Issue with multiple StudioVoiceEmitters

Changes from issue #1 from commit #f8911aa break functionality for more than two voice emitters, due to static _voiceSound.

Steps to reproduce:

1. Load three instances of the game.
2. After the second player joins, voice chat should work as intended
3. As the third player joins, player 2's  _voiceSound's handle is overwritten, and player 2 can no longer be heard by player 1


