Live data from Hacker News

Sound

ciechanow.ski

111–120 of 222 posts

Re: Sound

#111

Earlier quoted context omitted.

It’s a few lines of standard JavaScript. Nice touch used by many sites, not difficult.

> not difficult. And yet, not so common especially on popular websites with $$$ development costs.

Someone has to care enough to notice, often the case.

Re: Sound

#112
I wish there was a post like this about fire.

On atomic level. Like atoms oscilating? How many photons are emitted when say 5 carbon atoms connect with 5 oxyxen particles? I tried searching and no avail.

Re: Sound

#113
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…

* Lagrange's objections

Re: Sound

#114

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…

This webpage can be converted directly into a science class.

Re: Sound

#115
Incredible! Approachable and fun to learn.

All education should aim for this bar

Re: Sound

#116

Earlier quoted context omitted.

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…

* Lagrange's objections

whoops! thanks. Too late to edit.

Re: Sound

#117
post #38

Earlier quoted context omitted.

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…

Your intuition is right, in that most of the heavy math is simply unnecessary or irrelevant at the practical level. Complex number notation doesn't fall into that category, though. The notion of frequency is intimately tied to the notion of vector rotation, and just as you can't represent Cartesian translation without negative numbers, you can't represent Cartesian rotation without complex ones. The Smith book is def…

Saying that you can't represent cartesian rotation without complex numbers seems a bit much? You do need two numbers. But you can teach a trigonometry class without complex numbers, using either cartesian coordinates or polar notation. And matrices do work.

Re: Sound

#118

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…

The little touches like being able to switch the entire article to metric (or imperial) are incredibly nice and make it more approachable as a result

Re: Sound

#119
All of this with 207 kB over the network. The two slowest requests were to google analytics.

Re: Sound

#120
post #101

WARNING: sounds you can't hear can still damages your ear. DO NOT INCREASE THE VOLUME ON INFRA OR ULTRA SOUNDS BECAUSE YOU CAN'T HEAR THEM

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...
Post reply on HN