The SPL hearing meter.
An instrument, the SPL Hearing Meter, was devised for the measurement of hearing threshold with a hearing aid earphone in order to make a direct comparison between the hearing threshold and the output sound pressure level of a hearing aid. The author found this a handy tool for selection and adjustment of hearing aids.
D001298:Audiology / Q000295:instrumentation*; D001309:Auditory Threshold; D004867:Equipment Design; D006310:Hearing Aids; D011312:Pressure; D013016:Sound