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High resolution audio. The science, or lack of...?

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fr0g's picture
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First of all, I must apologize to Quadpatch for essentially wrecking his headphone thread...It wasn't the intention and in hindsight I can see that such topics can escalate...Probably best kept separate...

 

However, the topic interests me. WHF S&V themselves actively promote, or rather review and claim higher quality for HD music. whether it be 24/96 or higher.

Now, the last I had heard, and as far as I know, the good old CD and the theorum to which music data is recorded onto it, is more than enough for the absolute limit of human hearing.

ie Nyquist-Shannon states (and has been proven to be correct) to perfectly recreate an analogue signal, you need a sampling frequency of double the maximum sound frequency required. Or rather more accurately put (from WIki)

"If a function x(t) contains no frequencies higher than B hertz, it is completely determined by giving its ordinates at a series of points spaced 1/(2B) seconds apart."

 

Now some people here seem to believe that HD tracks will be better. Why? I have yet to see any links to any papers or proof on this, and in fact have seen some to studies that show the higher resolutions (192 KHz and above) can have an adverse effect on quality...

 

I do agree that many HD versions of music sound better. But experience tells me that these are simply better recordings...I used to buy HD and found it excellent...until I downsampled one to 16/44.1 myself and could not tell them apart...

 

As for the 16 bit v 24 bit for playback... Why does anyone think we need 24 bit? 16 bit gives us a 96 dB dynamic range (way higher than vinyl), and if we take an extremely well recorded CD with a DR of 30 dB (very unusual, they tend to be no more than 10-15), then we have a noise floor of -66 dB...which as far as I can see, is inaudible.

 

So please, without insults or petty put-downs, can someone give me any concrete,scientific information on why they think HD (for playback) is any better?

 

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BigH's picture
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RE: High resolution audio. The science, or lack of...?

HDTracks are remastered so that maybe the difference. I thought bits was the noise floor, so more bits lower noise so more dynamic range? But then most cds have a DR of less than 20DB anyway.

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RE: High resolution audio. The science, or lack of...?

Could it be what this article states "A vinyl record is an analog recording, and CDs and DVDs are digital recordings. Take a look at the graph below. Original sound is analog by definition. A digital recording takes snapshots of the analog signal at a certain rate (for CDs it is 44,100 times per second) and measures each snapshot with a certain accuracy (for CDs it is 16-bit, which means the value must be one of 65,536 possible values).

This means that, by definition, a digital recording is not capturing the complete sound wave. It is approximating it with a series of steps. Some sounds that have very quick transitions, such as a drum beat or a trumpet's tone, will be distorted because they change too quickly for the sample rate." and going to a higher quality gives a better approximation that is audible?

http://electronics.howstuffworks.com/question487.htm

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RE: High resolution audio. The science, or lack of...?

I see were you coming from.. If most people cannot hear differences in sound then it must be the case.. You could hear differences but could be so liitle that its not worth the extra money paid for HD music. I always say believe your ears not what someone else tells you.

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RE: High resolution audio. The science, or lack of...?

Native_bon wrote:

I see were you coming from.. If most people cannot hear differences in sound then it must be the case.. You could hear differences but could be so liitle that its not worth the extra money paid for HD music. I always say believe your ears not what some else tells you.

 

+1 whether its placebo or fact who cares if it sounds better too you.

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RE: High resolution audio. The science, or lack of...?

Dunno but if there is any doubt on how much difference there can be on so called 'HD downloads' ... a read of Paul Miller's measurements on monthly releases in HifiNews&RecordReviews will show that all are certainly not created equal ...

regards

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RE: High resolution audio. The science, or lack of...?

You want SCIENTIFIC information on this forum?   rolling on the floor laughing

 

Well . . . my tuppence is with my limited exposure to HD audio I could not tell the difference.  From what I hear, the quality of the original recording and how it was mastered is more important than HD or not.

