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Can You Really Hear a Difference with Dithering?
#3048795 06/13/20 07:55 PM
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This is a subject that comes up a lot at workshops and seminars. Often, when different dithering options are available, there's confusion about which type to use for different types of material, or whether even to use it at all.

So, I investigated dithering pretty deeply, and wrote an article that includes audio examples of a file exported as 16 bit undithered, 24 bit undithered, and with three Pow-r dithering types and Waves Type 2 (with pretty sophisticated shaping), as well as garden-variety Triangular dithering.

To make the dithering audible, the audio examples are normalized to a level where you can hear the results of dithering very clearly. I hope this clears up some of the mystery around using dithering, and am interested in your opinions about same.

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Re: Can You Really Hear a Difference with Dithering?
Anderton #3048798 06/13/20 08:30 PM
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The demonstration of the need for dithering by barely giving the original audio file enough bits to work with at all is generations old, but a good argument for both higher bit resolution and dithering. But to record at -80 dBFS is just plain dumb. Nobody does it intentionally, and generally fadeouts don't spend enough time down at that level to become noticeable in the real world.

Today's A/D converters are so good that you can happily truncate a 24-bit recording to 16 bits and it'll sound just like a normal 16-bit recording. In other words, the demonstration works, but the need to agonize over word length reduction may no longer exist. Far more damage can be (and usually is) done by converting to a lossy data compression format, which is how most audio is distributed nowadays. If you'e into Hi-Rez, there are plenty of sources for 24-bit audio files with no dithering (and none needed). But you need a good A/D converter and a lot of analog headroom in order to take advantage of all of those bits.

Re: Can You Really Hear a Difference with Dithering?
Mike Rivers #3048802 06/13/20 09:09 PM
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Originally Posted by Mike Rivers
But to record at -80 dBFS is just plain dumb.

...Unless you're trying to demonstrate the audible differences among dithering algorithms in an obvious manner. Besides, I don't know if you read the whole article, but I already covered what you said:

Can you even hear audio that low? Let’s find out, and listen to a bunch of audio examples.

1. Load a mixed audio file into your DAW, and set the volume for a comfortable listening level.
2. Now, normalize the file to -60 dB (or, use clip gain or a clip envelope to reduce the audio amplitude without changing the listening level).

Unless your idea of a comfortable listening level is to blow your ears off, playing the file back at -60 dB will be inaudible or at least, very faint. Bear in mind that this is the kind of level (and lower) where dithering does its thing.

As a result, dithering has the most impact with music that has wide dynamics, doesn’t necessarily hit 0 very often (if at all), and is at a fairly loud playback level. For example, you won’t hear the impact of dithering on highly-compressed pop music, but you may hear it on the reverb tails of acoustic symphonic recordings playing back from 16-bit CDs.


Bear in mind I've engineered/mixed several classical sessions over the years that ended up on CD. Dithering makes a difference at loud listening levels. But 16 bits isn't dead yet. I just finished mastering Martha Davis's new album and provided 24-bit files for the streaming services. However, CD Baby still requires receiving 16-bit, 44.1 kHz files, even when used for streaming.

A larger question is not whether you can hear super-low-level signals, but whether you can perceive them. I'm often reminded of a story Waves told me - they were A/Bing an emulation and hardware unit. No one could perceive a sonic difference between the two, yet several people said the emulation didn't sound "right." Waves analyzed the crap out of both the hardware and the emulation and couldn't find any measurable difference, except for extremely low-level noise in the hardware. When they added that to the emulation, without telling the people listening exactly what had been changed, they then felt that the emulation sounded right.

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Far more damage can be (and usually is) done by converting to a lossy data compression format, which is how most audio is distributed nowadays.

Well, that's changing. Windows 10 adopted FLAC as the replacement for WMA, and Apple has had a lossless codec (not an AAC variant) for over 15 years. But, they average around only 50% data reduction, so given the state of internet speeds, MP3 was more popular. Although speeds are getting friendlier to lossless files, there's also the question of whether people care, because if they did, Tidal would have taken over the world by offering lossless music. Some think Apple's Digital Masters is the penultimate step before offering lossless files as more or less standard, but that remains to be seen.

