Percussa micro super signal processor

November 29 is the 205th birthday anniversary of Christian Doppler, the Austrian mathematician and physicist who hypothesized what’s now called the Doppler Effect. (You know, that effect when an ambulance or other fast-moving vehicle flies by and the perceived pitch changes.) That calls for Doppler trivia, astrophysics, audio software, and a drink.

In celebration, go check out the excellent Wikipedia page on the Doppler Effect, including one of my favorite Physics equations (while I wasn’t failing.) And if the idea isn’t sinking in, there are plenty of online demonstrations of why this effect occurs. (Science aside, I also recommend celebrating by imitating the sound of an English police car driving by in a movie. It works best if you simultaneously run by your significant other at high speeds.)


Because light can be a wave as well as a particle, the Doppler effect applies to light as well as sound. An increase in the observed wavelength of light emanating from a star is called a redshift. The principle is the same: as the source gets further from you, the wavelength (what it sound we perceive as pitch) shifts; in the case of a star, that translates to observed color.


Here’s the mind-bending caveat: there’s a misconception that Doppler-like redshifts are what allow astrophysicists to measure the expansion of the universe. Wrong! Why? Because it’s not the stars moving away from you (a la the Doppler ambulance); it’s the intervening space stretching, as per the understanding of General Relativity. There you go; if that hasn’t convinced you to go have a drink in honor of Christian Doppler, nothing will. (Heck, it’d probably convince him to have a few drinks, were he alive.)


Back to digital audio: If you want to reproduce the Doppler effect accurately, GRM Tools Classic has one of the best Doppler plug-ins I know of, available for both Pro Tools (RTAS/TDM) and VST. See the detailed review from Electronic Musician of a few years ago. GRM Tools is a great collection of plug-ins, but if you’re on Windows you can also opt for the much-cheaper GBP 15 a la carte option, Spacestation (VST). (Thanks, Afro!)


Or just go have that Dopplertini. (Anyone got a good recipe? I think it involves throwing the drink at high velocity . . .)