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

[fr0g]

I think your tests have shown that you do not hear differences between standard 16bit 44.1kHz sources and an HD source (24bit/96kHz) hence it is not worth yourself paying extra for a suggested better experience, that you will not receive.

I have some Pure Audio blu-ray discs - i have not compared to CD as i do not have the original CD version - so i may be spending extra on something i too will not benefit from. The discs do sound good, but again, placebo affect may be the issue here.

Regards,

Shadders.

No, the tests have proven that there is nothing different between a HD file and a roughly downsampled version of it, other than some extremely quiet noise at a pretty high frequency.

All waveforms up to 17.5 KHz were "identical". Above that there is some noise at at least 75 dB below zero.

If you look at the waveform in Audacity of the difference it is flat.

If you analyze that it shows some noise way below the threshold of hearing outside an acoustic chamber, and noise that is above most people's hearing anyway.

Playback of the difference file produces silence. And looking at the spectral plot that is hardly surprising. Any inconsitencies in the downsampling algorithm would show up in a null test and make the difference more so, not less...And as said, the vast majority of the audible spectrum is completely identical.

The last test simply suggests that there are differences between the CD version and the HD version that are nothing to do with it being HD.

 

[shadders]

I think your tests have shown that you do not hear differences between standard 16bit 44.1kHz sources and an HD source (24bit/96kHz) hence it is not worth yourself paying extra for a suggested better experience, that you will not receive.

I have some Pure Audio blu-ray discs - i have not compared to CD as i do not have the original CD version - so i may be spending extra on something i too will not benefit from. The discs do sound good, but again, placebo affect may be the issue here.

Regards,

Shadders.

No, the tests have proven that there is nothing different between a HD file and a roughly downsampled version of it, other than some extremely quiet noise at a pretty high frequency.

All waveforms up to 17.5 KHz were "identical". Above that there is some noise at at least 75 dB below zero.

If you look at the waveform in Audacity of the difference it is flat.

If you analyze that it shows some noise way below the threshold of hearing outside an acoustic chamber, and noise that is above most people's hearing anyway.

Playback of the difference file produces silence. And looking at the spectral plot that is hardly surprising. Any inconsitencies in the downsampling algorithm would show up in a null test and make the difference more so, not less...And as said, the vast majority of the audible spectrum is completely identical.

The last test simply suggests that there are differences between the CD version and the HD version that are nothing to do with it being HD.

Hi,

I will have to disagree. The spectral test you have implemented is just indicating that there is 0.003% difference between the two spectrums for the 0Hz to 17.5kHz.

An example would be that i create a frequency sweep test file what has exactly the same spectral output as one of your test files. Here - quite obviously the files are different, but their spectral signature is so close, that the difference is as per your results.

You have resampled, or downsampled, depending upon the test. By this very fact, you have changed the original file to another file, proves that they are different.

I think you are confusing spectral similarity to no difference.

I agree that you cannot hear the difference between the test files, but this does not mean they are not different.

Regards,

Shadders.

 

[fr0g]

I think your tests have shown that you do not hear differences between standard 16bit 44.1kHz sources and an HD source (24bit/96kHz) hence it is not worth yourself paying extra for a suggested better experience, that you will not receive.

I have some Pure Audio blu-ray discs - i have not compared to CD as i do not have the original CD version - so i may be spending extra on something i too will not benefit from. The discs do sound good, but again, placebo affect may be the issue here.

Regards,

Shadders.

No, the tests have proven that there is nothing different between a HD file and a roughly downsampled version of it, other than some extremely quiet noise at a pretty high frequency.

All waveforms up to 17.5 KHz were "identical". Above that there is some noise at at least 75 dB below zero.

If you look at the waveform in Audacity of the difference it is flat.

If you analyze that it shows some noise way below the threshold of hearing outside an acoustic chamber, and noise that is above most people's hearing anyway.

Playback of the difference file produces silence. And looking at the spectral plot that is hardly surprising. Any inconsitencies in the downsampling algorithm would show up in a null test and make the difference more so, not less...And as said, the vast majority of the audible spectrum is completely identical.

The last test simply suggests that there are differences between the CD version and the HD version that are nothing to do with it being HD.

Hi,

I will have to disagree. The spectral test you have implemented is just indicating that there is 0.003% difference between the two spectrums for the 0Hz to 17.5kHz.

An example would be that i create a frequency sweep test file what has exactly the same spectral output as one of your test files. Here - quite obviously the files are different, but their spectral signature is so close, that the difference is as per your results.

