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Sampling rates higher than 44.1Khz?
Grand Dizzy
post Feb 5 2006, 01:10
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I recently met a musician who claims he can quite easily hear the difference between 44.1KHz and 96KHz.

This shocked me a little because I'd always been told that the human ear cannot hear any higher quality than CD (44.1KHz) quality.

So... was this guy just lying (or fooled by his senses), or was I being lied to when I was told the human ear cannot hear any higher quality than CD?

This post has been edited by Grand Dizzy: Feb 5 2006, 01:11
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AndyH-ha
post Feb 6 2006, 03:17
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MOST audio players (as part of the DAC) use anti-alaising filters. The image is reflected back down from the Nyquist limit. That means it gets mixed into the music. You generally can't detect it as something separate, on its own, it just adds stuff that should not be there.

It comes in reverse order. The lower the signal frequency, above the Nyquist limit, the higher the frequency of its image. Which also means, the higher the frequency above the Nyquist limit, the lower the frequency of its image.

Nyquist limit = 22,050 Hz at 44.1KHz sampling rate
image of audio at 24kHz appears at
(22,050 Hz - (24,000 - 22,050) = 1950Hz) = 20,100 Hz
image of audio at 28kHz appears at
(22,050 Hz - (28,000 - 22,050) = 5950Hz) = 16,100 Hz
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Grand Dizzy
post Feb 6 2006, 13:49
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Duhh... sorry, that all went completely over my head!
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krabapple
post Feb 7 2006, 17:48
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QUOTE (Grand Dizzy @ Feb 6 2006, 07:49 AM)
Duhh... sorry, that all went completely over my head!
*


simply put:
frequencies so high that you can't hear them, produce digital conversion artifacts in the range you *can* hear. This phenomenon is called 'aliasing'.

Antialiasing filters block out those artifacts.
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hdante
post Feb 7 2006, 18:06
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QUOTE (krabapple @ Feb 7 2006, 02:48 PM)
QUOTE (Grand Dizzy @ Feb 6 2006, 07:49 AM)
Duhh... sorry, that all went completely over my head!
*


simply put:
frequencies so high that you can't hear them, produce digital conversion artifacts in the range you *can* hear. This phenomenon is called 'aliasing'.

Antialiasing filters block out those artifacts.
*



Greetings !

I was just Googling about this right now. There's a site that says that anti-aliasing filters are already good enough at 44 KHz. You shouldn't probably hear the difference because of filter problems. The matter seems to be simpler than that. For example, take a violin and a cello. They may produce faint harmonics at ~ 30 KHz (let's say they the former has one higher peak at 30 KHz and the latter, at 32 KHz). If you listen to them (that is, nothing to do with recording), you may hear a 2KHz beating. However, when you record them, you would do that separately. Record the violin at 44 KHz and you'll lose that important peak. Then record the cello and you'll lose that other important peak. Now mix them together: there's no 2 KHz beating ! If you recorded them together you could sample at 44 KHz and still get the beating. Since you don't, then you'll have to record at least at ~65 KHz. 96 KHz would then be a convenience sampling rate (ie 2x48 KHz).

That's what I read. I'm no speciallist on that. You may google for it also.

Henrique Dante de Almeida
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SebastianG
post Feb 7 2006, 19:29
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QUOTE (hdante @ Feb 7 2006, 06:06 PM)
[...] For example, take a violin and a cello. They may produce faint harmonics at ~ 30 KHz (let's say they the former has one higher peak at 30 KHz and the latter, at 32 KHz). If you listen to them (that is, nothing to do with recording), you may hear a 2KHz beating. [...]
*


Why may I hear something like that ?

Sebi
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hdante
post Feb 7 2006, 22:27
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QUOTE (SebastianG @ Feb 7 2006, 04:29 PM)
QUOTE (hdante @ Feb 7 2006, 06:06 PM)
[...] For example, take a violin and a cello. They may produce faint harmonics at ~ 30 KHz (let's say they the former has one higher peak at 30 KHz and the latter, at 32 KHz). If you listen to them (that is, nothing to do with recording), you may hear a 2KHz beating. [...]
*


Why may I hear something like that ?

