[castleofargh]

In the sense that; something that doesn’t exist obviously cannot be audible. If we were to take the absolute demonstrated audible limit which I believe was about -8dBSPL, then anything lower than -88dB (at 80dB peak) is “definitely inaudible”. However, that was demonstrated by a young child with perfect hearing in a world class anechoic chamber using a signal in the critical band (roughly 3kHz), conditions the average audiophile obviously cannot achieve! In practice the noise floor of your amp, transducers and listening environment will be significantly higher, as will the noise floor of the music recording you’re trying to reproduce, an audiophile’s hearing will not be as perfect as a young child with perfect hearing and peak level in the critical band will almost always be lower than the peak level of the music recording.

You left out more fun.
That's achieved when the loudest test signal is 0dB or a handful below. With music that peaks at 80dB we'd get the auditory masking from those much louder signals.
Plus, with 80dB peaks the acoustic reflex would have been triggered for most people already.
Noticing something at 0dBSPL for an adult listening to music in his room, that's a sign he's dreaming. ^_^

 

[Ghoostknight]

If we account for dither and headroom, we “land with CD quality” at around -120dB

how is that when cd quality can have the noisefloor at -94-96 ? and imo you always need to account for -3db of headroom if you wanna avoid any intersample issues so we land at -90-91db

If we were to take the absolute demonstrated audible limit which I believe was about -8dBSPL, then anything lower than -88dB (at 80dB peak) is “definitely inaudible”. However, that was demonstrated by a young child with perfect hearing in a world class anechoic chamber using a signal in the critical band (roughly 3kHz), conditions the average audiophile obviously cannot achieve!

nice, never heared of this either

just googled the noisefloor of anechoic chambers > "The anechoic chamber in building 87, with a background noise level of –20.6 dB" , tho it doesnt really matter here i guess

but this actually means we would be able to hear 40-50db (in perfect conditions) below the theoretical noisefloor of normal rooms which is around 30-40db, were there any studys about if we could still perceive a tone under the noisefloor? (i guess the tone adds up with the noisefloor to a certain degree?) i never tested this myself

 

[71 dB]

how is that when cd quality can have the noisefloor at -94-96 ? and imo you always need to account for -3db of headroom if you wanna avoid any intersample issues so we land at -90-91db

The 120 dB figure he gave is perceptual dynamic range rather than technical. In fact, 120 dB perceptual dynamic range with 16 bit requires heavy shaping of the dither noise which lowers technical dynamic range a lot (down to 70 dB or so).

As for the intersample problem, it is worst at high frequencies which are typically weaker in music than low frequences. That's why with music 0.5-1 dB headroom is considered enough.

 

[gregorio]

You left out more fun.
That's achieved when the loudest test signal is 0dB or a handful below. With music that peaks at 80dB we'd get the auditory masking from those much louder signals.
Plus, with 80dB peaks the acoustic reflex would have been triggered for most people already.

Indeed, I left those out. I was trying to leave a bit of a safety margin for “definitely” inaudible, to account for potential extreme conditions that almost certainly won’t exist for a consumer but I can’t say definitely can never exist. For example a potential recording where the peak level is lot higher than the average level, occurs a long time before the quietest level, thereby the listener has possibly recovered from the acoustic reflex and where some critical band signal might not be masked, etc. Pretty much no chance of fulfilling all the required conditions IMHO but I don’t know “definitely”.

how is that when cd quality can have the noisefloor at -94-96 ?

The theoretical limit quoted for cd is 96dB, ~6dB per bit. With TPDF dither the noise floor would be roughly -93dB. However, noise-shaped dither increases the total amount of noise slightly (to around -90dB) but moves the noise in the critical band to regions of the spectrum where human hearing is drastically less sensitive, resulting in a noise floor significantly lower than -110dB in the critical band, perceptually down to about -120dB.

and imo you always need to account for -3db of headroom if you wanna avoid any intersample issues so we land at -90-91db

There are no inter-sample issues until you actually convert the data. So, the DAC should definitely have headroom, at least 3dB as you mention, but the CD itself doesn’t need any.

just googled the noisefloor of anechoic chambers > "The anechoic chamber in building 87, with a background noise level of –20.6 dB" , tho it doesnt really matter here i guess

Yep, the famous Microsoft anechoic chamber mentioned, built around 8 or so years ago. Before that, the quietest anechoic chamber in the world was about -10dB.

were there any studys about if we could still perceive a tone under the noisefloor?

Yes, quite a lot, although I can’t cite any off the top of my head. You have to be careful here though, as mentioned above there is a difference between total noise and noise floor in the critical band. We can hear up to around 30dB below the total noise floor with noise-shaped dither but of course the noise floor in your sitting room is not noise-shaped.

G

 

[bigshot]

Human ears can't hear the full range of volume levels at one time. They require a minute to adjust to wide differences. In the real world, at best, you can hear about 50dB at a time. With music, if you have much more than that, you'll be constantly be reaching for the volume knob because sounds will seem too quiet or too loud.

So on a normal record album, you wouldn't be able to hear the quietest sounds possible at any point, no matter what. Even the silence between songs, because it is too short to allow your ears to adjust. Most music is mixed for a maximum range of no more than about 55dB. Even if you could possibly hear more than that, it wouldn't matter, because the ambient room tone of the recording venue would be higher than the noise floor. You would hear the air conditioning in the recording booth before you hear the digital noise floor. Sometimes thinking purely in terms of theory doesn't tell you what matters in the real world.

It's easy to throw numbers around but decibels are logarithmic, so 10 isn't half as loud as 20. When you start talking about 80dB, you are talking about a huge range of volume.

 

[71 dB]

Human ears can't hear the full range of volume levels at one time. They require a minute to adjust to wide differences. In the real world, at best, you can hear about 50dB at a time. With music, if you have much more than that, you'll be constantly be reaching for the volume knob because sounds will seem too quiet or too loud.

So on a normal record album, you wouldn't be able to hear the quietest sounds possible at any point, no matter what. Even the silence between songs, because it is too short to allow your ears to adjust. Most music is mixed for a maximum range of no more than about 55dB. Even if you could possibly hear more than that, it wouldn't matter, because the ambient room tone of the recording venue would be higher than the noise floor. You would hear the air conditioning in the recording booth before you hear the digital noise floor. Sometimes thinking purely in terms of theory doesn't tell you what matters in the real world.

It's easy to throw numbers around but decibels are logarithmic, so 10 isn't half as loud as 20. When you start talking about 80dB, you are talking about a huge range of volume.

The reason why more than 50-55 dB is needed is because different frequencies have different levels in music. The difference between the loudest low frequencies and the quietest high frequencies can be larger than 55 dB. If music had flat spectrum, 8 bit audio might be enough.

 

[Ghoostknight]

With TPDF dither the noise floor would be roughly -93dB

i will go with this figure since i actually dont remember if pipewire uses noise shaping
but i actually didnt know that noiseshaping pushes the noisefloor below -96db with cd quality, i guess the requirement is to still process in 24 bit with a 16bit file?

i know masking, and you are simply not "sensitive" enough while listen to 80db to perceive tones at -80db, but these -8db tested seem to give us a "absolute" figure of what "could" influence what we hear and with a normal listening level of 80db we land at -88db, this should atleast tell us that cd quality is pretty much "spot on" with theoretical noise level

personally i dont think noise levels do much, distortion is far more important to keep under control,
but i still question whether a "smooth sounding noise" might influence things more than a "irritating sounding noise" in terms of how we process the noise level subconsciously, even if its only barely perceptible
i definitely noticed that with my new BLA interface 1. the noise when you hear it actually sounds way smoother/pleasent than others 2. when i listen with -20-30 db on the interface i actually think the background becomes less "dark" ... i still dont hear "the noisefloor on its own" but it seems to influence how i perceive the music overall, its sounds a bit more "veiled"

if i go by the around -105db noisefloor or so of the BLA interface this means i landed at around -60-80db, before "it seems" like the higher noisefloor influences the music, tho keep in mind this is just my own theory here...

Also regarding headroom: i use a 10 band eq, each band is only subtracting frequencys, instead of a lowshelf filter to boost lows i use a highshelf filter to reduce highs for example... i use some higher q peak filters but these should nowhere go above +1-2db
now to get a around -3db peak level (with max pipewire volume) on the interface (it shows with lights) i actually have to set a pregain before the eq at -12db, i noticed the same with my aune x8 before, it simply sounds distorted if i dont set the pregain that low

i guess the imortant part is " the bla interface gets -3db" and "the noisefloor is at around -105db" unless i look into non-noise shaped dither, then my -12db pregain + normal dither with cd quality lands me at a around -80-82db noisefloor on max volume, if we account for my housecurve which further reduces highs these will be at -76-80db or so

now with these -76-82db noisefloor figures i get theoretically on my setup, these still seem very much fine, but if i would reduce the interface by further -10-20db and max my amp volume so i land around the same volume i will start to perceive a "brighter" background, i guess around -60 db actually

i think a real life example shows best why cd quality "might not be enough" in terms of headroom tho im still fine with my current setup, i just still doesnt seem to get why i need so much pregain reduciton ( i dont think something is messing around with volume levels, the plugin/program i use for overall volume also doesnt let you go above 100% volume, which some older pulseaudio plugins let you do )

EDIT: even with disabling EQ, i need a substantial reduction in volume to get no clipping lights on the interface, and i noticed the same thing audibly with my aune X8 before which doesnt show levels (i used deezer/firefox with max volume here, linux volume at 100% too and the +12db light on the interface is blinking up)

 

[Ghoostknight]

or the lights on the BLA indicate this : "Max Output Level = +12.224 dBu" but this would mean no light can be used as a real clipping indicator and audibly im still pretty certain that everything above 0db indicated on the lights sounds pretty surely worse than vs some headroom applied (with my aune x8 without lights i landed also around -15-10db of pregain), maybe my active speakers just dont like the higher input level?

 

[bigshot]

I defy anyone to hear -80dB under music at a normal listening level. That figure is overkill for home audio. It bears no relationship to how people actually use their equipment. You’re picking theoretical best case heaped upon best case just to prove your point. When you don’t know what the numbers mean in real world sound, you can bend them into proving up is down.

 

[Davesrose]

i will go with this figure since i actually dont remember if pipewire uses noise shaping
but i actually didnt know that noiseshaping pushes the noisefloor below -96db with cd quality, i guess the requirement is to still process in 24 bit with a 16bit file?

Oh why did we have CD players in the 1980s if 16bit (or 14bit) wasn't adequate enough?

 

[bigshot]

Just to remind certain people about the proofs they ignore repeatedly... In my sig file is a seminar by the AES where they take CD quality sound that has been dithered and compare it to undithered. Pretty much indistinguishable with normal music listening.

 

[Ghoostknight]

I defy anyone to hear -80dB under music at a normal listening level.

i didnt wanted to state this as a "fact", just that i could detect a (subjective) change in music with these kind of levels (around -60-70db is actually the number i compared i think) and i guess the real audible treshholds lies somewhere between -50-88db at 80db listening volume and 30db room noise

i just wanted to proof with my post that theoretical best case scenarios are good but you have to look at the real world.... what if you use digital volume control to reduce volume from max level?
i mean in theory cd quality sounds "good enough" with -96db but you can easly degrade it to the point where "it might be not good enough" with rather easy things like digital volume control or in my case apparently needing some more headroom for "pleasant" listening, i dont wanna bash cd quality here, i still use it myself, but these are simply facts that one cant simply ignore.... and its a unavoidable fact that we start talking about treshholds with cd quality first

Just to remind certain people about the proofs they ignore repeatedly... In my sig file is a seminar by the AES where they take CD quality sound that has been dithered and compare it to undithered. Pretty much indistinguishable with normal music listening.

oh atleast some interesting stuff to watch, thanks for the hint

Oh why did we have CD players in the 1980s if 16bit (or 14bit) wasn't adequate enough?

like i said before, even if the noise influenced the overall sound in some way, there are more important things to look out for than noise level to a certain degree i think

 

[sunjam]

At one point sunjam was addressing whether he was an AI bot, or he was just utilizing AI to come up with all his answers. At this point, what is the difference? He's able to lasso a few folks to engage with his fallacies and keep on with this thread. When I've engaged, he pretty much confirmed he knows nothing about medical science (including psychology) no matter his claims. The more anyone will engage, I'm sure he'll still claim he's knowledgable about all these subjects and can teach all of us something.

Thanks for your feedback.

"At this point, what is the difference?" <=== I agreed that is not much difference as my answers are factaul no matter I was an AI bot or not

Multidisciplinary Subject

I fully understand some people cannot master subjects that are multidisciplinary in nature. It required the mastering of multiple subjects that are involved, e.g. Physics, Psychology, Computer Science are heavily involved for digial audio / audio science. No wonder it is very hard to come by a real audio science expert on any audio science forum. It is like neuroscience, it is very difficult to master it as it requires the knowledge of many vary different subjects.

To make it clear again, I am at most at "primary level" for audio science. Having said that, I thought we discussing facts related to audio science here. Am I correct?
Or are we, in fact, focusing on discussing someone's mastery of certain subjects?

From my point of view, I don't care who speaks the facts. Even a primary school kid could be my teacher if he shows me something that I don't know. I would not consider facts as garbage just simply because of the speaker is a primary school kid. Correct?

I don't think people who have critical thinking would consider a primary school kid cannot show any fact in his comments for an on-line discussion. Have you ever encountered any kid who is considered as "smart kid"?

0.63 micro pascals does not exist? Hmm...

-23.7dBSPL is the figure generally accepted I believe, although it varies a bit by temp, altitude and humidity of course, a fact @sunjam appears unable to comprehend, presumably because his virtual assistant didn’t consider it. I’m not quite sure how you arrived at your figure but it would make MicroSoft’s anechoic chamber measurement and a handful of other chambers, impossible to achieve without pumping the air out of the chamber. Either way, producing noise+distortion artefacts at -30dBSPL isn’t possible, even without considering the performance of transducers.

Yes, you are 100% correct as I am not able to comprehend how "0.63 micro psacals does not exist" because I don't agree 1.000=1.001

Brownian motion and pressure:

There is a lot I don't fully understand about this. This is the first time I see Brownian motion mentioned in acoustics (or I have heard about this but I have completely forgotten about it). Do you know how this -23.7dBSPL is derived? Who, where and when has accepted this -23.7dBSPL figure?

Brownian motion in fluids, as far as I know, obeys -6 dB/octave spectrum (Brown noise has got its name from this), but the equations expressing Brownian motion in air seems to lead to +9 dB/octave spectrum! It is "violet" motion rather than "brown":

RMS pressure = (8𝜋𝜌kT*(f2^3-f1^3)/(3c))^0.5 => Power Spectral Density ∝ f^1.5

"This is the first time I see Brownian motion mentioned in acoustics" <=== same here. I found his idea is pretty interesting.

Let's look at what's Brownian motion:

I remember you were asking why "wouldn't -30 dB SPL and 0.63... micro pascals exist" as shown below:

Sorry about my laziness to try and find your explanation (for all the AI stuff and what not), but why wouldn't -30 dB SPL and 0.63... micropascals exist? Am I losing my mind?

And @gregorio was explaining to you with the idea of Brownian motion.
Given the definition of Brownian motion as shown about, do you think 0.63 micro pascal is possible? Does 0.63 micro pascal really not exist? Hmmm...

I can see at least two situations that could exist
1. close to vacuum
2. cold enough to slow down the random motion of particles

BTW, I thought the Ideal Gas Law is taught in high school physics. No?
Or the high school teachers, these days, teach a pseudo science version of the Ideal Gas Law in high school? i.e. the "correct but not absolute" version of the Ideal Gas Law?



Mis-leading materials used in High School

The more I digged into the influence of the misleading claims in the Monty's video, the more I found it is terrifiying .....
I just found out yesterday that a lot of high school students DID watch that video as a learning material for their classes related to digital audio. I checked with them and they were tricked (or manipulated) into believeing those pseduo science claims without a second thought...

I am really shocked to see how the video is poisoning high school students into believing that "Hi-Res is useless". I thought it was just in audio science forums....

All of a sudden, a sentence popped up in my mind "With great power comes great responsibility" ...

Playing Games?

It’s been clear what he is doing for almost a week. And it was clear where he was headed even before that. I don’t know why anyone would take a poster seriously when it’s so blatantly obvious he’s playing games. I have to conclude that he isn’t the only one who likes to spin his wheels and waste time.

Isn't it fun to learn with games? I found classic teacher / students setup/environment is pretty boring. Agree?

Reasoning fallacy example?:

Let's look at the following:

TBH, I read the calculation of it many years ago but don’t recall where exactly. It’s typically quoted roughly, Eg:

https://interestingengineering.com/science/quietest-room-world-sound-goes-die - “The absolute minimum sound that can be experienced in any atmosphere as theorized by mathematicians is -23dB, or Brownian motion.”
Or
https://www.bbc.com/future/article/20170526-inside-the-quietest-place-on-earth - “It gets close to the limit of what should be possible to achieve without creating a vacuum – the noise produced by air molecules colliding with each other at room temperature is estimated to be about -24 decibels.”

G

@gregorio is attempting to show with scientific evidence that there is an absolute minimum sound.

I don't know how this is related to the scientific evidence about "people cannot hear the difference between Hi-Res or CD" <=== I am not sure if @gregorio want to support such claim with the idea of "absolute minimum sound"

Concept 1: there is an absolute minimum sound (e.g. the "min" dB)
Concept 2: you cannot hear the difference between Y dB and Y + 'min' dB because the absolute minimum sound is 'min' dB

Is concept 2 supported by concept 1?

Critical Thinking? Do we have it?

One should be critical when reading sources like this. Not because the writers want to mislead the readers, but because the writers are not experts of a specific field like this (they are just people writing articles. They may have scientific background of a sort at best) and may write misleading things unintentionally. That's why I try to understand this topic well enough myself to be able to fact-check these claims myself, but the math/physics behind this is rather complex, perhaps not beyond my mental capabilities, but at least it requires time. I also find this interesting, because I never knew Brownian motion would be so close to human threshold of hearing!

Cool, I really love your rely. I think audio science needs more people like you who have excellent critical thinking. Please do comment more to share your view. Yeah!

Cheers!

 

[sunjam]

At one point sunjam was addressing whether he was an AI bot, or he was just utilizing AI to come up with all his answers. At this point, what is the difference? He's able to lasso a few folks to engage with his fallacies and keep on with this thread. When I've engaged, he pretty much confirmed he knows nothing about medical science (including psychology) no matter his claims. The more anyone will engage, I'm sure he'll still claim he's knowledgable about all these subjects and can teach all of us something.

Oh... It is a good example to show confirmation bias:

belief 1: "[I think] he'll still claim he's knowledgable about all these subjects"
belief 2: "[I think he'll still claim he] can teach all of us something"
belief 3: "[I think] he pretty much confirmed he knows nothing about medical science (including psychology) no matter his claims"

Tenedncy to search for, interpret, favor and recall information in a way that supports the beliefs: "He's able to lasso a few folks to engage with his fallacies and keep on with this thread"

Agree?

 

[bigshot]

You can degrade anything until it sounds bad. That isn't what standards are for. They aren't for best case scenarios either. Standards are designed to perform well for their intended purpose. The purpose of home audio is to play high fidelity music in the home. Redbook CDs take that one step further. They produce a signal that is indistinguishable from the original. The dynamic range, frequency response, distortion and timing are all better than human ears can hear. That means you don't have to reinvent the wheel or build in a little buffer just in case. All you need to do is play the digital file through a modern inexpensive player or DAC that is performing to spec and you're golden.

You can dive into theory to try to invent reasons why it MIGHT not be good, and you can think up ways to degrade the signal to insure it doesn't sound good. But all that is mental monkey spanking, because out of the box 16/44.1 is perfect to human ears. It's all you need.

I don't know why you guys bother reading sunbeam's blather. There's nothing to be gained from it. I wouldn't reply to goosenaught except that he slipped and actually started making some valid comments. I don't hold grudges, I just give the respect a person deserves, or doesn't as the case may be. I'm sure I'll be rewarded with disrespect soon from our tag team professional wrestlers.