The waveforms and parameters of electrically evoked auditory brainstem responses, eeABRs, registered in cochlear implant users, were compared with those of acoustically evoked auditory brainstem responses, aeABRs, recorded in normally hearing subjects. The eeABRs, in contrast to the aeABRs, contained dubious Wave IV, while missed Waves VI and VII. The eeABRs possessed also shorter peak-latencies, shorter inter-peak intervals, and greater amplitudes. The revealed differences have been explained by the lack of cochlear mechanisms in cochlear implant recipients. On the other hand, eeABRs and aeABRs exhibited similar stimulus intensity dependence. Both had also lower thresholds, shorter peak-latencies, and greater amplitudes in females than in males.

Background. Numerous people with cochlear implants (CI) report difficulties in listening to music even though they understand speech quite well. One reason for this is a limited perception of pitch and timbre. In this study ability of adult CI subjects to discriminate musical pitch is investigated.Patients and methods. In two psychoacoustic experiments, each conducted in 10 adult CI subjects provided with MED-EL Combi 40+ cochlear implant devices and a control group of subjects with normal hearing, individual discrimination abilities for musical pitch perception were determined. To investigate the influence of the group of instruments on discrimination ability, stimuli representing four different groups of instruments were used: woodwind (clarinet), brass (trumpet), strings (violin) and keyboard instruments (piano).Results. The discrimination thresholds determined varied between individual CI subjects, and on averaged they were significantly higher for the piano than for the other three instruments.Conclusions. The results show that in subjects with CI pitch perception differs from instrument to instrument and is in general worse than in persons with normal hearing.

Zahlreiche Träger von Kochleaimplantaten (CI) berichten trotz guten Sprachverständnisses über Probleme beim Musikhören. Eine Ursache dafür liegt in einer eingeschränkten Wahrnehmung von Tonhöhe und Klangfarbe. In dieser Studie wird die Diskriminationsfähigkeit von erwachsenen CI-Trägern für musikalische Tonhöhen untersucht.

Introduction. Most acoustic neuromas (AN) originate from the inferior vestibular nerve (IVN). Vestibular evoked myogenic potentials (VEMP) are accepted as the only unilateral test for the function of the sacculus and the IVN.Methods. The influence of the origin from the IVN and superior vestibular nerve (SVN), and the position of the AN in relation to the internal auditory canal on VEMPs was investigated. A total of 39 patients (aged: 30-67 years, mean: 53 years) were examined. The VEMPs were recorded on the activated sternocleidomastoid muscle and averaged over 200 stimuli. Tone bursts (95 dB nHL; 500 Hz; stimulation rate 5 Hz) were used to generate the VEMPs.Results. The exact origin of the AN from the SVN or the IVN could be determined intraoperatively and correlated using VEMP in 28 patients.Conclusion. The origin of the AN has only a marginal influence on the results of VEMP measurements. The position of the AN in relation to the internal auditory canal seems to have more influence than the origin.

In 2/3 der Fälle geht ein Akustikusneurinom (AN) vom N. vestibularis inferior (IVN) aus. Die vestibulär evozierten Muskelpotenziale (VEMP) stellen den einzigen einseitigen Test der Sakkulusfunktion bzw. des innervierenden IVN dar.

INTRODUCTION:Most acoustic neuromas (AN) originate from the inferior vestibular nerve (IVN). Vestibular evoked myogenic potentials (VEMP) are accepted as the only unilateral test for the function of the sacculus and the IVN.METHODS:The influence of the origin from the IVN and superior vestibular nerve (SVN), and the position of the AN in relation to the internal auditory canal on VEMPs was investigated. A total of 39 patients (aged: 30-67 years, mean: 53 years) were examined. The VEMPs were recorded on the activated sternocleidomastoid muscle and averaged over 200 stimuli. Tone bursts (95 dB nHL; 500 Hz; stimulation rate 5 Hz) were used to generate the VEMPs.RESULTS:The exact origin of the AN from the SVN or the IVN could be determined intraoperatively and correlated using VEMP in 28 patients.CONCLUSION:The origin of the AN has only a marginal influence on the results of VEMP measurements. The position of the AN in relation to the internal auditory canal seems to have more influence than the origin.

