Normally, a good dose of cider ('hard cider' to Americans, for some reason) sends me to sleep.
However, if you are like me and you ferment your cider in your bedroom (just in case you need a tipple at 3am and can't wait for it to finish fermenting) then the constant 'plop' 'plop' from the airlock might drive you bonkers.
It certainly drives me bonkers.
Step 1: Make a Muffler
One night, a very vigorous fermentation was 'plopping' away, every second.
I won't even have a mechanical clock, ticking in my bedroom so the cider equivalent is unwanted too.
I took a towel and folded it a few times to make a muffler.
Step 2: All's Quiet on the Cider Front... Almost
The towel muffler is balanced on top of the airlock.
This won't create a seal so the carbon dioxide can still pass through the airlock and the 'plopping' is deadened somewhat.
My demijohn is in my bedroom cupboard and with the muffler in place, I get a good night's sleep.