Sebi
*



It was just an example. If you were talking that the 2 KHz was a mistake, I'm sorry, it should be 1 KHz. If not, it's because of the following. I supposed that there would be an instrument which would produce a significant harmonic at 30 KHz (actually this is true, for example, for violins and flutes), and another that would produce it at 32 KHz. Since those frequencies are actually a pressure in the same medium (that is the air and then your ear), the expansions and compressions generated by the instruments will add to each other some times and cancel each other some other times at a rate of 1 KHz. Mathematically, cos(32KHz)+cos(30KHz) = 2*cos(31KHz)*cos(1KHz). Add the time in equation and you have a 1 KHz harmonic with a variable intensity of 2*cos(31KHz*t). In practice, you should have a few harmonics for every instrument in this region. For most of them, they will be so faint, that you won't ever notice it. The already cited instruments, however, are known to cause audible beating which enrich the listening experience. Unfortunately I have no link to that, except one that also claims this is true, but doesn't cite sources either :-/.

http://www.dvdsoftwareguide.com/all-about-dvd-4-guide.html

One should hope, thus, that every recording is made at very high sampling rates. After they are mixed and filtered with high quality equipment, they may be safely downsampled to human listening limits again.
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mandel
post Feb 7 2006, 23:51
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QUOTE (hdante @ Feb 7 2006, 10:27 PM)
QUOTE (SebastianG @ Feb 7 2006, 04:29 PM)
QUOTE (hdante @ Feb 7 2006, 06:06 PM)
[...] For example, take a violin and a cello. They may produce faint harmonics at ~ 30 KHz (let's say they the former has one higher peak at 30 KHz and the latter, at 32 KHz). If you listen to them (that is, nothing to do with recording), you may hear a 2KHz beating. [...]
*


Why may I hear something like that ?

Sebi
*



It was just an example. If you were talking that the 2 KHz was a mistake, I'm sorry, it should be 1 KHz. If not, it's because of the following. I supposed that there would be an instrument which would produce a significant harmonic at 30 KHz (actually this is true, for example, for violins and flutes), and another that would produce it at 32 KHz. Since those frequencies are actually a pressure in the same medium (that is the air and then your ear), the expansions and compressions generated by the instruments will add to each other some times and cancel each other some other times at a rate of 1 KHz. Mathematically, cos(32KHz)+cos(30KHz) = 2*cos(31KHz)*cos(1KHz). Add the time in equation and you have a 1 KHz harmonic with a variable intensity of 2*cos(31KHz*t). In practice, you should have a few harmonics for every instrument in this region. For most of them, they will be so faint, that you won't ever notice it. The already cited instruments, however, are known to cause audible beating which enrich the listening experience. Unfortunately I have no link to that, except one that also claims this is true, but doesn't cite sources either :-/.

http://www.dvdsoftwareguide.com/all-about-dvd-4-guide.html

One should hope, thus, that every recording is made at very high sampling rates. After they are mixed and filtered with high quality equipment, they may be safely downsampled to human listening limits again.
*



That's really interesting actually. I just created a 96khz wav file with a 30k and a 32k tone and could hear a beat frequency as you say. Though at 2khz not 1khz

Why do you say the hi-res mix may be safely downsampled to 'human hearing limits'? If I resampled the above wav file to 44.1khz I ended up with silence!

