Music is very powerful. According to Jewish tradition, as stated by the great Gaon of Vilna, music is the highest form of wisdom, after the Torah itself. And the Torah itself is described as a "song" in the section of Ha'azinu. When the Red sea split, the people sang, and in that song were elevated to highest levels of prophecy.
Yes, music is very powerful indeed. It is an international language, that speaks to the human on the emotional level. Music expresses tension and relief, mystery, holiness, drama, resolution. Music is an absolute requirement in a movie, for it provides the "soundtrack of our lives".
So what music is forbidden? Well, as with anything so powerful, it can be perverted for the bad. Music also accompanies the worst of orgiastic sins. It can lead the thoughts and emotions to lust. Thus, a lot of contemporary music, with its sexual innuendo - and sometimes overt content - is not acceptable to religious Jews.
Songs that urge us to "Come on and do the fill-in-the-blank", when whatever fill-in-the-blank referred to is forbidden, should not be listened to. Period. Despite what Spock says, Harold Robbins steamy novels are not great literature. Music can create a HUGE emotional drive to do something, so we have to be careful that it's for the good.
Fortunately, there is so much good music out there that no sacrifice is necessary. I've heard of an occasional rabbi criticizing classical music, but I can't accept that. He reasoned that military marches advocate warfare and bloodshed, which are not Jewish values. In my opinion, that's an extreme point of view. I doubt someone will go kill someone after listening to Tchaikovsky.
But after listening to some of today's hip-hop stars, I can definitely see murder as a possibility, God forbid. Recall the connection between a certain singer and the Columbine High School killers. Scary. and something to take warning from.
Music is required on Shabbat and festivals. We are to sing special songs for Shabbat, starting with Lecha Dodi and Shalom Aleichem, and continuing through the zemirot. These songs, sung at the meal, are an extension of the Biblical commandment of Kiddush, of sanctifying the day. They should be sung, and thus we fulfill a greater level of mitzva.
Synagogue services require music. In fact, I have an old German prayer book that has printed the traditional melody required in a number of places for some ancient prayers. The cantor's job is to inspire the congregation. Without music, that would be impossible. Even the Torah is read to a singsong melody.
Judaism NEEDS music, of the uplifting quality.
And that is why a lot of so-called Hasidic music is so very wrong. Yes, wrong. Verses from the Torah should not be set to tunes that could be played in a disco. It cheapens them. I've heard too many songs where the words don't even fit, yet the composer insisted on creating some "dance" style pop hit.
If you want to write a pop hit, by all means do so. Write your own lyrics, that are in the same spirit as your pop-dance-whatever melody. Keep it clean, and go for it. Don't take some poor pasuk-verse and twist it into a twisted creation.
Look at Carlebach. His tunes are lively, joyful, and in complete harmony with the words of the verse he chose. That must always be the goal. What is more uplifting than singing the same Carlebach or similar REAL Hasidic tune over and over as you dance with the joy of the festival?
Also, what is more uplifting than Beethoven's Ode to Joy? They are all examples of how important music can be to us. It must be used, not abused. Remember, our Messiah will descend from David, who was the "Sweet Singer of Israel". The more we sing, the better the world!