High-frequency audiometry. Masking of air- and bone-conduction signals

Interaural attenuation has been investigated for both air-conduction and bone-conduction signals in the frequency ranges 0.25-18 and 0.25-16 kHz respectively. Ear canal occlusion is recommended when using the Koss HV/1A earphone for BC masking, as acoustic transmission occurs through the headset in the high-frequency range. Minimum masking levels for 1/3-octave filtered white noise were established for bone-conduction signals in the frequency range 8-16 kHz. Central masking of bone-conduction signals proved to be of the same order of magnitude in the conventional- and high-frequency ranges, while the cross-masking level was approximately 10-15 dB lower above 6 kHz. Recommendations are made for a masking procedure in the high frequency range.