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fr0g's picture
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RE: High resolution audio. The science, or lack of...?

josh05 wrote:

Could it be what this article states "A vinyl record is an analog recording, and CDs and DVDs are digital recordings. Take a look at the graph below. Original sound is analog by definition. A digital recording takes snapshots of the analog signal at a certain rate (for CDs it is 44,100 times per second) and measures each snapshot with a certain accuracy (for CDs it is 16-bit, which means the value must be one of 65,536 possible values).

This means that, by definition, a digital recording is not capturing the complete sound wave. It is approximating it with a series of steps. Some sounds that have very quick transitions, such as a drum beat or a trumpet's tone, will be distorted because they change too quickly for the sample rate." and going to a higher quality gives a better approximation that is audible?

http://electronics.howstuffworks.com/question487.htm

 

The problem with that quote is it is nonsense. The original analogue wave can be "perfectly" reconstructed as long as we sample at 2x the maximum sound frequency. That's the whole point of the theorum, and it has been proven to be correct. 

As for people saying "Just go by what you hear". That isn't the point...there are 2 reasons why we shouldn't do that.

1. We can be conned by our own brains.

2. We can be conned by recordings being made purposefully better in the higher resolution (read, more expensive) format. 

ie. In the 1st instance we "expect" the HD track to be better...so it is, and in the second, it "is" better, but need not be, or rather, the SD track "could" be just as good.

The maths shows us clearly that a 0-22 KHz analogue signal can be digitised, then made analogue again and will not differ at all from the original for those frequencies.

Yes, the digitised signal is indeed snapshots, but once that digital signal goes back through the ADC, the signal should be identical to what went in.

 

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RE: High resolution audio. The science, or lack of...?
fr0g's picture
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RE: High resolution audio. The science, or lack of...?

altruistic.lemon wrote:

Trust your ears, and try these http://www.audiocheck.net/testtones_highdefinitionaudio.php

 

Not sure what the point is. Most equipment won't play back such high frequencies anyway. So at the very best they won't sound like anything. At the worst they could cause distortion as aliasing, as they mention.

 

Either way, we can't hear them and attempting to recreate them is fairly pointless.

 

 

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Joined: 25 Jul 2011
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RE: High resolution audio. The science, or lack of...?

The point is people can try and hear for themselves. Nothing wrong with that - you afraid the results may not be what you think, mate? 

You talk big words about science but when it comes to applying it, you don't want to.

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RE: High resolution audio. The science, or lack of...?

josh05 wrote:

Could it be what this article states "A vinyl record is an analog recording, and CDs and DVDs are digital recordings. Take a look at the graph below. Original sound is analog by definition. A digital recording takes snapshots of the analog signal at a certain rate (for CDs it is 44,100 times per second) and measures each snapshot with a certain accuracy (for CDs it is 16-bit, which means the value must be one of 65,536 possible values).

This means that, by definition, a digital recording is not capturing the complete sound wave. It is approximating it with a series of steps. Some sounds that have very quick transitions, such as a drum beat or a trumpet's tone, will be distorted because they change too quickly for the sample rate." and going to a higher quality gives a better approximation that is audible?

http://electronics.howstuffworks.com/question487.htm

Whilst the graph in your link illustrates the point it exaggerates the difference between an analogue and digital waveforms to make it. The so called CD 'approximation' shown is more like a square wave and would not sound anything like the original. A better representation is shown here:

http://www.synaudcon.com/site/blog/digital-audio/digital-audio-at-last/

I think the fundamental question is has current digital sound quality reached a point where it's not possible for most people to detect any further improvement whether it be any increased sample rates or purely analogue recordings.

Even with anaglogue there are limitations in the equipment used to record and reproduce the original sound exactly and may or may not be better than digital equipment.

Also even contemporary vinyl records may contain recordings of sounds that were produced and recorded digitally. 

Personally I find CD technology to be more than adequate and the important thing is to enjoy the music rather than trying to listen for imperfections.