This post has been edited by mandel: Feb 7 2006, 23:56
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hdante
post Feb 8 2006, 00:48
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QUOTE (mandel @ Feb 7 2006, 08:51 PM)
That's really interesting actually.  I just created a 96khz wav file with a 30k and a 32k tone and could hear a beat frequency as you say.  Though at 2khz not 1khz

Why do you say the hi-res mix may be safely downsampled to 'human hearing limits'?  If I resampled the above wav file to 44.1khz I ended up with silence!
*


Could it be that it's not really safe to downsample the sound ? :-D. Try downsampling to integer frequencies (ex: 48 KHz) to see if it works :-/

Henrique Dante de Almeida
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Posts in this topic
- Grand Dizzy   Sampling rates higher than 44.1Khz?   Feb 5 2006, 01:10
- - AndyH-ha   The most profound differences are not higher frequ...   Feb 5 2006, 03:34
- - gameplaya15143   call him/her on it... make em prove it to you it ...   Feb 5 2006, 03:38
- - Grand Dizzy   Andy, I didn't realise antialiasing filters we...   Feb 5 2006, 21:48
- - AndyH-ha   MOST audio players (as part of the DAC) use anti-a...   Feb 6 2006, 03:17
|- - Grand Dizzy   Duhh... sorry, that all went completely over my he...   Feb 6 2006, 13:49
|- - krabapple   QUOTE (Grand Dizzy @ Feb 6 2006, 07:49 AM)Duh...   Feb 7 2006, 17:48
|- - hdante   QUOTE (krabapple @ Feb 7 2006, 02:48 PM)QUOTE...   Feb 7 2006, 18:06
|- - SebastianG   QUOTE (hdante @ Feb 7 2006, 06:06 PM)[...] Fo...   Feb 7 2006, 19:29
|- - hdante   QUOTE (SebastianG @ Feb 7 2006, 04:29 PM)QUOT...   Feb 7 2006, 22:27
|- - mandel   QUOTE (hdante @ Feb 7 2006, 10:27 PM)QUOTE (S...   Feb 7 2006, 23:51
|- - RockFan   QUOTE (mandel @ Feb 7 2006, 02:51 PM)That...   Feb 8 2006, 00:07
||- - krabapple   QUOTE (RockFan @ Feb 7 2006, 06:07 PM)QUOTE (...   Feb 8 2006, 00:27
|- - hdante   QUOTE (mandel @ Feb 7 2006, 08:51 PM)That...   Feb 8 2006, 00:48
||- - mandel   QUOTE (hdante @ Feb 8 2006, 12:48 AM)QUOTE (m...   Feb 8 2006, 01:04
||- - WmAx   QUOTE (mandel @ Feb 7 2006, 08:04 PM)Here is ...   Feb 8 2006, 01:15
|||- - mandel   QUOTE (WmAx @ Feb 8 2006, 01:15 AM)QUOTE (man...   Feb 8 2006, 01:28
|||- - ChiGung   QUOTE (mandel @ Feb 7 2006, 08:04 PM)Here is ...   Feb 8 2006, 04:39
|||- - WmAx   QUOTE (mandel @ Feb 7 2006, 08:28 PM)- Here w...   Feb 9 2006, 06:22
|||- - bug80   QUOTE (WmAx @ Feb 9 2006, 07:22 AM)Did you no...   Feb 9 2006, 10:48
|||- - WmAx   QUOTE (bug80 @ Feb 9 2006, 05:48 AM)QUOTE (Wm...   Feb 9 2006, 15:32
||- - hdante   QUOTE (mandel @ Feb 7 2006, 10:04 PM)Same res...   Feb 8 2006, 15:41
||- - mandel   QUOTE (hdante @ Feb 8 2006, 03:41 PM)QUOTE (m...   Feb 8 2006, 18:12
|- - WmAx   QUOTE (mandel @ Feb 7 2006, 06:51 PM)Why do y...   Feb 8 2006, 00:57
