9 ms·

There's a lot of scientific-sounded content in this, but unfortunately most of it couldn't be further from the truth. I'm an ex-audio engineer and studied digit

by cmer 15y ago

There's a lot of scientific-sounded content in this, but unfortunately most of it couldn't be further from the truth. I'm an ex-audio engineer and studied digital and analog audio engineering; this has been debated to death over the last 15 years. Digitally recording a triangle is the best example of why 48kHz is very limiting. The distinct sound of the triangle constitutes of a high fundamental frequency, ballpark 5kHz and of many very high-pitch harmonics. Most of these harmonics are above 20kHz. The harmonics are what makes it sound like a triangle, not the frequencies below 20kHz. This is why the triangle is one of the hardest instruments to digitally record. It always sounds like crap. In theory, it's true that the human hear can't hear above ~18kHz, but it can hear the influence of the very high pitch harmonics on a lower frequency. EDIT: here's more data backing what I said http://www.cco.caltech.edu/~boyk/spectra/spectra.htm http://www.cco.caltech.edu/~boyk/spectra/spectra.htm EDIT 2: typos, frequency mistake

tompagenet2 15y ago
Hey cmer, thanks for posting I don't think I understand quite what you're saying and wondered if you could explain more. You and the article both say that humans can't hear above about 20kHz. If there are higher frequencies that create a harmonic at a lower frequency (e.g. a 33kHz harmonic that produces a sound at 16.5kHz) then surely that lower harmonic (16.5kHz in this case) will be recorded by the original recording equipment assuming it is recording at a frequency at least twice that of the highest audible frequency (let's say that this would be 48kHz, although there might be other DAC-related reasons to go higher). I'm possibly being very daft here!
- cmer 15y ago
  Let's make things super simple. Let's say you record 4 sine waves at a 192kHz sampling rate: 15kHz, 30kHz, 45kHz and 60kHz. All 4 frequencies will be captured and the 15kHz frequency will sound different to your hear because its harmonics. If you take this recording and master it for a CD (44.1kHz), you'll effectively get up to ~20kHz (since they're a low pass filter starting at around 16-18kHz). This means that only our first frequency will be captured: 15kHz. It will be exactly the same as if you only recorded 15kHz alone. The harmonics don't modify the fundamental frequency, they just trick the human hear. But when they're gone, they have no effect whatsoever. Hope this helps! EDIT: the frequency numbers I used are actually somewhat of a bad example. Harmonics are never exactly double, triple the fundamental. Those would be mostly inaudible. But you get the idea.
  - glassx 15y ago
    > Harmonics are never exactly double, triple the fundamental. Those would be mostly inaudible. But you get the idea. Actually, they are: https://en.wikipedia.org/wiki/Harmonics https://en.wikipedia.org/wiki/Harmonics
    - cynicalkane 15y ago
      The second half of the statement is wrong, but the first half is right. Harmonics in real-world instruments are not usually exact multiples of the fundamental. A simple diffeq model of a rigid oscillator will show you this mathematically. An extreme example is present on modern pianos, where the high rigidity of the loud, heavy piano strings can cause tuners to stretch the lowest and highest notes as much as a half-semitone so that their harmonics are in tune with the note the next octave down or up. In other words, the first harmonic on the lowest note of a piano can be as much as 1/2 of a note sharp. And when your oscillator is no longer one-dimensional, most harmonics aren't even close to integer multiples. The harmonics of bells, cymbals and drums are all over the place. That's what gives them their percussive sound. (Edit: some of these modes of vibration aren't harmonics in the linear sense.)
      - Anechoic 15y ago
        Harmonics in real-world instruments are not usually exact multiples of the fundamental. A simple diffeq model of a rigid oscillator will show you this mathematically. That is absolutely incorrect, mathematically speaking, harmonics are by definition "integral multiples of the fundamental." (Fundamentals of Acoustics, Kinsler & Frey).
        shabble 15y ago
        People from a musical, non-signals background tend to use 'harmonics' as a synonym for 'overtones' or 'partial tones', which is where the confusion arises, I suspect. There's a measure -- inharmonicity[1] -- of how far the actual overtones of a particular instrument differ from their theoretical fundamental multiples. [I suspect you already know this. This reply is probably for others' benefit] [1] https://en.wikipedia.org/wiki/Inharmonicity https://en.wikipedia.org/wiki/Inharmonicity
