Figure 5

Sound spectrum of the masking noises from the single-sided headphone and the speaker. For the right ear, the sound intensity of noises from the speaker (B, red line) was weaker than that from the headphones (A, red line), at a frequency of 200 Hz to 2 kHz. However, the sound intensity at a frequency around 4 kHz, which is the frequency of the simulated tinnitus, from the right-sided speaker (B, red line), was almost the same as the noise from the right-sided headphone (A, red line). The sound intensity of around 4 kHz or higher was further attenuated in the left ear (B, blue line) than the right ear (B, red line) when the noise was delivered by the right-sided speaker.