Lots of people have discovered the Lost Chord, but didn't know it or call it that. It's actually a whole class of lost chords. Coming from me, I bet you can figure out that you can't play them in equal temperament.
If you recall Harry Partch's "One Footed Bride" and other measures of interval consonance, you'll see a big lump - the foot if you will - near the octave (2/1):

The Bride's missing left foot (1/1) is actually where the Lost Chords reside. That is to say, the mind altering, fascinating, hypnotic chords of song and story are the extremely close intervals near 1/1. Anyone with a comb filter or chorus/flange effect could have told you that, but here's the thing: as the interference beats get slower, the more this timbral fusion passes from a perceived effect to a composition itself. Also, you need a really stable and pure bunch of sound sources, which my apps Droneo and Srutibox amply provide.

Sir Arthur Sullivan - or rather Adelaide Anne Proctor - appropriately provides a clue in that the Lost Chord is played on an organ, which has the feature of rather stable tuning and lack of modulation - which means a pair of really closely tuned reeds or pipes could actually produce "Lost Chords". In fact, it's hard to imagine any meaningful practical microtonal research without the stability of reed and pipe organ "oscillators". Strings, except for Ellen Fullman's Long String Instrument, have too many unstabilizing influences!

If you play with the harmonic sliders, the timbre will change. There's also a convenient "zero" button for each one. You'll hear each harmonic beating in and out by how many times the period is divided by the harmonic number. That is, if it's a 20 second beat, and you crank up the 4th harmonic, it'll beat every 5 seconds. That's where the micro sequences of polyrhythms comes from. You can also type a number into box next to the slider in case you want to be more precise. Underneath the Seconds to Cycle text box, it shows the frequency of the second signal and its ratio compared with the base frequency.

You can set the pitch of the base frequency using the convenient buttons, and drop it or increase it by octaves. You can also type in the frequency of your choice for more precision. The "Beating" frequency can be changed with the slider, showing how long a beat of the 1/1 pitch will be (all others are beat time/harmonic), and you can also type in a direct ratio or calculate it as a numerator/denominator or cents value. When these change, the time, ratio, and cents are updated, and the numerator is set, based on the demoninator. No ratio can be below 1.0 (or 0 cents).

Interesting effects happen when you set up high harmonics of a low note that beat really slowly. In this interface, you can type in any numbers you like, while the sliders are just for convenience and have a more constrained range of values.

There are a few convenient presets for initializing and processing the harmonic content.

Base Frequency

- Oct A A#/Bb B C C#/Db D D#/Eb E F F#/Gb G G#/Ab + Oct
Seconds to cycle

Ratio calc helpers: num/den: /   cents:

Start AudioStop Audio
Clear AllClears all harmonics
Clear TopClears the top octave
Clear BottomClears all harmonics below 17th
Keep OddLeaves odd harmonics
SpikeSets all harmonics to 1.0
TriangleSets all harmonics to 1.0/n
ElgnairtLike triangle, but backward
Odd HarmonicsOnly Odd harmonics, set to 1.0
Scale High DownQuiets higher harmonics
Scale High UpLoudens higher harmonics
Scale Low DownQuiets lower harmonics
Scale Low UpLoudens lower harmonics
Scale Down by HalfDecrease: new amp = amp/2
Scale Up by HalfIncrease: new amp = 1-((1-amp)/2) if >0
Scale SmoothSmooths amplitudes with neighboring ones
Start AudioStop Audio


Click on these links to bookmark or load a timbre and pitch, beat time, and loudness.

The Lost Chord plays a role in Ergo Phizmiz' light operatic reimagined production "The Dimbola Mikado"(WayBack machine link). You can see the opera in its entirety on YouTube (unless they take it down). Throw Ergo some tips!

        -- J. Henry H. Lowengard -