[HN Gopher] Show HN: Why does an A note sound different across i...
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Show HN: Why does an A note sound different across instruments?
Author : OmarShehata
Score : 57 points
Date : 2021-03-01 20:52 UTC (2 hours ago)
(HTM) web link (omarshehata.me)
(TXT) w3m dump (omarshehata.me)
| souprock wrote:
| There is a fun program that can display this sort of data as you
| play notes with your ordinary QWERTY keyboard:
|
| https://github.com/kevinacahalan/piano_waterfall
|
| It's portable to Linux and Windows at least. It won't run well in
| a virtual machine (including a ChromeBook) because it needs a GPU
| that can scroll the window fast enough.
|
| There are 3 windows. One just shows the selected waveform. The
| others show an 8192-bucket FFT in red, a 1024-bucket FFT in
| green, and the active MIDI notes in blue. It's live, scrolling up
| at 93.75 pixels per second.
|
| The QWERTY row becomes the white keys, and the number row becomes
| the black keys. F1 through F4 choose the type of sound. Left and
| right arrows change the octave in use; your speakers probably
| don't handle the full range very well. The program turns out to
| be a great speaker test, especially if you change the sound to a
| sine wave. It's also a great keyboard test; see how many keys you
| can hold down before your keyboard won't register any more.
| Individual colors in either window can be toggled with the 2x3
| keypad that has Insert, Delete, Home, End, PgUp, PgDn. (the
| screenshot has green toggled off)
|
| To make a trombone sound, first switch to a type of sound with
| lots of harmonics, like a sawtooth wave. Pick a low note, then
| find notes to line up well with the first two harmonics. Switch
| to the sine wave, and play all three of your chosen notes. For
| more of a clarinet sound, release the middle of the three that
| you have selected.
| spoonjim wrote:
| I'd love to hear a synthetic instrument that's halfway between a
| piano and a violin.
| [deleted]
| sova wrote:
| 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 wrote:
| > 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://www.maa.org/sites/default/files/pdf/upload_library/2...
| 11thEarlOfMar wrote:
| 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 wrote:
| 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.
| yobert wrote:
| I read somewhere about people doing this with samples of
| thunder, to recreate the shape of the lightning bolt. So cool!
| leetcrew wrote:
| 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 wrote:
| 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
| sova wrote:
| 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 [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.
| conformist wrote:
| 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 wrote:
| 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 :)
| cjbenedikt wrote:
| Depends on the frequency
| https://en.m.wikipedia.org/wiki/A440_(pitch_standard)
| Closi wrote:
| Did you read the article? This point is debunked right at the
| start (i.e. two instruments playing the same frequency still
| sound different).
| TheActualWalko wrote:
| Here's some code on WavTool for trying out overtone combinations:
| https://wavtool.com/?code=3
| barnabees wrote:
| Surprised to see no mention of fundamental frequencies or
| harmonics
| neltnerb wrote:
| My electronic music professor literally defined exactly what
| this article is trying to describe as "timbre" meaning the
| overtone sequence (oddly "overtone" and "timbre" are not
| present in the article?) plus off-harmonic frequencies that are
| present for any real instrument.
|
| This is pretty well studied, but kudos to the author for trying
| to explain it again, it's an odd topic. But I suggest looking
| up "timbre" at least and perhaps updating the article with the
| terms used by actual musicians to mean exactly this.
|
| Timbre - "the quality of tone distinctive of a particular
| singing voice or musical instrument"
| nathanyo wrote:
| https://www.youtube.com/watch?v=Wx_kugSemfY
|
| Andrew Huang's video on the harmonic series does a really cool
| dive into this
| TaupeRanger wrote:
| Or literally anything about the physics of sound, which is very
| well understood and has names for all of the concepts the
| author is talking about without mentioning any of them.
| zokier wrote:
| I think it's bit of a shame that the time dependence is left as a
| footnote. ADSR envelope and other expressive dynamics have also
| huge influence on the perceived sound of different instruments
| (for at least me..). This has been then explored by electronic
| musicians by mixing and matching the dynamics and overtone
| patterns to create all sorts of interesting novel sounds.
| odyssey7 wrote:
| This fact was confusing for me back in my school's chorus. I
| don't know if it was confusing to anyone else, but it was to me.
|
| How does a person match the pitch of the piano? I could hear a
| few different pitches when one note was played (in a confused
| way, I would zero in on different parts of the sound), any of
| which might have been the target pitch to be matched.
|
| And was I supposed to make my voice sound more like the piano?
| Was that part of "matching the note?"
|
| Complicating things was the fact that my own voice had different
| pitches in it. Which part of my voice was supposed to match the
| note?
|
| What a time. Now I know I was noticing the fundamental of the
| piano note at times and overtones at some others. Also, changing
| the timbre of your voice can mirror the overtones of the piano
| better, but that isn't normally the goal of a singer.
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