Concept

Virtual pitch — where it appears

A fundamental the auditory system infers from a set of components, whether or not that frequency is present. It is what makes a small loudspeaker seem to produce a bass note it cannot physically radiate.

Named by 9 essays across 3 fields — each of them below, with the objects they name alongside it.

a major triad, C–E–G. The partials are at 261.6, 329.6, 392.0 Hz. Each row is a harmonic series they are consistent with to within 30 cents: the filled dots are the partials in their assigned slots and the open dots are slots the series predicts that nothing occupies. There are 2 such series with harmonic numbers up to 16, the best fitting them to 10.1 cents with a fundamental of 65.54 Hz and no unoccupied slot. The rest sit at one half of it and their arithmetic is exactly as exact; what separates them is the count of empty slots, which is why a residue pitch built from few partials is reported an octave out by a minority of listeners and not by the rest.

The root an ear supplies

A major triad's notes fit 4:5:6 with nothing missing and a fundamental two octaves below the bass. A minor triad's fit two different series with two different answers a major sixth apart, and the model cannot choose between them. The ambiguity theorists argued about for two centuries is a computable quantity, and the spectrum invented to remove it is one no object produces.

intervals · The triad
Every 3-note stack of one interval. Each chord built by repeating a single interval 2 times from the root, scored for summed roughness on a string spectrum and asked whether one low fundamental accounts for all its notes within 30 cents. 8 of the 11 are smoother than the major triad, which scores 0.288: stacked major thirds (an augmented triad) at 0.279, stacked fourths at 0.218, stacked tritones at 0.144, stacked fifths at 0.140. And 3 of them have no fundamental at all — stacked minor sixths, stacked major sixths, stacked major sevenths — meaning no series of harmonics up to the 16th accounts for their notes to within a 30-cent tolerance.

A stack that is not thirds

Build every chord that repeats a single interval and score them all. Eight of the eleven three-note stacks are smoother than the major triad; the four-note stack of fourths is smoother than a dominant seventh by a third and has no fundamental any matcher can find. Two absences, both computable, and both are exactly what the chord was adopted for.

harmony · The triad
The pitch moves and the repetition rate does not. Three partials around harmonic 10 of 200 hertz, shifted together by up to 200 hertz, with three curves. The flat line is the envelope repetition rate, which the shift cannot move at all. The rising line is the shift divided by the harmonic number — 200 hertz becoming 220.0 — which is what a harmonic template predicts and is what listeners report. The third curve is the next-best template, which overtakes the first partway along: the pitch is ambiguous, and it drops back rather than rising indefinitely.

The pitch that moves the wrong distance

Take three partials two hundred hertz apart and move every one of them up by forty. The spacing has not changed, so anything reading the pitch off how often the waveform repeats must give the same answer as before. The pitch moves to 204 — the shift divided by the harmonic number — which is what a harmonic template predicts and what listeners report. Push the shift to a hundred and a second reading overtakes the first, so there are two pitches and neither is the spacing. This is the measurement that closes the question, and it closes it by ruling out one mechanism rather than by choosing between the two that are left.

perception · Missing fundamental
Which note a chord would rather have twice. Every complete four-part voicing of each chord inside the SATB ranges, grouped by which member sounds twice and scored for roughness — 480 voicings for a triad. The order for a major triad is root < fifth < third, which is the rule every part-writing treatise states. For a minor triad it is fifth < root < third, which is not. The numbers printed under each bar are the mean error, in cents, with which the four sounding notes fit a single harmonic series, and that measure separates the three far more sharply than roughness does.

