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Sub-harmonic Chords

Musical chords can include frequencies below the supposed hearing level
  (+2, -4)
(+2, -4)
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I got this idea when I once was listening to Pink Floyd albums while watching the frequencies of the music displayed on an oscilloscope.

Why the artificial barrier between rhythm and melody? Can we really not hear frequencies below 40Hz? What about a 1Hz drum beat (once a second)? We can hear that pretty well. When music changes stanzas regularly, doesn't that represent a frequency in the range of 0.1 or even 0.01Hz?

Our minds naturally appreciate musical chords. We even feel different emotions with different types of chords (minor chords are usually sadder than major chords). I think that if we build up the 'key' and chords of a particular piece of music and include the frequency of the rhythm of that music into the chord, that we can hear it and appreciate it.

How low in frequency do you go? We ought to start and experiment with rhythm, but you can go lower to include day-to-day, year-to-year, even include a whole lifetime in the chord! Isn't that the rhythm/music of living? Alright, maybe I'm taking this idea a little too far, but this is the 'halfbakery' afterall.

Note that I'm not a musician and haven't figured out the frequencies of rhythms/chord changes that match particular chords but I think it would be interesting to try.

newt, Apr 17 2005

Beat editing Natural_20beat_20editing_20software
A tool that could be used in creating sub-harmonic chords [newt, Apr 17 2005]

Bias and Subsonics in Mixing and Stereo Imaging http://www.themusic...icles/BiasGood.html
Some general info about subsonic freqs in sound engineering. [half, Apr 17 2005]

See last sentence of idea Sexularity
[JesusHChrist, Apr 17 2005]


       Questions, young Padishwans. What is the invention here?
gnomethang, Apr 17 2005

       "...1Hz drum beat (once a second)? We can hear that pretty well." A 1Hz drum beat is made up of many frequencies above 1Hz.   

       Is the use of subsonic harmonics really a new idea?
half, Apr 17 2005

waugsqueke, Apr 17 2005

       + absolutely. The harmonic beats that happen when two tones slightly vary -- the ones you can hear as you tune two guitar strings to the same pitch -- can themselves act as a subsonic tone. If two people sing an approximate unison, the harmonic beats created as their tones slightly vary could act as a mutual clock on which to base other timed communication. See the last sentence of (linked) idea "Sexularity".
JesusHChrist, Apr 17 2005

       As written, your idea has precisely nothing to do with subharmonics.
bristolz, Apr 17 2005

       My, God! [Ian], all these years I've just been sitting back & mellowing out. I should have known I needed an oscilloscope to do it properly.
I suppose next someone is going to say that the only true way to listen to the Doors is in the dark with flashing led's embedded into the record label.
Zimmy, Apr 17 2005

       I think there's some confusion between subsonic frequencies on the one hand, and subsonic modulation of sonic (?) frequencies on the other. Every New Year, there is a spate of people singing "Auld Lang Syne", but this does not mean that the song has a meaningful audio component at 0.0000000317Hz.
Basepair, Apr 17 2005

       Some responses: what's the invention? New types of musical chords that no one has implemented into music before.   

       "this does not mean that the song has a meaningful audio component at 0.0000000317Hz" Yes it does, that's the whole point. But does this frequency match the other frequencies of the chord? Probably not. I am also not sure our brain would recognize the low frequency as part of the chord (but wouldn't it be fascinating if it turned out that the brain CAN recognize it). Maybe it needs to be sung every 200 days. I need to work out the math.   

       More realistically, I think that frequencies of 20hz down to 0.1hz can be added to chords --and that we would hear and appreciate it (if the frequencies were correct for the chord).   

       Yes 1HZ has lots of frequencies, but the one we notice the most is 1HZ. It would be interesting to build that 1HZ drum beat out of a sub-harmonic chord!   

       I like JesusHChrist's idea of harmonic beats that happen when two tones slightly vary. These sub-sonic frequencies are more pure than what I had envisioned, yet are still recognizable.
newt, Apr 20 2005

       Now now, Ian, no need to get personal.
Basepair, Apr 20 2005

       No, the one we notice most is not the 1 hz. If only one drum beat was played, we'd still hear it.   

       Yes, we can feel frequencies lower than 40 hz. Most people who haven't damaged their hearing via constant exposure to loud sounds can reliably hear a tonal quality down to about 20 hz. Some can identify all the way down to 10 hz, but at that point, it's felt more than heard.   

       If you were to play a pure square wave at 1 hz, you could hear it, but it wouldn't be as a tone, but rather as a pulse of white noise, since it would briefly stimulate all of the receptor hairs in your inner ear.   

       On the other hand, if you could amplitude-modulate a waveform at less than 40 hz, you could add some musical quality to the sound. But that's not a new idea either. Singers do it regularly. It can be done naturally as beat frequencies on double-strung (ie 12-string) guitars which are carefully mis-tuned, as well as pianos for all the keys which use multiple strings.   

       Properly "tuned" bagpipe drones produce slightly off-key harmonics which help to amplify and project the sound via subharmonic beats.   

       There's a language (nearly dead, I think) that relies on a group of several men singing slightly out of key, so that the amplified beat frequencies will carry great distances.   

       There's also a type of singing known as "throat singing", where the shape of the mouth and throat is carefully controlled to induce certain subharmonics and overtones.   

