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Spectograms of each note will also make it strikingly clear that there is a dominant frequency invoked and overtones (harmonics) also being invoked that give th

by sova 6y ago

Spectograms of each note will also make it strikingly clear that there is a dominant frequency invoked and overtones (harmonics) also being invoked that give the sound its full sound-profile. If sound is atmospheric texture, the overtones are irreplaceable grooves in the ether. The simple sine wave is exactly one dominant frequency in a spectrogram, a line. Instruments such as a trumpet will have upwards of 12 overtones, parallel lines, lessening in strength. One interesting idea that came to me last night was trying to reproduce the physical 3D model of an instrument based on its spectrographic fingerprint. With enough samples, this ought be possible, and with a 3D printer one might even be able to create interesting physical instantiations of instruments based on spectrographic fingerprints. One could even create never-before-seen instruments based on a generated spectrogram, in an interesting radar-to-ocean operation (as opposed to ocean-to-radar, how radar normally works). Maybe topography-from-radar is a clearer way to state the same. Generating audio from spectrograms is an open problem and I would love to see more open-source work in this domain.

CogitoCogito 6y ago
> One interesting idea that came to me last night was trying to reproduce the physical 3D model of an instrument based on its spectrographic fingerprint. In case you haven't already read it, this might be of interest to you: Mark Kac: "Can One Hear the Shape of a Drum?" https://en.wikipedia.org/wiki/Hearing_the_shape_of_a_drum https://en.wikipedia.org/wiki/Hearing_the_shape_of_a_drum https://www.maa.org/sites/default/files/pdf/upload_library/22/Ford/MarkKac.pdf https://www.maa.org/sites/default/files/pdf/upload_library/2...
- junon 6y ago
  Would be interested to see this applied to drums that have intra-beat tuning, such as the talking drum or the idakka.
11thEarlOfMar 6y ago
And this is why we can synthesize different instruments electronically. Reproduce the overtone patterns and you hear the same instrument. Not to mention, two different pianos or two different violins can sound very different.
- loganhood 6y ago
  The sustained overtones are only half the battle. Getting the attack correct (the sound profile of the first ~10 milliseconds) is really important for differentiating instruments. Plucking a guitar string and hammering a piano string have very different attack characteristics. A flute has a distinctively "breathy" attack. Many synthesizers use a sampled recording of the actual instrument for the attack, then synthesize the sustained portion of the instrument.
  - whiddershins 6y ago
    > The sustained overtones are only half the battle. Actually probably like 10% at most of the battle. My understanding is attack is overwhelmingly dominant in our perception of timbre.
  - dwd 6y ago
    This takes me back to when I played around with sound using the C64 midi. There were four attributes that you could adjust to try and emmulate the timbre of a particular instrument: attack, delay, sustain & release. Was a lot of fun when I was young.
leetcrew 6y ago
ignorant/lazy question: I'm a guitar player who took a few months of trumpet lessons when I was a kid. I recall that you can produce several different notes with the same fingering on the trumpet depending on the shape of your mouth. is this similar to the natural harmonics you can produce with a guitar by covering (but not fretting) the strings at certain nodes?
- jalgos_eminator 6y ago
  I don't play trumpet, but I think that is basically what is going on. You can do pinch harmonics on guitar, which silence certain harmonics or even the fundamental while retaining others. It sounds like changing mouth shape does a similar thing on trumpet. edit: here's a fantastic video on pinch harmonics: https://www.youtube.com/watch?v=eTWxCdoyol0 https://www.youtube.com/watch?v=eTWxCdoyol0
  - conformist 6y ago
    Yes, to first oder, a trumpet is a long tube with a standing wave, which works conceptually like a string (but with different boundary conditions). It's probably the player's imposed frequency hitting multiples of the lowest resonance frequency that leads to different tones.
  - bqmjjx0kac 6y ago
    Great video. In case it's not obvious, the different notes are purely a function of pick/thumb placement. The guitarist is not changing frets, but he seems unable to resist throwing in some vibrato :)
  - sova 6y ago
    Yes, that's exactly right. "Covering but not fretting" a string on the guitar will dampen the lowest harmonic because the full length of the string is unavailable for vibration [1]; frequency is one over wavelength (e.g. twice the frequency is one half the wavelength). You can pluck either side of the string when covering it to produce the same harmonic (neck side or body side). On a trumpet, the embouchure will affect the frequency of the vibration of the air compressed in the tube, and simply drop out lower harmonics, as can be confirmed via spectrogram. The same thing happens on a guitar, leetcrew I encourage you to try the spectrogram linked at that site with your guitar to note the effect [0]. [0] https://musiclab.chromeexperiments.com/Spectrogram https://musiclab.chromeexperiments.com/Spectrogram [1] I am under the impression that the fundamental tone of the string requires the whole string-length to resonate, and if it is clamped, pinched, or otherwise muted all you will hear are resonant harmonics that can exist on smaller string segment lengths.
yobert 6y ago
I read somewhere about people doing this with samples of thunder, to recreate the shape of the lightning bolt. So cool!
ttt0 6y ago
> Spectograms of each note will also make it strikingly clear that there is a dominant frequency invoked and overtones (harmonics) It's not even about which frequency is dominant. I'm not an expert on psychoacoustics from the "sciency" side, but basically our brains can figure out the fundamental note based on the harmonics alone, even if we don't hear the fundamental frequency itself. De-emphasizing the fundamental frequency is sometimes used in synthesis just to create an interesting sound, but most notably this phenomenon is heavily relied on in modern heavy bass electronic music and down-tuned metal. A really common trick is to distort the bass track, so it can be still heard even if speakers can't reproduce that frequency, as distortion generates more harmonics. I don't mean distortion in literal sense, but in audio effect sense, so effects like saturation, overdrive, fuzz, clipping, etc.
- hippira 6y ago
  Very interesting, since the artificial “ghost” note is at a lower frequency, would they essentially become an “undertone” ?
  - TylerE 6y ago
    No, not really. The fundamental is always the lowest frequency. All overtones are some (almost always integer, or _nearly_ integer) multiple of that.
  - ttt0 6y ago
    Undertone is something different, but I never explored that concept and what could it be useful for, so I can't really explain it Not an undertone, it's fundamental frequency. Harmonics/overtones follow a very specific pattern: https://en.wikipedia.org/wiki/Harmonic_series_(music) https://en.wikipedia.org/wiki/Harmonic_series_(music) ...so in most cases there isn't really any ambiguity on what the actual fundamental frequency is. The best way to demonstrate it is probably with a high-pass filter (aka. low-cut filter). High-pass filter allows only higher frequencies to pass through, or in other words it cuts out lower frequencies. On the example below you can hear that as the lower frequencies are getting removed from the signal, it's still the same note: https://www.youtube.com/watch?v=50lRE2Bgag0 https://www.youtube.com/watch?v=50lRE2Bgag0 I wish the filter sweeps were slower, but that's the best example I could find
m463 6y ago
Are you saying you could say, do a spectral analysis of someone singing or talking, then make a physical instrument that sounds similar?
- neltnerb 6y ago
  Sure, you can do that kind of thing in principle. I think the vocal cord model needs to be constrained which will not be very fair, but I was reading papers over a decade ago about simulating speech with physical models of the voice. I assume that's how they guess what dinosaurs might have sounded like. Of course, with such a complicated and underconstrained system you might need to basically tell it what a human vocal system roughly looks like and let it calculate parameters based on the model. Maybe not though, neural networks are surprising sometimes.