 

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RE: High resolution audio. The science, or lack of...?

altruistic.lemon wrote:

The point is people can try and hear for themselves. Nothing wrong with that - you afraid the results may not be what you think, mate? 

You talk big words about science but when it comes to applying it, you don't want to.

 

This post makes no sense at all Lemon.

"Listening" is NOT applying science. As I say, most speakers won't produce much anyway over 22 KHz. So feeding them such a signal won't have any effect, at best, at worst it will cause distortion.

And we can't possibly hear that high anyway.

I am extremely interested and open to other opinions that do indeed include scientific data. I am doing exactly what you accuse me of not doing...applying science. I used to buy HD music. I heard differences. But when I "applied science" and did my own downsample to CD quality, the difference was zero (audibly speaking). 

I have no intention of saying the OP is absolute fact. I am open to changing my mind. Just not from meaningless "Trust your ears" types of response.

A lot of work went into the CD standard, and as far as I know (for now), it has yet to be debunked. And on the other thread, that was locked, Mr Dalethorn only threw insults and claims. Claims he did not once back up with anything remotely scientific or concrete.

That is all I am asking for. I'd be thrilled to see evidence to the contrary, but it's yet to arrive. 

So for now, in my mind, CD quality is as high as it needs to be...any higher is a waste of money, bandwidth and storage space.

 

 

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RE: High resolution audio. The science, or lack of...?

The differences users hear between HD and CD is purely down to the mastering process, (One of the most important parts of the recording) and this is what you are paying for with HD recording. (The higher bit rate and frequency are of little relevance to playback in a domestic environment so long as the minimum CD level is met)

NOTE: Not all music in HD has been mastered properly (Some manufactures just use it as a selling point) and could be worse than the original CD, so buyer beware.

Bill

fr0g's picture
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RE: High resolution audio. The science, or lack of...?

abacus wrote:

The differences users hear between HD and CD is purely down to the mastering process, (One of the most important parts of the recording) and this is what you are paying for with HD recording

 

This is my current understanding.

Thanks.

 

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RE: High resolution audio. The science, or lack of...?

fr0g wrote:

First of all, I must apologize to Quadpatch for essentially wrecking his headphone thread...It wasn't the intention and in hindsight I can see that such topics can escalate...Probably best kept separate...

 

However, the topic interests me. WHF S&V themselves actively promote, or rather review and claim higher quality for HD music. whether it be 24/96 or higher.

Now, the last I had heard, and as far as I know, the good old CD and the theorum to which music data is recorded onto it, is more than enough for the absolute limit of human hearing.

ie Nyquist-Shannon states (and has been proven to be correct) to perfectly recreate an analogue signal, you need a sampling frequency of double the maximum sound frequency required. Or rather more accurately put (from WIki)

"If a function x(t) contains no frequencies higher than B hertz, it is completely determined by giving its ordinates at a series of points spaced 1/(2B) seconds apart."

 

Now some people here seem to believe that HD tracks will be better. Why? I have yet to see any links to any papers or proof on this, and in fact have seen some to studies that show the higher resolutions (192 KHz and above) can have an adverse effect on quality...

 

I do agree that many HD versions of music sound better. But experience tells me that these are simply better recordings...I used to buy HD and found it excellent...until I downsampled one to 16/44.1 myself and could not tell them apart...

 

As for the 16 bit v 24 bit for playback... Why does anyone think we need 24 bit? 16 bit gives us a 96 dB dynamic range (way higher than vinyl), and if we take an extremely well recorded CD with a DR of 30 dB (very unusual, they tend to be no more than 10-15), then we have a noise floor of -66 dB...which as far as I can see, is inaudible.

 

So please, without insults or petty put-downs, can someone give me any concrete,scientific information on why they think HD (for playback) is any better?

You are totally right of course fr0g. But this has been done to death and I fear that you're banging your head against a brick wall trying to explain to someone who doesn't understand Nyquist-Shannon theory why CD quality 16/44 is already past the limit of what humans can can hear and anything higher than that doesn't make any difference to the sound.

banging head against wall

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