Sound echos too much

I added btns for connection for voice between 3 players where the first player creates and joins the room and the other players join simultaneously. Now in first player, he is able to talk to all at once and also the rest 2 separately like the PTT demo in photon voice. The second and the third player only can talk to first by subscribing to audio group 12 and 13. The initial setup works but when launched on android platform it echo's in its own voice. The first player is constantly echoing after the sec or third joins. The echo is able to stop only when I click on the btns(talk to all or separate) to form connection(btn clicks from all players). What is the problem here and how do I fix it. Please ask if it is not clear.