by sova 6y ago

CogitoCogito 6y ago

> One interesting idea that came to me last night was trying to reproduce the physical 3D model of an instrument based on its spectrographic fingerprint. In case you haven't already read it, this might be of interest to you: Mark Kac: "Can One Hear the Shape of a Drum?" https://en.wikipedia.org/wiki/Hearing_the_shape_of_a_drum https://en.wikipedia.org/wiki/Hearing_the_shape_of_a_drum https://www.maa.org/sites/default/files/pdf/upload_library/22/Ford/MarkKac.pdf https://www.maa.org/sites/default/files/pdf/upload_library/2...

junon 6y ago
Would be interested to see this applied to drums that have intra-beat tuning, such as the talking drum or the idakka.

11thEarlOfMar 6y ago

And this is why we can synthesize different instruments electronically. Reproduce the overtone patterns and you hear the same instrument. Not to mention, two different pianos or two different violins can sound very different.

loganhood 6y ago
The sustained overtones are only half the battle. Getting the attack correct (the sound profile of the first ~10 milliseconds) is really important for differentiating instruments. Plucking a guitar string and hammering a piano string have very different attack characteristics. A flute has a distinctively "breathy" attack. Many synthesizers use a sampled recording of the actual instrument for the attack, then synthesize the sustained portion of the instrument.
- whiddershins 6y ago
  > The sustained overtones are only half the battle. Actually probably like 10% at most of the battle. My understanding is attack is overwhelmingly dominant in our perception of timbre.
- dwd 6y ago
  This takes me back to when I played around with sound using the C64 midi. There were four attributes that you could adjust to try and emmulate the timbre of a particular instrument: attack, delay, sustain & release. Was a lot of fun when I was young.

