This script uses sox (invoked as "play") to simulate various soothing ambient sounds via synthesising noise and manipulating it
Original idea from https://unreasonable.org/white_noise_generator_with_sox_for_Linux - and definitely worth visiting for more ideas in the comments
Also discussed on fb and IRC in 2016, and revisited again 2023
Notable thanks to IRC's Neale and Paul
- Only minimal effort has been made to make the various sound themes consistent in invocation options or style - and most important as an issue: volume
- Many themes throw WARNs to stderr
- Many themes have an unpleasant audio glitch at start