Accuracy and precision of direct bone conduction measurements

Area of Science:

• Audiology
• Biomedical Engineering
• Hearing Implant Technology

Background:

• Variability in Baha® sound processor fittings is influenced by implant-to-bone transmission and transcranial attenuation.
• Single-sided sensorineural deafness presents unique challenges for predictable Baha® fittings.
• Accurate bone conduction thresholds are crucial for optimizing Baha® system performance.

Purpose of the Study:

• To evaluate the predictability of Baha® sound processor fittings using direct bone conduction measurements.
• To assess the reliability of the BC Direct feature in measuring individual bone conduction thresholds.
• To compare direct bone conduction measurements with traditional transcutaneous audiometric thresholds.

Main Methods:

• 138 adult Baha® System users participated in the study.
• Direct bone conduction thresholds were measured using the BC Direct feature of Cochlear™ Baha Fitting Software and BP100 sound processor.
• Test-retest reliability was assessed in 58 participants.

Main Results:

• Direct bone conduction measurement confirmed improved sound transmission via the implant compared to transcutaneous methods.
• BC Direct thresholds were generally closer to unmasked audiometric thresholds.
• In single-sided deafness, BC Direct results showed elevation due to transcranial attenuation, consistent with expectations.
• Test-retest reliability for BC Direct measurements was within ±5 dB, meeting audiometric standards.

Conclusions:

• Direct bone conduction measurement offers a validated approach to compare audiometric transcutaneous thresholds with Baha® processor responses.
• Baha® fittings based on direct bone conduction measurements may necessitate less fine-tuning.
• This method enhances understanding of bone conduction sound pathway variability, leading to improved patient outcomes.