[A sound reproduction system using wave field synthesis to simulate everyday listening conditions]

Test procedures used in clinical routine are often not sufficiently accurate to evaluate the auditory benefit of hearing systems and the improvements brought by new signal preprocessing algorithms.The aim of the study was to realize and evaluate a sound reproduction system for simulation of everyday listening conditions.A sound reproduction system was developed using 128 loudspeakers. By appropriate superposition of the loudspeaker signals (so-called wave field synthesis), it is possible to create almost arbitrary everyday listening conditions in a reproducible laboratory setting. Auditory scenes can be changed in real time. The sound reproduction system was mechanically evaluated by measuring the sound field with a microphone array. To validate the system, speech reception thresholds (SRT) were measured in bilateral cochlear implant (CI) users in moving and diffuse noise conditions. Furthermore, the impact of different types of directional microphones on speech perception was assessed.With a moving noise source in the dorsal half-space, CI users showed significant SRT improvements by using directional microphones with higher directional sensitivity (2.5 dB improvement) as well as with adaptive directional sensitivity (8.5 dB). The benefit of adaptive directional microphones is reduced in environments with diffuse noise.Wave field synthesis is a useful tool to simulate everyday listening conditions in a reproducible laboratory environment. This technique can complement established clinical methods to assess the benefit of a hearing device fitting or of signal preprocessing algorithms in dynamic listening conditions.