A comparison of functional gain and 2 cm3 coupler gain

Area of Science:

• Audiology
• Hearing Science
• Acoustics

Background:

• Hearing aid gain is crucial for audiological rehabilitation.
• Standard 2 cm3 coupler measurements provide a benchmark but may not reflect real-world performance.
• Individual patient factors and fitting characteristics can influence functional gain.

Purpose of the Study:

• To empirically determine the difference between individual functional gain and 2 cm3 coupler gain for wide-band hearing aids.
• To identify and quantify known measurement differences contributing to this discrepancy.
• To assess the impact of earmold type (occluding vs. non-occluding) on functional gain.

Main Methods:

• Empirical measurement of functional gain in 20 hearing-impaired adults.
• Comparison of functional gain with 2 cm3 coupler gain.
• Analysis of contributing factors: coupler response, real-ear response, earmold acoustics, and sound field pressure differences.

Main Results:

• Accounting for known measurement differences provided a reasonable estimate of the median difference between functional gain and coupler gain.
• Significant individual variability in functional gain was observed, even after accounting for known factors.
• Both occluding and non-occluding earmold fittings were evaluated, with differences noted.

Conclusions:

• While standard measurements offer a baseline, individual functional gain in hearing aids exhibits substantial variability.
• Accurate hearing aid fitting requires consideration of individual patient responses beyond coupler measurements.
• Further research may be needed to fully understand and mitigate individual variability in hearing aid outcomes.