Sensor to sense a shock wave/ preassure wave??

So I'm a hobbyist fireworks enthusiast, and one thing I would like to build is something that can calculate the time between when a fuse is lit on a firework, to the time the firework is shot up into the sky. I have already figured out how to detect the start time (when the fuse is lit), but need something that could detect when the firework is launched. Ideally this would be able to detect the shockwave (I know it wouldn't be much of a shockwave), and translate that into an electrical signal that I can read on an arduino.

I guess my first question is: Am I looking for the right type of sensor, or would something else work?

And second, assuming this is the right type of sensor, does anyone know of an affordable sensor that would do the trick?

Triskal

Regular microphone could do a trick, you only have to include calculation of the delay in equation, depends on distance.

A piezo disk would be the inexpensive implementation of a microphone.

More generally if you google for "Arduino drum" (which use piezo sensors) you'll get more examples.