The incoming signal still has to be higher than the squelch setting. That is why a lower squelch setting betters the odds of not hearing the companding. The resultant companding can always be heard if listening for it. Anytime the incoming signal from the transmitter falls below the squelch threshold, it will gate the audio. It is not as noticeable when you have a hot signal and the ends of the words are sharp. If it does it to all five units, then it is one of two things. A low transmitter level allowing for the squelch to gate the signal, or the squelch being set too high for the level that the transmitter is sending. Again though, if you have a quiet signal coming into the receiver you will hear the companding.
The HH mic having better results than the Lav mics is no surprise really. The HH will have a less sensitive capsule that is more directional and is invariably closer to the source of noise. You can usually run a lower sensitivity level with the HH mics and since the source audio is pretty loud in comparison to the background noise, companding is hard to notice. With Lav mics, it is further from the source and much more sensitive. It picks up a lot of the background noise. So as the speaker ends a word the tail of it can become part of the background noise. Since you also have to have a higher sensitivity setting with a Lav mic the background noise is higher as well. This background noise when someone talks softly can be gated by the companding if it falls below the threshold.
It is something to try in a better environment one day. Setthe squelch fo rthe lowest setting it has and talk really quietly into the mic. It should be pretty hard to hear the companding. Now as you raise the squelch higher and higher, you should notice the gating much easier and easier. It is a threshold setting like that of a gate, so it requires a certain level of incoming noise before it opens up. Which also means it will cut of words that have a soft ending too.
While I appreciate your explanantion, it's not really addressing what I hear.
Let me try to explain better. This is not and RF signal level isue.
I put a HH and lav on the table and listen to the background room sound.
The HH works as expacted but the lav needs a little bit of noise to get it to "open".
RF signal is full on and squelch settings have no effect on the audio abberation.
It's so noticable that my web cast guy wanted to know if I was gating.
Took one of the offending TX packs home and set up a test.
Of course, now the lav works as expected and I can hear "room" tone with no "gating" effect.
Another interesting note is that i walked the room and saw the audio peak light flash on the pack and while monitoring with headphones, heard nothing that I caould connect to the light coming on.
Not a bad cable or handeling noise.
Not happening at home.