Honestly your solution is probably already the simplest unless you're short for disk space. Maybe someone knows a way to make Ubuntu create a special file that

Honestly your solution is probably already the simplest unless you're short for disk space. Maybe someone knows a way to make Ubuntu create a special file that contains a buffer with brown noise, like one of those old tape to CD converters, so that the system sees a music file but it just keeps going. It sounds like a lot of work. Using 'play -n synth brown' is easy if it's an option. I'd probably use a sound file if it were harder.