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Poll: Can you hear sound over 20kHz? - Page 17

Poll Results: Can you hear sound over 20kHz?

 
  • 23% (101)
    Yes
  • 76% (324)
    No
425 Total Votes  
post #241 of 543
Originally Posted by xnor View Post
Originally Posted by kiteki View Post

Thanks, there are straight lines in audio though right?  http://en.wikipedia.org/wiki/Non-sinusoidal_waveform
Nope, digital audio is bandlimited. Even if you used a very high sampling rate you'd still see ringing if you zoom in. See Gibbs phenomenon
1 kHz square wave sampled at 44.1 kHz (each square is a sample)

 

OK, I will keep reading..., soo you're saying if you zoom in enough on a triangle or sawtooth waveform they're actually all sinusoidal right?  In nature too?  What about something like a Commodore=64 or Casio sound chip?

 

 

Quote:
Originally Posted by bigshot View Post

Frequencies double with each octave. The difference between 5kHz-10kHz is the same as the difference between 20kHz-40kHz. 24kHz is just about one note different from 20kHz in the musical scale. Negiligible.

I really don't know why people seem to want to hear above 20kHz. There's nothing up there to hear except headache inducing sqeals from bad florescent light ballasts.

 

It's not the fundamental note, it's the overtones etc., which is why 44.1kHz sounds a lot better than 32kHz, I can easily hear it with vocals on my useless laptop speakers, despite the fact no one is singing notes above 16kHz. =p


Edited by kiteki - 5/10/12 at 7:53pm
post #242 of 543
Quote:
Originally Posted by kiteki View Post

It's not the fundamental note, it's the overtones etc., which is why 44.1kHz sounds a lot better than 32kHz, I can easily hear it with vocals on my useless laptop speakers, despite the fact no one is singing notes above 16kHz. =p

The core frequencies of music don't go anywhere near 16kHz. In fact, there have been studies where people were asked to listen to music with everything above 10kHz chopped off and most people said it sounded fine. 20kHz is about three octaves of upper harmonics... Overkill.

A person whose hearing only goes up to 15kHz is only missing third level harmonics on cymbal crashes. Everything else will sound fine.
post #243 of 543

i cant hear past 16khz. none of my friends can hear past 17khz. i know a classically trained pianist who has babied the crap out of her ears and she cant hear past 17khz

post #244 of 543

I'm confused, I thought 44.1khz was the amount of cycles recorded per second or something. I had no idea it meant the sound went up to 44khz. If people can't hear above circa 20khz what would be the point of having higher frequencies that are perceivable? 

post #245 of 543
44.1 only goes up to a little past 20kHz. Two different measures.
post #246 of 543
Quote:
Originally Posted by kiteki View Post

Quote:
Originally Posted by xnor View Post

Quote:
Originally Posted by kiteki View Post

Thanks, there are straight lines in audio though right?  http://en.wikipedia.org/wiki/Non-sinusoidal_waveform
Nope, digital audio is bandlimited. Even if you used a very high sampling rate you'd still see ringing if you zoom in. See Gibbs phenomenon
1 kHz square wave sampled at 44.1 kHz (each square is a sample)

OK, I will keep reading..., soo you're saying if you zoom in enough on a triangle or sawtooth waveform they're actually all sinusoidal right?  In nature too?  What about something like a Commodore=64 or Casio sound chip?

What xnor means is that there is no straight lines in audio because of its nature as a band limited signal, thus, there is no true straight square waves or triangle waves in audio either. A true square wave is the sum of an - infinite - number of sine waves as described but the following sum: dc1ca9de7f258a89d3c579f55d29ed05.png

And since audio is band limited, the sum is stopped at some point, and all you have is an approximation of a square wave, thus the Gibbs phenomenon.

I would suggest reading on Fourier decomposition and harmonic analysis to understand the issue, the wiki articles are not bad, but can be challenging for the layperson.
post #247 of 543
Originally Posted by bigshot View Post

In fact, there have been studies where people were asked to listen to music with everything above 10kHz chopped off and most people said it sounded fine.

 

Link it.

 

 

Originally Posted by DNZGamer View Post

I'm confused, I thought 44.1khz was the amount of cycles recorded per second or something. I had no idea it meant the sound went up to 44khz. If people can't hear above circa 20khz what would be the point of having higher frequencies that are perceivable? 

 

44.1kHz = the sound goes up to 22.05kHz

 

In the real world there's a lot of sound above 22.05kHz which creates a lot of audible noise in the recording, so you have to remove the noise with filters.

 

From the air in front of the mouth of a singer to the air in front of your speaker, it should be a pure process with as few filters as possible.

 

At extremely loud levels people can hear sound up to ~25kHz, at what level we can perceive sound is inconclusive, but there are theories that insect repellors or cleaning devices can cause stress with their ultrasonic frequencies, and likewise that 24bit / 192kHz audio sounds better than CD quality, of which there is a cult following.

post #248 of 543
Quote:
Originally Posted by DNZGamer View Post

I'm confused, I thought 44.1khz was the amount of cycles recorded per second or something. I had no idea it meant the sound went up to 44khz. If people can't hear above circa 20khz what would be the point of having higher frequencies that are perceivable? 

