Search

Purpose of this essay is to provide a historical overview how music has dealt with the emotion and sensation of pain, as well as an overview over the more recent medical research into the relationship of music and pain. Since the beginnings of western music humans have put their emotions into musical sounds. During the baroque era, composers developed musical styles that expressed human emotions and our experiences of nature. In some compositions, like in operas, we find musical representations of pain. During Romanticism artists began to intrude into the soul of their audience. New expressive harmonies and styles touch the soul and the consciousness of the listener. With the inception of atonality dissonant sounds where experienced as a physical pain.The physiology of deep brain structures (like thalamus, hypothalamus or limbic system) and the physiology of the acoustic pathway process consonant and dissonant sound and musical perceptions in ways, that are similar to the perception of pain. In the thalamus and in the limbic system music and pain meet.The relationships of music and pain is a wide open research field with such interesting questions as the role of dopamine in the perception of consonant or dissonant music, or the processing of pain during music listening. Musicology has not yet embarked on a general investigation of how musical compositions express pain and how that has developed or changed over the centuries. Music therapy, neuro-musicology and the performing arts medicine are scientific fields that offer a lot of ideas for medical and musical research projects., (© Georg Thieme Verlag KG Stuttgart · New York.)

Objective: The simple insight in the central serotonergic activity would allow a more specific pharmacotherapy of disorders with serotonergic deficits and could thus serve as a predictive parameter. An antidepressive treatment could be chosen due to the verification or falsification of such a deficit with a serotonergic or noradrenergic substance. In search of predictive parameters we have investigated the loudness dependence of auditory evoked potentials (LDAEP), a parameter that has already been discussed concerning this matter, and serotonin levels in the human blood serum regarding their correlation., Methods: Eight outpatients of a lithium clinics were investigated neurophysiologically after blood samples had been taken., Results: A significant negative correlation between LDAEP and serotonin level in the serum was found, a low serotonin level correlates with a high LDAEP., Conclusions: The result of this pilot study justifies further investigations with larger sample sizes. In case of further and stable evidence the use of serotonin levels in the serum as a predicitve parameter is conceivable.

Background: Cochlear implants (CI) convert acoustic events into electrical pulses. The auditory nerve picks these tiny electrical pulses up and sends them to the brain. The dynamics of the audible sound is compressed considerably. The limits for stimulation are determined with the patient. A map law determines which sound pressure level is assigned to which stimulation level. A sufficient speech understanding requests an allocation of high stimulation levels for weak sound signals. The higher the sound level, the lower the increase. Unfortunately, with such kind of map law unwanted background noise is also presented as well audible stimulation. These stimuli are often annoying to CI users in everyday situations., Patients and Method: The possibility to give an s-shaped course to these map laws was examined in 9 patients. After the fitting procedure their speech understanding were tested. The results were compared with the results of former tests., Results: 8 patients reported definite improvement of their hearing situation. Such map laws seem, therefore, suitable to optimise speech processor programming.

Introduction: Tinnitus is one of the most common symptoms in patients with profound sensorineural hearing loss (SNHL). Cochlear implantation (CI), which has become a standard method to rehabilitate profound SNHL, has been also observed to effect tinnitus in many cases. In the Salzburg Cochlear Implant Center,more than 230 profoundly deaf patients, mainly children,have been provided with CI between 1992 and 2000., Patients and Method: In a retrospective study, 39 adult patients were assessed by questionnaire for the frequency of tinnitus, subjective loudness sensitivity, and tinnitus-specific impairment before and after the CI., Results: Before implantation 26 patients had tinnitus, while 24 patients had the same symptoms after the CI. In 13 patients (50%) tinnitus remained unaffected by the operation. Intensity of tinnitus decreased in seven patients (26.7%), and in four patients (15.4%) it completely disappeared after the implantation.However, intensity increased in two patients (7.7%), and in another two patients, who had not experienced tinnitus before, it began first after the implantation. No correlation has been found between the daily using time of CI and the tinnitus impairment.Also no effect of tinnitus was seen on postoperative hearing assessed by Freiburg numbers, monosyllables, and Innsbruck sentence test scores., Conclusion: CI significantly reduces the subjectively perceived impairment, although the reduction in the subjectively perceived loudness of the tinnitus is not significant.

