However, I disagree that all computer-based systems are lacking. My Dell computer has an M-Audio Delta 66 sound card, and it's definitely clean for both recording and playback down to the noise floor of 16 bits.
Hmmm. The discussion started with you saying "any PC sound" card is that good. To the extent you now are saying that your specific configuration sounds good then we have made a ton of progress!
That said, how do you know your configuration resolves 16-bits? How did you measure it? And can you post those results? Delta makes really good cards but once you plug it into a random PC, you are never assured of its performance.
Yet look at how many people read that jitter is a problem, and then spend ten times more than needed to buy a converter that some ignorant reviewer claims sounds better than usual due to its low jitter.
I would say that the other side has not found an effective way to communicate its message then
. Besides your side is guilty too. This very same argument over this paper is going on in another forum as I type this. People are quoting that paper as gospel and when I asked the poster what the conclusion meant, he couldn't even spell it alone know what it meant!
I suggest we put aside solving for world peace and continue on with the merits of the matter. Whether someone should or should not be worrying about jitter is not something that changes the facts. If you and I do a good job of discussing it, maybe there will be less of it
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The task isn't to worry about the listener's playback system, only to create a file with jitter-like artifacts at a level that's typical. This is the crux of it. If you create a pair of files and run a poll asking people to choose which file they think has the added jitter, the poll results will hold the answer. If out of 100 people over multiple trials nobody can reliably pick the file with the added artifacts, that proves to my satisfaction that jitter is not an audible problem.
I think we are still talking past each other. I already explained how Jitter can have infinite variations. Which profile would I simulate and why? And how do you enable people to use their home systems rather than clicking on a file on their laptop and testing that way? Burning CDs and such is a lot of work to ask people in the process.
I'm sure you think you can hear jitter, but how do you know that for sure?
Well, let me say that I am more sure of hearing it than you are that you can't hear it
. At least I have positive proof for something. You are relying on negative logic that if I have not heard it in my limited testing (or worse, assumptions), then it must not be audible.
As I explained in my AES video, the only way to know at what level jitter is audible to you is with a box that let's you add from zero to a lot. Better, someone else would turn the knob while you listen blind, and you say when you think you can just hear it. Do that ten times and see if the thresholds are consistent, and below the noise floor of a CD. If so, you win. If not, I win.
Ethan, this is getting a bit frustrating. I have said repeatedly that there is no one number you can dial this way. It is not frequency response or volume where you could just have one dial to affect it. As a minimum, you would have to have three dials and the last dial, would have to have infinite dials itself to represent all the spectrum distributions.
Let's put that aside for now. Please explain why I heard what I heard. Aren't there only two explanations?
1. Jitter is audible.
2. I imagined it, even though I am schooled in objective and scientific testing of audio and have an engineering background to boot, with an opinion prior to testing that all of this was non-sense as you, and that the test was run blind?
Remember, my goal here is not to prove audibility of jitter. But rather, giving you a perspective that it is not just ordinary audiophiles who worry about jitter but people with extensive experience in the science of audio (especially the perceptual aspects of it) solid enough knowledge of the engineering behind it. In other words, as long as you accept that the case is not open and shut as you thought, then I am golden
. I have no higher aspirations.
I can't see how reducing the bit-rate of lossy-compressed audio until you hear it is related to increasing jitter until you hear it. One is added noise, the other creates holes in the frequency response.
That's incorrect in the way you are stating it. If you look at compressed music, it will appear to have full response (at high enough data rates and with modern codecs than MP3). There will be no holes in its spectrum. Let's review again what how we perform lossy audio compression:
1. Signal is transformed from time domain (PCM samples) into frequency domain. Think of dancing bar graphs in an equalizer. For now, assume if the samples are 16 bits each, the frequency "bins" are also 16 bits.
2. Those frequencies are analyzed and based on perceptual model of the ear, we reduce the number of bits we assign to each frequency. So for example, if there is a loud sound at 1 KHz, we will leave that band alone but take bits away from another sound at 900 Hz since that is in the "masking" shadow of the 1 KHz sound.
