What computer operating system is your Premiere Elements 11 running on?
Have you tried to apply the Notch audio effect to your audio file. The Notch audio effect is found under fx Effects/Audio Effects/Notch
Also see description of Notch in Premiere Elements Effects References document
You could also look into the Notch in the free audio editor Audacity
Please review the above and determine if any of that works for you.
I forgot to mention...be working in the Expert workspace and its fx Effects Tabs to get to the Audio Effects.