Category loudness scaling was used to investigate the loudness perception of 31 patients with a cochlear hearing loss (Group 1) by comparing the results with those found in 15 patients with retro-cochlear hearing loss caused by an acoustic neuroma (Group 2). Narrow-band noise signals at four different frequencies (0.5 to 4.0 kHz) were used. In the cochlear hearing-impaired subjects the slopes of the level-loudness functions tended to increase with increasing hearing loss, indicating positive recruitment, whereas the much shallower slopes associated with retro-cochlear lesions were presumed to reflect negative recruitment. The graphic representation of the iso-loudness functions revealed a different dynamic range between Group 1 and 2 with the ability to discriminate small differences of stimulus levels reduced in the presence of an acoustic neuroma. Category loudness scaling has been shown to be a valuable tool describing the individual perception of sound in a qualitative and quantitative manner. Furthermore, the method can be employed as an indicator of recruitment without any restrictive preconditions. For this reason the categorical loudness scaling can be a desirable method for supplementing the audiological diagnosis of a retro-cochlear hearing impairment through the frequency-specific description of a usable hearing-field and its dynamic range.

The present paper provides a brief review on topical issues of auditory physiology. Recent data on transduction mechanism and adaptation in hair cells as well as on the possible role of outer hair cells in amplifying basilar membrane motion are presented. Strategies of present physiological research in dealing with sensorineural deafness are discussed.

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.

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.

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.

Background: The purpose of the study was to examine the latencies between tonal stimuli and response of normal ears at the threshold compared with ears with a frequency-specific threshold above 70 dB., Patients and Methods: Reaction times to tonal stimuli of 122 adults with normal hearing and adults with hearing loss were compared at the threshold of hearing to reaction times beyond the threshold. The study group of tested patients was divided into four groups corresponding to the frequency-specific hearing loss on the basis of previous audiometric investigations., Results: The results reveal that response latencies in ears with normal hearing asymptomatically approach the auditory threshold. In contrast, we failed to measure a significant prolongation of reaction times in presence of extensive hearing loss (above 70 dB) even at the minimum level of auditory perception. In the presence of extensive hearing loss (above 70 dB), we detected a significantly lower rise of threshold response latencies at normal audiometric frequencies than in normal ears., Conclusion: The reaction time results are evaluated, and the possible role of the outer hair cells are discussed.

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.

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.

Noise-induced temporary impairment of cochlear function was measured with several audiometric tests in order to evaluate which method best predicts a vulnerable cochlea. We tested 10 normally-hearing and 13 subjects who were positive for temporary threshold shifts (TTS). The latter were selected from 194 soldiers who demonstrated a TTS higher than 15 dB after regular training with firearms. Acoustic distortion products (DPOAE), click-evoked otoacoustic emissions (TEOAE), upper limit of hearing (ULH) and pure-tone and high-frequency audiometry were used to evaluate possible increased vulnerability of the cochlea. Tests were conducted at lower sound intensities (white noise, 90 dB SPL, 5 min; impact noise, 100 or 106 dB SPLs, 10 impulses/s, 5 min). Seventy per cent of the TTS-positive soldiers studied exhibited significant reductions of TEOAE amplitudes, whereas a stable emission was observed in all control subjects. DPOAE alterations were seen in 38% of the soldiers tested. These results indicate that TEOAE is the most sensitive, objective method for detecting a positive disturbance in cochlear function. Although the upper limit of hearing was also a very sensitive method, variability of this psychoacoustic method depended on the help and experience of the subjects being tested.

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.

To investigate the dynamic properties of human hearing, experiments in vivo and with cadaver specimens can be carried out. Furthermore, electrical or mechanical models can also be used to study specific phenomena and parameter sensitivities. Present electrical and mechanical models are often based on crude structural and kinematic simplifications in which testing is restricted to static loading or simplified investigations. To investigate both static and dynamic behavior of normal and pathological ears spatial mechanical models have to be established. The different parts of sound transmission--i.e., airborne sound, elastic membranes, fluids, and ossicles have to be represented by different mechanical systems. In this investigations, a rigid body model of the middle ear was investigated. For verification, simulation results with respect to static loads were compared with measurements reported previously by Hüttenbrink. In further investigations, the dynamic behavior of the model will be evaluated. Models for the tympanic membrane and inner ear will also be formulated in order to create a compositive model that describes the whole hearing process. By so doing the successful development of prostheses as well as diagnostic methods will be supported.

