Loudness discomfort levels: a clinical procedure for hearing aid evaluations.

Before any amplification system is evaluated, prescribed, or recommended, the audiologist must determine that the limits of its output across frequency are not greater than the levels at which clients experience discomfort, that is, their Loudness Discomfort Levels (LDL). After reviewing terminology, reasons for obtaining LDLs, and several sources of variability in LDL measurements, a new clinical LDL measurement procedure for hearing aid evaluations is suggested. The main aspects of this procedure are the instructions (from Morgan, Wilson and Dirks, 1974), the stimuli (sweep-frequency pulsed pure tones), the psychophysical method (tracking procedure), the calibration of the stimuli (by a hearing aid receiver attached to a 2 cm3 coupler), and the presentation of the stimuli (through the hearing aid receiver coupled to the client's earmold). This technique is suggested as clinically feasible and as a defensible procedure for obtaining LDLs for the purpose of more closely specifying an appropriate SSPL90 curve.