No, you would not hear anything other than your own engine in a closed cockpit - guns and hard hits (cannons, or MG close to the cockpit or main structural pieces) through a little audible reception, vibration would be the major "sound" factor here. Just like how your own voice will sound different to you than on an audio recorder, you will hear things through vibrations.
No, you would not hear anything other than your own engine and the wind in an open cockpit, guns and hits the way I mentioned above.
-SW