Probe-determined hearing-aid gain compared to functional and coupler gains.

Area of Science:

• Audiology
• Hearing Science
• Biomedical Engineering

Background:

• Accurate hearing aid gain measurement is crucial for effective amplification.
• Traditional methods like coupler measurements may not fully represent real-ear performance.
• Understanding occluded ear canal effects is important for precise gain assessment.

Purpose of the Study:

• To compare hearing aid gain measured by a probe-earmold system with coupler (HA-2, ear simulator) and functional-gain measurements.
• To investigate the influence of occluded ear canal length on gain measurements.
• To evaluate the accuracy of different gain measurement techniques in subjects with moderate sensorineural hearing loss.

Main Methods:

• Fifteen subjects with moderate sensorineural hearing loss were tested.
• Hearing aid gain was measured using a probe-earmold system, HA-2 coupler, ear simulator, and functional-gain measurements.
• An optical method with an operating microscope was developed to measure occluded ear canal length.

Main Results:

• Probe-earmold system gain, corrected for ear canal length, closely aligned with functional and ear-simulator gain up to 4.0 kHz.
• At 5.0 and 6.0 kHz, the probe-earmold system underestimated gain compared to the ear simulator.
• Average differences between HA-2 coupler and functional gain matched previous studies, but individual variation was smaller than reported.

Conclusions:

• The probe-earmold system, when corrected for occluded ear canal length, provides accurate hearing aid gain measurements up to 4.0 kHz.
• Discrepancies at higher frequencies suggest limitations of the probe-earmold system or ear simulator.
• The study highlights the importance of considering ear canal acoustics for precise hearing aid fitting and verification.