Music & Sound

14 breaks

Vibrations, harmony and why some sounds feel right.

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Why a CD takes 44,100 snapshots a second: Nyquist and the tone that folds back A CD stores music as 44,100 numbers a second, with nothing in between. Sample more than twice as fast as the highest pitch and the wave can be rebuilt exactly… Music & Sound4 min read Why dragging a bow makes a steady note: stick-slip and Helmholtz's travelling kink A bow moves at a steady speed, yet the string under it vibrates in an exact rhythm hundreds of times a second. The secret is stick-slip: rosin grips the… Music & Sound4 min read Why two steady rhythms can fight and still groove: the hidden grid of 3 against 2 Tap a steady beat with one hand and three evenly spaced taps in the same time with the other, and you get a 3:2 polyrhythm: two perfectly regular clocks that… Music & Sound4 min read Why you hear a note that isn't there: the missing fundamental Play only 220, 330 and 440 hertz and most people hear a note at 110 hertz — a frequency that is not in the sound at all. This is the missing fundamental: the… Music & Sound5 min read Why two almost-equal notes make a wobble: beats and the piano tuner's trick Play two almost-equal notes together and you hear one pitch that swells and fades. Those swells are beats, and their rate is simply the difference in… Music & Sound4 min read Why a piano can never be perfectly in tune: twelve fifths overshoot seven octaves Climb twelve perfect fifths and you should land back on your starting note, seven octaves up. You don't: you overshoot by 23.46 cents, nearly a quarter of a… Music & Sound4 min read Why a flute and a clarinet sound different on the same note: harmonics and timbre Play the same note on a flute and a clarinet, at the same pitch and loudness, and you can still tell them apart at once. That difference is called timbre, and… Music & Sound4 min read Why sand on a vibrating plate draws pictures: Chladni figures Sprinkle sand on a thin metal plate, draw a violin bow along its edge, and the sand leaps into sharp, symmetrical lines. Change the pitch and the picture… Music & Sound4 min read Why a tone can climb forever without getting higher: the Shepard illusion Play a tone that climbs and climbs, forever, and never gets any higher. It sounds impossible, but it only takes a few sine waves and one volume curve. A… Music & Sound3 min read Why you hear bass from a speaker too small to make it: the missing fundamental Your phone speaker is far too small to produce a deep bass note, yet you still hear the bass. The trick is that pitch is not a frequency in the air. It is a… Music & Sound3 min read Why guitar frets get closer together as you go up the neck Guitar frets crowd together toward the body because of one fact about hearing: we hear pitch by ratio, not by difference. Each fret has to raise the note by… Music & Sound5 min read Why some notes sound sweet together and others seem to fight Play C and E together and they sound sweet. Play C and C sharp and they buzz. The notes aren't the problem: the clash only happens when they meet. Every… Music & Sound5 min read