Method of operating a system having a plurality of electro-acoustic transducers (4,5) deployed in a listening environment, the method determining characteristics of an acoustic field generated by at least one of the electro-acoustic transducers (4,5) of the system, the method comprising: acquiring data for a plurality of zones within the listening environment (7,8), the acquiring data step comprising: measuring sound, produced in response to test signals, supplied to the electro-acoustic transducers, a respective sound measurement being made at each of a plurality of microphone positions within the listening environment (7,8), each test signal comprising a frequency response test signal supplied to one or more of the plurality of electro-acoustic transducers (4,5); for each sound measurement, calculating microphone position data, representing the microphone position relative to positions of the electro-acoustic transducers (4,5), determining frequency response data, detected by the microphone in response to sound, produced by the one or more electro-acoustic transducers (4,5) that receive the frequency response test signal, assigning a weight index to each zone according to the location of each zone within the listening environment (7,8), and calculating a weighted frequency response, based on the frequency response data weighted according to the weight index of the zone encompassing the microphone position. acquiring data for a plurality of zones within the listening environment (7,8), the acquiring data step comprising: measuring sound, produced in response to test signals, supplied to the electro-acoustic transducers, a respective sound measurement being made at each of a plurality of microphone positions within the listening environment (7,8), each test signal comprising a frequency response test signal supplied to one or more of the plurality of electro-acoustic transducers (4,5); for each sound measurement, calculating microphone position data, representing the microphone position relative to positions of the electro-acoustic transducers (4,5), determining frequency response data, detected by the microphone in response to sound, produced by the one or more electro-acoustic transducers (4,5) that receive the frequency response test signal, assigning a weight index to each zone according to the location of each zone within the listening environment (7,8), and calculating a weighted frequency response, based on the frequency response data weighted according to the weight index of the zone encompassing the microphone position. measuring sound, produced in response to test signals, supplied to the electro-acoustic transducers, a respective sound measurement being made at each of a plurality of microphone positions within the listening environment (7,8), each test signal comprising a frequency response test signal supplied to one or more of the plurality of electro-acoustic transducers (4,5); for each sound measurement, calculating microphone position data, representing the microphone position relative to positions of the electro-acoustic transducers (4,5), determining frequency response data, detected by the microphone in response to sound, produced by the one or more electro-acoustic transducers (4,5) that receive the frequency response test signal, assigning a weight index to each zone according to the location of each zone within the listening environment (7,8), and calculating a weighted frequency response, based on the frequency response data weighted according to the weight index of the zone encompassing the microphone position.