Cannot hear voice of someone I'm jamming with

[markgrebey@gmail.com]

Hello,

I'm having trouble within a jam session.  This is a two guitarist jam session.  Within the session I can hear the other guitarist's guitar but I cannot hear his voice.  He can hear both my guitar and my voice.  We are both using the built in microphone on our laptops (mine a MacBook Air, his a Microsoft Surface) for our Voice Chat configuration.

Anyone else experience this or have any tips on how we can resolve so that I can hear his voice?

Thanks much!

Mark