Air-radiated sound from bone vibration transducers and its implications for bone conduction audiometry

Area of Science:

• Audiology
• Acoustics
• Hearing Science

Background:

• Air-borne sound leakage from bone conduction audiometry vibrators is a known issue.
• Quantifying this effect is crucial for accurate hearing threshold measurements.

Purpose of the Study:

• To quantify the air-borne sound radiation from B70A, B71, and B72 bone conduction vibrator types.
• To assess the impact of this sound on hearing threshold measurements.

Main Methods:

• Sound pressure levels were measured at the ear canal entrance for three examples of each vibrator type on four human heads.
• Measured values were compared to hearing threshold levels using two methods: international standards and direct subject measurements.

Main Results:

• None of the tested vibrators fully met international standards for air-borne sound radiation across all frequencies.
• Significant errors in threshold measurements are unlikely at 3 and 4 kHz when a high-quality earplug is used.

Conclusions:

• Bone conduction vibrator air-borne sound can influence audiometric results.
• Proper use of earplugs, particularly at 3 and 4 kHz, can mitigate potential measurement errors.