Tin Can Sound?

Ok PC Audio fans,why does the audio from my pc,either through headphones or the small onboard speakers sound like it's coming from inside a tin can?Almost sounds like some form of reverb is turned on.Thanks for your input.
Maybe reverb is turned on. :^) Most sound drivers include a mixer and dsp settings for effects. Check that and make sure you are setup for 2ch sound. Make sure your speaker and headphone input are from the Front L/R connector on audio outs on mother board or card. Connecting to Rear L/R may cause the software to simulate surround sound and you are hearing generated rear channel audio from 2 ch input. Just some thoughts since you didn't get into too much detail on config.
Excellent suggestions by Larry. Also, are any connections present that could cause you to be listening to the same music via two different signal paths at once? For instance, are line-out and line-in both connected to some external device, such as some sort of recorder, that may be passing its input signal to its output? If so, you need to mute line-in in your volume mixer software when you are not listening to that device.

-- Al
Unless there is some problem with the settings, it's likely just the sound card in your computer. Typically they are not very good. That's why a lot of people are going to an outboard DAC to bypass the internal sound card. And certainly the speakers in your computer are there just there for making those beep and pop sounds the computer makes. Think of the sound system in your computer as competing with a $20 clock radio.
Thanks for your help guys.There was something called Echo Cancellation that was turned on in the SRS Audio program,now sounds much better.Thanks again.