Binaural masking effects in bone-conducted noise

Area of Science:

• Audiology
• Psychoacoustics
• Auditory Neuroscience

Background:

• Binaural unmasking, the improvement in hearing a sound in the presence of noise due to differences in the sound's presentation to both ears, is well-documented for air-conducted noise.
• The potential for binaural unmasking with bone-conducted noise, particularly when presented at the midline of the forehead, has not been extensively studied.

Purpose of the Study:

• To investigate whether binaural unmasking occurs when pure tones are masked by bone-conducted noise presented at the midline of the forehead.
• To compare the magnitude of binaural unmasking for bone-conducted noise with that of correlated air-conducted noise and monaural noise.

Main Methods:

• Determined the amount of masking for pure tones using narrow bands of noise centered at 240, 500, 910, and 1900 Hz.
• Employed a block up-down two-interval forced choice procedure with four female subjects (under 30, hearing threshold ≤10 dB HTL).
• Calculated the masking-level difference (MLD) by comparing masking levels across binaural and monaural conditions.

Main Results:

• Binaural unmasking effects comparable to those found with correlated air-conducted noise were observed for midline bone-conducted noise.
• The magnitude of binaural unmasking was consistent across the tested frequencies (240-1900 Hz).

Conclusions:

• Midline bone-conducted noise can elicit binaural unmasking effects, similar to air-conducted noise.
• These findings suggest that interaural phase relations of bone-conducted noise play a role in auditory perception.
• The results have potential clinical implications for understanding and diagnosing hearing disorders.