誘発耳音響放射測定プローブN-1

抄録

A new model of an acoustic probe N-1for e-OAE measurement was designed by utilizing a box of a behind-the-ear type hearing aid as the power source for its microphone. The probe consisted of an alminium holder connected with a minuature microphone (Knowles, EM3056) and an earphone (Cortitone, 20W). Instead of barrelled tubes in the probe two acoustic holes were bored at the metal plane of the extremity of the probe tip. In the recording of OAE, a plastic earplug of appropriate size was slipped onto the tip of the probe, as in tympanometry.
The frequency sensitivity response curve of the earphone for the input voltage of 1×10^-3W was measured by 2cc coupler (B & K, HA-2) varied within 5dB between 150Hz and 4kHz. While the frequency sensitivity response curve of the microphone for the input of 94dB SPL varied within 10dB in the range from 150Hz to 9kHz. Thus, the probe N-1had anexcellent frequency characteristic similar to that of the probe K-3which we have been usedconventionally.
As for its transient characteristic, this probe produced clear sonud wave forms without any residual oscillation in response to short tone bursts examined at thesound intensity of 10dB nHL when examined in a dummy ear.
In comparison between the results of e-OAE obtained by the probe N-1and those by the probe K-3, there was no difference at all.
The probe N-1 with a case box included a battery weighed 13.5g. The probe securely fitted to the external auditory canal owing to its holding system with the battery case of behind-the-ear type and it was possible to examine OAE at the sitting position. This probe is feasible for performing the examination even in a soundproof room for the single-person use. In consequence it is useful for the measurement of OAE in out-patient clinics.