When I call someone or someone calls me, my voice sounds like the chipmunks. I have to hang up and call again to correct the problem. I have a pro 9000.

* Right click on the speaker icon (bottom right of taskbar)
* Click on recording devices
* Select the webcam microphone
* Click Properties then select the Advanced tab
* Under "Default Format" select something other than the default option (which is probably 48k Hz).
* Click Apply
* Then go back to the 48k Hz and click Apply.

1) make sure your mic is set as default
TEST SPEAKERS
Right click on speaker icon in System Tray or from Control Panel
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 (webcam) 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
2) Check you have DirectX 9 or later installed to support your cam
3) You may have to re-install the software - browse the photo gallery and click on your model - check out any known problems as well

http://www.logitech.com/index.cfm/405/&cl=us,en?prodcrid=405