Thermax

I'm trying to help people with tinnitus by making up masking CD's to mask the sound of their tinnitus. I'm working with a tone Generator to help find the frequency of their tinnitus. My question is this, when I'm listening to high frequency tones like 26000HZ can that hurt my ears ? The only info I can find on the web is all related to high volume levels. How would I know when 26000 HZ is to load to be safe? Thank you