Insertion Gain
The difference in sound pressure level at the eardrum between the aided and unaided conditions, expressed in decibels across frequencies.
Full Definition
Insertion gain quantifies the net acoustic benefit provided by a hearing aid by comparing the sound level at the eardrum with the device in place (aided) against the level without it (unaided). It is a key metric in real-ear measurement procedures and is used to verify that a hearing aid meets a prescribed fitting target such as NAL-NL2 or DSL. Editors should note that insertion gain differs from functional gain, which is a behavioral measure derived from audiometric testing rather than direct acoustic measurement. Negative insertion gain values are clinically significant and indicate that the hearing aid is attenuating rather than amplifying at a given frequency. The term is always lowercase unless it begins a sentence.
Usage
Usage note: Always lowercase. Editors should verify whether the author means 'real-ear insertion gain (REIG)' specifically or is using 'insertion gain' generically; these distinctions matter in measurement-focused articles.
In Context
- "The insertion gain measurements showed a deficit of 8 dB at 3000 Hz, indicating that the high-frequency targets were not being met." — Hearing aid verification report
- "The paper used 'insertion gain' and 'functional gain' as synonyms, which the editor corrected as they reflect distinct measurement paradigms." — Journal manuscript review