Why 24bit/48kHz/96kHz/, If 16bit/44.1kHz is good enough?
Why 24bit/48kHz/96kHz/, If 16bit/44.1kHz is good enough?
Dec 29 2005, 13:45
Joined: 8-January 02
Member No.: 959
Yes, I have searched the forum.
Yes, maybe I am dumb.
But it seems I cannot find the answer.
Why do we need 24bit/48kHz/96kHz/192kHz if 16bit/44.1kHz is good enough? Are there any situations that 16bit/44.1kHz simply cannot satisfy? In other words, is there any real need for the higher bit depth and sampling rate?
Thanks for answering.
This post has been edited by William: Dec 29 2005, 13:47
Mar 19 2006, 06:58
Joined: 19-March 06
Member No.: 28575
16bit means 2^16 = 65536 possible values
for each 1/(44.1*10^3) portion of a second.
24bit would hence be 2^24=16.7 million values.
That is 2^(24-16) = 2^8 = 256 as many.
The misunderstanding people make is that one would
not really be able to hear the difference.
The curve is round enough. We are just humans.
But here is what they forget:
=== An example: ===
When you listen to a live recording,
the band plays at normal volume, with their
peaks till the full range of these (when recorded
in 16bit) 65536 values.
But the band does not always play loudly.
And even while they do, there are also sounds
that are not so loud. The drummer might
hit his ride gently.
Those rides have an interesting colorful sound.
A good drummer would be able to guess the brand
of the rides, with his eyes closed.
And also estimate what type of drum stick is used.
Since these rides are but played softly,
their range lies not in the full 65536 values,
but, say, only from +6% to -6%.
If one would be able to mute all loud instruments
(for this explanatory example), we would only
hear the rides in 3932 'blocks', or approximately 12bit.
If you now would turn up your volume
(of the headphones you use to listen to all this),
you would not hear an elegant ride sound at all.
So, in summery, a 24bit recording sounds nicer
than a 16bit recording because you can hear the
soft and gentle sounds better.
Someone in audience using a teaspoon and cup to
add some unasked percussion.
We can hear the stage has a wooden floor because
the horn player taps his foot.
PS. I have not read all posts in this thread,
so forgive me if I am repeating something
PPS. I am just an amateur too.
I could be mistaken in my details,
but I think the essence is correct.
This post has been edited by harlekeyn: Mar 19 2006, 22:21
Mar 19 2006, 22:07
Group: Super Moderator
Joined: 29-September 01
Member No.: 73
QUOTE (harlekeyn @ Mar 19 2006, 07:58 AM)
If you turn up your volume loud enough, you can always hear some noise.
It would be more interesting to use some extremely dynamic samples, and play them in a silent environment at the loudest possible volume for music listening. This would simulate the "worst case" situation.
Studying the advantage of high sample rates is extremely difficult.
First, one needs "super tweeters" in order to play ultrasonic content. Few speakers are capable of playing back sounds above 20 kHz.
Then, in the last version of his paper, David Griesinger reports that intermodulation distortion at high frequencies, that can make a "counter-difference" between 44100 Hz and 96000+ Hz (96 khz sounding worse), occurs mainly in amplifiers, rather than in speakers.
Even with super tweeters, an amplifier may then produce distortion when fed with ultrasonic content.
On the other hand, there are evidences that ultrasonic intermodulation occurs in air : http://www.atcsd.com/hss.html
However, it occurs at high sound pressure. Around 130 dB, for example. Ultrasonic content in musical instrument is below 60 dB. Moreover, in order to produce audible ultrasonic intermodulation, focused sonic beams are used, while a music instrument radiates sonic energy in all directions. It seems that ultrasonic intermodulation in air should be inaudible, but I don't know about studies on this.
Scientific papers featuring blind listening tests about high definition sound are rare.
Two are published on the web :
The first one shows positive results, but give absolutely no details on how the statistic confidence have been evaluated. The result is even considered as minor, since it was not the goal of the experiment, that focuses on electro-encephalograms.
The second link above is a similar experiment, that failed.
I've heard about a third one, discussed here : http://www.hydrogenaudio.org/forums/index....st&p=307155
However, the role of ultrasonic content in the success of this test is unsure : http://www.hydrogenaudio.org/forums/index....st&p=307619
But unscientific blind listening tests have sometimes showed that CD players operating at 44100 Hz 16 bits are not fully transparent :
The 24/96 challenge : http://www.hydrogenaudio.org/forums/index....showtopic=17118
Analog copies from two different CD players : http://www.homecinema-fr.com/forum/viewtopic.php?p=169329500
Analog copy (44100 Hz 16 bits playback -> 48000 kHz 16 bits recording) vs resampled digital file : http://www.hydrogenaudio.org/forums/index....f=21&t=6651
All these tests deal with files undergoing digital filtering near 22 kHz, and 16 bits rounding or dithering.
One can argue that 44100 Hz and 16 bits are enough in order to acheive transparency on a decent hardware, and that the above tests use samples suffering from bad recording or processing. But I listened to the samples of the first comparison in the second link, and could not hear any difference. The guy who got 8/8 have got better ears than me.
So we can wonder if raising the resolution of the digital format could improve the sound quality in these cases. I cannot tests this hypothesis because my listening abilities are not good enough to make the difference between two CD players.
This post has been edited by Pio2001: Aug 8 2010, 20:01
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