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24/16 Bit Sound test


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#1 Charlie Seper

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Posted 13 August 2005 - 02:44 PM

We had some fun with a test concerning video and film stills a while back in the Video Forum. I said then that it wasn't a coincidence that after 10+ years of selling digital-audio recorder/workstations that recorded at 16/44.1 or 16/48, and sales lagging considerably since everybody already had one, that manufacturers suddenly decided we needed more bits and higher resolutions after all. Thus the introduction of 24 and 32-bit recording and resolutions up tp 96 and beyond. I had a friend who worked at MacMurray Music in St. Louis at the time the first 24-bit recorders came out. He and I both sat in wonder when we heard the playback. Not because it was such a thrill, but because we could hear no difference in the sound at all except for a very slight betterment in stereo seperation which you needed to wear headphones to hear at all, and by the time you dithered your 24-bit recording down to 16-bits to burn a CD with, that tiny bit of extra stereo seperation went away.

Yes, you get a bit more headroom at 24 bit, but unless you're recording a symphony with huge volume dynamics you probably won't benefit from it. And yes, you get a little bit of a better signal to noise ratio at 24-bit, but we were practically dead silent at 16-bit anyway, so again--it was a mostly useless benefit. And yes, you can make more changes to a 24-bit file before hearing any degradation in the sound, however; you could already make at least 6 changes to a 16-bit sound file before hearing any degradation, which is more than most people will ever make.

24-bit may look good on paper but it won't sound any better or different to your ears in my opinion. I still think now, as I did upon hearing that first 24-bit sound file, that 24-bit recording was a gimmic based on the guile of the puplic to entice people to invest in new wrokstations, and new soundcards.

I don't know as much about video or film as most of you people, having only been messing around with it for a couple of years now. But I've operated a recording studio in S. IL. since my college years. This is what I do best so...I thought I'd make some recording tests to put my theory on the line. You'll find four sound files on the following web page. The files are all 16/44.1 wave files, 30-seconds or so in length. I used a great pair of Octava (Russian made) microphones in a typical X-pattern that are reknowned for their abilities to record acoustic guitar sounds. I played the exact same simple piece of music for each recording, at various bit/resolutions, dithering the final results down to 16/44.1 files. No reverb or other effects were used that could alter/color the sound. See if you can tell which is which if you're so inclined.

Also, I put a link at the bottom of the page to a different web page that gives the answer to which file was recorded at which bitrate/resolution. I wanted to give the answers ahead of time so this wouldn't be some kind of contest. Well...its a contest with yourself. I only present it as an informational help.

Sound Test

Edited by Charlie Seper, 13 August 2005 - 02:50 PM.

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#2 Brandon Adams

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Posted 13 August 2005 - 04:25 PM

Hmm, I'll have to burn these and give them a listen later.

But what about outputting at hi-res... isn't that the point of having the 24-bit recording capabilities, to output at 24-bit?
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#3 Charlie Seper

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Posted 13 August 2005 - 04:44 PM

Hmm, I'll have to burn these and give them a listen later.

But what about outputting at hi-res... isn't that the point of having the 24-bit recording capabilities, to output at 24-bit?

<{POST_SNAPBACK}>


Not really. 24-bit recording was originally marketed toward recording studios simply making everyday music CD's for which 16/44.1 is still the standard. We were told that recording at 24-bit with high resolutions and then dithering your end result to a standard 16/44.1 CD file would somehow sound better.

Making 24/96 DVD audio was a later ploy. Those are usually encoded with surround sound. Now I must say that 24-bit when used with surround sound and staying completely within the 24-bit range from beggining to end will yeild a little more stereo seperation. However, you'll need to wear headphones or sit with your head right between the speakers to notice it, not to mention owning a great stereo setup and speakers capable of taking advantage of 24-bit recording. Not cheap! But even then, if you step 5 feet back from the speakers you might as well be listening to 16-bit. Besides, is there anyone who actually likes surround sound? I hated it when it first came out as "quadraphonics" in the 70's and I still hate it. But to each his own.
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#4 Filip Plesha

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Posted 13 August 2005 - 05:51 PM

I listened to the samples...

each seems to be a slightly different recording (and performance) so it is hard to isolate that from the actual sound quality.

I think most of my preference is about the performance and recording, and have nothing to do with sampling, but to me it's like this:

A sounds worst to me, C sounds best to me...

I'd put them in this order accoarding to my preference from best to worst:

C
B
D
A
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#5 Filip Plesha

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Posted 13 August 2005 - 05:55 PM

I just checked the results. It is as I have assumed, I was judging the takes, not the sound. Therefore, I couldn't hear the difference.

