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Sound

ciechanow.ski

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Re: Sound

#181

Post by dsego »

rectang wrote: post #38
nonrandomstring wrote: post #20

+1 for the recommendation for "The Scientist and Engineer's Guide to Digital Signal Processing" by Steven W. Smith. I spoke to Steven many years ago about his putting all of the book PDFs online for free and since then have recommended at least 5 university libraries to buy it because the students could get free copies of a great book that can be referenced in the library. FWIW the The Scientist and Engineer's Guide…

I have this conviction that I ought to be able to code up crude audio DSP processors before I understand the totality of the theory. For example, every DFT/FFT explanation seems to start with complex numbers. I wish there was a resource that was programming focused, starting with "Step 1: Process this artificially created periodic signal by multiplying it by sine waves of frequencies from from 1 to N. There are our b…

I once found one article that started with the concept of "probing" with a test signal, and then you need to probe with both sine and cosine to reconstruct the phase. Complex numbers seem to be a neat mathematical notation for this sin/cos pair.

Re: Sound

#182

Post by marginalia_nu »

marcodiego wrote: post #120
owenfi wrote: post #101

Earlier quoted context omitted.

Would love some additional info on this if you are aware of any. My intuition says (and could very well be very wrong) sound at one frequency would only damage that or very nearby frequencies hearing range? If wrong I'm curious what the range of damage is (I'm interested in exploring ultrasound data protocols, so curious what frequency I have to go to to avoid damaging anyone's - and potentially animals as well - hea…

"With protracted exposure, inaudible ultrasound can also contribute to hearing loss." https://www.health.belgium.be/en/ultrasound-and-high-frequen...

Operative word being protracted.

It's also important to realize that especially with infrasound, you're always exposed to it along with most regular sounds.

The modulation applied to sound to turn it into speech (i.e. amplitude and frequency shifts on order ~0.5-2 Hz) shows up in the frequency spectrum at those sorts of frequencies.

If you say "hey hey hey hey hey", that's a 1 Hz-or-whatever sound wave you're producing with a higher frequency carrier wave.

Re: Sound

#184

Post by mandmandam »

panic wrote: post #173
jackphilson wrote: post #161

Earlier quoted context omitted.

Now imagine if all education were like this. What if there was a market that incentivized the creation of top-quality educational content like this? Create it for one topic, usable forever.

A market would ruin it. This type of work is done for love, not for money.

I don't think that's necessarily true.

The markets we have are perversions. They are captured; regulated and deregulated in all the wrong places.

It is possible that small changes in how money or capital works could enable far better markets.

Re: Sound

#185

Post by tsp »

I encountered a strange bug on iOS: after visiting the Sound website, which uses the Web Audio API to play sounds, web-views in other apps (e.g. Lieferando, a food-delivery app) would play the same sound. So it seems like all web views share the audio context. Really weird.

Re: Sound

#186

Post by mandmandam »

account42 wrote: post #174
jackphilson wrote: post #161

Earlier quoted context omitted.

Now imagine if all education were like this. What if there was a market that incentivized the creation of top-quality educational content like this? Create it for one topic, usable forever.

How do you expect a market to incentivize this?

Basic income could let people work on stuff like this without the fear of starvation.

The tech is there, the resources are there. The will is there, if you ask the right questions. But powerful interests like things the way they are, and are willing to kill millions to keep things that way.

Re: Sound

#187

Post by Synaesthesia »

zasdffaa wrote: post #180
alberth wrote: post #149

Earlier quoted context omitted.

For the HN crowd who like to roll with JS turned off, you’re missing out on great interactive illustrations.

Useful tip, thanks. I never enable JS on my machine, starting up a VM as I type. Hmm, is it me or does the 440Hz sound seem higher pitched than it should? I'm not a musician at all but the 330Hz sounds closer to what I'd expect.

That's a 440. It's quite a high note.

Re: Sound

#188

Post by andrepd »

ChicagoBoy11 wrote: post #122
PostOnce wrote: post #79

This man needs a genius grant, and this is about the 6th time I've thought this. Any one of these pages would be a feat, an achievement to be proud of, but as a collection, it forms one of the greatest educational resources of its type that I have known. These things can give you more intuition about a subject in 45 minutes than a textbook might be able to in 3 months, because it's interesting and not dry. I wish I h…

I saw your comment and was like: "wait a minute... surely its not the same guy as the mechanical watch thing, is it?!?!?!" Absolutely blown away. As someone with a "design for learning" degree which I've found to be rather useless, I'd gladly have traded by dozens of thousands of dollars for a chance to learn with this guy. The technical sophistication combined with the incredibly didactic and clear flow of his work…

The watch, the ICE, and the ship are my favourites.

Re: Sound

#189

Post by distcs »

Anyone here knows what tools are being used to make the wonderful animations in the OP article?

Re: Sound

#190

Post by andrepd »

AceJohnny2 wrote: post #43
comboy wrote: post #39

Earlier quoted context omitted.

> Lagrange had insisted that such an approach could not be used to represent signals with corners, i.e., discontinuous slopes, such as in square waves. Isn't that true though? You can only approximate it, right?

In practice, yes you can only approximate it, because in theory it requires an infinite series of sinusoidal waves. But since maths is all about the theory, Laplace's objections were silly. (though I admit I don't know what the state of acceptance of infinite series was at that time) Also, it's fine to cut off the infinite series of sinusoidal waves because all physical systems cut off around a given frequency, for e…

Not quite, that's not the problem. We're in the realm of maths here and therefore of pure abstraction, so that's not the point. Adding terms to the Fourier series of a square wave you have an overshoot that does not converge to zero as the number of terms goes to infinity. This is called the Gibbs phenomenon https://en.wikipedia.org/wiki/Gibbs_phenomenon
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