Blow your mind with interesting sound factoids..

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dooj88
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Blow your mind with interesting sound factoids..

Post by dooj88 » Fri Oct 08, 2021 11:15 am

ok, so i'm pilfering interesting facts from wikipedia.. but having more information than "A SQUARE WAVE SOUNDS BUZZY!" makes working with sound more engaging, and may lead to more intricate synthesis techniques. most of this will probably be things engineers will roll their eyes at like "duh!" so feel free to hit me with harder stuff!

The ideal square wave contains only components of odd-integer harmonic frequencies, while sawtooth waves contain all integer harmonics. a triangle wave contains only odd harmonics as well, however, the higher harmonics roll off much faster than in a square wave.

a square wave is equivalent to a sine wave at the same frequency, the difference is an infinite series of odd-multiple frequency sine waves at diminishing amplitude, which we can (theoretically) do with filtering.

[click on the image, it's a gif]
800px-SquareWave.gif
a sine wave viewed from a different perspective is just a repeating perfect circle - seems obvious now that i know it, but i may not have been able to articulate it before. this whole video has loads of interesting facts on fourier transformations.



random thing that's always fascinated me: decibels are measured on a logarithmic scale. this means that every time you double the volume, the power (sound pressure level) required to achieve this is 10x not 2x, and why loud sounds can be so incredibly damaging to our hearing.

ok, that's by far enough procrastinating for now

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Re: Blow your mind with interesting sound factoids..

Post by KSS » Fri Oct 08, 2021 5:25 pm

For me the most interesting sound factoid is how slow sound travels and how that relates to *any* and *every* live performance! <--where in-ear devices aren't used.*

On even a small stage the time it takes for the sounds of each band member's instruments to get to the ears of the other member's means that every player is anticipating what the others are doing. Because sound travels too slowly for them to react and respond without everyone noticing.

Sound travels roughly 750 MPH at sea level, or a mile in about 5 seconds. Works out to about 1milisecond per foot. When the bass player and guitarist are ten feet apart, that's 10mS. The reality of audio latency.

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It's also true for our other senses and muscular response. They're pretty slow to respond. Put this in the context of dance, sports or any thing where humans are coordinating together and I can't imagine how anyone's mind isn't blown by the results we are able to achieve.

* How much has music been affected by the ability we have today to reduce this latency with in-ear devices? And stage monitors before that?
What would happen when you take someone from this modern era into a pre-electronic situation like the classic performers used? A string quartet, big band, jazz ensemble or orchestra would all be good examples.

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Re: Blow your mind with interesting sound factoids..

Post by wolfelli » Wed Oct 13, 2021 3:47 pm

one thing i never see too much discussion on is how the fourier series as described above is only the 1D version. the world is 3 dimensional so for a travelling wave there is a 2D wave front. there are other bases into which we can decompose a signal. for example, a vibrating membrane (drum) has natural modes of sines and cosines multiplied by Bessel functions.

One thing i have been thinking about is how exactly does the ear react to sound, and how does the brain process that sound? Do certain modes resonate with our eardrum making them harsher? And does the brain do some fourier decomposition of the incoming sounds? or is it something else like a wavelet decomp?
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Re: Blow your mind with interesting sound factoids..

Post by Kattefjaes » Wed Oct 13, 2021 3:52 pm

KSS wrote:
Fri Oct 08, 2021 5:25 pm
For me the most interesting sound factoid is how slow sound travels and how that relates to *any* and *every* live performance! <--where in-ear devices aren't used.*

On even a small stage the time it takes for the sounds of each band member's instruments to get to the ears of the other member's means that every player is anticipating what the others are doing. Because sound travels too slowly for them to react and respond without everyone noticing.

Sound travels roughly 750 MPH at sea level, or a mile in about 5 seconds. Works out to about 1milisecond per foot. When the bass player and guitarist are ten feet apart, that's 10mS. The reality of audio latency.

-------------
It's also true for our other senses and muscular response. They're pretty slow to respond. Put this in the context of dance, sports or any thing where humans are coordinating together and I can't imagine how anyone's mind isn't blown by the results we are able to achieve.

* How much has music been affected by the ability we have today to reduce this latency with in-ear devices? And stage monitors before that?
What would happen when you take someone from this modern era into a pre-electronic situation like the classic performers used? A string quartet, big band, jazz ensemble or orchestra would all be good examples.
The fun thing is that due to latency, we never actually experience the present at all, but there are perceptual tricks at work to make us think that we do:

https://blogs.scientificamerican.com/ob ... erception/

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Re: Blow your mind with interesting sound factoids..

