Music is extremely emotional; I don’t think any pro musicians would do it if they didn’t feel touched by it. Emotion in music can be extremely important in interpretation; what do you feel the piece is about? What imagery do you get? etc. These are things that are not always universal from person to person. Some program music is specifically meant to evoke certain imagery, while absolute music is not meant to be specifically about anything–it’s just music.
Mental Imagery and emotion in music can’t be taught, it’s just something that happens when a performer or listener connects with a piece. This happens to everybody. It’s that tingly feeling you get when hearing good music or performing a piece that you’re very into. It’s powerful and moving and, to put it mildly, #$%^ing amazing.
Certain things can be taught. These are the things that people can really talk about. Things like levels of rubato or accents on specific beats (outside of the downbeat) or how to perform an appioggiatura can be taught. These are things that people are not born with. The idea that people come out of the womb with some inherent knowledge of art music performance practice is ridiculous. It’s learned through listening and learning about music.
Interpretation is the act of combining your personal connection with a given piece with all the knowledge about music you have and all the information given by the composer. 20th century music is full of instructions on how to perform a piece. Composers like Debussy may use colorful, imagery-evoking statements like, “out of the mist gently sing” which requires an interpreter to decided exactly how he/she feels that means in sound. Dynamics are often included. Tempo markings, slowing and speeding up is indicated, repeats are indicated. Cadences can be found with a bit of analysis. But then there’s things not on the page. Dissonance on a strong beat, resolution on a weak beat should be performed with the dissonant note louder then a softer resolution. There are other examples and that’s where knowledge comes into play. Most of the guitar music is completely without phrasing slurs. Look a page of piano music and they’re everywhere. Does that mean that we are to perform music without phrasing? No. That’s ridiculous. A performer has to make the call on how to phrase. That decision should be made using a combination of intuition and knowledge–and listening and thinking, “Does that sound good?”
Interpretation is the act of combining emotion and connection with a piece with musical knowledge.