nwhitehead 15y ago
The article doesn't suggest only using 48kHz for recording and mixing. I don't think the author would disagree that recording triangles is difficult. He would argue that once you've decided what final audible frequencies you want to present to the listener, the best way to distribute them is at 16-bit 44.1/48kHz. It's a compelling case.
- newman314 15y ago
  What if you want to sample the song later? That's one thing I find concerning with the move to digital. With analog media, you can go back, re-record and get an improved result (provided the source is good) but District 9 (which was shot on Red One) will never have improved quality other than resampling because the source is set to a particular digital format with associated data quality.
  - shabble 15y ago
    There seems to be some strange idea that analogue means 'infinite detail'. In this particular case, there's no significant difference between being limited by the original digital recording resolution and the grain size of a film recording. "[...] provided the source is good" is begging the question; it's no different from saying "District 9 could be better if they hadn't recorded in 4k (or whatever the Red One was using) and downsampled it for my DVD" The nature of the source is irrelevant, barring the fact that film might provide a higher resolution, if film scanning technology increases, and you can afford to both capture on film, process and store your film properly (archiving film is rather difficult, I believe), and get the best quality digitisation possible.
    - newman314 15y ago
      Obviously, I am not claiming infinite detail. There is going to be a limit based on the grain and the size of the film (35mm, Super, IMAX). 65mm film shot is going to be of higher quality than what digital is capable of today. While I have no doubt that digital will eventually catch up and surpass film, there inevitably is going to be a transition period where quality films were recorded (let's just say at 2k) where the input is constrained and extrapolation be the only available option. 4k is the current state of the art. It will not be so forever and because it's recorded at 4k, we can't go back and extract more dynamic range due to the limitation of the sensor. Whereas you can go back, redigitize an IMAX film (say Chronos shot in 1985) that is in good condition and get way more info than something shot on 4k yesterday. TL;DR IMO input still absolutely matters. 35mm is not the upper limit. We went through this with photography and am now doing the same with video/film. EDIT: After thinking more about it, here's a more extreme example. I purchased a Kodak DC20 back in the 90s (early adopter yay!), even if the camera had decent glass, there's no way I can go back to an image captured by that camera and magically get the equivalent of 22mp 5D camera by resampling. If I had used a film camera, I can get a much improved scan. EDIT2: Here's a good example. Slumdog Millionaire was mostly shot on a SI-2K which recorded at 2k. You can't go back and get 4k output on the digital portions. So generations later, we will be stuck enjoying an Academy Award winning film at that level of quality. http://www.siliconimaging.com/DigitalCinema/News/PR_01_31_09_Slumdog.html http://www.siliconimaging.com/DigitalCinema/News/PR_01_31_09...
Joeboy 15y ago
> Digitally recording a triangle is the best example of why 48kHz is very limiting The article's about distribution, not recording. I don't think anybody disputes the usefulness of higher sampling rates when recording. > In theory, it's true that the human hear can't hear above ~18kHz, but it can hear the influence of the very high pitch harmonics on a lower frequency. ...and 48kHz audio contains those lower frequencies.
- cmer 15y ago
  Stripping frequencies above 20kHz negates the effect on the lower frequencies since those lower frequencies are not "modified" by the higher ones. The human hear can actually hear the very high harmonics when they're combined with a lower fundamental frequency. For example, the human hear will hear a 30kHz frequency if it's fundamental is 10kHz. If it's played at 44.1kHz, the 30kHz frequency is gone and all you'll hear is 10kHz, not a "different sounding" 10kHz.
  - deleted 15y ago
    [deleted]
  - Anechoic 15y ago
    For example, the human hear will hear a 30kHz frequency if it's fundamental is 10kHz You are going to have to provide me with a citation to back that up because that goes against everything I've learned and experience in 17 years of working in acoustics.
    - cmer 15y ago