The note that sounds twice

A triad has three notes and a four-part texture has four voices, so one note is doubled — and the voicing model used here leaves the choice free because the rules have an opinion about it. Asked properly, the arithmetic agrees with the treatises for the first time in nine essays: root, then fifth, then third. For a minor triad it does not agree, and for a symmetric chord it correctly has nothing to say.

intervals · The triad
A bell is never minor alone. For bells whose hum is on C1, E1, G1, C2, E2, G2, C3, E3, G3, C4, struck so that the hum is at 20 to 110 decibels: whether the masked-threshold count delivers the tierce, the minor third above the prime, and the deciem, the major third above the nominal. C1: ···MMMM············; E1: ··MMMMMMMM·········; G1: ··MMMMMMMMMM·······; C2: ·MBBBMMMMMMMMMM····; E2: ·BBBBBBBBMMMMMMM···; G2: ·BBBBBBBBBBMMMMMM··; C3: BBBBBBBBBBBBBMMMMM·; E3: BBBBBBBBBBBBBBBMMM·; G3: BBBBBBBBBBBBBBBBMMM; C4: BBBBBBBBBBBBBBBBBMM (B both thirds, M the major only, m the minor only, a dot neither; levels in steps of five from 20). Of 190 cells, 82 deliver both thirds, 59 the major third only, 49 neither, and 0 the minor third alone. A dot in a cell marks a stroke at which fewer than two of the three modes that imply the strike note survive.

A bell is never minor alone

A tuned bell carries two thirds: the tierce, a minor third above the prime, which is why a bell is called minor, and the deciem, a major third above the nominal. Run the masking count across every register and every stroke and the minor one is never delivered without the major one. Struck softly a bell delivers both; struck harder, only the major; and below C2 the tierce is never delivered at all. The deciem survives because it is masked by one mode barely louder than itself, the tierce by two that outweigh it.

perception · Masking
A bell whose deciem is the tierce's octave is minor at every stroke. For bells whose hum is on C1, E1, G1, C2, E2, G2, C3, E3, G3, C4, struck so that the hum is at 20 to 110 decibels, with the deciem tuned from 2.5 times the prime to 2.4 — a minor third above the nominal and exactly an octave above the tierce: whether the masked-threshold count delivers a third at all. C1: ···mm··············; E1: ···mmmmmm··········; G1: ··mmmmmmmmm········; C2: ·mmmmmmmmmmmmm·····; E2: ·mmmmmmmmmmmmmm····; G2: ·mmmmmmmmmmmmmmm···; C3: mmmmmmmmmmmmmmmmm··; E3: mmmmmmmmmmmmmmmmmm·; G3: mmmmmmmmmmmmmmmmmm·; C4: mmmmmmmmmmmmmmmmmmm (m a minor third, a dot none; levels in steps of five from 20). 131 of 190 cells read minor and none major. Of the 59 cells in which the bell as cast delivered only its major third, 49 now deliver a minor one.

A bell can be made minor by the third nobody tunes

A low bell struck hard delivers its major third, the deciem, and loses its minor one, the tierce, to masking. A founder could flatten the deciem from a major to a minor third above the nominal, which puts it exactly an octave above the tierce. The masking count says that move costs the deciem only one or two decibels of stroke at the top of its window, so the flattened deciem still outlasts the tierce in every register. A bell tuned that way reads minor in every cell of register and stroke that delivers a third at all. In-between tunings read as neutral thirds, so the move only works if it goes all the way.

perception · Masking
A bell with a major tierce is major wherever it delivers a third. For bells whose hum is on C1, E1, G1, C2, E2, G2, C3, E3, G3, C4, struck with the hum at 20 to 110 decibels, the deciem as cast at 2.5 times the prime and the tierce at 1.25, 386 cents above the prime: which third the masked-threshold count delivers. C1: ···MMMM············; E1: ··MMMMMMMM·········; G1: ··MMMMMMMMMM·······; C2: ·MMMMMMMMMMMMMM····; E2: ·MMMMMMMMMMMMMMM···; G2: ·MMMMMMMMMMMMMMMM··; C3: MMMMMMMMMMMMMMMMMM·; E3: MMMMMMMMMMMMMMMMMM·; G3: MMMMMMMMMMMMMMMMMMM; C4: MMMMMMMMMMMMMMMMMMM (M major only, b a minor tierce with the major deciem, n a neutral tierce, a dot none; levels in steps of five from 20). 141 cells major, 0 with thirds that disagree, 49 with none. Dots mark the 10 cells in which this bell delivers a third and the minor bell with its deciem flattened to the tierce's octave delivers none.