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.

Direct loudness scaling has been known as an audiological tool for about four decades. Although numerous publications have shown its clinical importance, loudness scaling has not been used in audiology and hearing aid fitting until now. This might be due to the lack of audiometers equipped with loudness scaling devices as well as missing evidence for its clinical applicability. In this study normal data for a single-step direct scaling procedure were established and loudness determinations of 105 patients with sensorineural hearing losses collected. The results show that normal level loudness functions exhibit very similar shapes for narrow band stimulation in the frequency range of 500 to 4000 Hz. However, loudness scaling is affected by the gender of the subjects: females scale systematically louder than do males. In hearing-impaired subjects the slopes of the level loudness functions tend to decrease with increasing hearing loss, indicating negative recruitment. This holds particularly true in the high-frequency range, e.g. at 4000 Hz. Our long-term experience with single-step direct loudness scaling has proven its clinical feasibility in typical patients of an audiology unit. Loudness scaling will prove useful for the localization of hearing impairments, as it can be employed as a quantitative indicator of recruitment without any restrictive preconditions. In addition, it allows the evaluation of hearing aids and cochlear implants by frequency-specific gain measurement.

The electrical stimulation of the acoustic nerve is essential for evaluating patients for cochlear implants. Different tests are used to assess the performance of the cochlear nerve in a deaf ear. The use of category scaling of loudness leads to a more efficient test routine.

The acoustic result following reconstruction of the middle ear is often disappointing and unpredictable. Apart from biologic factors, this is due to insufficient knowledge of the mechanism of sound transmission through the operated middle ear. Therefore, temporal bone experiments with simulated middle ear operations were set up to investigate the sound transmission following different prosthesis' designs, materials, etc. We developed a tiny hydrophone which has a frequency range from 100 Hz to 10 kHz in order to measure the sound pressure in the cochlear fluid. By comparing the sound pressure in the inner ear with the sound pressure at the drum membrane, we were able to analyze the transfer function of the manipulated middle ear. First results with different reconstruction techniques, prosthesis' designs and attachments demonstrated the usefulness of this measuring technique for the development of acoustically better middle ear reconstructions.

Distorsion product otoacoustic emissions (DPOAE) are generated by a continuous bitonal stimulation of the cochlea. The resulting emissions are measurable in a definite mathematical function of the primaries (mf1 +/- nf2; f1 < f2). In humans sound emission at the frequency 2f1-f are usually detectable. To determine if a disturbance of DPOAE-amplitude is associated with a cochlear lesion in the frequency region of the evoked emissions or the primaries, we performed suppression experiments using normal-hearing, healthy probands (n = 14). DPOAE were measured in the frequency range between 800 Hz and 8 kHz with different sound-pressure levels for the primaries. Evoked emissions for each proband were measured with these different stimulus parameters to determine baseline values. In suppression experiments sound emissions were evoked continuously with different stimuli between 800 Hz and 8 kHz, disturbed simultaneously with a third tone of 1, 2 and 4 kHz and then compared with baselines. Suppressor tones (1, 2, 4 kHz) reduced significantly the DPOAE amplitudes in the frequency region of the geometric mean of the primaries. This indicates that a reduction of the emission amplitude in associated with a cochlear lesion near the generation site of the DPOAE. The suppression curves exhibit a sharp and steep graph, indicating their relation to cochlear frequency selectivity.

Psychoacoustic tuning curves (PTC) can be regarded as filter curves, whereas their forms represent hair cell activity. Different influences--for example, noise, toxins, pharmacological causes and age--can change the PTC as a consequence of changed frequency selectivity without indication of deterioration in the audiogram. The objective of this investigation was to determine the visually perceivable change in the PTC as a quantifiable result. In so doing, the PTC was transformed into a hyperbola characterized by a parameter Q5. An example demonstrates the temporal change of Q5 under the influence of pharmacological drugs.

