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Shepard tone (wikipedia.org)
99 points by mekoka on Oct 21, 2012 | hide | past | favorite | 34 comments

It's also possible to make such a thing as a shepard rhythm, using much the same principles. It's a lot harder though. Here's an excellent example: http://stretta.bandcamp.com/track/as-clean-as-fire

I highly reccommend listening to and purchasing the whole album if you like bach style soothing-yet-maths-based music.

Some interesting ideas in there but, dear god, have they picked some awful synth patches. And too many of them... I'd like to hear this played with just a single high-quality piano sound for all the instruments.

Autechre did something similar, but getting slower rather than faster, and less subtle:


Another good example is nsi. - risset. preview: http://www.discogs.com/nsi-Squelch/release/1393612

For the record, stretta is a badass:


Mostly associated with the monome.

That's pretty cool! Is there an analysis of this song (or album) somewhere?

There's this blurb he wrote on the soundcloud page:

"When I see a photo of a modular synthesizer, I wonder, as I think many others do, what the thing sounds like. What possibilities lurk within this strange hardware? I want to hear something orchestrated and controlled. I want to hear someone commanding the instrument with authority, not merely floating on waves of serendipity. I want to hear something composed for the instrument, leveraging its strengths, not a orchestration of an existing composition.

'A Funneled Stone' is a pure modular synth release, tracked the old-shool, 1970's way: one monophonic line at a time. Every sound you hear was created, patched and recorded for that moment in time. When a new sound is needed, the patch is torn down and a new one is built. Polyphony is achieved by tracking each voice individually.

A modular album is, by definition, unapologetically synthetic. I also tried to take a more minimalist approach to orchestration, so the individual sounds can be more fully isolated and appreciated. I spent much of the final month of production taking elements out, and editing for length. Sometimes this results in the remaining elements merely hinting at the underlying harmonic movement.

As you can imagine, this process is very time-consuming, but fun. I hope you enjoy the results as much as I enjoyed creating it."

For more super-hi-tech-math-music have a listen to this: http://detroitunderground.net/blog/2012/05/03/vaetxh-libet-t...

That page has technical descriptions of what's happening in each track. Risset illusions are just the start of the psychoacoustic trickery which goes on in that record.

A word of warning however: unlike the stretta stuff, the Vaetxh tracks are REALLY NOT SOOTHING. If you are soothed by them, seek help.

In GEB, Hofstadter argues that Bach's music is highly maths based.

Yes, that's what JohnnieCache said.

Hm, to me it sounds like a sequence of overlapping falling tones. There's a noticeable point where the falling tone is supplemented by one above it. This first happens about 20s in.

edit The noticeable change seems to be very close to 22s.

I studied music undergrad; I remember learning about Shepard tones in one of the early theory classes, and finding the idea fascinating, but it was a disappointment when we actually heard examples.

I'm not quite sure what I imagined the experience would be, but to my perception you're right... even when the switch-over (from the higher note as the most prominent, to the one an octave below) is very smooth, there's just a moment where you hear both notes clearly, then the higher note fades out.

It might be more interesting to play with Shepard tones in a more complicated arrangement -- i.e., instead of one prominent note that fades into the next one an octave down, you might have 4-5 prominent notes, fading into others with staggered switch-overs -- possibly all at octave splits, but possibly in a more interesting harmonic blend.

The idea is still interesting. :)

I couldn't hear anything like that. Mind you, I expect the phenomenon is highly subjective and varies from person to person.

The human ear is not equally sensitive to different frequencies, and it's most sensitive at a fairly narrow band at a few kHz.

If you don't correct for that when synthesizing your tones, then one pitch may be much more prominent than the others.

FWIW I am also able to notice those points very clearly.

It does sound like an auditory illusion to many, as not everyone can isolate tones in a mixed sound.

I'm curious if you happen to be a musician or a sound engineer?

Nope, I'm not a musician or sound guy. I'm a coder. But I do enjoy music.

That falling tone on the Wikipedia page sounds like something from one of coil's tracks. I can't pinpoint which one though? they use similar sounds here http://www.youtube.com/watch?v=c6IR90tgtDI and here http://www.youtube.com/watch?v=9_R-mXRONh0

edit Expectation may pay a part - when told "come and listen to this 'endlessly falling' auditory illusion" of course I'm going to try and pick out the subtle seams. I might not notice if it was in the background, unannounced.

I usually can't hear individual tones in, say, a chord, but I heard this effect too. But far more prominent on my crappy laptop speakers (which produce no low tones whatsoever) than with cheap headphones that have a more linear frequency characteristic.

This effect was also used for the infinite stairs in Super Mario 64


Yes! until the batpod replaced it from collective consciousness. Thanks for the memories!

These are mentioned at least once in GEB.

My dad made an animation with a visual effect in the same spirit: https://plus.google.com/109509141493915423605/posts/jokA4Ccu...

Águas de Março is a famous Brazilian song by Antonio Carlos Jobim that employs Shepard tones. It is very easy to hear the use of the technique in the song: http://www.youtube.com/watch?v=srfP2JlH6ls

From Wikipedia: http://en.wikipedia.org/wiki/Waters_of_March

The inspiration for "Águas de Março" comes from Rio de Janeiro's rainiest month. March is typically marked by sudden storms with heavy rains and strong winds that cause flooding in many places around the city. The lyrics and the music have a constant downward progression much like the water torrent from those rains flowing in the gutters, which typically would carry sticks, stones, bits of glass, and almost everything and anything. The orchestration creates the illusion of the constant descending of notes much like Shepard tones.

I hear a loop ~22 seconds long of a falling tone. I can clearly hear the higher pitch tone fade in at the start of each cycle. I'm not such I get the "gets no higher or lower".

I'm listening to this version: http://www.youtube.com/watch?v=DfJa3IC1txI

Why is this the top HN story? There are tons of perceptual audio examples that have been around for decades. Check out Curtis Road's Computer Music book for an in-depth analysis of this technique and more.

Because it's cool and hackers like cool things. I would never have known about this if it didn't make it to the top of HN.

So can we come up with an meaningful definition of 'cool'? There is an infinite number of arbitrary 'cool' things in the world - audio perception is definitely interesting, but so is granular synthesis, binaural audio and physical modelling.

I'm just not sure if the role of HN is to educate users on 'cool' things. Maybe its because most of the US is currently sleeping...

On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.


It's a weekend. Different content rises to the top on the weekend.

If you already know everything about perceptual audio techniques...

I didn't know about it, and found it interesting.

Because it's Saturday... From first-hand experience, it's not hard to get to the top on HN on most Saturdays.

Cool find. It says that it can be interpreted either as a rising or a falling tone, but I only can hear a falling one, even if I try to interpret it as rising.

Each tone is either rising or falling. This example is falling.

You can also use this illusion to make 'octveless notes': http://www.jefftk.com/octaveless/

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