People can hear you during loading screens even if your microphone is turned off

[(PSN)Oracle-Raven]

I play on PS4 and use the Ear Force PLa headset from TurtleBeach.
It has two sound volume wheels on the side (one for game volume, and one for chat volume), along with an on/off switch for talking into the headset's microphone.

For Warframe, the chat wheel does nothing. Both in-game volume and in-game voice chat are affected by the wheel for game volume.

I started a game set to public (a simple Nightmare mission on Mercury), and no one but a single person joined in mid-game. There were no other people.
I was listening to music on Spotify, with the microphone switch turned off, and the chat volume wheel set to zero (even though that volume wheel does absolutely nothing in Warframe anyways).

Still, the person asked in chat what was the music he was hearing, meaning he could hear my Spotify music through my headset's microphone, even though it was turned off.

Based on past experience where I could hear other people's microphones during loading screen (and no longer once I had joined the game and took control of my character), I suspect he might have only been able to hear me during his loading screen (where you fly around in your landing craft) while he was still joining my game (I was host).

EDIT:
Not sure if relevant, but I have a wired connection, and my controller's battery was almost empty.
My headset is plugged via its USB cable (I don't use its Red & White analog RCA cables) into a Nexxtech 4-port 2.0 USB Hub on my PS4's second USB port at the front. Also I'm on the original PS4, not the PS4 Pro.

Edited May 6, 2019 by (PS4)Oracle-Raven

[(PSN)jester_of_clubz]

I use Turtle Beach Stealth 400's, wireless with a PS4 Pro, also with the dual wheel adjusters and a mic on button. The reciever plugs into a USB port and the other small wire with the tiny square jack, sorry I forget the name, into the audio on the tv. Anyway, I was playing one night, on public, which I very rarely do, and I guess the chat volume wheel was not turned down. Suddenly, a voice goes, "Hey, man stop breathing so loud into your mic." I was totally shocked then realized that what he was hearing was my mic brushing against the couch pIllow, because of how I had it folded up out of the way. I have always had a problem with the mic turning istelf on and off. Usually, I catch it, because I can hear the side tone hissing in the little mouth reciver. I've tried every setting that I can find to fix this, in game, and on my old and now new tv and on every game that I play. It just persists. It was worse on my PS3. At one point, I stuck a pencil eraser over the mic to silence the hiss. Also, if I forget to take them off and go outside to walk the dog quickly, they start saying 'mic on-mic off' repeatedly. This led me to believe that my issue was the wireless, I guess it is via bluetooth, connection. Coversely, I have not experienced hearing folks with my chat volume turned down. 

Sorry that I have no solution, but since we both have Turtle Beach products I figured I would speak up.