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.

We investigated the influence of varying compliance of the tympanic membrane on the sound pressure level of the human ear canal using a model with adjustable compliance. Decrease of compliance augments the sound pressure close to the tympanic membrane due to the increase of reflected sound pressure. This augmentation occurs in a narrow frequency area near the maximum resonance frequency and reaches 6 dB (SPL). These experimental data correlate well with clinical investigations in patients with middle ear effusion before and after operation and in patients performing the Valsalva manoeuvre.

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.

The authors developed a surgical approach to the acoustic nerve enabling the introduction of an electrode into the acoustic nerve. A multichannel electrode was implanted by this method in a deaf patient. The receiver casing for percutaneous transmission was fixed in the mastoid. Encouraging hearing results were obtained over a period of two months by electrical stimulation of the acoustic nerve.

It was the aim of this study to settle the problem whether the post-stimulatory pattern of the extent of excitation (amplitude, latency) registered with the cortical evoked potentials can be verified in the recovery phase via leads from the brain stem region and cochlea. In this context electrophysiological measurements with human and animal material were performed. After a five-minute stimulation with a wide-band noise of various intensity we examined in the post-stimulation phase the specific stimulus pattern of the evoked potentials during an interval of 5 minutes with a resolution of 5 sec. We determined the change in response patterns of evoked potentials. Finally, the relevance of the results with regard to various nuclei of the auditory pathway is compared with corresponding electrophysiological measurements of the cochlear microphonics potentials, the VIII nerve compound action potential, and evoked potentials of different units of the brain stem and brain.

Using a category scale we measured the loudness of narrow band noises experienced in 3 age groups (15-23, 33-45, and 60-75 years old). The narrow band noises had center frequencies between .125 and 8 kHz with sound pressure levels of 60, 75, and 90 dB each. We found the well-known high-frequency loss. However, we also found a hypersensitivity at middle frequencies correlated with high-frequency loss. The presumable causes of this hypersensitivity and its consequences for hearing aid fitting will be discussed.

In psychoacoustical and electrophysiological experiments the time resolution ability in monaural and binaural hearing was investigated for defined signal parameters. The binaural stimulation is characterized by signals of different structure (dichotic stimulation). With regard to different functional changes in the peripheral and central areas of the hearing organ caused by presbycusis, these investigations confirm that there are similar changes in time resolution processes which may influence speech discrimination in presbycusis to a high degree. In patients with sensorineural hearing loss time resolution ability was reduced only slightly. No defined correlation between lack of time resolution ability and type or degree of hearing loss could be established.

The binaural summation of the simultaneous contra- and ipsilateral acoustic stapedius reflexes was examined in 20 normal-hearing patients. In these patients, the effect of summation was most pronounced with subthreshold intensities. A contralateral reflex was increased by ipsilateral intensities 8 db below threshold. A reflex could also be elicited by binaural intensities which were contra- and ipsilaterally 4 db below threshold. As a result of our studies, we recommend a revision of the definition of a positive Metz-recruitment. Because of possible binaural summation effects, the absolute value of the contralateral stapedius reflex threshold should not exceed 105 db HL in spite of possible sensorineural hearing loss.

This review presents recent findings on the micromechanics of the basilar membrane. Active processes are essential for basilar membrane motion. It may be that contractile proteins within the outer hair cells play an important role for this amplification. The coding of acoustic information within the auditory nerve depends on spectral analysis (place information) as well as on the time structure of the stimulus. This latter time analysis seems to play a major role.

The Nucleus 22-electrode cochlear implant should be fitted individually for both pitch and loudness. Loudness is related to the charge delivered, and is usually controlled by current amplitude. In special cases the loudness may be influenced by stimulation mode and pulse width. 3 examples demonstrate optimal fitting with low current intensities, using these possibilities. In addition the threshold level and comfortable level date were analysed over a 2-year period. No significant changes were found, indicating that electrical stimulation caused no damage to the remaining auditory nerve fibres.

