In general, imbalance within the autonomic nervous system (of which the vagus nerve controls half—the parasympathetic portion) has been shown to be related to everything from heart disease to irritable bowel syndrome to having an irritable personality:
http://en.wikipedia.org/wiki/Autonomic_nervous_system
I tried it out with a signal generator (wav file) and an audio amplifier cranked way up, it felt like AC and made some muscles twitch but nothing compared to mechanical vagal maneuvers.
In general, imbalance within the autonomic nervous system (of which the vagus nerve controls half—the parasympathetic portion) has been shown to be related to everything from heart disease to irritable bowel syndrome to having an irritable personality: http://en.wikipedia.org/wiki/Autonomic_nervous_system