Can an AM signal be picked up and decoded via software?
No, it is not practical to transmit audio nor any other information at such low frequencies. The passive antenna would have to be much bigger than the very distance you want to transmit. When I am saying bigger I am talking about a dipole hundreds of meters long. 

An alternative would be to use an active antenna but without proper experience in RF circuits I think this would complicate your design a lot.

For such an application a better approach is to use IR modulation. Or use an RF transmitter on frequencies much simpler to deal with. Like an FM microphone, for which plenty of commercial solutions exist.