Hi,
Here is a link to the ifixit guide on how to replace the speakers, in your Flip 2.
It is handy as it shows how to gain access to the speakers to see if they are not secured properly and it is the actual speaker assembly that is vibrating at high volume (when it shouldn't) or if there is a loose connection etc. on them which may be vibrating when the volume is high thus giving the unwanted sound.
Check to see if you can determine which end of the speaker the problem seems to be coming from so that you know which end to look at first when dismantling the speaker.
[guide|60727]