Sound wave propagation on the human skull surface with bone conduction stimulation
Ivo Dobrev1, Jae Hoon Sim1, Stefan Stenfelt2
1Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zürich, Switzerland; University of Zürich, Zürich, Switzerland.
Hearing Research
|October 2, 2017
Summary
Bone conduction hearing stimulates the inner ear via skull vibrations. This study found skull bone motion is rigid-body-like at low frequencies but becomes transverse traveling waves above 2 kHz.
Area of Science:
- Biomechanics
- Auditory Neuroscience
- Biomedical Engineering
Background:
- Bone conduction (BC) offers an alternative to air conduction for inner ear stimulation.
- BC stimulation propagates to the cochlea via skull bone and other cranial structures.
- Investigating wave propagation on the skull surface during BC is crucial for understanding auditory stimulation.
Purpose of the Study:
- To investigate skull bone surface wave propagation during bone conduction (BC) stimulation.
- To analyze vibration patterns at the forehead and mastoid locations.
- To characterize the frequency-dependent mechanical response of the human skull.
Main Methods:
- Measurements were conducted on five human cadaveric heads.
- A bone-anchored hearing aid (BAHA) transducer was used for stimulation at the mastoid and forehead.
- Skull vibrations were measured using scanning laser Doppler vibrometry (SLDV) and 3D LDV systems.
Main Results:
- Rigid-body-like motion dominated below 1 kHz, while transverse traveling waves were observed above 2 kHz.
- Surface wave propagation speeds reached approximately 450 m/s at 8 kHz.
- 3D velocity measurements confirmed complex, frequency-dependent skull responses, with normal motion dominant above 2 kHz.
Conclusions:
- Skull bone vibration during BC exhibits distinct low-frequency rigid-body motion and high-frequency traveling waves.
- Transverse deformations and surface waves are significant above 2 kHz, with speeds around 450 m/s at 8 kHz.
- Understanding these wave propagation dynamics is key for optimizing BC hearing aid technology.
Keywords:
3D laser Doppler vibrometryBone conductionFull-field measurementsHuman cadaver headRigid body motionTransverse deformationWave propagationMore Related Videos
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