You have resampled, or downsampled, depending upon the test. By this very fact, you have changed the original file to another file, proves that they are different.

I think you are confusing spectral similarity to no difference.

I agree that you cannot hear the difference between the test files, but this does not mean they are not different.

Regards,

Shadders.

I have not once said they are not different. They are.

But. The difference between an HD track and the same track downsampled to 16 44.1 and then null tested is minimal.

There is ZERO difference up to 17.5 KHz.

There is a small amount of noise at 17.5 and above, but at -75dB or lower which in a normal listening room would be inaudible even if you can hear past 17.5 KHz.

In an acoustically sealled room, if you can hear that high frequency, which most people over 30 cannot, it would be incredibly quiet. (Try setting your AV amp volume to -75 dB)

After that is some more noise at an equally low level, and at a frequency that is absolutely guaranteed inaudible.

So. In any normal listening room, there is nobody who will "hear" the extra noise in the difference sample.

The only way you can believe there is a meaningful, audible difference is if you believe that you can a) feel those frequencies (and at an incredibly low volume) or b) that they interact with the lower frequencies somehow.

In the end, the track was equally good quality at the lower bitrate and sampling frequency. Not an opinion, an observation.

 

[shadders]

I think your tests have shown that you do not hear differences between standard 16bit 44.1kHz sources and an HD source (24bit/96kHz) hence it is not worth yourself paying extra for a suggested better experience, that you will not receive.

I have some Pure Audio blu-ray discs - i have not compared to CD as i do not have the original CD version - so i may be spending extra on something i too will not benefit from. The discs do sound good, but again, placebo affect may be the issue here.

Regards,

Shadders.

No, the tests have proven that there is nothing different between a HD file and a roughly downsampled version of it, other than some extremely quiet noise at a pretty high frequency.

All waveforms up to 17.5 KHz were "identical". Above that there is some noise at at least 75 dB below zero.

If you look at the waveform in Audacity of the difference it is flat.

If you analyze that it shows some noise way below the threshold of hearing outside an acoustic chamber, and noise that is above most people's hearing anyway.

Playback of the difference file produces silence. And looking at the spectral plot that is hardly surprising. Any inconsitencies in the downsampling algorithm would show up in a null test and make the difference more so, not less...And as said, the vast majority of the audible spectrum is completely identical.

The last test simply suggests that there are differences between the CD version and the HD version that are nothing to do with it being HD.

Hi,

I will have to disagree. The spectral test you have implemented is just indicating that there is 0.003% difference between the two spectrums for the 0Hz to 17.5kHz.

An example would be that i create a frequency sweep test file what has exactly the same spectral output as one of your test files. Here - quite obviously the files are different, but their spectral signature is so close, that the difference is as per your results.

You have resampled, or downsampled, depending upon the test. By this very fact, you have changed the original file to another file, proves that they are different.

I think you are confusing spectral similarity to no difference.

I agree that you cannot hear the difference between the test files, but this does not mean they are not different.

Regards,

Shadders.

I have not once said they are not different. They are.

But. The difference between an HD track and the same track downsampled to 16 44.1 and then null tested is minimal.

There is ZERO difference up to 17.5 KHz.

There is a small amount of noise at 17.5 and above, but at -75dB or lower which in a normal listening room would be inaudible even if you can hear past 17.5 KHz.

In an acoustically sealled room, if you can hear that high frequency, which most people over 30 cannot, it would be incredibly quiet. (Try setting your AV amp volume to -75 dB)

After that is some more noise at an equally low level, and at a frequency that is absolutely guaranteed inaudible.

So. In any normal listening room, there is nobody who will "hear" the extra noise in the difference sample.

The only way you can believe there is a meaningful, audible difference is if you believe that you can a) feel those frequencies (and at an incredibly low volume) or b) that they interact with the lower frequencies somehow.

In the end, the track was equally good quality at the lower bitrate and sampling frequency. Not an opinion, an observation.

Hi,

I need to confirm your methodology - i assume it is as follows :

1. You used Audacity to process the audio file (24bit/96kHz) to obtain a spectral plot.

2. You used Audacity to downsample the 24bit/96kHz to 16bit/44.1kHz file.

3. You used Audacity to process the 16bit/44.1kHz audio file to obtain a spectral plot.

4. You used Audacity to subtract the two spectral plots to obatin the 0Hz to 17.5kHz -90dB response, with the increase to -76dB above 17.5kHz.

