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Biomedical subjects

H Stiglbrunner

Publications and source records attributed to H Stiglbrunner.

6 recordsLinked to original sources
PubMed1991

Acoustic reflex in patients with cochlear implants (analog stimulation).

Stapedius reflexes were tested in 21 deaf patients with the Vienna cochlear implant using intra- or extracochlear electrodes. Sinusoidal bursts of 125, 500, 1,000 and 2,000 Hz were used as stimuli presented in a randomized sequence. The contralateral acoustic reflex was monitored by synchronized sampling of the acoustic impedance of the ear. Results obtained were compared to psychoacoustic sensation values. The reflex threshold always was located close to the uncomfortable loudness level within the subjective dynamic range, or at least above the most comfortable loudness level. Practical applications of reflex testing and limitations of the method for use in children are discussed.

Adolescent↗
PubMed1990

Stapedius reflex growth function in cochlear implant patients.

The growth function of the contralateral stapedius reflex elicited by analog electrostimulation via cochlear implant was investigated in 9 patients and compared to reflex functions obtained for acoustic stimulation in 3 normal-hearing subjects. Sinusoidal signal bursts with the same time pattern were used for the two stimulation modes, the contraction of the middle ear muscle was monitored by sampling the compliance change in the contralateral ear. The reflex amplitudes were found to increase with increasing stimulus intensity in all individuals except in 1 with electrical stimulation. The slope of the intensity function for electrostimulation ranged between 5 and 85%/dB and in the acoustical mode between 2 and 4%/dB. In case of electrostimulation a frequency effect was observed.

Acoustic Stimulation↗
PubMed1990

Dynamic range of the contralateral stapedius reflex in cochlear implant patients.

The dynamic range of the contralateral Stapedius reflex elicited by analog electrostimulation via cochlear implant was investigated in 8 subjects supplied with a Vienna prosthesis. The study comprised patients fitted with intracochlear devices as well as patients with extracochlear devices. Sinusoidal bursts of 125, 500, 1,000 and 2,000 Hz were used as stimulation signals. Only in one patient was saturation of reflex amplitude observed. The dynamic range of the Stapedius reflex was defined either by the difference in stimulus level for reflex saturation or individual uncomfortable loudness level and reflex threshold. Two different methods were used, yielding values between 0.1 and 12 dB, with a median of 4 dB. The individual results were compared with individual psychoacoustic quantities, i.e. subjective dynamic range (difference between sensation threshold and uncomfortable loudness level) and residual dynamic range (difference between most comfortable loudness level and uncomfortable loudness level). The reflex dynamic range is located within the residual dynamic range of electrostimulation. Thus the Stapedius reflex dynamic range can be applied as a rough estimate of minimum residual dynamic range.

Acoustic Stimulation↗
PubMed1988

Stapedius reflex threshold in cochlear implant patients.

The contralateral stapedius reflex elicited by sinusoidal electrostimulation via cochlear implant was investigated in 12 patients. Contraction of the middle ear muscle was monitored by time-resolved synchronized digital sampling of the impedance change in the contralateral ear. The reflex was detected in all patients in whom the uncomfortable loudness level (UCLL) could be reached and who had intact middle ear function. Generally, the reflex threshold is located in the upper part of the dynamic range between the most comfortable loudness (MCL) and the UCLL. The demonstrated method may provide suitable assistance in speech processor adjustment in difficult-to-test patients.

Adult↗