Hi, I've noticed a lot of streamers have white/background noise on their streams. Here's a short guide on how to remove it.
1. Open OBS
2. Click on the cog next to your microphone input
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3. Click on filters
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4. Click on the '+'
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5. Click 'Noise Suppression'
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6. Click ok and tweak the level of suppression to your liking. From my experience the default value works just fine.
This also works on StreamlabsOBS it just looks a bit different.
I would also recommend adding a noise gate along with this, this will stop your mic from picking up every small noise you make. This also works on mumble under 'Settings' -> 'Audio Input'.