If the above methodology you have used is correct then :

The -90dB from 0Hz to 17.5kHz is a difference between the frequency responses. This shows that across that audio band 0Hz to 17.5kHz that the difference between the two, spectrally, is 0.003%.

You have stated :

There is a small amount of noise at 17.5 and above, but at -75dB or lower which in a normal listening room would be inaudible even if you can hear past 17.5 KHz

In an acoustically sealled room, if you can hear that high frequency, which most people over 30 cannot, it would be incredibly quiet. (Try setting your AV amp volume to -75 dB)

After that is some more noise at an equally low level, and at a frequency that is absolutely guaranteed inaudible.

So. In any normal listening room, there is nobody who will "hear" the extra noise in the difference sample.

The -75dB is not noise, it is the difference between the two files based on spectral plots only. This increase from -90dB to -75dB is the difference in energy between the files across that audio band from 17.5kHz to whatever the frequency is at the -75dB difference point..

It is not a sound you cannot hear at -75dB. It just means that the energy at this specific frequency is 15dB more that the 16bit/44.1kHz file at this same frequency.

The only way you can believe there is a meaningful, audible difference is if you believe that you can a) feel those frequencies (and at an incredibly low volume)

Again, this is not an incredibly low volume, but the difference between the two based on spectral energy at the specific frequency.

If you recall that for original 16bit recordings, that they add dither. This is a modulation of the least significant bit of the 16bit sample to reduce the correlation of the quantisation noise with the signal being sampled.

This was added because people could hear the effect without dither.

16bits provides a theoretical dynamic range of 96dB. If people can hear the effect of quantisation noise correlation with the signal (audio) at this low level then would you agree that 90dB difference in spectral responses can be heard ?

It is not a problem - if you cannot hear the difference - it is not an issue - others may be able to hear the difference.

Regards,

Shadders.

 

[spiny norman]

OK, so this may be a bit of a wild and wacky idea, but anyone actually tried using all this stuff to listen to some music?

 

[jcbrum]

Yes, . . . . I have.

There is nothing wrong with listening to 24/96 recordings playing on your domestic hifi, or even buying them, if you want to, and don't mind file sizes which are four times bigger, or even greater, than they need be.

But, assuming they're from the same master, a 16/44 file sounds just as good.

Personally, since most recordings are created at 24/96 in the first place, nowadays, even if they are released in 16/44 format, I can't see any real justification for a price differential.

JC

 

[fr0g]

I think your tests have shown that you do not hear differences between standard 16bit 44.1kHz sources and an HD source (24bit/96kHz) hence it is not worth yourself paying extra for a suggested better experience, that you will not receive.

I have some Pure Audio blu-ray discs - i have not compared to CD as i do not have the original CD version - so i may be spending extra on something i too will not benefit from. The discs do sound good, but again, placebo affect may be the issue here.

Regards,

Shadders.

No, the tests have proven that there is nothing different between a HD file and a roughly downsampled version of it, other than some extremely quiet noise at a pretty high frequency.

All waveforms up to 17.5 KHz were "identical". Above that there is some noise at at least 75 dB below zero.

If you look at the waveform in Audacity of the difference it is flat.

If you analyze that it shows some noise way below the threshold of hearing outside an acoustic chamber, and noise that is above most people's hearing anyway.

Playback of the difference file produces silence. And looking at the spectral plot that is hardly surprising. Any inconsitencies in the downsampling algorithm would show up in a null test and make the difference more so, not less...And as said, the vast majority of the audible spectrum is completely identical.

The last test simply suggests that there are differences between the CD version and the HD version that are nothing to do with it being HD.

Hi,

I will have to disagree. The spectral test you have implemented is just indicating that there is 0.003% difference between the two spectrums for the 0Hz to 17.5kHz.

An example would be that i create a frequency sweep test file what has exactly the same spectral output as one of your test files. Here - quite obviously the files are different, but their spectral signature is so close, that the difference is as per your results.

You have resampled, or downsampled, depending upon the test. By this very fact, you have changed the original file to another file, proves that they are different.

I think you are confusing spectral similarity to no difference.

I agree that you cannot hear the difference between the test files, but this does not mean they are not different.

Regards,

Shadders.

I have not once said they are not different. They are.

But. The difference between an HD track and the same track downsampled to 16 44.1 and then null tested is minimal.

There is ZERO difference up to 17.5 KHz.

There is a small amount of noise at 17.5 and above, but at -75dB or lower which in a normal listening room would be inaudible even if you can hear past 17.5 KHz.

