I would suspect the heightened realism provided by the sound triggers a slightly elevated response by the autonomic system and feel a bit more pressure if you w

I would suspect the heightened realism provided by the sound triggers a slightly elevated response by the autonomic system and feel a bit more pressure if you will as the situation feels more life or death than it does without the audio. Edit: Try listening to the sound in Mono, Stereo, and Surround Sound to see if that makes a difference. Also try different volumes