Also https://mynoise.net/ under "Sleep Aid". Website author is a brilliant sound guy.
@mynoise <- this guy
@TallSimon @nina_kali_nina @mynoise He also did Purrli, a dedicated cat purr generator: https://purrli.com/
though I must say that I was slightly disappointed to discover that it uses recordings of cats, rather than being a parametric model of a cat’s voice box.
(I would like to see a purely algorithmic cat purr synthesiser, because I suspect that a frequency-variable cat-like purr would make a good alternative to binaural beats for light/sound brainwave meditation machines)
@nina_kali_nina @mynoise @acb Mine have learned that monkey-Dad's magic window just makes that noise every now and then and it's not a feline Kaiju come to eat everyone.
(Although little black stray does check the surroundings just to be sure.)