A mobile communication device (50) receives an audio stream as input and delivers a processed audio stream as output. The mobile communication device has a data connection providing access to the Internet, and a short range data connection for delivering a processed audio stream as output to a specific hearing aid (10). The mobile communication device acquires a data set containing hearing aid settings for the specific hearing aid from a remote server (71), and adjusts the emulation software application by means of the data set containing hearing aid settings for the specific hearing aid (10). The mobile communication device transmits the control signals and a processed audio stream to the specific hearing aid via the short range data connection and the specific hearing aid outputs the audio signal to the user without additional amplification. The invention also provides a method of signal processing in a mobile communication device.