I know little about music, but my friend, a musician, says that musicians hear and compose music in their heads. According to him, if you have a musical ear, and it is absolute, then you can “hear” music in your head while reading music. Looking at the score, you can imagine how it will sound (with very high fidelity). By the way, my friend also composes music on his own and says that he will get interesting chord combinations thanks to the chord progression generator https://chordchord.com/ This website is dedicated specifically for musicians, who are willing to find some catchy and interesting chord progressions.