      Humans will hear the impact > 20kHz frequency has on the lower frequencies, not the 30kHz frequency itself. That's been proven a million times.
      - surrealize 15y ago
        Note the lack of citation
colanderman 15y ago
That data doesn't back your point at all. That data concerns what frequencies are present, not what frequencies can be heard.
amouat 15y ago
I'm no sound engineer, but as far as I can tell, the main point of that paper is that some instruments produce harmonics at frequencies greater than 20kHz, not that these frequencies matter to humans. However, section X references other papers that apparently make this claim. Just because it is difficult to record a triangle does not necessarily mean it is impossible to accurately recreate the sound (to human ears) using 48kHz.
- cmer 15y ago
  The only "good sounding" triangles you'll hear are those buried in a mix. Alone, it always sounds weird and "muted". EDIT: Listen to the triangle at the beginning of Rush's YYZ. It's an old recording, but it sounds significantly worse than the analog version. It's been digitally mastered some time ago so if it was mastered today, it would probably sound better, but still not great. I heard a rumor that Rush is remastering all their albums "for iTunes" at the moment, so hopefully we'll be able to compare soon!
  - TylerE 15y ago
    Not a very good example, because that's a Crotale (A Flat, ~4" cymbal, basically), not a triangle.
    - cmer 15y ago
      Wow! I didn't know that! All these years I was convinced it was a triangle just like pretty much everybody I guess. Thanks :)
      - FrankBooth 15y ago
        It's not like it has been a secret: http://en.wikipedia.org/wiki/YYZ_%28instrumental%29 http://en.wikipedia.org/wiki/YYZ_%28instrumental%29
- glassx 15y ago
  > I'm no sound engineer, but as far as I can tell, the main point of that paper is that some instruments produce harmonics at frequencies greater than 20kHz, not that these frequencies matter to humans. However, section X references other papers that apparently make this claim. Yes, you're right. In fact, some of the section X references don't even mention hearing, they talk about "alpha-EEG rhytms" (in this case "listeners explicitly denied that the reproduced sound was affected by the ultra-tweeter") and "bone-conducted ultrasonic hearing" trough the "saccule" ("organ that responds to acceleration and gravity and may be responsible for transduction of sound after destruction of the cochlea"). -- In fact, most of the claims of the article are around the fact that there is energy over 20khz and how it can affect recording process. This is a well known fact, and this is exactly why engineers filter out sub-sonic and super-sonic frequencies, especially today: stuff that you can't hear (or feel) will just suck your headroom and make you lose the loudness war.
leephillips 15y ago
The linked article was accurate. You are confused. "I'm an ex-audio engineer" Hard to believe. "The distinct sound of the triangle constitutes of a high fundamental frequency, ballpark 10kHz" That's a pretty high note - higher than the top key on the piano. But an "audio engineer" would know that. "many very high-pitch harmonics" Since the next harmonic after the fundamental would be at 20khz, which only young people can hear, and none of the others are audible to any human, I don't understand what you are talking about. "Most of these harmonics are 20kHz." OK, you don't either. "it can hear the influence of the very high pitch harmonics on a lower frequency." Sure....
- leif 15y ago
  You clearly have little to no musical background, and think that your basic math skills are a substitute. The overtones present in a cymbal or triangle are not straight multiples of the fundamental, they are chaotic, and are very important in determining the timbre. Anyone (and I mean that) can easily tell the difference between a cymbal with and without a low-pass filter with the threshold around 22kHz, because these "inaudible" frequencies are lost.
  - cmer 15y ago
    This is a much more polite response than what I had in mind. Better this way I guess :)
  - mortil 15y ago
    If anyone can hear it, then surely it must have been verified through a double-blind test. Can you provide a citation?
    - leif 15y ago
      I don't know of any to point you to. They probably exist, but I haven't read them. Let me know if you stir some up.
  - leephillips 15y ago
    1: He said "harmonics", not overtones. 2: You can not hear inaudible frequencies. Because they are inaudible.
untangle 15y ago
> In theory, it's true that the human hear can't hear above ~18kHz, but it can hear the influence of the very high pitch harmonics on a lower frequency. That may well be true. But those mixed-down harmonics that are heard "live" would then be captured by the 16/44 (or whatever) sampling. IOW, the recording captures what you heard. Those upper harmonics have no emergent properties. Their effect is captured. Bob
