aimed at overcoming tinnitus sensation.

Adaptation, Psychological↗
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↗
PubMed1998

Increasing-loudness aftereffect following decreasing-intensity adaptation: spectral dependence in interotic and monotic testing.

Listening to decreasing intensity leads to illusory increasing loudness afterwards. Evidence suggests that this increasing-loudness aftereffect may have a sensory component concerned with dynamic localisation. This was tested by comparing the spectral dependence of monotic aftereffect (adapting and testing one ear) with the spectral dependence of interotic aftereffect (adapting one ear and testing the other ear). Existence of the proposed component implies that monotic aftereffect should be more spectrally dependent than interotic aftereffect. Three listeners were exposed to a 1 kHz adapting stimulus. From responses of "growing softer" or "growing louder" to test stimuli changing in intensity, nulls were calculated; test carrier frequencies ranged from 0.5 kHz to 2 kHz. Confirming the hypothesis, monotic aftereffect was about three times as strong as interotic aftereffect for the 1 kHz test carrier frequency, while monotic and interotic aftereffects were comparable in magnitude for test carrier frequencies below about 0.8 kHz and above about 1.2 kHz. The latter residual aftereffects are attributed to cognitive processing, perhaps concerning response bias. Sensitivity did not vary systematically across conditions; this is consistent with evidence that changing intensity entails mainly direct processing. The results cannot be attributed to the loudness adaptation elicited by steady stimuli.

Adaptation, Psychological↗
PubMed2004

Associative learning shapes the neural code for stimulus magnitude in primary auditory cortex.

Since the dawn of experimental psychology, researchers have sought an understanding of the fundamental relationship between the amplitude of sensory stimuli and the magnitudes of their perceptual representations. Contemporary theories support the view that magnitude is encoded by a linear increase in firing rate established in the primary afferent pathways. In the present study, we have investigated sound intensity coding in the rat primary auditory cortex (AI) and describe its plasticity by following paired stimulus reinforcement and instrumental conditioning paradigms. In trained animals, population-response strengths in AI became more strongly nonlinear with increasing stimulus intensity. Individual AI responses became selective to more restricted ranges of sound intensities and, as a population, represented a broader range of preferred sound levels. These experiments demonstrate that the representation of stimulus magnitude can be powerfully reshaped by associative learning processes and suggest that the code for sound intensity within AI can be derived from intensity-tuned neurons that change, rather than simply increase, their firing rates in proportion to increases in sound intensity.

Acoustic Stimulation↗
PubMed2001

Bone-conducted sound lateralization of interaural time difference and interaural intensity difference in children and a young adult with bilateral microtia and atresia of the ears.

Bone-conducted sound lateralization tests to determine interaural time difference (ITD) and interaural intensity difference (IID) were conducted by means of a self-recording apparatus in 20 children and a young adult with bilateral microtia and atresia of the ear. This apparatus changes ITD automatically from 0 to 2,000 micros at 50 micros/s and IID from 1 to 40 dB at 1 dB's. When ITD exceeds approximately 200 micros/s and IID exceeds 5 dB in normal subjects the sounds are recognized separately. The test stimulus was a continuous narrow-band noise at 500 Hz and 30 dB SL applied to the right and left mastoids through bone vibrators. In the patients with bilateral atresia of the ears, ITD results revealed approximately normal thresholds of discrimination in half the patients and IID results revealed threshold elevation in only 10%. It is noted that bone-conducted sound lateralization abilities of ITD or IID are maintained in many of these patients.

Adolescent↗
PubMed2006

Brain-derived neurotrophic factor treatment does not improve functional recovery after hair cell regeneration in the pigeon.

CONCLUSIONS: Brain-derived neurotrophic factor (BDNF) supply to the inner ear does not improve the time course or the extent of functional recovery after hair cell regeneration. Specifically it does not improve the residual threshold elevation observed after the completion of spontaneous recovery. OBJECTIVE: The avian inner ear is capable of hair cell regeneration and substantial functional recovery, but residual hearing deficits remain. We investigated whether functional recovery can be improved by intracochlear application of BDNF, which plays an important role in auditory ontogenesis and maintenance during adult life. METHODS: Hair cells in adult pigeons were destroyed by local application of gentamicin. After 3 days either BDNF or control solution was administered to the scala tympani by implanted osmotic minipumps for 8 weeks. Auditory brain stem responses (ABR) to tone pips were used to assess recovery of hearing thresholds in both groups. RESULTS: The application of gentamicin caused a frequency-dependent hearing loss that ranged from 24.8 dB SPL at low frequencies to 66.2 dB SPL at high frequencies. After day 10 substantial recovery was observed, but a significant threshold shift remained. The time course of recovery in the control and BDNF-treated groups was similar, without significant residual threshold differences in any frequency range.

Administration, Topical↗
PubMed2006

A longitudinal study of electrical stimulation levels and electrode impedance in children using the Clarion cochlear implant.

CONCLUSIONS: Electrical stimulation levels and electrode impedance values (EIVs) in children using the Clarion cochlear implant (CI) programmed with CIS strategy stabilized after 3 months of implant use. The data presented here may be useful as a general guideline for the programming of infants and young children and may further be of help for the identification of patients who fall outside the "average" range. OBJECTIVES: The purpose of the present study was to evaluate changes in electrical stimulation levels, i.e. threshold (T) levels, comfortable (M) levels, dynamic range (DR), and EIVs during the first 18 months of implant use, in children using the Clarion CI. MATERIALS AND METHODS: The maps of 18 pre-lingual children (mean age at implantation 4.2 years; range 1-8), using the Enhanced Bipolar 1.2 or Bipolar standard electrode with the S-Series speech processor programmed with CIS strategy, were examined at five time points: connection, and 3, 6, 12, and 18 months post-initial stimulation. T levels, M levels, DR and EIVs were analyzed according to four cochlear segments: apical, apical-medial, medial-basal, and basal. RESULTS: During the first 3 months of implant use T levels increased to some extent, whereas M levels and DR increased significantly. From 3 months and through the entire follow-up, T and M levels as well as DR were stable. EIVs of current carrying electrodes decreased significantly from connection to the 3-month visit; thereafter a stabilization of values was evident. Electrical stimulation levels and EIVs did not differ among the cochlear segments during the entire follow-up.

Adolescent↗