"Your right that Metal is very harsh to the ears, and so is some modern expressionist classical music (Schonenberg, Berg,Webern)..." (I don't how to get that italic quote!)
Most modern atonal classical music is just as harsh as Heavy Metal Rock, and it's very boring too. I don't mind playing some of it in short ensemble works - striving for the ultimate dissonant resolve. However, into the ears of this beholder it's plain painfully awful to listen to it.
Schoenberg explored an interesting tonal/compositional theory,though.
Yeah, formative conditioning and exposure are factors. There are studies on the influence of music upon physiological systems and cognizance as well as psychological indicators. For instance, studies affirm the positive therapeutic effects of Native American drumming and Gregorian chants. Also, studies show that there is significant mental enhancement and ability to concentrate among children who are brought up listening to Mozart.
"But dissonance is in some ways relative to culture. For example, what we take as light jazz would have been harsh to Bach's ears."
What makes Bach profound is that he resolved dissonance (mordance) to a profound conclusion. Some of his fugues really do reach far into dissonance before they resolve. Mozart's string quartet has pronounced dissonance. Dissonance without resolve bespeaks of chronic dischord.
Thank heavens for the freedom of choice in listening to music.
Merry Christ Mass...