It come from the theorem of Nyquist Shannon, to reconstruct a signal band limited to 20 kHz (sound), you have to sample it at double its frequency, in this case 40 kHz.
For CDs, the sample rate is 44.1 kHz, means that the reconstructed sound can have frequencies up to 22.05 kHz.
post #249 of 543
Originally Posted by khaos974 View Post
Originally Posted by kiteki View Post
Originally Posted by xnor View Post
Originally Posted by kiteki View Post

Thanks, there are straight lines in audio though right?  http://en.wikipedia.org/wiki/Non-sinusoidal_waveform
Nope, digital audio is bandlimited. Even if you used a very high sampling rate you'd still see ringing if you zoom in. See Gibbs phenomenon
1 kHz square wave sampled at 44.1 kHz (each square is a sample)

OK, I will keep reading..., soo you're saying if you zoom in enough on a triangle or sawtooth waveform they're actually all sinusoidal right?  In nature too?  What about something like a Commodore=64 or Casio sound chip?

What xnor means is that there is no straight lines in audio because of its nature as a band limited signal, thus, there is no true straight square waves or triangle waves in audio either. A true square wave is the sum of an - infinite - number of sine waves as described but the following sum: dc1ca9de7f258a89d3c579f55d29ed05.png

And since audio is band limited, the sum is stopped at some point, and all you have is an approximation of a square wave, thus the Gibbs phenomenon.

I would suggest reading on Fourier decomposition and harmonic analysis to understand the issue, the wiki articles are not bad, but can be challenging for the layperson.

 

Ok thx that makes sense!  If a square wave is an infinite number of sine waves...

 

However it seems like digital processing draws straight lines, such as in this example - http://www.head-fi.org/t/571259/hi-rez-another-myth-exploded/15#post_7748362

post #250 of 543
Quote:
Originally Posted by kiteki View Post

Quote:
Originally Posted by khaos974 View Post

Quote:
Originally Posted by kiteki View Post

Quote:
Originally Posted by xnor View Post

Quote:
Originally Posted by kiteki View Post

Thanks, there are straight lines in audio though right?  http://en.wikipedia.org/wiki/Non-sinusoidal_waveform
Nope, digital audio is bandlimited. Even if you used a very high sampling rate you'd still see ringing if you zoom in. See Gibbs phenomenon
1 kHz square wave sampled at 44.1 kHz (each square is a sample)


OK, I will keep reading..., soo you're saying if you zoom in enough on a triangle or sawtooth waveform they're actually all sinusoidal right?  In nature too?  What about something like a Commodore=64 or Casio sound chip?


What xnor means is that there is no straight lines in audio because of its nature as a band limited signal, thus, there is no true straight square waves or triangle waves in audio either. A true square wave is the sum of an - infinite - number of sine waves as described but the following sum: dc1ca9de7f258a89d3c579f55d29ed05.png

And since audio is band limited, the sum is stopped at some point, and all you have is an approximation of a square wave, thus the Gibbs phenomenon.


I would suggest reading on Fourier decomposition and harmonic analysis to understand the issue, the wiki articles are not bad, but can be challenging for the layperson.

Ok thx that makes sense!  If a square wave is an infinite number of sine waves...

However it seems like digital processing draws straight lines, such as in this example - http://www.head-fi.org/t/571259/hi-rez-another-myth-exploded/15#post_7748362

I am skeptical at that claim, given a sampled 22.05 kHz sine wave and a 44.1 kHz, it's will be reconstructed into a 22.05 kHz sine wave; if it were reconstructed into a 22.05 kHz triangle wave, it would require an infinity of harmonics.
post #251 of 543

192/2 = 96khz? 

Man that is a lot of frequencies I wouldn't even be able to hear. Wonder what difference that makes. 

post #252 of 543
Quote:
Originally Posted by DNZGamer View Post

192/2 = 96khz? 

Indeed.
Quote:
Man that is a lot of frequencies I wouldn't even be able to hear. Wonder what difference that makes. 

And considering that no microphone is linear up to 20 kHz.... yeah it's pretty useless.
post #253 of 543
Quote:
Originally Posted by kiteki View Post

Ok thx that makes sense!  If a square wave is an infinite number of sine waves...

However it seems like digital processing draws straight lines, such as in this example - http://www.head-fi.org/t/571259/hi-rez-another-myth-exploded/15#post_7748362
a) Yes
b) This guys' drawing don't make sense, not even the analogue one.
post #254 of 543
Originally Posted by DNZGamer View Post

Man that is a lot of frequencies I wouldn't even be able to hear. Wonder what difference that makes. 

 

You don't necessarily need to hear it.

 

"Hosoi H, Imaizumi S, Sakaguchi T, et al. Activation of the auditory cortex by ultrasound Lancet 351:496-497, 1998.

Imaizumi S, Hosoi H, Sakaguchi T, et al. Ultrasound activates the auditory cortex of profoundly deaf subjects. Neuroreport 12(3):583-586, 2001."

post #255 of 543
Quote:
Originally Posted by kiteki View Post
However it seems like digital processing draws straight lines, such as in this example - http://www.head-fi.org/t/571259/hi-rez-another-myth-exploded/15#post_7748362

 

I would have thought reverb is typically a linear time invariant effect (i.e. convolution with an impulse response, which does not produce any aliasing), but even if time varying delays and/or slight distortion are added to increase the complexity, it is not clear why it would need to be more than 20 times slower than real time on currently available hardware to avoid aliasing; this sounds like snake oil.

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