The major-third bell has no mirror problem

A minor bell struck hard loses its tierce to masking and delivers its major deciem instead. Raise the tierce to a major third and the two thirds agree — but the raised tierce sits closer to the quint, and it was fair to fear that the quint would bury it as the prime buried the minor one. It does not. The prime is what masks a tierce, and moving away from it gains four to twelve decibels of stroke while the quint stays nine decibels too weak to matter. Tuned to agree, the major bell delivers its colour in 141 of 190 cells; the minor bell, made consistent, in 131.

perception · Masking
With the tierce at 1.25 times the prime, the lower modes point only at the strike note's own name. For bells whose hum is on C1, E1, G1, C2, E2, G2, C3, E3, G3, C4, struck with the hum at 20 to 110 decibels, the tierce at 1.25 times the prime, 386 cents: the series the delivered lower modes — hum, prime, tierce and quint — fit best, within thirty cents. C1: ···················; E1: ·······SSS·········; G1: ·····SSSSSSS·······; C2: ··SSSSSSSSSSSS·····; E2: ·SSSSSSSSSSSSSSS···; G2: ·SSSSSSSSSSSSSSS···; C3: SSSSSSSSSSSSSSSSS··; E3: SSSSSSSSSSSSSSSSSS·; G3: SSSSSSSSSSSSSSSSSS·; C4: SSSSSSSSSSSSSSSSSSS (S the strike note's name, 3 the note a major third below it, a dot fewer than two lower modes delivered; levels in steps of five from 20). 124 cells point at the strike's name, 0 a major third below, 66 at nothing.

The raised tierce points the bell at its own note

A bell's four lowest modes — hum, prime, tierce and quint — can imply a pitch of their own. With a major tierce they are the second, fourth, fifth and sixth harmonics of the prime two octaves down: the strike note's own name, with one empty slot. It was the minor tierce that pointed elsewhere all along. Its lower modes are the fifth, tenth, twelfth and fifteenth harmonics of the note a major third below the strike, and in 82 of 190 struck bells that is the series the delivered modes fit. Raising the tierce removes a competitor rather than adding one.

perception · Masking
In a ring of minor bells, five of the eight hidden pitches fall off the scale the ring rings. A ring of eight bells with minor tierces tuned to a major scale, the tenor's strike note C4: for each bell and each stroke with the hum at 40 to 90 decibels, what the delivered lower modes — hum, prime, tierce and quint — imply. C4 (hidden A♭, off it): 333333333SS; D4 (hidden B♭, off it): 3333333333S; E4 (hidden C, on the scale): 33333333333; F4 (hidden D♭, off it): 33333333333; G4 (hidden E♭, off it): 33333333333; A4 (hidden F, on the scale): 33333333333; B4 (hidden G, on the scale): 33333333333; C5 (hidden A♭, off it): 33333333333 (3 the note a major third below the strike, S the strike's own name, a dot too few lower modes delivered). 33 strokes imply a note on the ring's scale and 52 a note off it.

A ring of minor bells rings a second scale a major third below

A minor-tierce bell's four lowest modes, read as a residue, imply a note a major third below the bell's strike note. Put eight such bells in a ring tuned to a major scale and the implied notes are that scale moved down a major third — a ring in C carries the scale of A♭ major underneath it. Only three of the eight land on notes the ring rings, from the mediant, the submediant and the leading note; the tonic, the octave, the supertonic, the subdominant and the dominant all imply notes the ring never sounds, each a semitone from two that it does. Above a tenor on C3 the lower modes deliver the implied note at nearly every stroke. A reading that weights the whole spectrum still hears none of it.

perception · Masking

Named alongside it

The objects these essays reach for when they reach for this one.

MaskingRegisterSpreading functionResidue pitchDynamicsTriadChord qualityRoughnessVoicingAutocorrelationDoublingFrequency ratio

All concepts