       But no, rythym and tone are two completely separate things.
Freefall, Apr 20 2005

       //Properly "tuned" bagpipe drones// which?
Basepair, Apr 20 2005

       [FF], that's odd. Why would the beat frequency carry further than the waves of its constituents?
RayfordSteele, Apr 20 2005

       Low frequency waves travel further, i think.
Ling, Apr 21 2005

       I've heard throat singing. It has been said that Pres. Clinton sometimes used these types of sounds in his speaking voice (unconscously, but very effectively).   

       Nah, I still think that frequency and rhythm have been artificially separated by musicologists. The brain activity is full of frequencies from hearing down to the sub-Hertz.   

       Maybe I'll have to fully bake the idea to convince anyone!
newt, Apr 21 2005

       Take it down to DC for the ultimate thrill.
bristolz, Apr 21 2005

       That's wind.
Ling, Apr 21 2005

       A beat frequency is not a 'sound frequency' at all, in the strict sense of a pressure wave. It is simply the increasing and decreasing of the volumes of the average carrier frequency. It cannot be divorced from its carrier, and therefore cannot travel further than its carrier.
RayfordSteele, Apr 21 2005

       If we are talking about carrier waves, for example, radio signals then sure, I agree. Two signals would need to be received in order to get the beat.   

       But I'm not so sure about sound waves, where they can be mixed at source.
Ling, Apr 21 2005

       [Basepair]: hence the quotes around "tuned". Personally, I think a single bagpipe sounds like a sick angry cat being strangled, but massed pipes (large groups of pipers and drummers) blend together in such a way as to be absolutely beautiful.   

       [RayfordSteele]: The beat frequencies don't carry further. It's a side-effect of what a beat-frequency actually is: an amplitude-modulated source frequency formed by the blending of two slightly out-of-phase signals.   

       With two close-matched but not exact frequencies are played simultaneously, there will be times where the wafeforms add constructively (the "peak" of the beat frequency), and some times where they add destructively (the "valley" of the beat frequency). When the tones are close, you don't hear two seperate tones, but one single tone which increases and decreases in amplitude. Since the peaks are louder than any of the single tones alone, the sound carries farther.
Freefall, Apr 21 2005

       First, let me jump in on what looks like an obvious misunderstanding (or a really bad turn of phrase). "What about a 1Hz drum beat (once a second)? We can hear that pretty well."   

       No, you can't. You can hear another note modulated at 1 hz, but not the 1hz note itself. Try it. Get a fan. Wave it at 1 Hz. You get a nice swish of wind, so there's plenty of amplitude there, but no note (if you do hear something it'll be a resonant harmonic resulting from the shape and weight distribution of the fan). If you built a sensor that could detecct this 1Hz wind, you could display it on an oscilloscope, but you still wouln't hear it.   

       The second thing is one that I find quite interesting. If you modulate a note with one half its frequency (ie an octave below) and keep doing this until you get to quote long 1Hz-ish freqencies is the sound at all interesting... and, if you play this note along-side other notes that harmonise well with the first note, will this, too, sound pleasing or will the different frequencies of repetition jar horribly. After all each note has an effective echo set for it, the length of the echo being dependent on the note and therefore being different for every note in a piece.   

       As an aside, isn't this how DSPs build sounds -- by adding together sine waves of different frequencies -- it's just that they don't go sub-aural, allowing the musician to decide the rhythm of the piece rather than the note itself.
st3f, Apr 21 2005

       //If you modulate a note with one half its frequency (ie an octave below) and keep doing this until you get to quote long 1Hz-ish freqencies is the sound at all interesting//
Sounds like the difference between a giant church organ and a little circuis calliope. So I'd say yes, it sounds interesting.

       As an experiment, I played with a tone generator hooked up to an oscilloscope and a large ported-box subwoofer this afternoon. I started at about 100 hz, and turned down the frequency until I could no longer hear a proper homogeneous tone. I found that I could hear down to about 12 hz. Below that, I could still feel the sound, but there was no audio quality to it.   

       Just out of curiosity, I modified the waveform from pure sine to a heavily clipped sine (to approximate a square wave) and I found that there was audible sound all the way down, but it was more of a buzz that transitioned to a rapid clicking, as opposed to a proper homogeneous tone.
Freefall, Apr 21 2005

       [FF], yeah I know. I see what you're saying with the distance carried. Simply more amplitude.   

       st3f, at those low frequencies, it's difficult to discern tonal differences at all, so the 'ultra-base' notes could harmonize with nearly anything.
RayfordSteele, Apr 21 2005

       [freefall] //a single bagpipe sounds like a sick angry cat being strangled, but massed pipes... blend together in such a way as to be absolutely beautiful.//

Yes, it's odd, that, isn't it? Sort of the audio-equivalent of a piece of sand in your eye versus walking on a beach.
Basepair, Apr 21 2005

       "it's difficult to discern tonal differences at all, so the 'ultra-base' notes could harmonize with nearly anything."   

       Down at 1Hz, it's rhythm not tone. If you start playing a three note chord that harmonises, the question is, are their different delay echoes going to sound good together, too?   

       That's not a question that I'm equipped to answer. I wonder if anybody here has the ability and the inclination to demo this.   

       A random thought, just occurred to me: Since a note tends to bring out its harmonics by driving sympathetic oscillations (don'tcha just lurve long words), sub-aural harmonics are a natural fact of life. It's just that the effect is rather weak when you get to frequencies that are long way from the primary.
st3f, Apr 22 2005

       [freefall] If you clipped the sine wave, you would hear the higher frequencies caused by the discontinuities. Same with the square wave you suggested. Try FFTing the clipped waveform and look at the spectrum.
AbsintheWithoutLeave, Apr 22 2005


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