leetcrew 6y ago

ignorant/lazy question: I'm a guitar player who took a few months of trumpet lessons when I was a kid. I recall that you can produce several different notes with the same fingering on the trumpet depending on the shape of your mouth. is this similar to the natural harmonics you can produce with a guitar by covering (but not fretting) the strings at certain nodes?

jalgos_eminator 6y ago
I don't play trumpet, but I think that is basically what is going on. You can do pinch harmonics on guitar, which silence certain harmonics or even the fundamental while retaining others. It sounds like changing mouth shape does a similar thing on trumpet. edit: here's a fantastic video on pinch harmonics: https://www.youtube.com/watch?v=eTWxCdoyol0 https://www.youtube.com/watch?v=eTWxCdoyol0
- conformist 6y ago
  Yes, to first oder, a trumpet is a long tube with a standing wave, which works conceptually like a string (but with different boundary conditions). It's probably the player's imposed frequency hitting multiples of the lowest resonance frequency that leads to different tones.
- bqmjjx0kac 6y ago
  Great video. In case it's not obvious, the different notes are purely a function of pick/thumb placement. The guitarist is not changing frets, but he seems unable to resist throwing in some vibrato :)
- sova 6y ago
  Yes, that's exactly right. "Covering but not fretting" a string on the guitar will dampen the lowest harmonic because the full length of the string is unavailable for vibration [1]; frequency is one over wavelength (e.g. twice the frequency is one half the wavelength). You can pluck either side of the string when covering it to produce the same harmonic (neck side or body side). On a trumpet, the embouchure will affect the frequency of the vibration of the air compressed in the tube, and simply drop out lower harmonics, as can be confirmed via spectrogram. The same thing happens on a guitar, leetcrew I encourage you to try the spectrogram linked at that site with your guitar to note the effect [0]. [0] https://musiclab.chromeexperiments.com/Spectrogram https://musiclab.chromeexperiments.com/Spectrogram [1] I am under the impression that the fundamental tone of the string requires the whole string-length to resonate, and if it is clamped, pinched, or otherwise muted all you will hear are resonant harmonics that can exist on smaller string segment lengths.

yobert 6y ago

I read somewhere about people doing this with samples of thunder, to recreate the shape of the lightning bolt. So cool!

ttt0 6y ago

> Spectograms of each note will also make it strikingly clear that there is a dominant frequency invoked and overtones (harmonics) It's not even about which frequency is dominant. I'm not an expert on psychoacoustics from the "sciency" side, but basically our brains can figure out the fundamental note based on the harmonics alone, even if we don't hear the fundamental frequency itself. De-emphasizing the fundamental frequency is sometimes used in synthesis just to create an interesting sound, but most notably this phenomenon is heavily relied on in modern heavy bass electronic music and down-tuned metal. A really common trick is to distort the bass track, so it can be still heard even if speakers can't reproduce that frequency, as distortion generates more harmonics. I don't mean distortion in literal sense, but in audio effect sense, so effects like saturation, overdrive, fuzz, clipping, etc.

hippira 6y ago
Very interesting, since the artificial “ghost” note is at a lower frequency, would they essentially become an “undertone” ?
- TylerE 6y ago
  No, not really. The fundamental is always the lowest frequency. All overtones are some (almost always integer, or _nearly_ integer) multiple of that.
- ttt0 6y ago
  Undertone is something different, but I never explored that concept and what could it be useful for, so I can't really explain it Not an undertone, it's fundamental frequency. Harmonics/overtones follow a very specific pattern: https://en.wikipedia.org/wiki/Harmonic_series_(music) https://en.wikipedia.org/wiki/Harmonic_series_(music) ...so in most cases there isn't really any ambiguity on what the actual fundamental frequency is. The best way to demonstrate it is probably with a high-pass filter (aka. low-cut filter). High-pass filter allows only higher frequencies to pass through, or in other words it cuts out lower frequencies. On the example below you can hear that as the lower frequencies are getting removed from the signal, it's still the same note: https://www.youtube.com/watch?v=50lRE2Bgag0 https://www.youtube.com/watch?v=50lRE2Bgag0 I wish the filter sweeps were slower, but that's the best example I could find

m463 6y ago

Are you saying you could say, do a spectral analysis of someone singing or talking, then make a physical instrument that sounds similar?

neltnerb 6y ago
Sure, you can do that kind of thing in principle. I think the vocal cord model needs to be constrained which will not be very fair, but I was reading papers over a decade ago about simulating speech with physical models of the voice. I assume that's how they guess what dinosaurs might have sounded like. Of course, with such a complicated and underconstrained system you might need to basically tell it what a human vocal system roughly looks like and let it calculate parameters based on the model. Maybe not though, neural networks are surprising sometimes.