Loudness of music is a subjective measure.
Objective measures are: sound pressure, sound intensity or sound power. The decibel (dB) is logarithmic unit of sound intensity; 10 times the logarithm of the ratio of the sound intensity to some reference intensity.
Music can be divided into different genres in several ways.
Rap songs often promote anger, misogyny and violence, but some people say that rap relaxes them. Country music has been linked to depression and even suicide but it makes some people feel better.
Sound exposure levels should not exceed 85-90 dB for an 8-hour period, 100 dB for an hour, or 115 dB for 15 mins or less. 10dB sound is like soft rustling of leaves, 30dB is very soft music, 60dB - normal conversation, 70dB - freeway traffic, 80dB - moderate home stereo, 110dB - moderate rock concert or music in a dance club, 120dB - loud rock concert.