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A bell that rings two notes at once (2017) [video]
- chrisdave 3y agoAs 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.
- pintewn 3y agoI 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 https://m.youtube.com/watch?v=jbJPIRurJYE [2] https://m.youtube.com/@matthiasrandomstuff2221 https://m.youtube.com/@matthiasrandomstuff2221
- quanto 3y agoI 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) https://en.wikipedia.org/wiki/Beat_(acoustics)
- 77pt77 3y agoIt's impressive the concept of bear frequency wasn't even mentioned briefly.
- deleted 3y ago[deleted]
- analog31 3y agoA 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 3y agoYes. Numberphile had a video on this: https://youtu.be/MfzNJE4CK_s https://youtu.be/MfzNJE4CK_s
- esperent 3y agoI 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 3y ago“This isn’t a gong, it’s a pot”
- michaelcampbell 3y agoHe's been around for a long time; great content. Most woodworkers know him quite well.
- jakzurr 3y agoWow, that vid really did it for me. Amazing sounds. Thanks for digging that up.
- deleted 3y ago[deleted]
- bluepod4 3y agoSome people can do this with their vocal cords. Sometimes it’s more than 2 notes. https://en.m.wikipedia.org/wiki/Overtone_singing https://en.m.wikipedia.org/wiki/Overtone_singing
- jacquesm 3y agoSuch as Anna-Maria Hefele: https://www.youtube.com/watch?v=vC9Qh709gas https://www.youtube.com/watch?v=vC9Qh709gas
- FpUser 3y agoThis 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.
- jacquesm 3y agoIt 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.
- praptak 3y agoShe has a video with a spectral analyser, YT search something like "overtone singing spectral analysis".
- deleted 3y ago[deleted]
- matheist 3y ago> 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 3y agoAlso has a text version (though of course the video illustrates the sounds better): https://woodgears.ca/physics/bell.html https://woodgears.ca/physics/bell.html