I was listening it on the computer with hi-fi headphones, on an integrated Asus sound hardware.
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#6 Saul Pincus

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Posted 13 August 2005 - 08:27 PM

Yes, you get a bit more headroom at 24 bit, but unless you're recording a symphony with huge volume dynamics you probably won't benefit from it. And yes, you get a little bit of a better signal to noise ratio at 24-bit, but we were practically dead silent at 16-bit anyway, so again--it was a mostly useless benefit. And yes, you can make more changes to a 24-bit file before hearing any degradation in the sound, however; you could already make at least 6 changes to a 16-bit sound file before hearing any degradation, which is more than most people will ever make.

24-bit may look good on paper but it won't sound any better or different to your ears in my opinion.Sound Test

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You're absolutely right you'll hear the difference recording a symphony in 24-bit. I have. But you'll also hear the difference when you pre-mix those tracks for the final mix, then hear the difference again when those tracks are combined with dialogue, sound FX and ambiences at the final mix.

As for public exhibition, I'd have to agree 24-bit isn't necessary in most cases. But thick 5.1 film mixes done in the 24-bit realm sound better. I have heard it myself vividly on mix stages over the past five years.

Saul
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#7 Charlie Seper

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Posted 14 August 2005 - 05:04 PM

I think those 24 bit surround sound mixes can appear to sound better if they stay in the 24-bit realm all the way to the finished product Saul. Actually, I don't think they sound better; I believe however that most people that sit close to the speakers can hear a little bit better stereo seperation and this they percieve as better sonics. Record and play back those same 24-bit sound files in mono and I think you'll see those differences go away. Its a bit of a trick our ears play on themselves. We hear a stereo sound that's wider and we automatically think, "That sounds better." Actually, it just sounds wider.

I didn't say that a symphony could sound better at 24-bit. I said you'd have more headroom available. That's a slight improvement in "volume" dynamics, meaning you can have sounds that are a tad louder before distortion sets in. 24-bit has nothing to do with frequency range however. Recording with more bits won't change the sound at all sonically speaking. Neither will 32-bits. Resolution is where a difference in frequencies come into play. But again, we're already well past the threshold of human hearing at 44.1 (w/oversampling) and its not really logical to think that recording at high resoltuions will have any effect that a human being could hear. In fact, it could have a negative effect that we don't yet know about or understand. For instance, we know that subsonic sounds (extremely low tones below the threshold of human hearing) around 16Hz can cause panic and fear in humans. No one can say why it happens but it does. Some old movie house back in the 40's and 50's used to have speakers set up to induce that very tonal range when playing scarry movies. The effect really works. There's no reason to think that playing frequencies higher than 20k might not have some kind of negative effect also. We just don't know. Like those subsonic sounds, it may not be an effect you can hear, but rather, one you can feel.

Sonics can be a strange field to play around in. I made several brain wave (theta and delta) files a few years back that were supposed to induce strange mental states in people and they really work.
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#8 Saul Pincus

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Posted 15 August 2005 - 12:28 AM

I think those 24 bit surround sound mixes can appear to sound better if they stay in the 24-bit realm all the way to the finished product Saul. Actually, I don't think they sound better; I believe however that most people that sit close to the speakers can hear a little bit better stereo seperation and this they percieve as better sonics.

<{POST_SNAPBACK}>

I can appreciate your perception, your professionalism and your experience, Charlie. Perhaps it's just better stereo separation, but I can indeed perceive the difference when listening to 24-bit material. I'm speaking not as a mixer, but as someone who's run a good number of them. I'm also speaking as an audiophile. Maybe I'm imagining things, but in side-by-side comparisons with 16-bit material I feel I perceive a definite improvement with 24-bit material not only in stereo separation or dynamics but in resolution as well.

I didn't say that a symphony could sound better at 24-bit. I said you'd have more headroom available. That's a slight improvement in "volume" dynamics, meaning you can have sounds that are a tad louder before distortion sets in.

<{POST_SNAPBACK}>

You're correct - you didn't say that. But I feel strongly those "volume" dynamics matter, particularly within quieter and less bombastic sections of symphonic score. I realize I'm speaking primarily through perception here. But I'm most assuredly not forming my opinions though industry demos! I recall, for example, Dolby's early travelling demo of Dolby Digital (then called Dolby SR-D). They ran the last reel of "Star Trek VI" in SR, then again in SR-D. This had the audience in awe - though not me. The 70mm Dolby SR magnetic print was much, much better to my ears.

Saul

Edited by Saul Pincus, 15 August 2005 - 12:30 AM.

