Comparison of three procedures for initial fitting of compression hearing aids. I. Experienced users, fitted bilaterally

Abstract

We compared the effectiveness of three procedures for the initial fitting of hearing aids with multi-band compression: (1) CAMEQ, which aims to amplify speech so as to give equal loudness per critical band over the frequency range important for speech intelligibility, and to give similar overall loudness to 'normal': (2) CAMREST, which aims to amplify speech so as to restore 'normal' specific loudness patterns, over a wide range of speech levels; (3) DSL I/O, which aims to map the dynamic range of normally hearing people into the reduced dynamic range of hearing-impaired people, with 'full' restoration of audibility. Ten experienced hearing aid users with moderate sensorineural loss were fitted bilaterally with Danalogic 163D digital hearing aids, using each procedure in turn; the order was counterbalanced across subjects. The fitting required specification of gains for input levels of 55 and 80 dB SPL at six centre frequencies. Real-ear measurements were made to ensure that target gains were reached (+/-3 dB). Immediately after fitting with a given procedure, and one week after fitting, the gains were adjusted when required by the minimum amount necessary to achieve acceptable fittings. The amount of adjustment required provides one measure of the adequacy of the initial fitting. On average, the adjustments were smallest for the CAMEQ procedure. The gain changes were slightly larger for the CAMREST procedure and were largest of all for DSL I/O. For the latter, the gain changes were mostly negative, especially for high frequencies and the higher input level. This indicates that the DSL I/O procedure prescribes more high-frequency gain than is preferred by adult users. After these gain adjustments, users wore the aids for at least three weeks before filling out the APHAB questionnaire and taking part in laboratory measurements of the speech reception threshold (SRT) for sentences in quiet and in steady and fluctuating background noise at levels of 60 and 75 dB SPL. Following these tests, the hearing aids were re-fitted with the next procedure. The scores on the APHAB test and the SRTs did not differ significantly for the three procedures. We conclude that the CAMEQ and CAMREST procedures provide more appropriate initial fittings than DSL I/O.

Evaluation of a method for enhancing interaural level differences at low frequencies

“…This difficulty is only partly alleviated by the use of hearing aids (Moore et al, 2001). Moreover, hearingimpaired listeners achieve less binaural gain in intelligibility than normal-hearing listeners when the speech and background sources are spatially separated (Levitt and Rabiner, 1967;Bronkhorst and Plomp, 1989;Koehnke and Besing, 1997;Richards et al, 2006;Moore et al, 2010a).…”

The Desired Sensation Level Multistage Input/Output Algorithm

“…Clinical trials that have compared DSL[i/o] with alternative fitting procedures generally have shown that adults prefer less gain than prescribed by DSL, either from a lower-gain prescription such as CAMFIT (Moore et al, 2001) or from a patient-driven procedure that customizes gains to preference (Lindley and Palmer, 1997).…”

“…Clinical trials that have compared DSL[i/o] with alternative fitting procedures generally have shown that adults prefer less gain than prescribed by DSL, either from a lower-gain prescription such as CAMFIT (Moore et al, 2001) or from a Between 1999 and 2000, we entered into a clinical collaboration with two audiology clinics that routinely used the DSL Method v4.1 with their adult populations. The audiologists at these clinics were interested in beginning a routine hearing instrument outcome test battery, in part because of the recent attention outcome measurement has received in the literature (e.g., Humes, 1999).…”

“…Some studies show positive and acceptable results (Humes, 1999;Hornsby and Ricketts, 2003); others show good speech recognition but higher loudness ratings than would be ideal (Lindley and Palmer, 1997;Alcántara et al, 2004;Smeds, 2004). Higher loudness ratings tend to be more pronounced with higher-level inputs or higher frequencies, or both.Clinical trials that have compared DSL[i/o] with alternative fitting procedures generally have shown that adults prefer less gain than prescribed by DSL, either from a lower-gain prescription such as CAMFIT (Moore et al, 2001) or from a Between 1999 and 2000, we entered into a clinical collaboration with two audiology clinics that routinely used the DSL Method v4.1 with their adult populations. The audiologists at these clinics were interested in beginning a routine hearing instrument outcome test battery, in part because of the recent attention outcome measurement has received in the literature (e.g., Humes, 1999).…”

The DSL Method for Pediatric Hearing Instrument Fitting: Historical Perspective and Current Issues

“…In addition, since the release of the computer-assisted implementation of DSL v4.1 in 1997, anecdotal reports from clinicians, research studies in our laboratory, and published studies indicated some modifications could be applied to the algorithm for more appropriate adult application (e.g., Moore et al, 2001).…”