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Taraxian t1_iy4clfd wrote

Reply to comment by RB181 in Headphone wizardry by SupOrSalad

A lot of audiophile woo can be dismissed by fully internalizing that human hearing is a purely "one-dimensional" sense -- at any given moment the only thing an eardrum perceives is an increase or decrease in air pressure, a single number going up or down, and this one number going up or down over time is what makes the waveform whose varying frequency makes a sound

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Taraxian t1_iy4e3pi wrote

I guess technically this makes hearing in one ear a "zero dimensional" sense -- all you hear is a presence or absence of varying intensity with no "position" data -- and stereo sound is "1D"

I.e. all you have is two eardrums that let you judge how far a sound source is to the right or left of you by whether it's louder in your right or left ear

The other two dimensions of "3D audio", front/back and up/down, are illusory information your brain calculates via deduction, based on your personal HRTF -- clever little hacks based on stuff like the shell shape of your outer ear causing subtle changes in high treble frequencies depending on exactly where a sound is coming from (treble sounds coming from behind you get blocked while ones coming from in front get amplified) and making little judgments based on subtle 3D movements and rotations of your head

Which is the whole reason binaural audio works even though it's just recorded with two mics and played with two speakers in your headphones, and why it's so much more instantly convincing when it includes head tracking the way AirPods do

It's also why, even though your ability to hear positional sound is very convincing to the brain, it cannot be relied on without vision backing it up and why the game of "Marco Polo" is surprisingly difficult

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Username_Taken_65 t1_iy5qoo0 wrote

Directional hearing is not only about volume differential, it actually has more with the slight delay between ears caused by the speed of sound.

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[deleted] t1_iy7u956 wrote

[deleted]

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Username_Taken_65 t1_iy82owz wrote

Yeah, because if something is to your left it will take slightly longer for it to reach your right ear because the speed of sound isn't that fast

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gooftrupe t1_iy5ugmi wrote

Can it not also perceive frequency as well as change in sound pressure? I’m not sure that’s really one dimensional.

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Taraxian t1_iy5uz36 wrote

Frequency IS an increase in sound pressure, it's literally a measure of how fast sound pressure changes back and forth (a vibration)

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Taraxian t1_iy5w05v wrote

Like, frequency is how fast the magnitude of sound pressure changes, amplitude is how far up it goes before it goes back down, but both those numbers are just derived from one number that's going up and down over time

Failing to understand this is where a lot of audiophile woo sneaks in, like this is why "high-resolution" sound files just means files that can record higher frequency sounds, these two concepts are the same thing

This is the principle behind how a DSD file works and why it has a "bitrate of 1" -- at any given timestamp there's just a 1 or 0 telling you whether the magnitude is currently increasing or decreasing (as opposed to PCM, which directly encodes the 2D image of a waveform we look at, there's a 16 or 32 or 64 bit number telling you what the volume of sound pressure is at any given timestamp)

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THEOTHERONE9991 t1_iy6fmgt wrote

I don't know what DSD is, but a bitrate of 1 per ear I assume? Otherwise it would have to be mono I suppose. Wait, actually even with that I don't see how a decent result could be produced... I mean maybe. Sorry this is interesting to me, I'd like to know more. This would also require very high samplerates so it can do really weird stepping up and down to reproduce frequency? If it can only go up and down there would be some singular ideal frequency and amplitude (but still subject to samplerate loss) and anything other than that / as it gets farther from it causes more and more loss... also it wouldn't be able produce silence... But I suppose it could produce a very high pitched sound that's above the drivers / human hearing instead. Okay... I want to read more about this now haha, I'm probably overlooking something but I can't imagine how a bitrate of 1 could work.

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NahbImGood t1_iy87zhy wrote

*bit depth of 1, bitrate of 1 would be 1 bit per channel per second, which wouldn’t sound too good

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gooftrupe t1_iy5vfyz wrote

Yes of course but the sound pressure + time is two dimensional

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Taraxian t1_iy5wdfo wrote

Yeah but all our senses include time

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gooftrupe t1_iy5z296 wrote

Right and therefore those senses are two dimensional

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13Zero t1_iy6aujl wrote

It’s one dimensional. One input (time) and one output (pressure). When you add stereo, it becomes two dimensional because there are two outputs (right pressure and left pressure).

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petalmasher t1_iy8shj1 wrote

Frequency and amplitude can be graphed with one line, can't it? http://www.sengpielaudio.com/calculator-wavegraphs.htm

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gooftrupe t1_iyb3z8m wrote

A one dimensional line would never change direction or osciallate because it has not other dimensions besides length. An x-y plot has 2 dimensions: x and y. Similarly, a sound wave has two dimensions amplitude (sound pressure) and time.