eatmyshorts 15y ago
Yes, but our ears only hear 20Hz-20KHz. So, according to Nyquist theory, you can recreate the entire signal that the human ear hears by recording those sonic artifacts that result from interference between supersonic harmonics. So while it's true that the human ear can't hear well above ~18KHz, and the interference between high order harmonics are audible, it's also true that a properly recorded signal, sampled at 44.1KHz, oversampled, and filtered, can reproduce the exact signal the human ear is capable of hearing. At least according to theory. The human ear is capable of detecting sound pressure as well as sound intensity, and while playback of the interference between harmonics can be reproduced faithfully in the sound intensity realm, the sound pressure levels will differ, and it is theorized that people may be able to tell the difference between the two. However, as far as I am aware, nobody has been able to demonstrate this reliably in practice.
- tzs 15y ago
  What about sound outside 20-20k that affects us via mechanisms other than being directly sensed in the air by our ears? For instance, consider frequencies below 20 Hz that we can feel with our feet as vibrations in the floor, instead of hear with our ears? Or what about the possibility of sound above 20k causing a vibration in something other than our ears, which could have a subharmonic in 20-20k that gets conducted to our ears via bone? I'd prefer recording technology to err on the side of capturing what we need to reproduce all of that, even if we aren't sure that we need it.
  - panacea 15y ago
    >I'd prefer recording technology to err on the side of capturing what we need to reproduce all of that, even if we aren't sure that we need it. Again, this article is about distribution, not recording.
- jwatte 15y ago
  Nyquist is true for static signals. Music is not static. Brick wall at 20 kHz and get audible phasing artifacts! (Even if your filter is phase linear)
retrogradeorbit 15y ago
I'm an audio engineer, too, and I agree that this has been debated to death. And I agree that frequencies above the threshold of hearing are more important than standard dogma (based on Nyquist theory combined with Pure tone audiometry) allows. It helps explain how audio gear with a 100kHz bandwidth sounds clearer than gear with a 20kHz bandwidth even when they measure the same in the audible band. Have you read the Audio Technology magazine interview with Rupert Neve? Greg Simmons: Geoff Emerick, the famous British Producer ? Rupert Neve: Yes, he started me off on this trail. A 48 input console had been delivered to George Martin's Air Studios, and Geoff Emerick was very unhappy about it. It was a new console, made not long after I had sold the Neve company in 1977. George Martin called me and said, "please come and make Geoff happy, while he's unhappy we can't do any work". They'd had engineers from the company there, and so on. The danger is that if you are not sensitive to people like Geoff Emerick, and you don't respect them for what they have done, then you are not going to listen to them. Unfortunately, there was a breed of young engineers in the company ( I hasten to say this was after I sold it !) who couldn't understand what he was bitching about. So they went back to the company and just made a report saying the customer was mad and there wasn't really a problem. Leave it alone, forget it, the problem will go away. They were acting like used car salesmen. I was very angry with it. So I went and spent time there, at George Martin's request, and Geoff finally managed to show me what it was that he could hear, and then I began to hear it, too. Now Geoff was The Golden Ears - and he still is - and he was perceiving something that I wasn't looking for. And it wasn't until I had spent some time with him, as it were, being lead by him through the sounds, that I began to pick up what he was listening to. And once I'd heard it, oh yes, then I knew what he was talking about. We measured it and found that in three out of the full 48 channels, the output transformers had not been correctly terminated and were producing a 3dB rise at 54kHz. And so people said, "oh no, he can't possible hear that". But when we corrected that problem, and it was only one capacitor that had to be added to each of those three channels, I mean, Geoff's face just lit up ! Here you have the happiness/ unhappiness mood thing the Japanese were talking about. copy here: http://poonshead.com/Reading/Articles.aspx http://poonshead.com/Reading/Articles.aspx
- deleted 15y ago
  [deleted]

