I have never looked at the score before hearing the work; hearing the work was what got me interested in the score in the first place. Nevertheless, one can get quite a bit out of a new score by looking at the tempo or expressive markings. Mahler, for instance, can be quite detailed in how he wants something played from the descriptive indications at the very beginning of the score, and I think that just about any score can be revealed this way and just about anyone can understand those descriptions if they look up the Italian words. Looking at a score and hearing all the parts simultaneously is I feel meant for the true expert, something that only a true conductor of talent can do or certain musicians. But one does not need to read the notes to get a great deal out of a score, including key-change indications and tempo changes, though it can certainly help... If I were starting over, I'd start by learning a list of basic musical terms probably starting with tempo markings, such as Allegro, Allegretto, moderato, presto, and so on. Then it gets really interesting to see how every conductor has a little bit different kind of an idea of what those words mean in terms of speed, because the tempos that different conductors use, even with the same markings on the score, are never exactly the same because they feel them differently. Now, noticing those changes can really take one into the heart of the music and why interpretations can be so different from one conductor to another.

Some of markings found in scores: https://en.m.wikipedia.org/wiki/List_of_musical_symbols

 

If its a sheet of music its easy enough to know what it will sound like (in your head) and if that fails then play it on whatever is your instrument, when you are learning an instrument a lot of the pieces will be new to you, but for a full score that depends on how good you are.

 

I wonder, when writing music do you hear the notes in your mind or do you have to play them?

 

I'm going to confess that I don't always hear them and I complete some of the harmonies according to harmonic theory, though even there I have an idea how the harmonies sound.

When reading a full score I have a look at the different instrumental groups and I tend to look at the strings (which hopefully are already sounding at the beginning) or whichever group is active, might be brass or woodwinds. Then I look at the introductory melodies wherever they are and try to get a feel for structure.
I'm sure some folks do this in their heads, but I'll happily play parts of it on the piano, where you do a rough and ready 'reduction' and get a picture of the harmonies going on between the instrumental groups (there's usually doubling going on so you don't need to play every bit). A real piano reduction is invaluable for this sort of familiarising.

 

FYI, I can't read music. I'm fascinated by the complexity when I look at music and wonder about the experience.

 

If you look at a musical score or sheet music and haven't heard the piece:

What is your experience? How do you process it? Do you hear the music in your mind? Does it all make sense to you?

What goes on when you read a musical piece for the first time?

I've been playing long enough that I can figure out what notes sound like on paper. I don't seem to process the difference in sounds called for, like trumpet versus clarinet, but I can get a sense of the direction of the music. But it can be laborious, especially when you get into late Romantic works like Schoenberg's Pelleas, where themes are flying all over the place, and you have to look at each measure and piece everything together.

One great experience I had was when our art museum had a collection of books of hours, which are highly illustrated music books. When no one was in the room, I sang from one of them. It was a tremendous connection with the past, without all the accompanying disease and bad teeth.

 

I play piano at a very, very amateur level. If I look at some relatively simple sheet music I can read it and know what it sounds like. If it gets too complex or chromatic I start to have trouble. I've never spent much time trying to study orchestral scores, unless I'm curious about a particular part of a piece I've already heard - the transposed instruments and alto and tenor clefs make it kind of a slog for me.

 

For me, reading music is like reading words: I cannot NOT do it. When you see printed words in a language you know you automatically read it - like it or not. Same with music - when I see it I "read" it in the sense I translate it into sound. Timbres, rhythm, volume, melody - all of it. Harmony can be a bit trickier no doubt. But most 18th, 19th c scores present no trouble at all anymore. It's a skill that takes time and training for most of us. Some music schools offer a course called "Score Reading" where you also learn to play a full score at the piano. It's hard.

Let me just give you one reason why having this ability is important: there are many opportunities for composers to write music for a competition of some sort. The composer submits a score. Then the judges have to read through them to decided what's good and what's not. They don't get to hear it performed, usually don't have recordings, and no one wants to hear a computer generated version. The judge must have a fine ear and be able to internalize what they see.

And yes, with enough experience, practice and talent, you write music on paper (or computer) without needing to play it on piano or something. You hear something in your head and just write it down with minimal difficulty.

 

Fascinating ......

 

It's a skill I have always envied. Alas, I could never acquire it; with no amount of study or practice could I ever learn to read even simple tunes, let alone whole orchestral scores. I guess I'm musically dyslexic.

 

There's a related skill that I used to think everyone had - I can memorize music easily from hearing it, and then replay the "record" in my head. I can pull up things I haven't heard in a long time. It surprises me all the time. As a sometimes conductor, it's a fabulous skill to have - I don't have to bury my head in the score. But the weak link is that I can't memorize all that well from playing. I could play a Brahms waltz on piano 100 times and still need to use printed music to get through it. That's frustrating! Then there are players who memorize dozens of piano concertos, all the Beethoven sonatas -- amazing. That skill, I envy.