The soul of music is physical.
This statement comes from a relatively recent discussion with Daniel Barenboim about the physicality of music and the role of a conductor.
I agree with Barenboim. I believe that when music is removed from the physical, it loses something. Perhaps that's why I prefer acoustic music to music that is purely electronic. It is possible to appreciate electronic music with the mind, but that is, for me, the extent of it.
I also believe that we listen to music with our bodies. When we hear a projecting voice that is deep and rich, or high and lithe, we unconsciously put our vocal and breathing mechanisms in positions that might approximate what the singers are doing. That's why some of us go to operas again and again.
Perhaps one of the reasons people consider a nice non-projecting voice that is amplified so "relaxing," is that the physical state of the singer is often relaxed. S/he can sing in a whisper and still be heard. S/he doesn't have to worry about projecting diction any sort of distance when singing softly into a device that does most of the "heavy lifting."
The instrumentalists I prefer listening to are people who have intense physical connections with their instruments. Scraping and blowing on tubes and strings that we make longer and shorter with our fingers and arms is very physical. Using sticks, fingers, or hands to hit stuff is very physical. Watching and listening to people do these things well allows us to enjoy the relationship of the physical action to the sound that it produces. We tend to allow our bodies to echo the physical states of the people performing, even when we don't see them. When we play chamber music, we allow our bodies to echo the physical states of the people we are playing with. That's also how many of us learn from our teachers: we try to emulate the physical approach our teachers have to their instruments.
Sometimes the body learns more quickly than the mind, but most of the time there is a disconnect between the mind and the body, because we imagine that intellectualizing comes first and physicalizing comes second. It is also difficult to truly remember a physical state by purely physical means. That's why we need to practice. Just knowing something is never enough. It needs to become an unconscious habit. Teaching by demonstration is sometimes frowned upon, but I believe that it is the most effective way to teach. I also think that the teacher needs to be able to physically empathize with a student in order to figure out where that person's particular points of tension are. Rinse and repeat.
I think that it is important to write music with physicality in mind. After all, we write music for people to play, and it should feel good to do it. That's why instrumentalists and singers return again and again to Bach, Mozart, Haydn, Beethoven, Schubert, Brahms, Dvorak, Schumann, and Tchaikovsky (not to mention Paganini, Chopin, and Liszt, Shostakovich, and Britten). They all understood what Barenboim understands: that the soul of music is physical.