I like the idea the game, but I felt it was difficult to locate the missiles through  sounds.  In particular as there were many missiles falling at once. I felt I was hitting missiles more by luck than by ability. it was a better strategy for me to try to make an arc movement with the mouse and hitting space bar as fast as I could than trying to guess at the location of the missiles. Maybe adding a limit to the ammo and a reload mechanic would discourage this strategy, so players are encouraged to play  how the game is intended. I don't know what would help with making it easier to locate the missiles through sound. Maybe adding a sound to indicate how close or far your aim is from a missile?

Fun game! I liked that there are visual cues and sound cues and that one can assign any key to play the game. It is really accessible to a varied range of players. If you are interesting on expanding the game, it would be interesting to add levels with specific goals to achieve each level. In the earlier levels the game would be easier, with simple and short sequence of tones, and later levels the sequences would get longer, more complex,  faster. Maybe each round instead of one new tone,  two or three would be added at once. Anyway, good job!