In church today, a woman told a story about her college days and a roommate who played hard music too loud. The intended message was that hard music is bad and makes the spirit leave. I think that's the wrong approach to take when evaluating music.
From the LDS church publication, For the Strength of the Youth, which seems to be the most authoritative church statement about music:
"Choose carefully the music you listen to. Pay attention to how you feel when you are listening. Don’t listen to music that drives away the Spirit, encourages immorality, glorifies violence, uses foul or offensive language, or promotes Satanism or other evil practices."
It's usually pretty clear what music "encourages immorality, glorifies violence, uses foul or offensive language, or promotes Satanism." At least if you're paying attention to the lyrics. But how to evaluate "music that drives away the Spirit?" Can music drive away the Spirit if it doesn't encourage immorality, glorify violence, etc.? Probably, although perhaps not as often as we think.
Elder Gene R. Cook spoke once to my mission; he stated that, due to an interaction he had with a famous rock star, he and his family never listened to rock music. (Personally, I think the rock star was probably just having some fun with Elder Cook at Elder Cook's expense, and Elder Cook took him seriously when he should have realized the guy was pulling his leg, but whatever). Contrast that, however, with Brother Richardson, a member of the Sunday School General Presidency. While details like a General Authority's tastes in music are generally not well-known, I took a class from Brother Richardson at BYU prior to his call as a General Authority. My notes from that class clearly indicate that Brother Richardson is a Styx fan. Not exactly the stance Elder Cook takes. I think that as we have more and more General Authorities who were teenagers in the 60's and 70's, more and more of them will be rock fans.
One trend I have noticed--people who don't like rock or hard music are very quick to identify their dislike as "music that drives away the Spirit." I think that's a bit dishonest (whether they realize it or not). I don't like country--in fact, I cringe when I hear country. I don't like most pop. I don't like rap. But as long as that music doesn't fit any of the categories listed above (encourages immorality, etc.) I'm probably not going to say that it drives away the Spirit. I just don't like it.
The true test for whether music that doesn't encourage immorality, etc. drives away the Spirit? First, do you like the genre? If you don't, you might have difficulty determining whether it drives away the Spirit or if you just don't care for the genre. Second, if you like the genre, do you feel the Spirit withdraw when you listen to it? There's one classic metal band that I get "bad vibes" with when I listen to. I love the sub-genre, the vocalist has a great voice, I like the music, but I just don't like the feeling I get when I listen to them. Some of their songs might "promote evil practices." But much of their music doesn't, and I still get those bad vibes. That's clear evidence of music that drives away the Spirit. The ugly feeling I get when I listen to country? Not so much. That's just a matter of taste. As is, I think, most people who claim that a whole genre of music drives away the Spirit.
The funny thing in all of this is that, while genres like metal might get attacked more than they deserve, genres like pop, which are overflowing with the "encourages immorality" bit, are often seen as harmless. I can honestly say that my large progressive/power metal collection is very very light on encouraging immorality, foul language, violence, and Satan-worship. In fact, if immorality is mentioned, it's more likely to discourage the practice than it is to encourage it. And, other than the one band mentioned above, I haven't eliminated any of my music due to language, etc. Even my heaviest music is low on the categories mentioned in For the Strength of Youth.
The take-away message? Don't assume that your dislike of a genre corresponds directly with the Spirit withdrawing. Just because you don't like it doesn't mean it's morally bad. And you might want to pay more attention to the lyrics your kids are listening to than how much you don't like their favorite genre.