Hi Don.

I guess I wasn't clear about signal and noise. I was speaking informally. Indeed, it's not a signal-to-noise problem. The squelch circuits I am familiar with operate to cut off the microphone when the transmitter is keyed, so at most all one receives is carrier, which obviously is discarded upon reception (no signal in the sense of communication information). So, as I believe you described, no background noise is transmitted (noise in the sense of extraneous noncommunicative signal).

The cocktail party effect: I'm not sure whether you're trying to be serious here or not. The cocktail party effect is where one is LESS able to hear due to reverberation. There comes a point where you cannot even hear someone standing very close to you due to all the other conversation. Everyone begins to speak louder and louder, with no improvement in ability to perceive what is being said. Everyone starts to move closer to the people they are trying to listen to, etc. (See, for example: Allan D. Pierce. Acoustics: An Introduction to its Physical Principles and Applications. Acoustical Society of America / American Institue of Physics, 1989, pages 276-277. Originally published by McGraw-Hill in 1981.) Now there may be some psycho-acoustic effect wherein one can still recognize the voice of one's spouse, but I don't have any information on that --- certainly not that this is the definition of the cocktail party effect.

I still think it's premature and arbitrary to rule out the possibility of phone monitoring. The phone monitoring may have been done to gather information IN ADDITION to the fact that "authorities" were being contacted, for example prior to the crime. I wouldn't assume that there was monitoring, either. There really isn't any evidence of it that I am aware of.