Changing with the Times: Re-examining the Aided Threshold Understanding the role of functional gain, real-ear response, and insertion gain in linear and nonlinear fittings

What is the Aided Threshold? During threshold determination, the dispensing professional determines the lowest input level on the audiometer dial that the client needs to barely detect the presence of a sound. Therefore, the aided threshold, logically, is the lowest input level that the client hears (ie, the softest sound) while wearing hearing aids set to a specific gain setting. A related term is the functional gain (FG), defined as the improvement in hearing sensitivity (unaided threshold minus aided threshold) consequent to the wear of the hearing aid in the same listening environment. Historically, this term is necessary because the coupler gain on a hearing aid may not reflect the in-situ gain received by the wearer. The aided threshold, representing the softest audible sound, includes four important concepts: