A hearing assistance system having an audio signal wireless transmission unit for transmitting a stereo audio signal with left and right ear channels, a first ear unit for being worn at a user's ear and having a hearing instrument and a wireless audio signal receiver unit, the hearing instrument providing the first receiver unit with information as to which ear of the user the hearing instrument is being worn and information as to whether, or not, there is a like second ear unit. The first receiver unit is adapted to decide, depending on the received information as to which ear the first hearing instrument is fitted and whether a second ear unit is worn at the other ear, to receive one of the right and left ear channels, and, in absence of a stereo channel, to supply the respective mono channel of the audio signal to the first hearing instrument.