- - enry2k   I know that oversampling in A/D and D/A converters...   Feb 6 2006, 14:06
- - Hollunder   QUOTE (Grand Dizzy @ Feb 6 2006, 01:49 PM)Duh...   Feb 6 2006, 15:53
|- - Grand Dizzy   Oh I think I get it. It's a lot like picture ...   Feb 6 2006, 23:40
- - Hollunder   right, it's principialy the same I found a ni...   Feb 7 2006, 12:58
- - RockFan   QUOTE (Grand Dizzy @ Feb 4 2006, 04:10 PM)I r...   Feb 7 2006, 20:38
|- - krabapple   QUOTE (RockFan @ Feb 7 2006, 02:38 PM)Now as ...   Feb 7 2006, 22:11
||- - RockFan   QUOTE (krabapple @ Feb 7 2006, 01:11 PM)Wrong...   Feb 7 2006, 23:21
||- - WmAx   QUOTE (RockFan @ Feb 7 2006, 06:21 PM)You sim...   Feb 7 2006, 23:45
||- - RockFan   QUOTE (RockFan @ Feb 7 2006, 02:21 PM)Of cour...   Feb 7 2006, 23:51
|- - hdante   QUOTE (RockFan @ Feb 7 2006, 05:38 PM)On play...   Feb 7 2006, 22:37
||- - RockFan   QUOTE (hdante @ Feb 7 2006, 01:37 PM)Again, I...   Feb 7 2006, 23:40
||- - krabapple   QUOTE (RockFan @ Feb 7 2006, 05:40 PM)QUOTE (...   Feb 8 2006, 00:00
|||- - RockFan   QUOTE (krabapple @ Feb 7 2006, 03:00 PM)I loo...   Feb 8 2006, 00:11
|||- - RockFan   You bore me. The last word is yours, please do sa...   Feb 8 2006, 00:19
||- - hdante   QUOTE (RockFan @ Feb 7 2006, 08:40 PM)But man...   Feb 8 2006, 00:22
|- - WmAx   QUOTE (RockFan @ Feb 7 2006, 03:38 PM)Please ...   Feb 7 2006, 23:39
|- - RockFan   QUOTE (WmAx @ Feb 7 2006, 02:39 PM)By reading...   Feb 7 2006, 23:44
- - sven_Bent   @gangran dizzy i hear alot of audiophiles around ...   Feb 7 2006, 23:04
- - AndyH-ha   QUOTE Why do you say the hi-res mix may be safely ...   Feb 8 2006, 00:27
|- - mandel   QUOTE (AndyH-ha @ Feb 8 2006, 12:27 AM)Q...   Feb 8 2006, 00:37
- - krabapple   http://www.ioforums.net/forums/view_topic....rum_i...   Feb 8 2006, 00:49
- - Grand Dizzy   This thread is fascinating! But most of it is ...   Feb 8 2006, 23:06
|- - ChiGung   QUOTE (Grand Dizzy @ Feb 8 2006, 10:06 PM)Thi...   Feb 9 2006, 02:53
|- - LoKi128   QUOTE (ChiGung @ Feb 8 2006, 08:53 PM)The que...   Feb 9 2006, 04:26
|- - ChiGung   QUOTE (LoKi128 @ Feb 9 2006, 03:26 AM)The sou...   Feb 9 2006, 13:53
- - LoKi128   Well, here is what little I can remember from RF t...   Feb 9 2006, 02:31
- - Hollunder   I guess the best way to proof that it has influenc...   Feb 9 2006, 04:26
- - krabapple   more on the 'beating' issue, from James Jo...   Feb 9 2006, 18:13
|- - hdante   There's too much interpreting here. I've f...   Feb 9 2006, 18:34
|- - ChiGung   QUOTE (hdante @ Feb 9 2006, 05:34 PM)QUOTE (m...   Feb 9 2006, 19:00
||- - SebastianG   QUOTE (ChiGung @ Feb 9 2006, 07:00 PM)Unfortu...   Feb 9 2006, 19:25
|||- - ChiGung   Points well made sebG - seems you are cool -Trie...   Feb 9 2006, 19:40
