[hyperpallium]

White noise generators (aka static), there's e.g. an open source android app ("chroma doze" - named for adjustable freq distr by colour bars), or a fan works too.

I need quiet to concentrate, but curiously find the background conversation of a busy cafe just as good as absolute silence - and far better than people whispering, or eating apples, crisps or celery in an otherwise quiet area... Celery

[_wiv7]

I've wondered if I'm unusual in finding white noise mentally exhausting.

[loco5niner]

You are not alone. For me, it activates my tinnitus if the source is close enough to my ears. Even before it started doing that, it was just plain annoying.

[maxxxxx]

You are not unusual. White noise bothers me a lot too.

[multimedial]

try www.noisli.com, it is free and offers different noises. The loops of the individual sound files are very long so that you won't notice when they repeat.