[HN Gopher] A bell that rings two notes at once (2017) [video]
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A bell that rings two notes at once (2017) [video]
Author : djoldman
Score : 102 points
Date : 2023-07-15 12:14 UTC (10 hours ago)
(HTM) web link (www.youtube.com)
(TXT) w3m dump (www.youtube.com)
| bluepod4 wrote:
| Some people can do this with their vocal cords. Sometimes it's
| more than 2 notes.
|
| https://en.m.wikipedia.org/wiki/Overtone_singing
| jacquesm wrote:
| Such as Anna-Maria Hefele:
|
| https://www.youtube.com/watch?v=vC9Qh709gas
| FpUser wrote:
| This sounds more like applying resonant filter to one of the
| harmonics. Voice is not a pure sine hence contains "many
| notes".
|
| Some of what singer from Laybach does sound 2 voice as well.
| In some cultures this style is a natural.
| srcreigh wrote:
| It's not just sound, it's literally entitled overtone
| singing.
|
| FYI for anybody. Your A440 is not the only frequency.
| There's every integer multiple (880, 1320, etc) as well.
| Different coefficients of those overtones are why you can
| sing "ahhh" and "eeee" at the same note but they sound
| different.
|
| Polyphonic overtone singing is a technique where one or
| more overtones are heavily emphasized in the timbre.
|
| This is also why major 3rds on pianos are noisy. A4 has a
| C# as it's 5th harmonic at 2200Hz (5*440). But C#5 (A4s
| major 3rd) on piano has a 4th harmonic (two octaves up)
| slightly higher at 2217.48.
|
| That's why if you listen close there will be a ~17Hz
| oscillation around C#7 when you play A4 and C#5.
| jacquesm wrote:
| It doesn't sound like that to me at all but tbh I haven't
| done any spectral analysis of what she's doing. But the
| steps she shows are very hard to do with just filtering
| without losing a lot of output volume and that doesn't seem
| to happen. It sounds like the overtones are added rather
| than filtered out. I'm also unaware of how you'd do the
| filtering from a physics perspective, unless she's able to
| somehow restrict certain modes from forming through muscle
| action.
| [deleted]
| praptak wrote:
| She has a video with a spectral analyser, YT search
| something like "overtone singing spectral analysis".
| matheist wrote:
| > _I 'm also unaware of how you'd do the filtering from a
| physics perspective_
|
| It's the same thing we do when we shape our mouths to
| make different vowel sounds, only much more precise. The
| physical thing that underlies what we perceive as "vowel
| quality" is the frequency of spectral peaks ("formant" is
| the linguistics terminology). When we shape our mouths
| (more generally our vocal tracts) to say "aaa" versus
| "iii" we are creating resonances at certain frequencies.
|
| Admittedly when creating vowel sounds the bandwidth of
| the resonator is pretty wide, and when we hear vowels we
| can still perceive "a" quality vs "i" quality with even a
| wide bandwidth.
|
| What Anna-Maria Hefele and other overtone singers do is
| much more precise. They can get a very narrow bandwidth
| by controlling their vocal tracts more precisely.
| bradrn wrote:
| Also has a text version (though of course the video illustrates
| the sounds better): https://woodgears.ca/physics/bell.html
| esperent wrote:
| I discovered Matthias's channel a couple of weeks ago, great to
| see it here. It's wonderfully real and unpolished compared to
| most YT stuff and he comes across at a lovely chap.
|
| Oh and bell is cool too!
| hinkley wrote:
| "This isn't a gong, it's a pot"
| michaelcampbell wrote:
| He's been around for a long time; great content. Most
| woodworkers know him quite well.
| pintewn wrote:
| I hoped it was Matthias when I recognized the title.
|
| He is one of my favorite science educators on yt, and that may
| well be because he'd likely argue that his content fills a
| different archetype all together.
|
| I love his casual but data, and pen and paper equations, driven
| approach to development.
|
| He creates clever contraptions to collect data to challenge
| hypotheses.
|
| (A recent favorite was a sleigh and a kitchen scale to measure
| fan thrust.[1])
|
| All the while without the, abhorrent to me, "ScIeNcE iS FUN!"
| facade inexplicably so often found in science education.
|
| Rather, the science is simply shown for what it is, and it's just
| him that is fun.
|
| ~"Let me just take an angle grinder to this steel pipe!"
|
| I definitely recommend you check out his other channel.[2]
|
| He split it off because he felt the content was in conflict with
| his main channel, or yts algo did, but I feel people who enjoy
| this video will also enjoy what he posts there.
|
| [1] https://m.youtube.com/watch?v=jbJPIRurJYE
|
| [2] https://m.youtube.com/@matthiasrandomstuff2221
| jrockway wrote:
| Matthias has gotten enough mileage out of his Raspberry Pi to
| make up for all the people that bought them and threw them into
| a drawer.
| f1shy wrote:
| If I had to choose one YT channel, I would choose his. Just
| great, I have learnt so much from him...
| jakzurr wrote:
| Wow, that vid really did it for me. Amazing sounds. Thanks for
| digging that up.
| chrisdave wrote:
| As someone who is not great at visualizing this stuff, I
| appreciate how well this video illustrates the concept. I also
| appreciate the effort he was willing to put in to avoid buying a
| bell.
| analog31 wrote:
| A coffee cup rings two notes at once too. Go around the edge,
| tapping with a pencil, to find the two modes. Now tap on the back
| and side of the handle.
| leipert wrote:
| Yes. Numberphile had a video on this:
| https://youtu.be/MfzNJE4CK_s
| quanto wrote:
| I did not see it clearly in the video: the 'wa wa wa' effect he
| refers to is due to beat frequency [1] that is produced when two
| frequencies are present.
|
| Also, the video alludes to this briefly but worth repeating: if
| the bell (or the pipe) is perfectly circular, i.e. radially
| symmetric, there wouldn't be two separate modes as demonstrated
| (higher frequency harmonic modes would still exists at lower
| amplitudes, but not relevant to discussion here). Grinding the
| bell down on the sides is breaking the symmetry, and thus,
| separate modes.
|
| Coincidentally, Joseph Fourier studied harmonics using a metal
| ring and a heat source, analogous to the circular bell shown
| here. With a heated metal ring, you can visually see the
| different modes (including higher harmonics).
|
| [1] https://en.wikipedia.org/wiki/Beat_(acoustics)
| [deleted]
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