Open the "Actions" menu and click "Call Setup" to open the "Call Setup Assistant." Follow the instructions on the screen to test your sound system.

You can also manually test your system:

1. Left-click the Speaker icon in your system tray (on the bottom-right corner of your screen) one time and raise the volume bar to the top. Make sure "Mute" is not checked. (If the icon is not there, click "Start" and select "Settings," "Control Panel," then "Multimedia" or "Sounds and Multimedia." Make sure that the "Show volume control on the task bar" option is checked and click "OK" at the bottom of the window).
2. If that's not sufficient, double-click the Speaker icon. Make sure that none of the options are muted and that all levels are turned above 50%.
3. Click "Options," "Properties," then "Recording" and click the "OK" at the bottom of the window. Make sure that "Microphone Balance" is the only option selected and the level is turned up above 50%.
4. Close the window and try to use Yahoo! Voice in Yahoo! Messenger.

Perform this simple test to determine whether your microphone and speakers are connected and adjusted properly:

1. If you are currently in a voice chat conference, close the conference window.
2. Close any other programs you have open that might be using your microphone or speakers.
3. Click the Windows "Start" button in the lower-left corner of the screen.
4. Select "Programs," "Accessories," then "Entertainment" or "Multimedia" and click "Sound Recorder."
5. Click the Record button (a red circle), say a few words into your microphone, then click the Stop button (a black square). While recording, you should see the sound waves from your voice displayed on the strip chart at the top of the Sound Recorder window.
6. Click the Play button (a black triangle) to hear what you just recorded.
7. If you don't hear anything but see the sound waves from your voice, then something is wrong with your speaker setup. If you don't see the sound waves from your voice, then the problem is with your microphone setup.

If you encounter an error along the way, you can also manually perform these tests:

1. Left-click the Speaker icon in your system tray (on the bottom-right corner of your screen) one time and raise the volume bar to the top. Make sure "Mute" is not checked. (If the icon is not there, click "Start" and select "Settings," "Control Panel," then "Multimedia" or "Sounds and Multimedia." Make sure that the "Show volume control on the task bar" option is checked and click "OK" at the bottom of the window).
2. If that's not sufficient, double-click the Speaker icon. Make sure that none of the options are muted and that all levels are turned above 50%.
3. Click "Options," "Properties," then "Recording" and click the "OK" at the bottom of the window. Make sure that "Microphone Balance" is the only option selected and the level is turned up above 50%.
4. Close the window and try to use Yahoo! Voice in Yahoo! Messenger.

If you have any further problems, please contact the company that made your computer for help setting up your speakers and microphone correctly.