by cmer 15y ago

tompagenet2 15y ago

Hey cmer, thanks for posting I don't think I understand quite what you're saying and wondered if you could explain more. You and the article both say that humans can't hear above about 20kHz. If there are higher frequencies that create a harmonic at a lower frequency (e.g. a 33kHz harmonic that produces a sound at 16.5kHz) then surely that lower harmonic (16.5kHz in this case) will be recorded by the original recording equipment assuming it is recording at a frequency at least twice that of the highest audible frequency (let's say that this would be 48kHz, although there might be other DAC-related reasons to go higher). I'm possibly being very daft here!

cmer 15y ago
Let's make things super simple. Let's say you record 4 sine waves at a 192kHz sampling rate: 15kHz, 30kHz, 45kHz and 60kHz. All 4 frequencies will be captured and the 15kHz frequency will sound different to your hear because its harmonics. If you take this recording and master it for a CD (44.1kHz), you'll effectively get up to ~20kHz (since they're a low pass filter starting at around 16-18kHz). This means that only our first frequency will be captured: 15kHz. It will be exactly the same as if you only recorded 15kHz alone. The harmonics don't modify the fundamental frequency, they just trick the human hear. But when they're gone, they have no effect whatsoever. Hope this helps! EDIT: the frequency numbers I used are actually somewhat of a bad example. Harmonics are never exactly double, triple the fundamental. Those would be mostly inaudible. But you get the idea.
- glassx 15y ago
  > Harmonics are never exactly double, triple the fundamental. Those would be mostly inaudible. But you get the idea. Actually, they are: https://en.wikipedia.org/wiki/Harmonics https://en.wikipedia.org/wiki/Harmonics
  - cynicalkane 15y ago
    The second half of the statement is wrong, but the first half is right. Harmonics in real-world instruments are not usually exact multiples of the fundamental. A simple diffeq model of a rigid oscillator will show you this mathematically. An extreme example is present on modern pianos, where the high rigidity of the loud, heavy piano strings can cause tuners to stretch the lowest and highest notes as much as a half-semitone so that their harmonics are in tune with the note the next octave down or up. In other words, the first harmonic on the lowest note of a piano can be as much as 1/2 of a note sharp. And when your oscillator is no longer one-dimensional, most harmonics aren't even close to integer multiples. The harmonics of bells, cymbals and drums are all over the place. That's what gives them their percussive sound. (Edit: some of these modes of vibration aren't harmonics in the linear sense.)
    - Anechoic 15y ago
      Harmonics in real-world instruments are not usually exact multiples of the fundamental. A simple diffeq model of a rigid oscillator will show you this mathematically. That is absolutely incorrect, mathematically speaking, harmonics are by definition "integral multiples of the fundamental." (Fundamentals of Acoustics, Kinsler & Frey).
      - shabble 15y ago
        People from a musical, non-signals background tend to use 'harmonics' as a synonym for 'overtones' or 'partial tones', which is where the confusion arises, I suspect. There's a measure -- inharmonicity[1] -- of how far the actual overtones of a particular instrument differ from their theoretical fundamental multiples. [I suspect you already know this. This reply is probably for others' benefit] [1] https://en.wikipedia.org/wiki/Inharmonicity https://en.wikipedia.org/wiki/Inharmonicity

nwhitehead 15y ago

The article doesn't suggest only using 48kHz for recording and mixing. I don't think the author would disagree that recording triangles is difficult. He would argue that once you've decided what final audible frequencies you want to present to the listener, the best way to distribute them is at 16-bit 44.1/48kHz. It's a compelling case.