In an acoustically sealled room, if you can hear that high frequency, which most people over 30 cannot, it would be incredibly quiet. (Try setting your AV amp volume to -75 dB)

After that is some more noise at an equally low level, and at a frequency that is absolutely guaranteed inaudible.

So. In any normal listening room, there is nobody who will "hear" the extra noise in the difference sample.

The only way you can believe there is a meaningful, audible difference is if you believe that you can a) feel those frequencies (and at an incredibly low volume) or b) that they interact with the lower frequencies somehow.

In the end, the track was equally good quality at the lower bitrate and sampling frequency. Not an opinion, an observation.

Hi,

I need to confirm your methodology - i assume it is as follows :

1. You used Audacity to process the audio file (24bit/96kHz) to obtain a spectral plot.

2. You used Audacity to downsample the 24bit/96kHz to 16bit/44.1kHz file.

3. You used Audacity to process the 16bit/44.1kHz audio file to obtain a spectral plot.

4. You used Audacity to subtract the two spectral plots to obatin the 0Hz to 17.5kHz -90dB response, with the increase to -76dB above 17.5kHz.

If the above methodology you have used is correct then :

The -90dB from 0Hz to 17.5kHz is a difference between the frequency responses. This shows that across that audio band 0Hz to 17.5kHz that the difference between the two, spectrally, is 0.003%.

You have stated :

There is a small amount of noise at 17.5 and above, but at -75dB or lower which in a normal listening room would be inaudible even if you can hear past 17.5 KHz

In an acoustically sealled room, if you can hear that high frequency, which most people over 30 cannot, it would be incredibly quiet. (Try setting your AV amp volume to -75 dB)

After that is some more noise at an equally low level, and at a frequency that is absolutely guaranteed inaudible.

So. In any normal listening room, there is nobody who will "hear" the extra noise in the difference sample.

The -75dB is not noise, it is the difference between the two files based on spectral plots only. This increase from -90dB to -75dB is the difference in energy between the files across that audio band from 17.5kHz to whatever the frequency is at the -75dB difference point..

It is not a sound you cannot hear at -75dB. It just means that the energy at this specific frequency is 15dB more that the 16bit/44.1kHz file at this same frequency.

The only way you can believe there is a meaningful, audible difference is if you believe that you can a) feel those frequencies (and at an incredibly low volume)

Again, this is not an incredibly low volume, but the difference between the two based on spectral energy at the specific frequency.

If you recall that for original 16bit recordings, that they add dither. This is a modulation of the least significant bit of the 16bit sample to reduce the correlation of the quantisation noise with the signal being sampled.

This was added because people could hear the effect without dither.

16bits provides a theoretical dynamic range of 96dB. If people can hear the effect of quantisation noise correlation with the signal (audio) at this low level then would you agree that 90dB difference in spectral responses can be heard ?

It is not a problem - if you cannot hear the difference - it is not an issue - others may be able to hear the difference.

Regards,

Shadders.

You are making it far more complicated than it is.

I would agree that there is a signal within the "possible" hearing capacity in an anechoic chamber. Or ratrher the difference is within the "possible" hearing capacity in such a room.

In any normal listening environment, the difference is effectively inaudible. That isn't an opinion.

 

[spiny norman]

Yes, . . . . I have.

There is nothing wrong with listening to 24/96 recordings playing on your domestic hifi, or even buying them, if you want to, and don't mind file sizes which are four times bigger, or even greater, than they need be.

But, assuming they're from the same master, a 16/44 file sounds just as good.

Personally, since most recordings are created at 24/96 in the first place, nowadays, even if they are released in 16/44 format, I can't see any real justification for a price differential.

JC

So by extension, that also means that, IYNSHO at least, there's no audible difference between 24/96 files and 320kbps MP3, or perhaps 192kbps, or Spotify, or internet radio, or YouTube videos played via a smartphone?

 

[cheeseboy]

So by extension, that also means that, IYNSHO at least, there's no audible difference between 24/96 files and 320kbps MP3, or perhaps 192kbps, or Spotify, or internet radio, or YouTube videos played via a smartphone?

that's not what was said at all, and you know it

 

[BenLaw]

Yes, . . . . I have.

There is nothing wrong with listening to 24/96 recordings playing on your domestic hifi, or even buying them, if you want to, and don't mind file sizes which are four times bigger, or even greater, than they need be.

But, assuming they're from the same master, a 16/44 file sounds just as good.

Personally, since most recordings are created at 24/96 in the first place, nowadays, even if they are released in 16/44 format, I can't see any real justification for a price differential.

JC

So by extension, that also means that, IYNSHO at least, there's no audible difference between 24/96 files and 320kbps MP3, or perhaps 192kbps, or Spotify, or internet radio, or YouTube videos played via a smartphone?

Logic not your strong point then.

It's also pretty weak on one post to adopt the 'just listen to music' stance and then start arguing about different files / sources and their SQ.

 

[shadders]

You are making it far more complicated than it is.

I would agree that there is a signal within the "possible" hearing capacity in an anechoic chamber. Or ratrher the difference is within the "possible" hearing capacity in such a room.

In any normal listening environment, the difference is effectively inaudible. That isn't an opinion.

Hi,

No, i am not making it more complicated.

You have made incorrect analysis in your use of Audacity (yourself to confirm methodology) and hence your statement that the difference is noise at -76dB is wrong.

That -76dB equates to 0.015% difference, not an absolute -76dB gain or signal level as you have stated.

The recording industry adds dither due to the least significant bit quantisation issues - this is at a -96dB/-90dB range. If people could hear the quantisation issues, which led to the requirement for dither - at these same/similar signal levels, then why can you not accept your analysis of the difference at the same level can be heard ?

No, the tests have proven that there is nothing different between a HD file and a roughly downsampled version of it, other than some extremely quiet noise at a pretty high frequency.

All waveforms up to 17.5 KHz were "identical". Above that there is some noise at at least 75 dB below zero

As above you have stated "identical" - your conclusions from your analysis are wrong, and your interpretation of the analysis is wrong too (-75dB is a difference analysis, not an absolute as you are stating)

Regards,

Shadders.

 

[spiny norman]

Logic not your strong point then.

It's also pretty weak on one post to adopt the 'just listen to music' stance and then start arguing about different files / sources and their SQ.

Phew! And I thought Google Alerts had stopped working.

Give it a rest, mate: while your attention is flattering, this knee-jerk reacton every time I post is getting almost as boring as people banging on about looking at file-plots on a screen rather than listening to music.

 

[BenLaw]

Logic not your strong point then.

It's also pretty weak on one post to adopt the 'just listen to music' stance and then start arguing about different files / sources and their SQ.

Phew! And I thought Google Alerts had stopped working.

Give it a rest, mate: while your attention is flattering, this knee-jerk reacton every time I post is getting almost as boring as people banging on about looking at file-plots on a screen rather than listening to music.

Again, you can't say on the one hand google alerts isn't working (I haven't been responding to you) and on the other that I react 'every time you post'.

The one who needs to give it a rest is you. If you had a genuine point you'd be able to stick to it but you're clearly just trying to spoil these people having a discussion they're interested in, as demonstrated by your use of mutually inconsistent arguments to disrupt them. Just because you don't find the discussion interesting doesn't mean they shouldn't, your views really are not important.

 

[spiny norman]

Again, you can't say on the one hand google alerts isn't working (I haven't been responding to you) and on the other that I react 'every time you post'.

It was irony, suggesting you must have me on Google Alerts because every time I post you feel the need to attack me, for whatever reason.

The one who needs to give it a rest is you. If you had a genuine point you'd be able to stick to it but you're clearly just trying to spoil these people having a discussion they're interested in, as demonstrated by your use of mutually inconsistent arguments to disrupt them. Just because you don't find the discussion interesting doesn't mean they shouldn't, your views really are not important.

Sorry, I forgot you were the self-appointed forum police. Silly of me.

Just out of interest, do you adopt this affected high-handed and patronising tone with people you talk to in real life (if that's not making too much of an assumption)? If so, how does being repeatedly smacked in the mouth feel? ;-)

But anyway, can we stop this being the 'BenLaw, Fighting for Justice' show now, and let the nice geeks get on with swapping their graphs?

 

[BenLaw]

The one who needs to give it a rest is you. If you had a genuine point you'd be able to stick to it but you're clearly just trying to spoil these people having a discussion they're interested in, as demonstrated by your use of mutually inconsistent arguments to disrupt them. Just because you don't find the discussion interesting doesn't mean they shouldn't, your views really are not important.

Sorry, I forgot you were the self-appointed forum police. Silly of me.

I'm baffled. If I shouldn't post suggesting your posts are unwanted, then why on earth are you telling the good people on this thread that they shouldn't be posting about a subject they're interested in? Some very warped double standards there.

Just out of interest, do you adopt this affected high-handed and patronising tone with people you talk to in real life (if that's not making too much of an assumption)? If so, how does being repeatedly smacked in the mouth feel? ;-)

Two consecutive very amusing jokes, well done. I tend to communicate with individuals not entirely consumed by their own ego, so the issue doesn't normally arise.

