Communication system, communication units, and method of ambience listening thereto

A communication system (300) comprises a subscriber communication unit (310) participating in a call and a monitoring communication unit (320) performing an ambience listening operation of the subscriber communication unit (310) when participating in the call. The monitoring communication unit (320) is configured to request modification of one or more audio quality parameters of the subscriber communication unit (310) whilst performing the ambience listening operation. A monitoring communication unit, a subscriber communication unit and a method of remotely controlling audio parameters thereof are also described. In this manner, a monitoring user/communication unit can adjust audio attributes of a remote subscriber communication unit, for example, to improve speech intelligibility, during an ambience listening call.