ABSTRACT The recent development of commercial hearing aids with digital signal processing (DSP) capabilities opens the door for an explosive growth in hearing aid sophistication. Current limitations on signal processing design due to hearing aid constraints, and the specialized needs of listeners with hearing loss, result in certain design specifications that any DSP hearing aid must meet. This paper will review the latest state-of-the-art with respect to current DSP hearing aids on the market, with an emphasis on the ReSound programmable DSP hearing aid, developed in a collaboration with GN Danavox and AudioLogic, Inc. Multiband compression, single-microphone processing, multi- microphone processing, and feedback reduction will be discussed.