Remote AudioSource has an echo

[Ollydbg]

The remote audio source still has an echo, even after I tried playing the audio remotely to process it through the AudioProcessing module.

Specific steps:

Join the room on device A and subscribe to the track.
Join the same room on device B, but do not subscribe to the track. Create an audio track on device B and play a WAV file through AudioSource.
Expected result:

The WAV file's sound should not be heard on device B.
The sound should be heard on device A, synchronized from device B.
Actual result:

Device A can hear the sound.
Device B hears an echo.

I suspect it has something to do with the way Unity renders sound.