1. An in-the-ear (ITE) hearing assistance device adapted to process sounds, including sounds from a wearer's mouth, comprising: a hollow plastic housing adapted to be worn in an ear of the wearer; and a differential sensor mounted to an interior surface of the housing configured to be placed in an ear canal of the wearer, the differential sensor having inlets located within the housing, wherein the differential sensor is configured to improve speech intelligibility of sounds from the wearer's mouth.