Einleitung: In der Routine erfolgt zur Diagnose einer akuten peripher vestibulären Störung eine einseitige kalorische Reizung des horizontalen Bogenganges. Bei Unerregbarkeit dieses Bogenganges wird ein einseitiger Gleichgewichtsausfall postuliert. Eine genaue Testung der einzelnen Anteile des Vestibularorgans, besonders der Otolithenorgane, erfolgt aufgrund des hohen apparativen Aufwands bisher nur selten. Die Registrierung der vestibulär-evozierten Muskelpotentiale (VEMP) erlaubt erstmals eine einseitige Testung der Sakkulusfunktion.

Die sichere Bestimmung des Hörvermögens bei kleinen Kindern ist nach wie vor problematisch. Ideal wäre eine Methode, die mit geringem Personal- und Geräteaufwand eine zuverlässige frequenzspezifische Hörschwellenbestimmung zulässt. Mit Hilfe der Amplitude Modulation Following Response (AMFR) könnten die diagnostischen Möglichkeiten verbessert werden.

This article presents a simple method of analysing speech test scores which are biased through ceiling effects. Eighty postlingually deafened adults implanted with a MED-EL COMBI 40/40+ cochlear implant (CI) were administered a numbers test and a sentence test at initial device activation and at 1, 3, 6, 12 and 24 months thereafter. As a measure for speech recognition performance, the number of patients who scored at the ‘ceiling level’ (i.e. at least 95% correct answers) was counted at each test interval. Results showed a quick increase in this number soon after device activation as well as a continuous improvement over time (numbers test: 1 month: 51%; 6 months: 73%; 24 months: 88%; sentence test: 1 month: 33%; 6 months: 49%; 24 months: 64%). The new method allows for the detection of speech recognition progress in CI patient samples even at late test intervals, where improvement curves based on averaged scores are usually assuming a flat shape.

Auditory P300 potentials obtained in cochlear implant users were evoked with tone bursts designed to reflect the frequency stimulation patterns of intracochlear electrodes. To visualize these stimulation patterns in MED-EL COMBI 40+ cochlear implants, we calculated color-coded plots of the charge of each stimulus pulse as a function of time and stimulation channel (stimulograms). The aim of this study was to investigate the effect of stimulation patterns on event-related potentials, such as the P300. The influence of electrode separation on the P300 response in postlingually deaf adults using a cochlear implant is demonstrated in two examples.

Amplitude modulation following responses (AMFR) to single near-threshold 40-Hz or 80-Hz amplitude-modulated tones of 1 kHz were recorded in 48 normal children between the ages of 2 months and 14 years. Children under the age of 2 years were tested during natural sleep, and older children were tested awake. The objectives of this study were to find out how the AMFR changes with age and to determine the most effective modulation frequency for objective threshold assessment at different ages. The optimal modulation frequency changed from higher to lower modulation frequencies at about 13 years. In younger children, the 80-Hz AMFR was larger than the 40-Hz AMFR. The 40-Hz response became similar to the adult response by the age of 14 years, while the 80-Hz response had an amplitude greater than half of an adult response by the age of 1 year, changed very little during the investigated period, and reached the amplitude of adult responses at the end of the investigated period.

Zusammenfassung Derzeit ist die Registrierung von Hirnstammpotenzialen die am weitesten verbreitete Methode zur Bestimmung der Hörschwelle im Rahmen der objektiven audiologischen Diagnostik. Dieses Verfahren ist jedoch mit einer Reihe methodischer Probleme verbunden: mangelnde Frequenzspezifität bei einer breitbandigen Stimulation, geringe Aussagekraft im tieffrequenten Bereich und hohe Subjektivität der Auswertung.Eine Lösung könnte die Registrierung von Amplitude Modulation Following Responses (AMFR) darstellen. Mit ihrer hohen Frequenzspezifität aufgrund ihrer sehr schmalbandigen Stimulation lassen sie Aussagen bis in den niederfrequenten Bereich des Hörens zu.Einen weiteren Vorteil stellt der objektive Nachweis dieser Potenziale auf Basis etablierter statistischer Verfahren dar.Umfangreiche Untersuchungen zum Einfluss der Stimulationsparameter und der Ableitbedingungen haben gezeigt, dass die Registrierung von AMFR als audiologisches Werkzeug erfolgversprechend ist. Im Vordergrund standen bisher Fragen nach der optimalen Modulationsfrequenz, dem Einfluss der Vigilanz auf die Potenzialausbildung und der Nutzung bei der objektiven Bestimmung der Hörschwelle.

