Altering audio?

Does anyone know how to alter the audio on a video so I can by pass content id?

Audacity + Adobe Premiere Pro should do it easily. Download the audio and video separately (Look for Youtube downloaders in Google. Premiere should have the option to save the audio only, too.. ). Modify the audio using audacity, then sync in premiere.

Edit: If your question was, exactly what to alter.. then I am not sure.. May be try adding some noise, changing pitch etc.