I see you have already responded to some of the comments made during the challenge.
I thought this was a very creative idea. If the depth of field had been a little less shallow, the guitar would have been in focus. I think that is the one main thing here.
It's also possible if you had been able to have a string vibrating as if it had just been plucked, and the rest still it would have conveyed even more the concept of sound.
In fact, the reflection is falling off the polished body of the guitar and without the shadow it would not be contrast enough. I liked the fact that the shadow looks like a loudspeaker of the old days and the center of image is the ligt (sound) waves which are in focus. That is why the guitar is not sharp and not accentuated at all. My mistake is that although reflections are sharp they are not percepted correctly withthe background of blurry shadow.
I take it that the wiggly lines in the left section are meant to represent sound waves. Okay. The guitar isn't as sharp as it needs to be. Also, for the sound waves to exist, the guitar strings need to be moving too. 4