The sound of running water
I will not brook the babbling of fools...
but for solace listen to the babbling brook
I was told that one of the most soothing sounds for humans is of rain falling.
A quick google reveals that "Our species evolved where trees met savannahs and where freshwater sources were present. Our brains are deeply encoded with the love of water – we revel in the delicious feel and noise of burbling brooks…" So if you can't make it down to the brook, substitute this micro version and find comfort.