Echo-y sound

On my new Windows 7 tower computer, when I plug in speakers or headphones, everything sounds like the bottom of a well. How can I get rid of that?

(Realtek High Definition Audio)
(Windows Home Premium SP 1)

Thanks,

I'd say you have somehow turned on one of the crazy Realtek sound effects (like sewer pipe) see pic



I can't think why those effects are there, apart from pranking your mates.

Thank you. How do I get to the screen you show?

Click the Realtek icon in Control Panel or or right click the icon in Task Bar and choose sound manager.

Control Panel did the trick. Thank you. It was set on auditorium environment.

Glad you got it sorted