Acoustics & Music Theory
why it sounds like that
Generator

a major triad, spread by 40 milliseconds

Three notes of a major triad, each lasting 600 ms, with their onsets 40 ms apart. The shaded band is the window in which all three are sounding — 520 ms, which is 87 per cent of a note's length. The chord exists as a simultaneity only inside that band; before it and after it the passage is a melody. At 40 ms the notes are further apart than the asynchrony at which a mistimed partial leaves its note.
a major triad, spread by 40 milliseconds. Three notes of a major triad, each lasting 600 ms, with their onsets 40 ms apart. The shaded band is the window in which all three are sounding — 520 ms, which is 87 per cent of a note's length. The chord exists as a simultaneity only inside that band; before it and after it the passage is a melody. At 40 ms the notes are further apart than the asynchrony at which a mistimed partial leaves its note.

Drawn above with its standard settings, which is almost never how an essay draws it: an essay states the numbers it is arguing about, so the figure a reader meets there is about that argument rather than about the drawing in general. Every option a placement passes is checked against the ones this function actually reads, because an option it does not read is silently ignored and the figure quietly draws what is above instead.

It makes a noise. 8 of its 8 placements carry sound, built from the same numbers as the drawing, offering these buttons: All three together, Spread 150 ms, from the bottom, Spread 150 ms, from the top, Spread 300 ms, from the bottom, Spread 300 ms, from the top, Spread 40 ms, from the bottom, Spread 40 ms, from the top.

Called by 2 essays

the blast radius of changing it

What a spread costs a chord. a major triad of 3 notes lasting 600 ms each, with the onsets spread by up to 320 ms. The upper line is the share of each note's length during which every note is sounding; the lower is the chord's roughness weighted by that share, since roughness is a property of two partials sounding at the same time. At a spread of 30 ms — the asynchrony at which a mistimed partial stops belonging to its note — the chord is still 89 per cent simultaneous. It stops being simultaneous at all at 300 ms, which is where the last note arrives after the first has finished.

The chord that is not played at once

Every chord until now starts its notes at the same instant, and no figure ever set the asynchrony to anything else. A spread chord is not a defective simultaneity: at forty milliseconds a triad of half-second notes is still eighty-seven per cent simultaneous, so it carries almost all its roughness, and it stops being a chord at all only when the last note arrives after the first has finished. What none of this can explain is the one thing every keyboard player knows — that a chord is rolled upward. The masking asymmetry that ought to explain it is 2.4 decibels at a close voicing, which is not enough.

intervals · The triad A loud chord is a smaller chord. The share of a voicing's partials that stand above what the rest of it masks, and the share of its computed roughness that is between partials a listener actually has, from 30 decibels to 100. Both fall: 83 per cent of the partials survive at 30 decibels and 38 at 100, and the roughness share goes from 88 per cent to 67. The direction is the upward spread of masking, which grows faster than linearly with level: a loud partial masks a band above itself much wider than a quiet one does, so the chord's own top disappears into its own bottom. Two earlier essays are drawn at one level, and this is what they were holding.

A loud chord is a smaller chord

Two earlier essays hold the level fixed, and the level decides how much of a chord a listener is given. At thirty decibels twenty of a triad's twenty-four partials stand above what the rest of it masks; at a hundred, nine do. Every roughness figure until now counts partials that are in the score, and a partial the chord masks is not a partial the listener has.

harmony · Masking

All figures · What can be heard