Comment on Feeling that groove

Zwiebel@feddit.org ⁨4⁩ ⁨days⁩ ago

• skulblaka@sh.itjust.works ⁨3⁩ ⁨days⁩ ago

  What I don’t get, personally, is how this one scratched-in groove wave can contain a bassline, a melody and a singing voice and they all can be differentiated coming out of the speaker.

  How speakers work in general is just black magic to me, actually.

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  • xthexder@l.sw0.com ⁨3⁩ ⁨days⁩ ago

    So there’s this thing called a Fourier series…

    Basically any wave can be created by adding together individual frequencies, and with some fancy math it’s possible to go the other way with a Fourier transform and get how loud every frequency is (like is displayed in a spectrogram).

    I think the real black magic is in how our ears and brains can decode the mess of information coming in and identify meaningful patterns.

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    • Elgenzay@lemmy.ml ⁨3⁩ ⁨days⁩ ago

      Image

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    • user224@lemmy.sdf.org ⁨3⁩ ⁨days⁩ ago

      A nice related bookmark I have saved. There’s also interactive pert with a slider where you can draw a wave and then add more and more sinusoids to get closer and closer. And of course the square wave, with infinite sinusoids (theoretically).
      www.jezzamon.com/fourier/

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      • SlurpingPus@lemmy.world ⁨3⁩ ⁨days⁩ ago

        This reminds me, Bartosz Ciechanowski has an explainer about the whole sound thing.

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  • Natanael@infosec.pub ⁨3⁩ ⁨days⁩ ago

    That’s because it doesn’t, your brain does

    Speakers do the simplest thing possible and literally just vibrate. A recording being played literally just recreates a recorded vibration. It’s a tiny choreography that your ears are incredibly sensitive for.

    All the fancy stuff happens in our brains, after our ears has split up the sound around us into different ranges of frequencies (you can think of the hairs in the inner ears as tuning forks). We learn to recognize which frequencies goes together, and then we learn how the frequencies from multiple sources can overlap, and we learn what it all means

    The real crazy part is how something as simple as sound can carry so much information and how reliably our brains can tell it all apart and make sense of it

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    • Zwiebel@feddit.org ⁨3⁩ ⁨days⁩ ago

      This.

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  • nocturne@slrpnk.net ⁨3⁩ ⁨days⁩ ago

    How speakers work in general is just black magic to me, actually.

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    • Imgonnatrythis@sh.itjust.works ⁨3⁩ ⁨days⁩ ago

      Nobody knows what magnets are. The best science can tell us is that you shouldn’t drop them into a glass of water.

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      • brb@sh.itjust.works ⁨3⁩ ⁨days⁩ ago

        Why?

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    • Malfeasant@lemmy.world ⁨3⁩ ⁨days⁩ ago

      Well, the big ones anyway. The little ones use crystals.

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  • Cethin@lemmy.zip ⁨3⁩ ⁨days⁩ ago

    An easier way to understand it, without knowing the math, is to know how it’s made. You play audio into a very similar device and it’s needle scratches the grooves. When you then have a needle pick up the grooves it’s moving the exact same way the needle was forced to move by the original.

    It’s similar to how a speaker and a microphone are basically the same device. If you take a speaker and plug it into a microphone input, it still works (though they’re tuned differently so it’s not as good). A microphone has a crystal vibrate, which creates an electric signal. If you play that electric signal into a crystal it vibrates and creates the same sound.

    There’s no math or anything being done for this to work. It’s purely mechanical. It’s just a copy of what the needle did when sound was played into it, so another needle running through it recreates the same sound. You can use math to represent it, but none is being done by the device (other than just the laws of physics).

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  • captainlezbian@lemmy.world ⁨3⁩ ⁨days⁩ ago

    Here’s a video on the topic.

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  • Bubs@lemmy.zip ⁨3⁩ ⁨days⁩ ago

    This is from a video about headphones. His layman’s explanation at the timestamp is probably the best I’ve heard it told:

    youtu.be/4-rgrSFrwrs?t=647

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  • prole@lemmy.blahaj.zone ⁨3⁩ ⁨days⁩ ago

    Exactly. It makes sense to me conceptually, but it still blows my mind

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• unexposedhazard@discuss.tchncs.de ⁨4⁩ ⁨days⁩ ago

  Even simpler to visualize: Its the movement of the membrane of the speaker turned into a physical line.

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• Eq0@literature.cafe ⁨4⁩ ⁨days⁩ ago

  That explains just a tiny part. There are so many different sounds at the same volume and frequency

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  • gnu@lemmy.zip ⁨3⁩ ⁨days⁩ ago

    All the sounds get mixed together as they approach you (as they compress the same air), by the time it gets to your ear it can be represented by one complex wave.

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    • mp3@lemmy.ca ⁨3⁩ ⁨days⁩ ago

      Like when you flatten all the layers in a graphics project.

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      • FishFace@piefed.social ⁨3⁩ ⁨days⁩ ago

        No, because flattening the layers is a lossy operation but this is reversible.

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      • davidagain@lemmy.world ⁨3⁩ ⁨days⁩ ago

        This is a really good analogy. I perceive more than I see.

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  • qjkxbmwvz@startrek.website ⁨3⁩ ⁨days⁩ ago

    If you can build up intuition around Fourier decomposition I think it gets much easier to understand.

    Multiple things going on at the same frequency are indistinguishable (up to a phase). Lots of stuff going on at different frequency can be separated. Light also has frequency (color) and volume (intensity)—it may be more intuitive to conceptualize in this way.

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    • Eq0@literature.cafe ⁨3⁩ ⁨days⁩ ago

      Ironically, I work a lot with Fourier Transform. Still feels like magic. I even taught it! I’m trying to develop more intuition about it (vs hard knowledge)

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      • prole@lemmy.blahaj.zone ⁨3⁩ ⁨days⁩ ago

        I forget most of them, but I remember there being several concepts in calculus that straight up felt like magic once I finally understood them.

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  • TowardsTheFuture@lemmy.zip ⁨4⁩ ⁨days⁩ ago

    Yeah, waves add. Which, well they add from the center which looks weird and bumpy. What’s more amazing is how good our ears are at picking out differences (it’s like 100x more sensitive to differences than other senses) so it can tell what all those individual waves would be so we can still hear the guitar vs drums vs bass vs vocals when it’s all one wave combined.

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    • Eq0@literature.cafe ⁨4⁩ ⁨days⁩ ago

      Magic!

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  • FishFace@piefed.social ⁨3⁩ ⁨days⁩ ago

    But all sounds are vibration. If you capture the vibration, you capture all of the sound. The “different sounds” are all a single pattern of vibration; it’s the brain and inner ear that decodes the vibration into separate sounds. And hence it can also be difficult to do, depending on what the sounds are.

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• Oisteink@lemmy.world ⁨4⁩ ⁨days⁩ ago

  It’s not that hard to grasp if you read up a bit. You are probably born early 1900’s and have never heard of stereophonic recordings. But fear not!! What you are seeing is left + right channel (mono). The left - right channel is encoded vertically. So your left channel is mono + vertical divided by 2, and the right is (mono - vertical) divided by 2.

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