The Weirdness of the Tritone Paradox

Round up a group of friends, and watch the above video. When it’s over, have everyone say whether the pitch increased or decreased during each of the four pairs of tones. You may be surprised to find that your friends disagree on the answer.To understand this paradox, you need to know a little about musical notes. A specific note has a specific pitch, which is how high or low it sounds. A note that is one octave above a second note sounds twice as high because its wave has twice the frequency. Each octave interval can be divided into two equal tritone intervals.

In the video, a tritone separates each pair’s sounds. In each pair, one sound is a mixture of identical notes from different octaves—for example, a combination of two “D” notes, one higher than the other. When the sound is played next to a second note one tritone away (for example, a G-sharp between the two D’s), you may validly interpret the second note as either higher or lower than the first.

Another paradoxical application of tritones is an infinite sound that appears to constantly drop in pitch, though it actually cycles continually. This video plays such a sound for 10 hours.