A primary reason for using a prescriptive hearing instrument fitting approach with infants and young children is that they cannot give the audiologist information about how well the hearing instrument performs or how much of speech is audible through the hearing instrument.
Historically, amplified sound field and/or functional gain measures were used to verify the adequacy of a hearing instrument fitting. These test procedures have numerous shortcomings including the fact that the measures are not sensitive to many of the signal processing differences across hearing aids.
Scollie and Seewald (2002) provides a comprehensive discussion of the efficacy of the two most common techniques used to verify hearing instrument performance (amplified sound field thresholds [ASFT] and probe microphone measures).
For a verification technique to be effective for children it must be able to accomplish the following goals:
The following table summarizes a comparison between the different evaluation techniques.