|||- - hdante   QUOTE (SebastianG @ Feb 9 2006, 04:25 PM)I co...   Feb 9 2006, 19:42
||- - hdante   QUOTE (ChiGung @ Feb 9 2006, 04:00 PM) That i...   Feb 9 2006, 19:39
||- - bug80   QUOTE (hdante @ Feb 9 2006, 08:39 PM)Ok, I th...   Feb 9 2006, 19:51
||- - hdante   QUOTE (bug80 @ Feb 9 2006, 04:51 PM)And how e...   Feb 9 2006, 19:58
||- - bug80   QUOTE (hdante @ Feb 9 2006, 08:58 PM)QUOTE (b...   Feb 9 2006, 20:06
||- - hdante   QUOTE (bug80 @ Feb 9 2006, 05:06 PM)I did and...   Feb 9 2006, 20:09
||- - bug80   QUOTE (hdante @ Feb 9 2006, 09:09 PM)QUOTE (b...   Feb 9 2006, 20:16
||- - hdante   QUOTE (bug80 @ Feb 9 2006, 05:16 PM)... yes? ...   Feb 9 2006, 20:23
|||- - bug80   QUOTE (hdante @ Feb 9 2006, 09:23 PM)QUOTE (b...   Feb 9 2006, 20:26
|||- - hdante   QUOTE (bug80 @ Feb 9 2006, 05:26 PM)By now, d...   Feb 9 2006, 21:19
|||- - bug80   QUOTE (hdante @ Feb 9 2006, 10:19 PM)QUOTE (b...   Feb 9 2006, 21:51
||- - ChiGung   QUOTE (bug80 @ Feb 9 2006, 07:16 PM)QUOTE (hd...   Feb 9 2006, 20:40
||- - bug80   QUOTE (ChiGung @ Feb 9 2006, 09:40 PM)QUOTE (...   Feb 9 2006, 20:45
||- - ChiGung   QUOTE (bug80 @ Feb 9 2006, 07:45 PM)QUOTE (Ch...   Feb 9 2006, 20:56
|- - mandel   QUOTE (hdante @ Feb 9 2006, 06:34 PM)There...   Feb 9 2006, 22:40
- - SebastianG   QUOTE (Grand Dizzy @ Feb 8 2006, 11:06 PM)Thi...   Feb 9 2006, 18:17
|- - hdante   QUOTE (SebastianG @ Feb 9 2006, 03:17 PM)So w...   Feb 9 2006, 18:46
|- - bug80   QUOTE (hdante @ Feb 9 2006, 07:46 PM)Remember...   Feb 9 2006, 18:54
- - krabapple   JJ again , at even greater length and detail, on h...   Feb 9 2006, 18:45
- - bug80   Here is a little Matlab code for anyone who likes ...   Feb 9 2006, 19:08
|- - ChiGung   QUOTE (bug80 @ Feb 9 2006, 06:08 PM)Here is a...   Feb 9 2006, 19:11
|- - bug80   QUOTE (ChiGung @ Feb 9 2006, 08:11 PM)QUOTE (...   Feb 9 2006, 19:15
|- - ChiGung   QUOTE (bug80 @ Feb 9 2006, 06:15 PM)QUOTE (Ch...   Feb 9 2006, 19:21
|- - bug80   QUOTE (ChiGung @ Feb 9 2006, 08:21 PM)QUOTE (...   Feb 9 2006, 19:25
|- - hdante   QUOTE (ChiGung @ Feb 9 2006, 04:21 PM)Ok, ill...   Feb 9 2006, 19:45
|- - ChiGung   QUOTE (hdante @ Feb 9 2006, 06:45 PM)QUOTE (C...   Feb 9 2006, 19:55
- - SebastianG   It's a matter of time/frequency resolution. If...   Feb 9 2006, 20:56
- - Pio2001   Oh no ! QUOTE (AndyH-ha @ Feb 5 2...   Feb 10 2006, 00:48
|- - ChiGung   I think i can see that happening in the amp - that...   Feb 10 2006, 01:53
- - Pio2001   QUOTE (mandel @ Feb 8 2006, 02:28 AM)Here whe...   Feb 10 2006, 00:49
|- - bug80   QUOTE (Pio2001 @ Feb 10 2006, 01:49 AM)QUOTE ...   Feb 10 2006, 11:17
|- - LoKi128   QUOTE (bug80 @ Feb 10 2006, 05:17 AM)Anyway, ...   Feb 11 2006, 04:04
- - Rotareneg   For an example of ultrasonic sound producing audib...   Feb 10 2006, 07:18


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