Clinical evaluation of a programmable three-channel automatic gain control amplification system.

This paper reports on the clinical evaluation of a commercially available head-worn programmable 3-channel automatic gain control (AGC) hearing instrument (Siemens, Triton 3000). A preliminary fitting procedure is developed for the 3-channel AGC amplification system, which is compared by 26 experienced hearing instrument wearers with their own single-channel AGC instruments. The benefits of both amplification systems are assessed by speech audiometry at different signal-to-noise ratios utilizing German rhyme test speech material. In addition, subjective judgements concerning sound quality, speech intelligibility and comparison with the subject's own instrument are evaluated. The results indicate that the multichannel compression instrument is superior to single-channel aids in competitive speech situations. If the 3-channel AGC instrument is used as an automatic noise reduction system in patients requiring a certain amount of low-frequency gain, a markedly better speech recognition can be achieved compared to the subject's personal aids.