Some people are very sensitive to noise, and others are not, so its hard for us to know what your lens is doing.
I'd return or exchange it if you can. If you bought it used, you may be stuck with a failing IS ... or it may last forever.
You can send it to canon for a check, however, before you do that, see if you can find a similar lens to try as a comparison. If they sound alike, then your lens is likely normal and the sound just resonates with your sensitive hearing.