I Habituated Really Quickly

Hi Caff:
Is your ringing a high pitch or low pitch? It seems that the high pitch ringing is the harder one to habituate to. I have a high pitch (almost like dog whistle noise). Unfortunately, the rain or waterfall sounds don't really work. I've used cricket noises, but they're so annoying, you cant go to sleep. Not sure if anyone has any ideas on masking a high pitched ring.

Thanks,
Mark K.