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Sample Rate, Frequency Achieved, Human Hearing, Distortion, and Dynamic Range Questions

luft262

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This topic has been covered heavily, so I apologize in advance if this thread is redundant, but I don't feel like I've found complete answers to some of my questions. Thank you for any help you can provide.

1. Is there any advantage to a higher sample rate other than to achieve higher frequency response output? For example, a CD has a sample rate of 44.1 kHz and can output a max frequency of about 22 kHz. I know from online hearing tests that at normal listening levels I can hear test tones only up to about 17 kHz. Based on this information there wouldn't be any advantage for me to listen to music above the readily available 44.1 kHz sample rate unless there are other advantages to a higher sample rate that I don't understand? Please clarify if there are any advantages to higher sample rates, other than the production of higher frequency sounds, that I am not understanding.

2. If a higher sample rate means your speakers will be producing, or trying to produce, higher frequency sounds that are inaudible I understand that that could produce more distortion in the inaudible spectrum. Now that distortion wouldn't be audible, but since your speakers/headphones/drivers are spending time/movement producing those higher, inaudible frequencies couldn't that affect the driver's ability to accurately produce lower, audible frequencies? Why make it harder for the driver to reproduce the audible music by adding a bunch of extra work for the equipment in the inaudible range?

3. I understand that the human ear can probably hear a maximum dynamic range of 120 dB, which equals out to 20 bits of depth. Are there any other advantages to a bit rate greater than the 16 bits provided by CD quality music other than to increase the potential dynamic range of the recording? Have there been any tests done on popular music, jazz, or classical recordings to verify what the maximum dynamic range produced by the recording was in order to identify how frequently, if ever, musical recordings make use of more than 16 bits of dynamic range?

Thank you for your help.
 

solderdude

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All of these questions have been answered extensively in the thousands of post here.
That's why there is a search function.

in short:

1: frequency response can be just below half the sample rate. The need for > 20kHz is heavily debated.

2: Speaker and amp dependent. Most speakers simply won't reproduce it accurately but don't necessarily intermodulate. Your ears can't hear that what isn't produced accurately above 16kHz anyway.

3: Listening to music the dynamic range is about 70dB. Still to reach 120dB SPL and hear no noise when music is off you will need around 120dB S/N ratio. Music will often mask harmonics unless it becomes really bad or harmonics are higher order and substantial in amplitude.
 
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luft262

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Well, despite your poor manners thank you for taking the time to answer my questions. I appreciate that you probably know more about this than I do so now that I've got your attention let me expand upon or reiterate my questions, because I don't feel like you quite got to what I want to know and I have been unable to find exactly what I'm looking for in other posts, despite the search function.

1. I already understand what you're saying here. What I was trying to ask is are there other advantages to a higher sample rate other than the production of sound at even higher frequencies. For example, when comparing a standard CD with a Hi-Res FLAC track playing at a 96 kHz sample rate would there be any difference between 20 hz and 20 kHz between the two tracks or would the track with a high sample rate only show differences above 22 kHz?

2. I already understand that you can't hear distortion being produced outside of your hearing range. My question is that, because the driver is trying to produce sounds outside of the normal 20 Hz to 20 kHz could that have a negative impact on the sound produced within the normal hearable range because the driver is spending time producing music that is inaudible?

3. Thanks. I think you basically answered my question here. Although, I was curious if there is a database or something like that that lists the dynamic range of popular songs or albums or gives averages for certain music types etc. If there are certain popular albums or tracks that have a particularly high dynamic range I could check them out in standard vs Hi-Res to see if I can discern a difference. That would be interesting to see.

Anyway, thanks again.
 

RayDunzl

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solderdude

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1: Nope there are no other advantages other than frequency extension. Only when using NOS filterless DACs (you know the type with actual staircase steps) there is an advantage.

2: There are speakers that can reproduce well over 40kHz. Most drop-off below it. They just cannot follow the input signal. Something to keep in mind is that all ultrasonic content present in music is very low level anyway. That is unless one is using filterless NOS DACs.

3: There probably is. Very high DR (> 30) music recordings do exist but simply have some very loud passages and the majority of music is recorded softly.
It is highly impractical to have such high DR as it would be unlistenable in cars, on radios, on phones and as background music. Most music is produced with those customers in mind.
 
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luft262

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I've seen that database before. Thanks. As far as I can see what exactly do their numbers mean? So like if the database says the dynamic range max is 15 does that mean 15 bits? I didn't see anywhere on the site that exactly specified that.

Thanks
 
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luft262

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OK cool. That's all helpful and good to know. It was probably explained elsewhere, but maybe it was worded differently or I just didn't see it. Thanks for the explanation.
 

solderdude

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The difference in dB between peak levels and average levels on a track or on an entire album.
In studio's they prefer to use LUFS.
The word Dynamic range is also used to describe the difference between the highest output signal and noise floor.
 

solderdude

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I've seen that database before. Thanks. As far as I can see what exactly do their numbers mean? So like if the database says the dynamic range max is 15 does that mean 15 bits? I didn't see anywhere on the site that exactly specified that.

Thanks

It means the difference between peaks and average levels is 15dB.
1 bit = 6dB difference.
 
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luft262

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OK. So if the min DR was 7 does that mean the sound floor of the album is 7dB? Like the quietest part of the album is 7dB?

Thanks
 

solderdude

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The noise floor is not shown in the DR. Only the peak levels vs average levels. It says nothing about the noise floor of the recording.

Dynamic range specs of amps and DACs only say something about the maximum output level vs the noise floor.

These two 'Dynamic Range' numbers are not related in any way.
 
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luft262

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I'm probably just bothering you by this point, but how could one determine how much dynamic range a given recoding is making use of? In that way one could see whether or not their amp, dac or even the bit depth of the recoding is a bottlneck?

Thanks.
 

solderdude

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By looking at the DR database or using a program that determines it.

It says absolutely nothing about amps or DACs required or present bit depths or anything else.
The limiting factor is always the recording not the DAC.
When it comes to max achievable SPL (the actual dynamic range of the entire system, not the recording) the limitation is always a combination of transducer efficiency and maximum output level of the amplifier.
How loud that is to someone also depends on that persons age and hearing abilities.
Basically you just want to be sure you can reach levels you want.
I would say 120dB SPL is loud enough for impressive listening levels and the system's S/N ratio should be around 110dB.
The vast majority of recordings will be much poorer in S/N ratio so will mask system noise (depending on spectral spread of the noise and hearing abilities)

When you don't need extremely loud but only loud you can shave off 10dB or so. In all cases... the recording will be much worse than the system.
 

Mart68

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I'm probably just bothering you by this point, but how could one determine how much dynamic range a given recoding is making use of? In that way one could see whether or not their amp, dac or even the bit depth of the recoding is a bottlneck?

Thanks.

Unless you make some really poor equipment choices none of those things are going to be a bottleneck. Loudspeakers and rooms eclipse everything else in that regard. Unless you already have perfect speakers in a perfect room I wouldn't fret about the other stuff.
 
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luft262

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1: Nope there are no other advantages other than frequency extension. Only when using NOS filterless DACs (you know the type with actual staircase steps) there is an advantage.

2: There are speakers that can reproduce well over 40kHz. Most drop-off below it. They just cannot follow the input signal. Something to keep in mind is that all ultrasonic content present in music is very low level anyway. That is unless one is using filterless NOS DACs.

3: There probably is. Very high DR (> 30) music recordings do exist but simply have some very loud passages and the majority of music is recorded softly.
It is highly impractical to have such high DR as it would be unlistenable in cars, on radios, on phones and as background music. Most music is produced with those customers in mind.


In regards to #1 I believe it. That's what I was seeing in my own research, but it was hard to believe it. If all H-Res sampling rate is doing is extending the range it's basically just a tweeter booster?! I feel like most consumers see the higher sampling numbers and assume it's increasing the resolution throughout the audible spectrum. Thanks for clarifying.
 

joe16tons

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Hi there, I am new to this forum.

I am currently studying my Masters after being in the studio business for over 30 years.

I am currently researching a difference between sample frequencies can be heard and after several years I have failed to find a suitable test where this comparison has been made properly

All the comparison tests I have found either use source material which has been recorded at a single frequency and then converted, or identical equipment has not been used to compare.

I have 2 identical recording systems recording the same signal at 96kHz and 44.1kHz and I am undergoing A/B listening tests in various studios with 2 identical systems playing back at the listener.

No conversion has been done to any of the audio files.

One of the most complicated parts of gathering source material has been finding preamps and microphones that will capture above 20kHz.

I believe these tests are especially relevant in this age of Class D amplifiers with onboard DSP even though "HD audio" has been around for quite some time. In many modern amplifiers the audio is resampled
The reason I say this is because with some speakers in very good listening conditions we have heard a clear between the 44.1kHz and the 96kHz recordings, but I know as a 51 year old sound engineer I can barely hear past 13kHz.

One important factor that we must remember is that our bandwidth of hearing slopes off like most analogue equipment, but when we talk about the bandwidth of digital recording the HF does not roll off, it just stops at half the sampling frequency.

I am satisfied that I have suitable source sounds for the tests to continue and if anyone is interested in the results please contact me.
Due to Covid the tests have been slowed down

As the tests go on I realise that the question has changed from "Can we hear a difference between standard and HD audio" into "In which situation can we hear a difference?"

thanks,
Joe
 

Blumlein 88

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Hi there, I am new to this forum.