The registration of brainstem potentials currently represents one of the most common methods in objective audiological diagnostics. However, regardless of their use, they are still known to possess important disadvantages, such as low specificity and validity in the lower frequency range due to broadband stimuli, or uncertainties due to the need for subjective evaluation. One potential solution to these problems could involve the registration of amplitude modulation following responses (AMFR). These potentials are being discussed much more regularly within the anglo-american literature due to their known frequency specificity within the high frequency range (resulting from a very narrow frequency band of stimulation), and also their ability to permit assessment of the hearing threshold at lower frequencies. Another additional advantage of AMFR results from the simple statistical verification of its presence.Extensive studies on the influence of both stimulating and recording parameters have also shown that the registration of AMFR could prove to be a very promising audiological tool, with past interest being focussed primarily on the optimal modulation frequency, the influence of vigilance of the generation of potentials, and the precise assessment of an objective threshold.

There have been several studies, which suggest that the amplitude of amplitude modulation following responses (AMFR) is correlated to the state of vigilance, similar to the 40 Hz event-related potentials. The aim of the present study was to compare the dependency of the AMFR-amplitude from the state of sleep for 40 Hz and 80 Hz modulation frequency. Eight normal hearing adults were investigated during natural and drug-induced sleep. The stimuli used were sinusoidally amplitude-modulated tones of 1 kHz carried frequency and 40 or 80 Hz modulation frequency at 60 dB nH stimulation level. For 40 Hz modulation frequency an increase of EEG-activity in the Delta-and Theta-band during periods of sleep correlates significantly with a decreased AMFR-amplitude whereas for 80 Hz no significant relation between stage of sleep and AMFR-amplitude could be found. The results suggest that in audiological use of 40 Hz-AMFR the state of vigilance should be monitored and stabilized at a high level.

A non-linear technique is predominantly used for the recording of transiently-evoked otoacoustic emissions (TEOAEs). The aim of this study was to compare linear and non-linear TEOAE recordings. TEOAEs were recorded in 22 normal hearing subjects to clicks from 90 to 30 dB SPL in 10 dB steps with the ILO88 system using both linear and non-linear recording techniques. The non-linear recording technique reduces stimulus artifacts for early latencies, but total elimination could not be proved. Both artifact reduction and significant differences between the two kinds of TEOAE recordings were reduced for longer latencies and lower stimulus intensities. For longer latencies (>10 ms) there was no significant difference between "linear" and "non-linear" TEOAEs. A higher signal-to-noise ratio was found for "linear" TEOAEs, resulting in better identification and a higher test-retest correlation. The linear recording technique, which includes new methods of artifact cancellation in comparison to the mainly utilized non-linear recording technique, should be used especially in hearing screening.

Amplitude modulation following responses (AMFR) allows good estimation of the hearing threshold due to the very narrow band excitation of the cochlea. Audiological use of AMFR requires knowledge of the relationship of these responses to the state of vigilance. The few studies published compared only qualitatively the amplitude of AMFR recorded in awake subjects to that recorded in sleeping subjects. A quantitative determination of the level of vigilance on the basis of recorded physiological parameters has not yet been carried out. In the present study, the relationship between the amplitude of AMFR and the level of vigilance was investigated quantitatively.In eight adults with normal hearing, the relationship between the AMFR amplitude and EEG amplitude in the delta- and theta-band was determined. The amplitude in both frequency bands was used to indicate the state of vigilance. The subjects were studied during natural and drug-induced sleep. A 1-kHz carrier tone with a sinusoidally modulated amplitude of 40 Hz or 80 Hz was used as stimulus.At 40-Hz modulation frequency, the AMFR amplitude correlates with the EEG amplitude both in natural and drug-induced sleep. An increase in EEG activity is paralleled by a significant reduction of AMFR amplitude. At 80-Hz modulation frequency, no relationship between AMFR amplitude and EEG activity could be detected. Under all conditions, the amplitudes of AMFR evoked by a modulation frequency of 80 Hz were significantly lower than those evoked by 40 Hz.These results suggest that for an audiological use of the 40-Hz AMFR the state of vigilance should be stabilised at a constantly high level. In spite of the lower influence of vigilance on the 80-Hz AMFR, this response appears less ideal for threshold estimation in adults due to the significantly smaller amplitudes.