Hearing sounds that aren't there is a type of hallucination, and both Zoloft and Prozac can cause hallucinations. In fact, you're supposed to contact your doctor if you have hallucinations as a result of taking Prozac--see what it says under "Prozac Side Effects":

Prozac Uses, Dosage, Side Effects & Warnings - Drugs.com

I hope you'll be in touch with the prescribing doctor so that an adjustment to the dosage can be made, or maybe you'll need to give up on the SSRIs.