How to mute someone?

Every morning Alice and I have a Lync conference call with Bob and Charlie from the other office. I sit next to Alice, so when she speaks, I can hear her twice—through the air and with a delay through the headphones. This is aurally annoying. I could take the headphones off, but then I can't hear Bob's interjections. How can I mute just Alice so I can't hear her through the headphones?

So far as I can tell, the only mute option built into Lync is of the presenter to mute someone entirely such that nobody on the conference can hear them.

There are some hardware solutions including noise-canceling phone headsets that I just found out existed thanks to Google and Amazon. You could look for one that fits your needs.

There may also be some non-Lync software solutions but I don't know of them.