Comparison of loudness adjustments by MCL and maplaw in users of the MED-EL COMBI 40/40+ cochlear implant system.

The programming of a CI speech processor involves measurement of electrical threshold and 'most comfortable loudness' (MCL) levels on each electrode. However, when the derived 'map' is activated the resultant percept is often too loud or too soft. In this situation, adjustments of MCL settings are usually made in order to achieve a comfortable percept.The present study examined the range of volume control adjustments in 24 users of the MED-EL C40/40+ device. Volume control settings varied from 36% to 126% with a mean of 84.3% (SD = 20.4%). Additionally, the output compression function ('maplaw') was adjusted to test whether this alternative manipulation could result in a comfortable percept. It was found that this could be achieved satisfactorily, with maplaw values ranging from 10 to 2000. Clinical implications of these findings are discussed.