Abstract
The increasing complexity of the non-linear signal processing of modern hearing aids makes the use of clinical assessment of hearing aid benefit more and more important. The paper discusses the general structure of such studies with regard to choice of test subjects, reference hearing aids and the advantage of double-blind and cross-over design. Assessment should contain at least the three dimensions: perceived hearing aid benefit (preferably including perceived sound quality and preference between test and reference aids), speech recognition in noise, and electroacoustic verification by means of real-ear measurements.