Our ears are very sensitive to loud sounds but listening to loud music for 30mins could not damaged your ears if that was the only time. Repeated action could really cause you damage to your ears. Gun shots or explosion could really affect or might trigger hearing loss. So it very important to take care of our ears before matter go worse.
Hi!
Usually a single episode of hearing loud music does not affect hearing. Gun shots and explosions only cause sounds loud enough to cause hearing loss in a single episode. So, am glad you realize that you should not hear loud music through ear phones. Buy a good set and keep the sound level down. Take care!