Analysis of the Acoustic Transcranial Bone Conduction

Area of Science:

• Skull acoustics
• Bone conduction hearing
• Auditory implants

Background:

• Understanding sound transmission through the skull is crucial for optimizing bone conduction hearing devices.
• Bone Anchored Hearing Aids (BAHA™) offer a solution for hearing loss, but optimal placement and sound transmission pathways require further investigation.

Purpose of the Study:

• To analyze preferential sound transmission pathways and wave properties within the skull.
• To identify optimal skull locations for bone conduction to the cochlea.

Main Methods:

• Utilized nine cadaveric heads in an anechoic chamber.
• Instrumented with six Bone Anchored Hearing Aids (BAHA™) implants and fifteen accelerometers.
• Measured cochlear response via laser velocimetry on the round window during frequency sweeps.

Main Results:

• Low-frequency sound predominantly travels via frontal pathways; high-frequency patterns were less defined.
• Optimal sound transmission to the cochlea occurred between 1000 and 2500 Hz.
• Implant location on the skull did not significantly affect sound transmission.

Conclusions:

• A distinct frontal transmission pathway exists for low frequencies, but not high frequencies.
• Skull implant location has no significant impact on ipsilateral or contralateral sound transmission.
• Findings contribute to optimizing BAHA™ device performance and patient outcomes.