I found this on the web. It may not help but worth a try.
They also say that skype mutes the windows mic because you would hear an ehco.
SKYPE-->Tools-->Options-->Sound Devices-->(untick) Enable Automating Sound Device Adjustment Settings-->Save
(You need to quit SKYPE first before you continue below):
After downloading and installing you may try toggling AGC via the config.xml file found in:
To find Config .xml copy and paste:
%AppData%SkypeSkype logon name in the address bar of Windows Explorer or IE and it will display all files, regardless of whether they’re hidden or not
Find one entry in the <Call> and one in <General>
<Call>
<AGC>1</AGC>
And
<General>
<AGC>1</AGC>
* To turn off AGC, set both values to 0. If the entries are missing in the file, add them). Save and close the file once done. Make sure you don't have Skype running while making any changes to config.xml (important!). When AGC is turned off you can also make changes to the microphone volume value (decreasing it may improve sound quality for the receiver e.g. reduce noise and increasing it will make you more audible). AGC by itself is a feature that controls volume automatically based on conditions and is activated by default because in most conditions it provides the best sound quality.
Now you need to check your Shared.xml file
copy and paste: %AppData%Skype in the address bar of Windows Explorer and it will display all files, regardless of whether they’re hidden or not.
In <VoiceEng> You need to insert <AGC>0</AGC> (see below)
<VoiceEng>
<AGC>0</AGC> <----------ADD this line and set to zero
MicVolume>255</MicVolume>
</VoiceEng>
255 is max volume and 0 = low. Range is 0 (off) to 255 (maxim)
255 could be much too high, so please reduce if necessary
If the volume is too high, the sound will be distorted and clipped
set for best audio quality, use echo123
Attention: MS sound recorder will NOT do this job
Save
Restart Skype
