I install a gear head web cam but the other person

You do not say what your OS is, if your computer is laptop or desktop or what program you want to chat in

Set up Audio

Laptop x webcam/mic x Vista x Yahoo Messenger

If you have an earlier OS, you may have to access your hardware from the Control Panel.

TEST SPEAKERS
Right click on speaker icon in System Tray
Select "Playback Devices"
The speaker icon ( checked as working) and volume level graph should be visible
Right click on the volume graph and click "Test"
Left hand speakers followed by right hand should be heard

SET DEFAULT & TEST MIC
Click "Recording" tab.
To set required mic as default - click on mic font to highlight and click "Properties"
In lower dropbox display "Use this device enable" click OK
Click "Levels" tab and ramp up sliders ( adjust to suit later)
Return to "Recording". Test mic by speaking and make sure volume graph displays
Restart computer
CONFIGURE TO MESSENGER

Open messenger - on top toolbar. Left click ( > ) Messenger > Preferences > Connection - Select 'no proxies' or 'connect direct to the internet' depending on the version of messenger you have
make sure your internet connection and country are correct in the lower two boxes > Apply > OK

Click ( > ) Messenger > Preferences > Calling and Audio
Set mic and speakers to show Default equipment
Run call up assistant to test audio equipment > Apply > OK

Other chat programs are less intensive for audio set up - Skype and MSN can be navigated via the 'Tools' option on the toolbar.