This parameter was confusing in three ways: 1. It should have been named "lock" because it was used to take and release the sound mutex, not to indicate whether it was locked. 2. In the one place this function gets called the locked argument was set to "true", so not much point in having it optional. 3. I can't imagine that it would ever be a good idea to skip taking and releasing the mutex. Reviewed By: sergey Differential Revision: https://developer.blender.org/D988