I can understand that. I have that problem with passing vehicles sometimes; there are certain cars and motorcycles that really hurt my ears when the owners rev the engines. I think in my case it has a little more to do with frequency than with actual loudness, but sometimes sheer noise level will do it too. This bike was actually ok though. :)

Indeed, horses do not make engine noises and in fact are fairly quiet overall. Other benefits include not being in traffic with very little protection, and the movement of the horse is supposed to be good for bodies too. Wishing you time for horses soon. :)