Evaluation of the CAMEQ2-HF method for fitting hearing aids with multichannel amplitude compression

A method for fitting multichannel compression hearing aids with an extended high-frequency response, called CAMEQ2-HF, was described by . This study describes an evaluation of the method, using a 16-channel behind the ear hearing aid incorporating slow-acting compression and providing gain for frequencies up to 7500 Hz.

Eleven participants with mild to moderate cochlear hearing loss were fitted bilaterally using the gains prescribed by CAMEQ2-HF. The fittings were checked using real-ear measurements with swept sinusoidal signals, and adjustments were made so that the target gains at the center frequency of each channel were achieved with a typical tolerance of +/-3 dB for an input level of 65 dB and with a typical tolerance of +/-5 dB for levels of 50 and 80 dB SPL. Participants were asked to wear the hearing aids as much as possible in their everyday lives and to fill in questionnaires and a structured diary about their experience of loudness and their listening problems in everyday life, both for listening unaided and after a period of use of the aids.

Scores obtained using the Profile of Aided Loudness (PAL) indicated that the hearing aids led to a clear increase in loudness (relative to unaided listening) for weak sounds and to smaller increases in loudness for sounds of medium and high intensity. For aided listening, strong sounds were typically rated as "loud, but OK." Satisfaction ratings for loudness obtained using the PAL showed only small differences between unaided and aided listening. Responses obtained via the structured diary (for aided listening only) indicated that target speech was usually judged as "loud enough" in a variety of situations. Clarity judgments ranged from "reasonably clear" to "OK" for most situations, but fell to "not very clear" for a noisy group situation. The loudness of background sounds was mostly judged as "OK," except for the noisy group situation in which the background was judged "bit loud." Results from the Abbreviated Profile of Hearing-Aid Benefit questionnaire indicated fewer problems with "ease of communication," "reverberation," and "background noise" for aided than for unaided listening, but more problems with "aversiveness." Nine of 11 ratings of overall sound quality fell in the categories "satisfied" or "very satisfied."

The CAMEQ2-HF fitting method generally led to satisfactory loudness and sound quality in everyday life for people with mild to moderate hearing loss.