I have a fidget-spinner. When it is still, it looks like this:

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When it is moving, it looks like this

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Physically, the prongs are always there. The issue is how my brain processes it. There is a certain speed at which, if the prongs move sufficiently fast, my brain has trouble telling them apart. And, once I reach that speed, the spinner goes from looking like a 3-pronged toy to a weird swirly circle, like in the picture.

I was wondering if a similar effect happens in music. For example, suppose I play a melody like happy birthday on the computer at a normal tempo. And I keep speeding it up until gradually the notes blur together. Then presumably something similar would happen with the notes. They would sound "blurred" together.

I can think of a couple examples of this off hand that sound this way to me.

First, Debussy's l'isle joyeuse, measure 1 where he has

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Chopin's fantaisie impromptu, measure 5

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Mozart Clarinet quintet movement 4, K. 581, 9 measures into the the adagio part after variation 4:

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I'm sure this is subjective and these may not be the best examples.

But this question seems important in part because, some people make the claim that music is similar to a language. But one of the important aspects of language is that you can actually hear the words being uttered. So, imagine saying a sentence like "The cat sat on the mat" so fast that the words blurred together, then it would be difficult to understand the sentence at all. It goes from being intelligible words to just sound.

To what extent can humans perceive musical notes when they "blend" together? Do composers intentionally create this effect? If so, where is the cutoff before notes stop being notes and instead become a messy auditory blur kind of like if you say a sentence too fast?

  • Short of a close vote, but I think what this question is really asking is about the limits of human auditory processing, which would be a physiological/neurological issue, not a musical one. There is no question that sounds can be sped up to a point where they're unintelligible (think fast-forward), but in non-computerized music there is a natural limit based on limits on how quickly people can produce sounds (or movements that produce sounds). At least in the examples given, I can hear the distinct pitches, but after years of musical training.
    – Aaron
    Dec 29, 2020 at 20:55
  • 1
    It should be straightforward to create an at-home experiment for this. Use some notation software with playback capability to notate a sequence of "fast" notes; then play it back at increasing tempos to find the (range of) speed(s) at which the notes "blend".
    – Aaron
    Dec 29, 2020 at 20:58
  • Two Thoughts: 1) Listen to Simon and Garfunkel's "The Boxer"; the solo is a cornet doubling a steel guitar. Sometimes the steel does a thing the cornet can't and that pops out, and sometimes the reverse happens. 2) John Coltrane experimented with what was called Sheets of Sound, where arpeggios and scales were played at great speed to imply several chords at once. Dec 29, 2020 at 23:22
  • 1
    A third thought: going full speed, Adam Neely argues and demonstrates that Polyrhythm are Polypitch Dec 29, 2020 at 23:25
  • I've actually read more about a reverse version of this: at roughly 1000 bpm or so, drum beats start sounding like musical notes with strange timbres instead of drums. This is used in extratone music (a type of electronic music related to speedcore).
    – Dekkadeci
    Dec 30, 2020 at 15:46

2 Answers 2


In a sense, this is usually the case. When the oboe plays 440Hz to tune the orchestra, you hear a continuous tone like your fidget spinner when it is fast. You do not hear 440 high pressure peaks a second. However, play lower and lower notes and when they get really low, you will hear separate pulses, like your spinner as it slows. I created a series of test tones from ridiculously low 4Hz up to 20000Hz (about as high as is possible with the usual digital sample rate). My purpose was to test my equipment and my ears. At the high end, I just cannot hear anything. The low end is different, it does not become inaudible but you start to discern (feel if not hear) the pulses,

  • 1
    Very true - in OP's examples, the first picture shows stasis; the second, motion. But without motion, there can be no sound. Dec 30, 2020 at 11:51

Yes, tones are intentionally blended.

It happens a number of ways.

One way is reverb. The ancient kind is a cave or a cathedral. Electronic reverb and delay do the same thing artificially. Some might say reverb is just an echo effect, some kind of vague "aura" in sound. But, I think you can make the case that some spaces were designed intentionally to have such strong reverb that tones blended until you got a sort of harmony with the reverberations. Guitarists definitely do that with electronic reverb.

A chord is by definition a blending of tones. A lot of harmony is limited to just 3 or 4 tones per chord, but 5 tones for a complete ninth chord only leave out 2 tones of a key. Certain modern styles of composition combine more tones. If you combine lots of adjacent tones it's called a tone cluster. At the very least I think your idea of blending tones comes into play with tone clusters.

The musical device glissando is basically a blending effect. Depending on the instrument the tones of the glissando are sustained, like a harp or piano. The tones move in a rapid flourish which is not a melody and not quite a chord. The quick sweep of tones is left to resonate against one another. You certainly hear the individual tones, but the effect of them all combining is the critical part. You hear it as a single blended unit too.

If you're looking for some kind of gradation or cut off points with perception, I would say things in order of increased blending might be:

  • melody (single pitches)
  • scale (all tones)
  • glissando (all of them really fast)
  • chord (simultaneous tones)
  • tone cluster (all tones, all at the same time.)

Consider "all tones" to be some limited set like a key or tone row, etc. basically the tones of the tonal palette.

I don't think it's a matter of whether such perception occurs, it's only a question of where you want to make the cut off points for levels of blending and applying labels to them.

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