I have been using the same Plantronics BT Headset with my HP laptop and BT USB dongle running 12.04 since 12.04 came out. Just in the last week or two I have started to have a problem where playing sound through the headset when in Chrome causes the sound (and video if watching Youtube or similar) to play in slow motion. If I switch off of the BT headset and keep playing the sound, it stays in slow motion. If I refresh the page, it plays properly. I've noticed this happening with Google Hangouts too.
Trying things in FF seems to be fine, and switching Youtube to HTML5 doesn't seem to help. This problem seems to coincide with a change to Ubuntu that has given me two BT icons in my task bar instead of one. I tried researching why that happened and came up empty there too. This could be a straight up chrome issue, but I thought I would go the Ubuntu + BT route for investigation first.