Limitations and Uses of the Aided Audiogram

Performance characteristics of hearing aids can be assessed through a variety of methods, including word recognition, sound quality and intelligibility judgments, probe-microphone measurements, aided sound-field thresholds, and functional gain. This article focuses on the use of aided sound-field thresholds and outlines many of the limitations of these measurements such as poor reliability, susceptibility to circuit and amplified room noise, time consuming nature of the measurements, the lack of any information about maximum output levels in the ear, and the restriction of only reflecting amplification for low-level inputs. A procedure that maps amplified speech signals into the residual dynamic range and provides information on maximum output levels is recommended as a more reliable and clinically useful alternative. Situations where aided sound-field measurements would seem to be justified include use with bone-conduction devices, cochlear implants, and middle ear implants. Even in these situations, however, the limitations of the measurements must be recognized.

KEYWORDS

Functional gain - aided sound-field thresholds - nonlinear circuitry - sound-field calibration - cochlear implants - middle-ear implants - probe-microphone measurements - DSL procedure

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