Comment 3 for bug 240623

I have this same issue with the same device. Jono (reporter) posted a workaround on his blog here:
http://www.jonobacon.org/2008/06/17/polycom-communicator-low-mic-volume/

I can confirm that this fix works.

However, it is extremely unintuitive. Both the Gnome sound control panel and alsamixer command-line tool do not help with this problem -- you can set it to 100% in alsamixer and over-amplify in Gnome sound control panel, which does affect the volume, but it is still deathly quiet. I would not mark this bug as Invalid, as there is a user interface issue here if nothing else.