Re: Can You Really Hear a Difference with Dithering?
Anderton #3048840 06/14/20 04:58 AM
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Crikey, I hadn't even thought of this in years.

I add ambient noise and analog hiss or that "organic" dithering. wink

Re: Can You Really Hear a Difference with Dithering?
Anderton #3048858 06/14/20 01:50 PM
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Originally Posted by Anderton
Originally Posted by Mike Rivers
But to record at -80 dBFS is just plain dumb.

...Unless you're trying to demonstrate the audible differences among dithering algorithms in an obvious manner. Besides, I don't know if you read the whole article, but I already covered what you said:

I indeed read the whole article, hoping you'd have something new and revealing to say. Craig, I respect you and your writing - you were, and still are, one of my important influences in my own writing. But I was just wondering why you were dredging up this old demonstration of what should no longer be a problem when working with the proper tools in the correct manner.

It's still a valid demonstration, however. I'll grant you that, and useful to those interested in the evolution of digital recording.

Re: Can You Really Hear a Difference with Dithering?
Mike Rivers #3048886 06/14/20 06:29 PM
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Originally Posted by Mike Rivers
But I was just wondering why you were dredging up this old demonstration of what should no longer be a problem when working with the proper tools in the correct manner.

That's a totally reasonable question. There are new people getting into recording all the time, and dithering remains confusing to many of them. Their DAWs have dithering included, but they don't know what it's about, whether they need to use it, why there are different types, etc. Also, CDs are not yet dead (50,000,000 were sold in 2019), especially for merch tables...although I guess that at the moment, merch tables are pretty much dead anyway. So when I explain dithering at seminars and such, my main points are: it's happening at levels so low you probably won't hear it except with very specific types of program matter, it's needed only when going from a higher bit resolution to 16 bits, and that there are still questions about perception and how our ears respond to low-level sounds.

People vary a lot in terms of hearing acuity. Several of the classical musicians I've worked with could tell the difference between dithered and undithered 16-bit masters. This was brought home to me when I was playing back a master and the artist commented there was something "wrong" with it compared to previous ones. I didn't hear a difference but tried to figure out what was going on. For that version, I had forgotten to enable dithering. I checked the box, ran off another copy, and it was perceived as sounding "right." This made me wonder whether they heard or perceived a difference. Of course, I don't know the answer...but when I have to do something 16-bit, I always use dithering under the premise of "can't hurt, could help."

Based on the audio examples in the article, it's obvious that 24-bit recording and playback solves the problem. You're right that the importance of dithering is fading, and it's kind of a forgotten topic. But it's not a 24-bit world yet, and as long as digital audio products include dithering, people will want to know what it does.

However, your raising the question about whether it's still relevant is well worth addressing, so I'm going to edit the article to elaborate on that. Second sets of eyes tend to be very helpful smile

Re: Can You Really Hear a Difference with Dithering?
Anderton #3051442 06/28/20 02:01 AM
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But who is number 1 ? ...
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Not to derail this too much, but for final mixdown — whether through a summing mixer or just taking a stereo mix out of the DAW — I used to like to come out analog into a Korg MR-1000 1-bit DSD recorder. These would be my mother archival stereo files. Korg then had decimation software that could re-render these into any multi-bit word format. At the time I heard a difference between this and doing a bounce inside the box with dithering (if I did I used the PowR algorithm in Logic at the time). I'm wondering if I'd hear the same difference today ... I know Craig is on record as perfectly fine with bounce-to-disk in Cakewalk and now Studio One.


"I'm just a confused musician who got sidetracked into this damned word business..." -Hunter S. Thompson

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Re: Can You Really Hear a Difference with Dithering?
Anderton #3051445 06/28/20 02:19 AM
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Although I'm not a wine-tasting audio kinda guy, DSD always sounded better to me. I believe it was because of the relaxed filtering requirements.

<<I know Craig is on record as perfectly fine with bounce-to-disk in Cakewalk and now Studio One.>>

However, remember that I'm fine with it because i upsample anything benefits from it. So, it's not that different from what you're describing.


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