Baseball is possessed of a rich and diverse collection of sounds. The shouting of the fans, their intermittent applause and jeers, and the crackling of the PA system all contribute to the cornucopia. Even limiting ourselves to the action on the field, baseball is aurally pleasing: the pulse of the ball pushing the air out of a glove, for instance.
First among all baseball sounds, without question, is the crack of the bat. Something about the whip striking the ball is downright electric. If you are like me, after watching so many thousands of baseball games, that crack still exercises a visceral and jolting effect on my nervous system. It is baseball’s leverage alarm: the contact could result in a routine groundout, or it could be a massive home run, but either way, the stakes just increased and you’d better pay attention to what happens next.
Yet the crack of the bat is itself diverse. Some balls are ripped with great force, and produce a crisp, single note. Others are walloped into the ground, off the bottom of the bat, and generate a dull thud. Some players routinely seem able to contact the ball with the kind of sound that is associated with hits, regardless of whether their screaming line drives find gloves.
I think many a sabermetrically-inclined fan of the game has wondered about measuring those sounds. Not that our ears are a bad guide, but human perception is subjective and can be biased. It would be interesting to know, for example, if your favorite player’s bat really does produce a special sound, or if you can tell the difference between a home run and a groundout based only on the crack.
Collecting sound data itself is not very difficult. To do so, I used my computer to directly record the sound feed from MLB.tv*. When you collect sound data, you can see a direct readout of it that looks like this:
Time is passing on the x-axis, and the y-axis relates the amplitude of the sound that’s being recorded. Loud sounds produce more significant departures from the line at 0, which represents silence.
The first task was to see whether the crack of the bat could be at all distinguished by the computer from the surrounding sounds. That turns out to be trivial, for two reasons.
The first reason is that the sound of the bat is extremely loud relative to the rest of the television feed. The second reason is that the sound is also very short. The combination of these characteristics gives us that crisp, sharp sensation which is so pleasing to the ear (and attention-grabbing).
Having now convinced myself that I could reliably identify the sound of the bat in the audio feed, I wanted to do a more detailed analysis of that sound. I first needed to gather a bunch of bat cracks. To do so, I used the condensed games feature on MLB.tv, which turned out to be ideal for this purpose. The condensed games strip out the announcers’ feed, leaving you with the sound of the game as it happens on the field. I collected several games worth of audio, saving individual audio files for each contact event, and noting the result of that contact in broad terms (fly out, groundout, home run, etc.).
The result of that work was a small sample (5-10) of each event variety. Before I get to the #GoryMath, let’s listen to that most glorious of sports sounds, the bat crack. For each event, I made a composite sound of that event by stacking all of the bat cracks on top of each other to produce a sort of ‘average’ sound. This, for example, is a composite home run, made from eight separate dingers: