Analog vs Digital: a Neurologist weighs in

[jabbr]

A) he isn’t a neurologist

B) issues raised go away with higher sampling rates

 

it’s not clear to me that 44.1 kHz recording sampling rates are adequate and ultimately I think he is saying that human audio perception (including skin) isn’t necessarily 20kHz band limited

[Ralf11]

what IS the HF limit for skin?

 

acoustic, not IR

[jabbr]

3 hours ago, Ralf11 said:

what IS the HF limit for skin?

 

acoustic, not IR

No idea, but bone conduction is reportedly ultrasonic. Point is that I’m not so sure about the dogma.

[Archimago]

On 10/31/2019 at 5:04 PM, Kal Rubinson said:

Neither is his neuroscience as presented in this gloss.

 

Agreed Kal...

 

Unfocused article and full of errors. Perhaps predictably, no comments section for readership to set him straight.

 

Reads like bad science fiction/fantasy especially the last sections.

[Abtr]

Softky states in his article: "Even the best CDs can only resolve time down to 23 microseconds [44 kHz]." That's a myth. Even though he mentions Nyquist-Shannon sampling theorem several times, he doesn't seem to be aware of the implication that with a sampling frequency of 44 kHz and enough encoding bits per sample, a continuous-time signal which is bandlimited to 44/2 = 22 kHz, can be reconstructed/interpolated almost perfectly by a good DAC, with a time resolution in the order of nanoseconds rather than microseconds.

[Kimo]

5 hours ago, Abtr said:

Softky states in his article: "Even the best CDs can only resolve time down to 23 microseconds [44 kHz]." That's a myth. Even though he mentions Nyquist-Shannon sampling theorem several times, he doesn't seem to be aware of the implication that with a sampling frequency of 44 kHz and enough encoding bits per sample, a continuous-time signal which is bandlimited to 44/2 = 22 kHz, can be reconstructed/interpolated almost perfectly by a good DAC, with a time resolution in the order of nanoseconds rather than microseconds.

 

So what can "the best CDs" resolve down to?

 

 

[jabbr]

13 hours ago, Archimago said:

 

Agreed Kal...

 

Unfocused article and full of errors. Perhaps predictably, no comments section for readership to set him straight.

 

Reads like bad science fiction/fantasy especially the last sections.

 

Hmmm ... perhaps I’m reading into what he is trying to say (this is prose) but consider this:

 

CD uses band limited signals in which a filter has been applied. The filter throws away/alters the information. There are assumptions made that the filtered away information *cannot* be important but this assumption is that.  In a stereo 44kHz digitized signal, small phase differences are quantized away also altered by the band limiting filter.  

 

The assumption is that they aren’t important. He is suggesting that the brain is particularly sensitive to the timing of axon potentials. There is no law of physics which says whether that’s the case or not. I’m not claiming that this is important but it could be. Again, bandwidth limiting CD is an assumption. MP3 is another assumption.

[firedog]

1 hour ago, jabbr said:

 

Hmmm ... perhaps I’m reading into what he is trying to say (this is prose) but consider this:

 

CD uses band limited signals in which a filter has been applied. The filter throws away/alters the information. There are assumptions made that the filtered away information *cannot* be important but this assumption is that.  In a stereo 44kHz digitized signal, small phase differences are quantized away also altered by the band limiting filter.  

 

The assumption is that they aren’t important. He is suggesting that the brain is particularly sensitive to the timing of axon potentials. There is no law of physics which says whether that’s the case or not. I’m not claiming that this is important but it could be. Again, bandwidth limiting CD is an assumption. MP3 is another assumption.

But his whole point is based on the 23 microsecond calculation, which is incorrect. Therefore his whole thesis is wrong. Digital does have the 2-3 microsecond resolution he says is necessary. 

[firedog]

 1 hour ago, Kimo said:

 

So what can "the best CDs" resolve down to?

answer from esldude:

... It is in the few dozen picosecond range for redbook.  Low or sub picosecond range for high res depending upon particulars.  

 

https://troll-audio.com/articles/time-resolution-of-digital-audio/

 

A short write up by mansr.

Mansr article re-brought to our attention by esldude

[firedog]

double post

 

[Kimo]

Maybe bad editing on the author's part?  Perhaps, he means to state what "the best" MP3 will do?

 

He writes earlier:

 

So, I grew up experiencing two technology transitions: from analog LPs and phones to digital CDs and voice-over-internet (VoIP), which sounded fine, then from those to highly-compressed MP3s and cellphones, which definitely sounded worse.

 

 

[esldude]

2 hours ago, jabbr said:

 

Hmmm ... perhaps I’m reading into what he is trying to say (this is prose) but consider this:

 

CD uses band limited signals in which a filter has been applied. The filter throws away/alters the information. There are assumptions made that the filtered away information *cannot* be important but this assumption is that.  In a stereo 44kHz digitized signal, small phase differences are quantized away also altered by the band limiting filter.  

 

The assumption is that they aren’t important. He is suggesting that the brain is particularly sensitive to the timing of axon potentials. There is no law of physics which says whether that’s the case or not. I’m not claiming that this is important but it could be. Again, bandwidth limiting CD is an assumption. MP3 is another assumption.

Band limiting CD isn't assumption.  Band limiting is needed for a sampled digital system to work.  Where to band limit isn't an assumption either.  It is known people don't hear more than 20 khz, so band limiting what they can't hear seems sound until someone can show it matters.  

 

Phase differences are known not to be very audible in the upper part of human hearing range.  Band limiting filters so close to the upper edge of hearing range does alter phase, but it matters somewhere between not at all and not much.  

[jabbr]

2 hours ago, esldude said:

Band limiting CD isn't assumption.  Band limiting is needed for a sampled digital system to work.  Where to band limit isn't an assumption either.  It is known people don't hear more than 20 khz, so band limiting what they can't hear seems sound until someone can show it matters.  

 

Phase differences are known not to be very audible in the upper part of human hearing range.  Band limiting filters so close to the upper edge of hearing range does alter phase, but it matters somewhere between not at all and not much.  

 

All these things you state are “known” is what he would say aren’t laws of physics, rather rules of neuroscience.