The reduced bits allocated to the 900 Hz band causes increased distortion which we call "quantization noise." If for example, we chop that band down to 8 bits, then we have created a much coarser signal and added distortion because of it. However, since this sound is likely to not be audible anyway, then butchering it this way is probably not harmful.
3. We then take all of those frequency bins values which are just a bunch of numbers and apply a *lossless* compression algorithm to it as we would with zipping a file on your computer. This is called an "entropy coder" if you want to impress your friends at the next holiday party
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4. The output of #3 is your compressed file. The player takes that file, applies the reverse of entropy coder and gets the frequency bins. It then does the reverse transform of that and gets the PCM samples. Data rate is reduced because we have reduced the bandwidth allocated to each bin variably and the entropy coder is optimized in compressing those values further.
While it is true that if you heavily compress a file, some of the bins may get zeroed out, in the high data rates that I mentioned, that does not occur. Instead, what we get is increased quantization noise at certain frequencies. The increased noise tends to rob the signal its ambiance which is at much lower level than the music and increases its high frequency content (symptom of over quantizing a signal). Both of these occur in a very similar way with jitter. Jitter reduces system resolution and as such, it can also obliterate low level detail and help increase the high level frequency energy of the signal.
Is the effect identical? No. But to the extent you learn to hear the artifacts of lossy music, you are a long way toward hearing artifacts rather than just hearing music. And that is key: there is a big difference in using your ears to enjoy something than to use it as an instrument, trying to find a flaw. Most people are not good at the latter. By practicing to hear lossy compression artifacts at high data rates, they learn what it takes to do that. If I may use a crude analogy, it is the difference between reading lips to understand someone in addition to hearing their voice or doing the latter alone. It takes practice to read lips, it doesn’t come naturally to people.
You are ahead of most members here in hearing acoustic flaws. I am sure you don’t take that skill for granted or there or there would be no need to do the demo videos you have done. Likewise, I feel that more experience is needed to hear digital artifacts than what a person may already know.
To me, low bit-rate compressed audio sounds like comb filtering. And that's because it is more or less.
You have a tendency Ethan to read everything through the lens of acoustic problems
. There are certain artifacts at very high levels of compression that might sound like comb filtering but that is not a correct generalization. Encode some speech and listen to it at 32kbps. It won’t sound like comb filtering but rather, will have a coarseness to it that is created by the effects I mentioned (more commonly called “pre-echo”).
I say that a typical amount of jitter is so soft that nobody can possibly hear it.
Have you ever heard jitter at any level Ethan? Do you have an external DAC and does it support multiple interfaces? If so, can you hook them up to your sound card and then switch between them and tell us whether they all sound identical? Try comparing S/PDIF, AES and Toslink. Then for the former two, try both a high quality short cable and long, crappy cable. Again, with every change, do an A/B against the other.
I have ran the above test and I was shocked to hear the differences. It was totally unexpected for me. I would say you owe doing tests like this way before we owe you getting 100 people to vote whether they hear jitter or not
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Not to turn this into a pitch for room treatment, but it kills me when some audiophiles talk about clarity and detail, while listening in a room where the early reflections are uncontrolled and only a few dB below the direct sound. That obscures clarity far more than a cheap sound card, and even cheap speakers. I'd rather have $100 bookshelf speakers in a treated room than [whatever expensive brand] in a room with bare walls and no bass traps. I guarantee the sound will be clearer with the $100 speakers.
Again, that is neither here nor there. People here want the best so you should assume that they have done all they can to their room and are now wanting to understand two things:
1. If they believe in digital, what is the best system for them.
2. If they believe analog sounds better, what would explain that.
I am trying to provide data for both. People natively understand analog concepts of distortion. They hear it readily. Turn up the amp too much and you hear clipping distortion. Get a speaker that has too much highs or is boomy and they hear that too. But where would they even begin to know what jitter sounds like? That is what I am trying accomplish here. Teach them the science as you do with acoustics. Tell them how it *could* be audible. And then let them “go fish.” We don’t control their pocketbook nor can we ever get into their heads to know what they hear. So let’s not keep debating where they should spend their money and what is good for them…