Krisp - Mute the background noise during your calls
Noizio - Feeling that the noise of the big city is too much for you to bear?
GitHub Audio - Tracks events across GitHub to generate calming work music
Noisli - Noisli is a fantastic background noise and color generator for working and relaxing. Online soothing ambient sounds like White noise, Rain and Coffee Shop.
A Soft Murmur - Ambient sounds to wash away distraction.
Silence Trimmer - Quickly cut out the silent parts of your media file.