A behind the ear-wearable speech processor for the Vienna cochlear prosthesis has been designed. In a comparative study 6 patients used the new device for 1 week and were then tested. The results from the auditory test battery and a speech tracking were about the same, only the perception of speech from an open list was better when the patients used the conventional processor. It is possible to reduce the size of a speech processor substantially by modifying the speech-processing strategy without major decrease of the performance. More patients have to be tested after using the device for a longer time.