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By Design



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[Linux] Unity picks up system sounds with Microphone.Start when no microphone is connected



Reproduction steps:
1. Download and open the attached project: ""
2. Enter Play Mode
3. Play a system sound e.g. raise the volume

Expected result: You can only hear the system sound
Actual result: You can hear the system sound and Unity playing it back as well

Reproducible with: 2018.4.32f1, 2019.4.20f1, 2020.2.5f1, 2021.1.0b7, 2021.2.0a4

- Tested on Ubuntu 18.04
- Reproducible in Editor and Player
- Ensure no microphone is connected to the system when reproducing the issue
- Does not reproduce on 11.1 or 10.15.7 macOS
- Unable to test on Windows due to Windows not asking for microphone permissions or the Editor freezing upon entering Play mode

  1. Resolution Note (2021.2.X):

    We have to close this issue and call it "By Design", even though that is far from what is desired. We were hoping to address the problem by making changes to FMOD and prevent it from calling down to PulseAudio when we can figure out that there is actually no microphone attached. However, it seems that the problem PulseAudio had to distinguish whether a mike was attached or not were very real, and cause by how devices are reported by Linux itself. In FMOD we therefore hit the same wall. I'm going to leave a request on the PulseAudio forums to look into this, but I doubt whether they can do much given all this. In fact, I see various related complaints there already, some fairly old. The only way around this problem for now would be to have a high-level toggle that prevents calling sound code paths when a microphone is (known to the human) not attached.

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