The sidewalls are 2 handheld microphones, one for the Capt and one for the F/O. These ‘hand mics’ are used instead of the headset.

In our cockpit have these handheld microphones no function, and they serve only as decoration. It gives a realistic touch to the cockpitinterieur ...

Additional info : http://www.flightdeck737.be/hardware/platform/zijpanelen/inopbouwonderdelen/