Ultimately the sensing microphone should be placed so that it’s picking up as much of the ambient noise as possible and as little of the speaker program as possible. The sensing microphone needs to “hear” the ambient sound within the controlled space. It is vital that you place the microphone where it primarily picks up a majority of noise rather than the paging or music that is going through the system. Do not locate the sensing microphone near a localized noise source that is not typical of the ambient noise level of the controlled zone, for example, the noise from a large machine of some sort, or maybe a kids play area, or a video game. If you do this the 371 will think that the zone is noisier than it really is.