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#9 Charlie Seper

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Posted 15 August 2005 - 02:29 PM

Maybe I'm imagining things, but in side-by-side comparisons with 16-bit material I feel I perceive a definite improvement with 24-bit material not only in stereo separation or dynamics but in resolution as well.
Saul

<{POST_SNAPBACK}>


Well it could be that the 24-bit material in question also had a higher resolution. However, I still tend to think that nobody could hear a difference in higher resolutions either. At least there's no valid reason why they should. I mean, you do hear self-proclained "experts" saying stuff about odd/even order harmonics having some influence on the sound even when its over 20k, but I've personally never bought into any of that. The reason is, that I've never met anyone yet who could consistently tell the difference in higher bitrate/resolution files if they were in mono. That tells me that people's ears are most likely fooling them into thinking there's something richer going on with the extra stereo seperation. Maybe in a couple of weeks I'll record some similar files in mono and post them.

There are a lot of guys my age and older (46) who have it in their heads that a good reel to reel deck can still outperform digital. I disagree with that too. Even the best Studer or Otari decks produce a bass bump down around 100 Hz or so. And while these decks are capable of producing frequencies higher than 20k, by the time you run the deck through a patch bay, or run through some compression, reverb, etc, you're going to lose a fair amount of highs. Another thing that steals high end is noise reduction, whether its DBX, Dolby SR, Dolby A or what have you. So what you end up with is a signal that's a little under 20k in the high end and has a little boost in the low end via the natural bass bump. I think the human ear actually prefers this. I don't doubt that these people think tape sounds better than digital; I just doubt the reason why. The heart and soul of music is in the lower mids. Boosting them can be quite pleasing to the ear. That's the reason my 70-year old dad loves the sound of Cardinal baseball games broadcast on AM through an old Grundig radio I gave him that sounds a lot like the tube radios he grew-up with. AM is only good for 500 Hr to 5k or thereabouts, but that's a very warm area so the ears like it. Having more high end or low end isn't always a good thing. If you ever heard an electric guitar through a hi-fi speaker with tweeters it'd run you out of the room. Guitar amps use speakers with almost nothing but midrange. They just sound better that way.

The human ear is one of the most baffling things the good Lord ever made. If you ever studied the way it works, its truly amazing. And what goes on with any sensory perception once it gets past the cortex, and how all those signals get seperated and form a coherent picture in the mind, is so profound a mystery that its doubtful anyone will ever come close to figuring it out.
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#10 Daniel J. Ashley-Smith

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Posted 15 August 2005 - 02:37 PM

Using higher bit depths and higher sample rates only gives you more overhead. Better for editing. For a start you need a device capable of playing audio files of that resolution. DVD-Audio and SA-CD players play this kind of audio, creative also do several sound cards that will output at that rate.

So.. for straight recordings, no you won't hear any difference. Although you will have more editing capabilities.

Most people seem to think DVD-Audio discs are great because of the advanced resolution. Far from it. About the best thing about those discs is the DVD features and the 5.1 surround sound.
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#11 Nate Downes

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Posted 17 October 2005 - 06:23 AM

I did audio testing ages ago, and I did hear a difference between 16-bit and 24-bit. But you needed to have an extremely high-end audio setup, the difference is too often lost in the line noise from the speaker wires, or from the speaker itself. That's one reason why headphones typically are easier to hear the difference with, less in the way to degrade the sound.

But then again, I use a Nagra for field recording, still. I just love the sound of the old thing.
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#12 Phil Rhodes

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Posted 17 October 2005 - 08:48 AM

Hi,

I'd be interested to hear more about the circumstances of your test. I would seriously doubt that a 16-bit downsample would be discernible from a 24-bit original. What can be much more audible is the better phase reproduction, particularly on sounds such as a string orchestra, if you sample at a higher frequency.

The purpose of capturing at a higher bit depth is generally so as to avoid excessive quantisation when making manipulations later, not because the difference is really discernible. This goes for image as well as sound - 8-bit colour is fine so long as you aren't going to try and grade it!

Phil
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#13 Nate Downes

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Posted 17 October 2005 - 09:17 AM

Oh, I didn't mean downsampled, comparing a source captured at 24-bit rather than 16-bit. Yes, a downsampled from 24-bit is indistinguishable to my ear, but one captured at 16-bit is.
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#14 Charlie Seper

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Posted 18 October 2005 - 02:16 AM

You know, I do have to say that at times I think I can hear a very slight difference between 44.1 and 48 resolutions. I really can only hear it when I stereo mike my acoustic guitar as in the above samples. The difference is so slight that it could well be my imagination. I know I don't hear any difference at resolutions above 48 on up to 192 though. At 44.1 you're recording with oversampling. At 48 and above you don't need oversampling, however; I've never been clear as to whether or not AD/DA converters are still oversampling when recording at higher resolutions. I know they don't need to but I'm not sure if there's any kind of circuitry that stops the oversampling once you get to 48. Maybe most soundcards and preamps continue to oversample anyway because it would be easier to just let it happen? Does anybody know?
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