Hi,
Method 1: Let’s update the webcam drivers and check if the issue persists. Refer to the link provided below to install the drivers for hardware that isn't working properly.
‘Update a driver for hardware that isn't working properly’
http://windows.microsoft.com/en-US/windows7/Update-a-driver-for-hardware-that-isnt-working-properly
You may download the latest drivers for the webcam from the following link.
http://www.logitech.com/en-us/435/7075
Method 2: If the above step did not help then follow the steps below and check if that helps,
a) Open Sound by clicking the Start button, and then clicking Control Panel. In the search box, type sound, and then click Sound.
b) Click the Recording tab, click Line In, and then click Properties.
c) Click the Listen tab, uncheck Listen to this device, and select 'Disable automatically to save power' and then click OK.
d) Click on Advanced tab and under Exclusive Mode, uncheck the 'Allow application to take exclusive control of the device'.
Method 3: Refer the following to troubleshoot the audio issues on the webcam and check if that helps.
You may also refer the following link for more information.
‘Tips for fixing common sound problems’
http://windows.microsoft.com/en-US/windows7/Tips-for-fixing-common-sound-problems