But anyway, can we stop this being the 'BenLaw, Fighting for Justice' show now, and let the nice geeks get on with swapping their graphs?

That was rather my point. You can denigrate them as 'geeks' if you like (although I understand that word is now used somewhat more positively than you may have intended it), but why don't *you* let them get on with what they want to get on with. And those who are interested in it can just read it.

 

[John Duncan]

Zzzzz.

 

[Alec]

Zzzzz.

+1

 

[jcbrum]

In an attempt to answer Spiny's deliberately provocative and thread-crapping question . . .

I think it's ok to allow consumers to purchase and listen to music in whatever format they wish . . .

However, it does seem to me that some very misleading marketing efforts are going on, in an attempt to justify higher prices.

JC

 

[altruistic.lemon]

Well, marketing does tend to be misleading, doesn't it? I mean, you'd know!

 

[spiny norman]

You can denigrate them as 'geeks' if you like (although I understand that word is now used somewhat more positively than you may have intended it), but why don't *you* let them get on with what they want to get on with.

let the nice geeks get on with swapping their graphs

 

[Andy Clough]

Zzzzz.

+2

 

[lindsayt]

So, what would happen if we were to repeat fr0gs experiment, but using a cassette deck instead of 16/44 files?

IE take a 24/96 file, make a cassette recording of it. Play that recording back into a decent ADC recording at 24/96, invert the phase and then compare that file against the original 24/96 file using the same methodology fr0g has used?

Would we again only have some differences at -70 odd dbs in the upper frequencies, or would there more difference than that?

 

[shadders]

So, what would happen if we were to repeat fr0gs experiment, but using a cassette deck instead of 16/44 files?

IE take a 24/96 file, make a cassette recording of it. Play that recording back into a decent ADC recording at 24/96, invert the phase and then compare that file against the original 24/96 file using the same methodology fr0g has used?

Would we again only have some differences at -70 odd dbs in the upper frequencies, or would there more difference than that?

Hi,

At a guess the cassette will reduce the higher frequency content, include tape and other noises and the difference will be much greater than the computer Audacity experiment.

I have just taken an audio file, copied, inverted the second, added to the first - obtained a completely zero valued sampling time domain file. Took a spectral plot and the graph seems have a minimum of -90dB.

As such, fr0g may need to examine his results as a text file to see the actual values. (export button on the graph)

The reason i state this is that all my values despite the graph minimum being -90dB, were all "negative infinity". So the graph may not be displaying the actual calculated values.

Regards,

Shadders.

 

[fr0g]

So, what would happen if we were to repeat fr0gs experiment, but using a cassette deck instead of 16/44 files?

IE take a 24/96 file, make a cassette recording of it. Play that recording back into a decent ADC recording at 24/96, invert the phase and then compare that file against the original 24/96 file using the same methodology fr0g has used?

Would we again only have some differences at -70 odd dbs in the upper frequencies, or would there more difference than that?

Hi,

At a guess the cassette will reduce the higher frequency content, include tape and other noises and the difference will be much greater than the computer Audacity experiment.

I have just taken an audio file, copied, inverted the second, added to the first - obtained a completely zero valued sampling time domain file. Took a spectral plot and the graph seems have a minimum of -90dB.

As such, fr0g may need to examine his results as a text file to see the actual values. (export button on the graph)

The reason i state this is that all my values despite the graph minimum being -90dB, were all "negative infinity". So the graph may not be displaying the actual calculated values.

Regards,

Shadders.

That's possible.

However, it does demonstrate that the difference is negligable and almost certainly not audible in a normal listening room. I think I linked the difference file somewhere, which as far as Audacity is concerned is a flat, null waveform. Only the spectral plot reveals anything.

 

[fr0g]

So, what would happen if we were to repeat fr0gs experiment, but using a cassette deck instead of 16/44 files?

IE take a 24/96 file, make a cassette recording of it. Play that recording back into a decent ADC recording at 24/96, invert the phase and then compare that file against the original 24/96 file using the same methodology fr0g has used?

Would we again only have some differences at -70 odd dbs in the upper frequencies, or would there more difference than that?

As soon as you introduce analogue to digital conversion you will introduce some kind of noise. It's only the other way around where the signal in the audible spectrum can be perfectly recreated and tested this way.

Whether we agree that that is at a 44.1 KHz sample rate or a bit higher, that's a different argument.