I found this interesting description in the April 19, 1862 version of the Covington Journal.
The Tone of Bullets
A soldier writing from one of the camps of the Potomac, thus alludes to the particular noise made by bullets passing through the air - "It is a very good place to exercise the mind, with the enemy's pickets rattling close at hand. A musical ear can study the different tones of the bullets as they skim through the air. I caught the pitch of a large-sized Minie yesterday - it was a swell from E to flat F and, as it passed into the distance and lost its velocity, receded to D - a very pretty change. One of the most startling sounds is that produced by the Hotchkiss shell. It comes like the shriek of a demon, and the bravest old soldiers feel like ducking when they hear it. It is no more destructive than some other misses, but there is a great deal in mere sound to work upon men's fears. The tremendous scream is caused by a ragged edge of lead, which is left on the shell. In favorable positions of light, the phenomena can sometimes be seen, as you stand directly behind a gun, of the clinging of the air to the ball. The ball seems to gather up the atmosphere and carry it along, as the earth carries its atmosphere through space.