Post by WarpHead » Wed Oct 13, 2021 3:55 pm

wolfelli wrote:
Wed Oct 13, 2021 3:47 pm
one thing i never see too much discussion on is how the fourier series as described above is only the 1D version. the world is 3 dimensional so for a travelling wave there is a 2D wave front. there are other bases into which we can decompose a signal. for example, a vibrating membrane (drum) has natural modes of sines and cosines multiplied by Bessel functions.

One thing i have been thinking about is how exactly does the ear react to sound, and how does the brain process that sound? Do certain modes resonate with our eardrum making them harsher? And does the brain do some fourier decomposition of the incoming sounds? or is it something else like a wavelet decomp?
Fascinating stuff, would love to hear more if you ever feel up to it.

Concerning the eardrum, or even the shape of the ear canal, and resonances -- that got me thinking about the hypothesis of there having emerged some type of evolutionary advantage to having certain sounds stand out in some (perhaps unpleasant) way, thus somehow selecting for certain physical features in or of the ear.

I'll see myself out. :lol:
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Re: Blow your mind with interesting sound factoids..

Post by wolfelli » Wed Oct 13, 2021 4:07 pm

WarpHead wrote:
Wed Oct 13, 2021 3:55 pm
wolfelli wrote:
Wed Oct 13, 2021 3:47 pm
one thing i never see too much discussion on is how the fourier series as described above is only the 1D version. the world is 3 dimensional so for a travelling wave there is a 2D wave front. there are other bases into which we can decompose a signal. for example, a vibrating membrane (drum) has natural modes of sines and cosines multiplied by Bessel functions.

One thing i have been thinking about is how exactly does the ear react to sound, and how does the brain process that sound? Do certain modes resonate with our eardrum making them harsher? And does the brain do some fourier decomposition of the incoming sounds? or is it something else like a wavelet decomp?
Fascinating stuff, would love to hear more if you ever feel up to it.

Concerning the eardrum, or even the shape of the ear canal, and resonances -- that got me thinking about the hypothesis of there having emerged some type of evolutionary advantage to having certain sounds stand out in some (perhaps unpleasant) way, thus somehow selecting for certain physical features in or of the ear.

I'll see myself out. :lol:
The short story of it is that certain physical systems have natural modes which depend on the symmetry of the system and other physical parameters. We use these "simple" systems that we can solve to analyze many physical systems including instruments, quantum systems, fluid waves, etc.
Here is a link to the drum problem on Wikipedia. ***warning*** it is a bit math instensive

https://en.wikipedia.org/wiki/Vibration ... r_membrane

Also an interesting linked article in that wiki page is whether or not we can hear the shape of a drum

https://en.wikipedia.org/wiki/Hearing_t ... _of_a_drum
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Re: Blow your mind with interesting sound factoids..

Post by EATyourGUITAR » Wed Oct 13, 2021 4:18 pm

WarpHead wrote:
Wed Oct 13, 2021 3:55 pm
wolfelli wrote:
Wed Oct 13, 2021 3:47 pm
one thing i never see too much discussion on is how the fourier series as described above is only the 1D version. the world is 3 dimensional so for a travelling wave there is a 2D wave front. there are other bases into which we can decompose a signal. for example, a vibrating membrane (drum) has natural modes of sines and cosines multiplied by Bessel functions.

One thing i have been thinking about is how exactly does the ear react to sound, and how does the brain process that sound? Do certain modes resonate with our eardrum making them harsher? And does the brain do some fourier decomposition of the incoming sounds? or is it something else like a wavelet decomp?
Fascinating stuff, would love to hear more if you ever feel up to it.

Concerning the eardrum, or even the shape of the ear canal, and resonances -- that got me thinking about the hypothesis of there having emerged some type of evolutionary advantage to having certain sounds stand out in some (perhaps unpleasant) way, thus somehow selecting for certain physical features in or of the ear.

I'll see myself out. :lol:
This is true. It varies with hormones such as during or after pregnancy. It varies by age and gender. The frequency of a human voice is where we can perceive the most detail. The frequency of a baby crying is where we can have our attention redirected instantly even at longer distances. This is used effectively in advertising. Sometimes it is also used in hit records. Next time you watch an advertisement edited for television check the FFT. You will notice something around 8K right in the beginning. Followed by human voice 2K. There is a pattern that works. This is not random. This is intentionally done by master's of advertising psychology.
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Re: Blow your mind with interesting sound factoids..

Post by gruebleengourd » Wed Oct 13, 2021 4:30 pm

KSS wrote:
Fri Oct 08, 2021 5:25 pm
Sound travels roughly 750 MPH at sea level, or a mile in about 5 seconds. Works out to about 1milisecond per foot. When the bass player and guitarist are ten feet apart, that's 10mS. The reality of audio latency.
But that doesn't make any difference, because players are not playing in time in response to each other, but rather than an internal tempo that being continually updated.

