Untersuchung zur simultanen Chirp-Stimulation in der Hirnstammaudiometrie bei Normalhörenden
Die Verwendung von simultan dargebotenen Reizen und die Aufzeichnung ihrer einzelnen Reizantworten in der elektrischen Reaktionsaudiometrie ist ein bekanntes Prinzip, welches auch in der klinischen Routine schon seine Anwendung findet. Die verwendeten Systeme in der Diagnostik wie z.B. das Eclipse A...
Hals- Nasen- und Ohrenheilkunde
Keine Tags, Fügen Sie den ersten Tag hinzu!
- The simultaneous application of multiple stimuli is a well established method for recording frequency-specific auditory steady-state responses (ASSR). The aim of this study was to determine the normal characteristics of interactions that occur in activating the same area of the basilar membrane by multiple broadband stimuli. In combination with an automated response-detection this can be useful to develop a fast and efficient automated threshold detection. In this study we used two Chirp-Streams with a repetition-rate of 20/s and 22/s. The stimulus levels we used were at 30 dB nHL and 50 dB nHL. Due to the difference of 2 Hz between the repetition rates, the time difference between the stimuli of the two stimulus streams follows a periodic cycling. The cycling period of 0.5 seconds contains ten 20/s-stimuli and eleven 22/s stimuli. The chirps with the repetition rate of 20/s were also presented singly. The results of this study show that the mean amplitudes of the responses to the simultaneously presented stimuli at 50 dB nHL were 82% (20/s) and 84.5% (22/s) of the amplitude of the singly presented stimuli. At 30 dB nHL they are 87.3% (20/s) and 87.2% (22/s). John et al. (1998) reported, that the simultaneously measurement of frequency specific responses is more efficient than the measurement with singly presented stimuli, when their response amplitudes are not less than 1⁄√N (with N= number of the simultaneously presented stimuli) of the response amplitudes to the singly presented stimuli. That means in our case, that they should not be less than 70% of the amplitudes to the singly presented stimuli. Since we have more than 80% of the amplitudes, the results are very promising regarding their use for a automated threshold detection. The study proved that it is possible to record auditory responses to multiple simultaneous stimulation of the same frequency region of the cochlea.