Prof. Dr. Jürgen Tchorz, Lübeck
“Frequency lowering algorithms in hearing aids: Fitting options and customer benefit”
One of the main goals of hearing aid fitting is the amplification of the speech spectrum into the audible range. In the high frequencies, this goal is sometimes difficult to achieve as the speech spectrum decreases with frequency, while the hearing loss typically increases. Amplifier gain, acoustic feedback and the frequency response of the receiver limit the amplification achievable. But even if audibility of high-frequency speech portions is ensured, speech intelligibility is not automatically guaranteed: the width of the critical bands of the auditory system increases with sensorineural hearing loss, and thus frequency discrimination, which is important for phoneme discrimination, decreases. Frequency lowering, which transforms high-frequency portions to a lower part of the spectrum, is a potential solution to this issue. By now, many manufacturers provide frequency lowering programs utilising different approaches to frequency transformation.
The talk gives an overview of these methods, their fitting parameters, and the current state of knowledge on the benefit one may expect to gain from frequency lowering.