24bit vs 16bit, the myth exploded!
Aug 16, 2021 at 7:25 PM Post #6,286 of 7,175
@audiokangaroo I see the point you are trying to make and I also think there may be something there
Such exploration is true science whether it proves fruitless or genius is for the future but the endeavour is science
Unfortunately this thread in spite of its name has little to do with science it would be better named sound engineering
You will not find any help in your quest here , I see the personal attacks are already beginning
I wish you all the best in your search for the truth
Thank you for your nice comment.
I'm pleased to read something positive. However, in spite of all the negative reactions I've met here, this discussion helped me to shape my theory and I think I
have now a better understanding of the phenomenons I tried to explain.
 
Aug 16, 2021 at 7:45 PM Post #6,287 of 7,175
These ultrasonic frequencies are inaudible as such, but they are for mathematical reasons, necessary to achieve a perfect capture of the waveform.
I am getting tired of you. Please, if you think this is even right in the slightest, please go and show the whole world how the Nyquist-Shannon Sampling Theorem is incorrect. Please, provide both mathematical and experimental evidence of your claims. Please, enlighten us and show how this theorem is wrong and your ideas that go against everything digital audio is are the right path.
 
Aug 16, 2021 at 8:18 PM Post #6,288 of 7,175
I am getting tired of you. Please, if you think this is even right in the slightest, please go and show the whole world how the Nyquist-Shannon Sampling Theorem is incorrect. Please, provide both mathematical and experimental evidence of your claims. Please, enlighten us and show how this theorem is wrong and your ideas that go against everything digital audio is are the right path.
You don't need to be rude. I'm free to explain my opinion, even though it doesn't match you dogma.
I never said that the Nyquist-Shannon theorem was wrong. However, it is applied in a context were people believe that the signal they want to sample is band limited. The theorem is mathematically correct, but its application is based on a wrong understanding of the concept of waveform. Please read what I wrote above where I try to explain why the waveform is not band limited, in spite of audible frequencies beeing band limited.
My point is that conflating the frequency input of the waveform and the frequency content of the waveform structure in a mistake, because there is a mathematical function between them.
 
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Aug 16, 2021 at 8:34 PM Post #6,289 of 7,175
they want to sample is band limited.
Anybody who knows how recording even works knows that you record analog signals, and these are not bandlimited since they are analog and come straight out of the instruments.
why the waveform is not band limited, in spite of audible frequencies beeing band limited.
What do you mean by this? It just does not make any sense. It does not matter what is audible, we can perfectly (plus quantization noise that is at least -90 dBFS from the fundamental @ 16 bits) reconstruct any signal from DC to Fs/2. We do not need extra ultrasonics to reconstruct signals below and at 22.05 kHz, we just sample at double the highest frequency desired. It works like this in audio and in RF.
My point is that conflating the frequency input of the waveform and the frequency content of the waveform structure in a mistake, because there is a mathematical function between them.
What 'function'? Samples will equal their analog counterparts since they are one and the same but in different domains. Maybe the 'mathematical function' that you are trying to describe is the Delta-Sigma modulation that allows encoding continuous analog signals into discrete digital samples.

Me highlighting does not mean I am rude at you, it is just a visual aid so you can see important points that you may be missing.
 
Aug 16, 2021 at 8:38 PM Post #6,290 of 7,175
I just checked that by recording a bass and played in the 100-200 Hz Reagion.

I recorded with 8 KHz 16bit and i recorded with 44.1 KHz 16bit

The 8 KHz sounds like crap, total garbage. Like someone is playing bass over an old telephone. The 44.1 KHz recording sounds excellent.

By your explanation, there should be no hearable difference below the 4000 KHz region, why do 100-200 Hz sounds, sound like crap when recorded with 8 KHz which should be way more than needed.

Please explain.
This is a very interesting and useful experiment. People should learnt from it.
If traditional digital audio theory was right, audible frequencies up to 4 KHz should have been reproduced properly.
But they were not.
 
Aug 16, 2021 at 8:43 PM Post #6,291 of 7,175
If traditional digital audio theory was right, audible frequencies up to 4 KHz should have been reproduced properly.
You are forgetting that even these instruments that produce these low frequencies have harmonics and overtones, and these go further than 4 kHz.
 
Aug 16, 2021 at 9:15 PM Post #6,292 of 7,175
Keith Phantom, analogue signals are not band limited, as you said. That's true, and then the signal received by the microphone and which is converted into a voltage isn't limited either ( inside the frequency response limits of the microphone, but we have to consider this response at a very low amplitude level, not only around -3dB, which is not relevant for our problem ).
Then the question is about if we need to sample all the frequencies that contribute to the waveform structure or only those corresponding to the audible band.
We are used to think that sampling the frequencies corresponding to the audible range is sufficient, as higher frequencies are inaudible.
However, I think that we are comparing here apples and oranges, because the frequencies produced by the instruments and the frequencies building the waveform at le microphone level have a different mathematical signification. There is a physical fusion between them, which can be described by a mathematical function with an input and an output. What the microphone can see is this output.
The reverse function is operated in the inner ear where this output is decoded into sinewaves corresponding to the audible band.
The key idea here is that the audible frequency content and the frequency content builing the waveform are two completely different things, and looking for a correspondance beteween them doesn't really make sense.
The recording experiment made by Vamp898 (see above) should be considered as a proof for what I say.
I know that my explanations are far from being perfect, and as I have limited mathematical skills I will not be able to back this with formulas.
 
Aug 16, 2021 at 9:22 PM Post #6,293 of 7,175
You are forgetting that even these instruments that produce these low frequencies have harmonics and overtones, and these go further than 4 kHz.

Absolutely. You can clearly see by a single bass guitar string being played and captured on an inexpensive iPad app that a 4 kHz limit is going to be quite disruptive from an audible perspective.

Watch from around 3:12 in this video.

 
Aug 16, 2021 at 9:22 PM Post #6,294 of 7,175
You are forgetting that even these instruments that produce these low frequencies have harmonics and overtones, and these go further than 4 kHz.
Your argument makes sense, but I don't think that it is sufficient to explain the extremely poor sonic result achieved with 8 KHz sampling.
If you were right, the result would sound like deprived from clarity rather that totally distorted. We would need to experiment further, though, to make a better
interpretation.
 
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Aug 16, 2021 at 9:32 PM Post #6,297 of 7,175
Try 16 kHz and see how it sounds. I think the harmonics and overtones would be too quiet to make an audible difference at that high of a frequency for a sub-100 Hz fundamental at rational volume levels.
How should an acoustic instrument sampled at 16 KHz sound, according to you ? Lacking airiness, lacking clarity or very thick and distorted ?
 
Aug 16, 2021 at 9:43 PM Post #6,300 of 7,175
I’m referring to your original bass note claim. Your sampling rate was too low and was not capturing the necessary harmonics and overtones.
My interpretation of low rate sampling is that it produces a global waveform distortion. As a consequence, it has an effect all along the audible band, and not only on the upper range that has been forgotten through the sampling process. The result should sound globally thick and distorted. The problem seems to go beyond the lack of overtones.
 

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