Figure 7

Sound spectrum of the inside-head (monaurally recorded) and outside-head (binaurally recorded) masking noise. (A) inside-head noise, (B) outside-head noise. For the right channel, the sound spectrums of the inside-head (monaurally recorded) noise (A, red line) and the outside-head (binaurally recorded) noise (B, red line) were identical. For the left channel, the sound spectrum of the inside-head noise (A, blue line) maintained the same shape as the right channel (A, red line), whereas the sound intensity decreased at 4 kHz or higher with the outside-head noise (B, blue line) compared with the right channel (B, red line).