In a noisy background the vocal intensity increases (Lombard reflex). The same effect is produced by binaural masking. We demonstrate the regulation of the vocal intensity in the beginning of phonation in eight normal subjects by Hilbert transformation via an FFT analyser. The signals were recorded under normal conditions and with binaural masking. The results are discussed.

Using the autoradiographic technique for water-soluble substances, the uptake of 3H-2-deoxyglucose (2-DG) was measured in the inner ear tissue. The experiments were performed on 26 albino rats (22-27 days). 10 microCi/g b.w. of 2-DG were applied i.v. and the control group was immediately kept in the Camera silens in darkness. The main group was exposed to pink noise (50 Hz - 10 kHz of 60-110 dB). 8 unilaterally sympathectomised animals were exposed to pink noise of different intensity after 24h. The highest uptake of 2-DG independent of the intensity of noise was observed in the cochlear lateral wall (stria vasc., sp. lig., sp. prominentia) in the basal turn and decreased to the apical turn. The uptake in the lateral wall increased from 30-40 dB to 60dB and decreased from 60 to 80 dB exposure. The region of the inner hair cells was clearly marked by 80 dB. With increasing intensity of noise exposure, 2-DG uptake in the spiral ganglion increased continually. Unilateral sympathectomy did not result in any significant difference in the uptake of 2-DG. Therefore, the hypothesis that the decrease of 2-DG uptake in the lateral wall may be due to sympathico-adrenergic vasoconstriction is not verified by our results.

Contradictory histological findings in patients with deafness following mumps led us to conduct electrophysiological investigations. Promontory testing (PT) and measurement of cochlear microphonics (CM) enabled us to distinguish between neural and sensory deafness. On the basis of a careful history and serological tests in 19 cases of unilateral deafness we found that the hearing loss was probably caused by mumps. In all patients except one auditory sensations could be obtained by electric stimulation of the acoustic nerve whereas no CM were detectable even with strong stimuli of 100 dB tonepips. In view of the electrophysiological findings, doubt is cast on the neural genesis of deafness following mumps as assumed by Lehnhardt (1962).

Twenty ears of normal-hearing subjects are investigated as to the influence of highpass filtering on latency, amplitude, and shape of auditory evoked brain stem potentials. For this purpose, three different Bessel-filters (steepness 24 dB/octave) with lower cut-off frequencies at 100, 200, and 300 Hz (3-dB down points) and an upper cut-off frequency at 3 kHz are used. Spectral composition of brain stem potentials is analyzed by digital filtering based on Fast Fourier Transformation. Results show decreasing latency and amplitude of the negative wave between Jewett V and VI with increasing lower cut-off frequency. With higher edge frequencies we find attenuation of wave V relative to wave IV amplitudes. For that reason we must assume that an essential part of brain stem activity is located below 300 Hz. In our experience moderate highpass filtering seems to be useful in neurological cases to eliminate low frequency components of the signal. In that way potentials I -- V are easy to be identified and interpeak latencies can be determined without any problems. For objective threshold determination, however, brain stem potentials should be derived preferably with broadband filter settings to improve correlation of tone audiometric hearing loss (at about 3 kHz) and brain stem response threshold. A filter set with different lower cut-off frequencies has proved to be really useful in routine work. However, it must by taken into account that highpass filtering means an alteration of the original response in any case.

A successful cochlear implant demands a functioning auditory nerve. A subjective and qualitative recording can be obtained by promontory testing (PT) whereas cochlear microphonics (CM) give information about the status of the hair-cells in the inner ear. The results of both tests together show different patterns: in sensory deafness in which a cochlear implant is indicated, no CM and no compound action potentials (CAP) can be obtained, whereas the patient reports hearing sensations (PT positive) in response to promontory testing. Deafness caused by lesions close to the second neurone of the auditory pathways can be localized by preserved CM and CAP, but there is no response to promontory testing. A ganglionic deafness ie. of the first neurone can be distinguished by preserved CM, absent CAP and a negative PT. The combined results of electrocochleography and promontory testing help in deciding whether a cochlear implant is indicated, and in localising the origin of the deafness, eg. neural or sensorineural. The possible results are illustrated by examples.