Your work "Music" really does portray the idea/concept precisely. I enjoy the fact that it is greyscale, as it mimics the black and white nature of sheet music and I really like the value gradients in this piece. The way you contrasted the softness of the ranges in the girl's skin and clothes with the sharp differentiation of the musical notes and staff bouquet really helps to push the bouquet forward into focus. Your technique appears top notch to me. The values seem to suggest the vast range that music can cover from soft, melodic classical music, to hard, staccato metal, or electronica. I might have only wished for a few more brighter highlights on the bouquet to really emphasize this facet. The fact that you used more musical notes in the background wallpaper, really helps to unify the whole piece within the theme.
As far as improvements, the girl's neck appears slightly askew, perhaps as a result of the shading below her chin being too dark. Her neck appears to swerve to the right in the picture instead of appearing to support her head squarely/solidly. What I mean to say is that something is making her head appear slightly out of balance with her shoulders. The fact that this piece is stylized as a more "cartoon-like" illustration, as opposed to a realistic interpretation, minimizes this issue somewhat. Also the fact that the focal point of her hand and bouquet is so close to this area, could potentially help to gloss over that issue.
The girl's expression, seems to appear more sombre than neutral, which suggests a more emotional context of loss, than the simple title "Music" might suggest. If she were smiling slightly, she might appear more content which would reinforce the message of music being a precious and beautiful commodity (as implied by the bouquet of notes) Depending on whether you intended to allow the viewer to infer this mood based solely on the drawing, or whether the title is meant to help guide the viewer's interpretation, I might be inclined to suggest a re-examination of that link (title vs mood) to ensure a better fit between the two.
To summarize, I think the concept works immensely well, the execution is very good, with areas for improvement being minimal. I really enjoyed viewing this piece and want to thank you for the opportunity to critique it!