These kind of latency issues typically only manifest themselves as problems when an inexperienced electronic music producer attempts to layer multiple transients (flamming) or bass sounds (phase cancelation) on top of each other using midi note on messages, particularly when using multiple sequencers.

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Re: Blow your mind with interesting sound factoids..

Post by Navs » Thu Oct 14, 2021 1:54 am

Thomas Dolby worked on Foreigner 4.

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Re: Blow your mind with interesting sound factoids..

Post by GuyaGuy » Thu Oct 14, 2021 2:32 am

dooj88 wrote:
Fri Oct 08, 2021 11:15 am


Wait WTF. Why did I have to watch this right before trying to fall asleep?
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Re: Blow your mind with interesting sound factoids..

Post by a100user » Thu Oct 14, 2021 2:37 am

Navs wrote:
Thu Oct 14, 2021 1:54 am
Thomas Dolby worked on Foreigner 4.
:yay: And they delivered a great album too.


On topic - I have always struggled with advanced maths, so my studies never got intellectually deep but I love these sorts of threads as they blow my mind (up to the point I can’t follow the maths anymore)
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Re: Blow your mind with interesting sound factoids..

Post by dooj88 » Tue Oct 19, 2021 1:09 pm

i had a thought the other day, wondering if someone can chime in: when we hear a pure tone, for example at 10khz, is there any spillover into wider frequencies? how can we be sure it's not a band from 9.95 to 10.05 khz? (as an extreme example.) it's probably more like a band from 9.9999 to 10.0001 guessing accuracy has to do with available computing resources and DAC quality?

and going a bit beyond that, what is the smallest increment of change in frequency we can percieve? 10khz to 10.001? 10.01? 10.1? this is going beyond my knowledge of how the math translates to cents in pitch, but the extent of my knowledge there is that each octave doubles the frequency, and each octave has consists of 1200 cents. so through fuzzy logical extrapolation: as a frequency increases, the ability to perceive the difference between cents decreases?

to illustrate the point: are we less likely to hear the same change of frequency from 10khz 10.1khz versus a 500hz to 510hz shift? (the scale of the hypothetical may not be exactly apropriate, but you get the idea.)

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Re: Blow your mind with interesting sound factoids..

Post by KSS » Tue Oct 19, 2021 2:20 pm

Our perception of pitch is not linear in its quality. <--I'm not here referring to the basic exponential nature of these senses, but rather whether each freq is heard at the same existential level as another. Evolution has 'bent' the response curve to emphasize some pitches and ranges compared to others. Look into Bark filters for a little more on the topic. Infrasonics aka 'subsonics' are another rich field to investigate. Psychoacoustics is another.

As for pure tone, the only pure tone is a perfect sine wave. Those are exceedingly rare. Anything besides that will definitely include 'spillover' from its other inherent component frequencies. And yes, accuracy of tonal results -in electronic sound generation and reproduction- does involve computing resources and DAC quality.

It's generally accepted that many-most people can discern a 3-6 cent pitch difference. But its also true that this depends on Amplitude, Pitch-freq, Tone-Timbre and environmental variables too. You're adAPTed to hear differently depending on these situational differences.

Since nearly nothing we hear is absolutely pure tone*, when you hear higher frequencies you're also hearing how they interact with other sounds and frequencies which can be 'guides' to perception and accuracy. You might not hear the change in the high tone, but you do hear the change in the lower tones associated with -or affected** by- it.

*Even when it is pure tone, the environmental factors can introduce additional elements to be used in perception.
**Beats and heterodyning are one example.

As humans we -and our experience- is variable. In the same way one person rarely missteps in a room with debris while another is the proverbial bull in a china closet, some people will have different experiences of the 'same' sonic event or situation. This is what makes online discussions about such things fraught with discord and contention. It is hard to accept someone else saying they hear something we personally have never heard. <--Our intellect says its possible but our emotion clouds the judgement.
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Re: Blow your mind with interesting sound factoids..

Post by dooj88 » Tue Oct 19, 2021 2:35 pm

when i posted that question, i was secretly hoping you'd respond, KSS. insightful and articulate as always, thanks! i hadn't considered how the environment and even individual perception would play a role as well. its somehow reliving to know the general answer is "it depends on A LOT of things."

it feels like we're teetering on the edge of an ontological discussion when going down this line of thinking: there is no such thing as "sound," it is merely a biological distinction - a perceptual transformation ocurring in the brain of a slice of information from the continuous universal energy spectrum.. and it may be different from one brain to another.

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