What is your opinion on listening to music while riding a horse? I am against it. Now, if it is playing over a speaker, that's fine, but personally in your ears? No way!
1. Listening is important. A horse is not like a vehicle, though a lot of people treat them as such. If you are blaring music, you can't listen to things around you. You will have no idea if some scary noise spooks your horse or not.
2. Secondly, it takes off some concentration
3. Talking and listening to your horse creates bonding. Hearing a horse snort, or maybe even hear a shoe come off, or a twig he stepped on, are all things to pay attention too, even his joints popping or belly rumbling.
I think it's just stupid, dangerous, and you should not do it when riding. All your attention should be on the horse, and noises around you. Will my horse spook at that plane flying over? That car going by rudely honking his horn? If you have ear phones listening to music, you won't even know anything like that is even there.