I use this sox command: #!/bin/bash play -q -c 2 -n synth brownnoise band -n 1600 1500 tremolo .1 30 You can adjust the frequency and other parameters

I use this sox command: #!/bin/bash play -q -c 2 -n synth brownnoise band -n 1600 1500 tremolo .1 30 You can adjust the frequency and other parameters to suit your environment. Adding tremolo makes it sound a bit like ocean waves.