I am currently studying my Masters after being in the studio business for over 30 years.

I am currently researching a difference between sample frequencies can be heard and after several years I have failed to find a suitable test where this comparison has been made properly

All the comparison tests I have found either use source material which has been recorded at a single frequency and then converted, or identical equipment has not been used to compare.

I have 2 identical recording systems recording the same signal at 96kHz and 44.1kHz and I am undergoing A/B listening tests in various studios with 2 identical systems playing back at the listener.

No conversion has been done to any of the audio files.

One of the most complicated parts of gathering source material has been finding preamps and microphones that will capture above 20kHz.

I believe these tests are especially relevant in this age of Class D amplifiers with onboard DSP even though "HD audio" has been around for quite some time. In many modern amplifiers the audio is resampled
The reason I say this is because with some speakers in very good listening conditions we have heard a clear between the 44.1kHz and the 96kHz recordings, but I know as a 51 year old sound engineer I can barely hear past 13kHz.

One important factor that we must remember is that our bandwidth of hearing slopes off like most analogue equipment, but when we talk about the bandwidth of digital recording the HF does not roll off, it just stops at half the sampling frequency.

I am satisfied that I have suitable source sounds for the tests to continue and if anyone is interested in the results please contact me.
Due to Covid the tests have been slowed down

As the tests go on I realise that the question has changed from "Can we hear a difference between standard and HD audio" into "In which situation can we hear a difference?"

thanks,
Joe
Actually your hearing slopes off rapidly much closer to digital than gradual analog roll off of microphones and such.
Look at Fletcher-Munson loudness curves. Notice how steep they become above 15 khz?
1623962804185.png


The basilar membrane has different positions that resonate at different frequencies. Its sizing is such that there is no place to represent anything above 15 or 16 khz. Possibly 19 khz in some invididuals. So above this point response is very poor because it is basically a leaky filter barely responding just out of its range. And the sensitivity goes down rapidly with increasing frequency. At extremely high sound levels a small percentage of individuals have some response to tones around 22 or 23 khz and simply nothing above that. Most of course have no response even that far.

As for hearing a clear difference with some speakers between 44 khz and 96 khz I'd be interested in the details of such listening tests. First off were they blind or sighted and next what gear was used. I'm not quite wiling to say no one can hear such a difference, but I'm pretty sure any such differences will not be "clear" or "large" or "obvious" unless there is poor filtering going on.
 

DonH56

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Usually the sampling rate is expressed in samples per second, thus 44 kS/s vs. 96 kS/s/ That distinguishes the sampling rate from the Nyquist frequency band of 22 kHz or 48 kHz.

For wideband recording equipment look at measurement mics and preamps, though many preamps do have fairly wide frequency response. I use an Earthworks M30 with 30 kHz bandwidth; the M50 goes to 50 kHz. There are a number of small condensers that reach to 40 kHz and beyond.

I cannot think of a case off-hand where extended frequency response was audible except due to higher noise (from the extended noise bandwidth) and/or problems in the reproduction (playback) chain, typically IMD in the electronics or speakers (especially the speakers) producing lower-frequency distortion products within the audio band.

HTH - Don
 

joe16tons

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Actually your hearing slopes off rapidly much closer to digital than gradual analog roll off of microphones and such.
Look at Fletcher-Munson loudness curves. Notice how steep they become above 15 khz?
View attachment 136212

The basilar membrane has different positions that resonate at different frequencies. Its sizing is such that there is no place to represent anything above 15 or 16 khz. Possibly 19 khz in some invididuals. So above this point response is very poor because it is basically a leaky filter barely responding just out of its range. And the sensitivity goes down rapidly with increasing frequency. At extremely high sound levels a small percentage of individuals have some response to tones around 22 or 23 khz and simply nothing above that. Most of course have no response even that far.

As for hearing a clear difference with some speakers between 44 khz and 96 khz I'd be interested in the details of such listening tests. First off were they blind or sighted and next what gear was used. I'm not quite wiling to say no one can hear such a difference, but I'm pretty sure any such differences will not be "clear" or "large" or "obvious" unless there is poor filtering going on.

I will be publishing all results as soon as I have finished adequate tests, I will also be recreating the conditions of the first test I spoke about as this is the only test so far that subjects have heard a difference. Participants in all tests since have not been able to distinguish between sample rates. (so far) and thanks for the information.
 

Wes

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1. higher allows more gentle filter slopes; "avoid brickwall filters and their artifacts"

It is not so much than benefits have been demonstrated via listening tests, it is that one can claim an advantage to the things the OP noted.
 
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