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petalmasher t1_iyf44ym wrote

Why are you talking about sound in terms of spatial detentions?

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gooftrupe t1_iyf4hvb wrote

My comments were in reply to a parent comment regarding the ear and hearing, which are spatial

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gooftrupe t1_iyb16u1 wrote

How is frequency an increase in sound pressure? I can alter frequency while maintaining constant sound pressure, as well as vice versa. Frequency is independent of sound pressure. Again two dimensional

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gooftrupe t1_iyb3pvk wrote

I think you might be conflating sound pressure (amplitude) and wavelength? Frequency is kind of like the speed of a wave yes, but it's not a product of the sound pressure at all. They're independent. If you haven't heard of sengpiel audio I highly recommend. He explained some of these things pretty well. I use the site for looking up acoustic calculations a lot.

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http://www.sengpielaudio.com/calculator-wavegraphs.htm

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alesimula97 t1_iy68xw0 wrote

If that were true, wouldn't I be unable to know where a sound is coming from? (Except for left and right)

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Taraxian t1_iy69ma5 wrote

>The other two dimensions of "3D audio", front/back and up/down, are illusory information your brain calculates via deduction, based on your personal HRTF -- clever little hacks based on stuff like the shell shape of your outer ear causing subtle changes in high treble frequencies depending on exactly where a sound is coming from (treble sounds coming from behind you get blocked while ones coming from in front get amplified) and making little judgments based on subtle 3D movements and rotations of your head

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alesimula97 t1_iy6al5u wrote

So how does that matter? Whether the dimensionality of sound is measured or "virtually" calculated, at the end of the day it is something we perceive (pretty accurately, I'd say)

So how would audio equipment taking advantage of this be "fluff"?

After all, what matters is that we can discern between two sound waves coming from different directions

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Emmerson_Biggons t1_iy7lh98 wrote

You seem to have missed the point

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alesimula97 t1_iy7lkj0 wrote

Then please enlighten me

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Emmerson_Biggons t1_iy7lu7o wrote

The point was about a lot of audiophile mumbo jumbo can be ignored as effectively as fantasy or just absurd nonsense. Which is true, audio is a very complicated mixture of tech for a very basic form of hearing that is easily tricked.

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alesimula97 t1_iy7nz4w wrote

That is the exact point I was arguing against, maybe you should read my comment again

Our hearing is not one-dimensional, whether the dimension of sound is measured exactly by our ears or interpreted by our brain does not matter, what matters is we DO perceive 3dimensional sound and that makes audio equipment that plays sound from different directions produce a noticeable effect

Now, you say that due to its "interpreted" nature it is easily tricked, but since it varies from person to person due to our personal HRTF, you cannot trick it both "accurately" and universally and it would require personalised tuning to achieve an identical result as sound coming from a specific direction

So wouldn't that make a "smart" headset that can adapt to its user or allow him to calibrate 3d sound, and an headset that actually plays 3d sound, both valid options?

And wouldn't the latter be the most accessible option, since it works ootb?

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Emmerson_Biggons t1_iy89iwg wrote

Our hearing is objectively mono individually; one dimension. Our ability to tell direction is an evolutionary trait categorizing the frequencies and time the sound is heard between ears. Our ears are incapable of discerning direction without our brain telling itself what specific sounds in a specific order mean. Our brain is easily tricked by simply recreating those specific frequencies or adjusting when/if each ear hears a sound.

There isn't a substantial enough difference between people's ability to discern direction to need a significant personalized change to achieve a given 3d effect. Everyone's hearing is rarely accurate to direction, especially up and down anyway.

All that aside, a smart headset is a really interesting way for someone to label audio processing. Adaptable audio already exists and is not practical for headphones, as for actual physically 3d sound I'm pretty sure that exists and they are called "Speakers" specifically surround sound setups. As for headphones, binaural audio mixing is vastly more practical and is highly effective. Even to the point people, mostly audiophiles, make up nonsense terms and other weird things to headphones capabilities.

If your Audio Mastering is shit and you didn't do it right it doesn't matter how special your headphones are it won't sound good. But if you do it right then you can get a convincing 3D effect out of shitty decade old $5 ear buds you found in the back of your closet.

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MathiasAudio t1_iy8jnmp wrote

> A lot of audiophile woo can be dismissed by fully internalizing that human hearing is a purely "one-dimensional" sense

I don't really think that dismisses anything tbh. Also, saying it is one-dimensional is just factually incorrect. There's a reason we represent audio waveforms on a two-dimensional graph; our perception of sound is dependent on time.

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