newman314 15y ago
What if you want to sample the song later? That's one thing I find concerning with the move to digital. With analog media, you can go back, re-record and get an improved result (provided the source is good) but District 9 (which was shot on Red One) will never have improved quality other than resampling because the source is set to a particular digital format with associated data quality.
- shabble 15y ago
  There seems to be some strange idea that analogue means 'infinite detail'. In this particular case, there's no significant difference between being limited by the original digital recording resolution and the grain size of a film recording. "[...] provided the source is good" is begging the question; it's no different from saying "District 9 could be better if they hadn't recorded in 4k (or whatever the Red One was using) and downsampled it for my DVD" The nature of the source is irrelevant, barring the fact that film might provide a higher resolution, if film scanning technology increases, and you can afford to both capture on film, process and store your film properly (archiving film is rather difficult, I believe), and get the best quality digitisation possible.
  - newman314 15y ago
    Obviously, I am not claiming infinite detail. There is going to be a limit based on the grain and the size of the film (35mm, Super, IMAX). 65mm film shot is going to be of higher quality than what digital is capable of today. While I have no doubt that digital will eventually catch up and surpass film, there inevitably is going to be a transition period where quality films were recorded (let's just say at 2k) where the input is constrained and extrapolation be the only available option. 4k is the current state of the art. It will not be so forever and because it's recorded at 4k, we can't go back and extract more dynamic range due to the limitation of the sensor. Whereas you can go back, redigitize an IMAX film (say Chronos shot in 1985) that is in good condition and get way more info than something shot on 4k yesterday. TL;DR IMO input still absolutely matters. 35mm is not the upper limit. We went through this with photography and am now doing the same with video/film. EDIT: After thinking more about it, here's a more extreme example. I purchased a Kodak DC20 back in the 90s (early adopter yay!), even if the camera had decent glass, there's no way I can go back to an image captured by that camera and magically get the equivalent of 22mp 5D camera by resampling. If I had used a film camera, I can get a much improved scan. EDIT2: Here's a good example. Slumdog Millionaire was mostly shot on a SI-2K which recorded at 2k. You can't go back and get 4k output on the digital portions. So generations later, we will be stuck enjoying an Academy Award winning film at that level of quality. http://www.siliconimaging.com/DigitalCinema/News/PR_01_31_09_Slumdog.html http://www.siliconimaging.com/DigitalCinema/News/PR_01_31_09...

Joeboy 15y ago

> Digitally recording a triangle is the best example of why 48kHz is very limiting The article's about distribution, not recording. I don't think anybody disputes the usefulness of higher sampling rates when recording. > In theory, it's true that the human hear can't hear above ~18kHz, but it can hear the influence of the very high pitch harmonics on a lower frequency. ...and 48kHz audio contains those lower frequencies.

cmer 15y ago
Stripping frequencies above 20kHz negates the effect on the lower frequencies since those lower frequencies are not "modified" by the higher ones. The human hear can actually hear the very high harmonics when they're combined with a lower fundamental frequency. For example, the human hear will hear a 30kHz frequency if it's fundamental is 10kHz. If it's played at 44.1kHz, the 30kHz frequency is gone and all you'll hear is 10kHz, not a "different sounding" 10kHz.
- deleted 15y ago
  [deleted]
- Anechoic 15y ago
  For example, the human hear will hear a 30kHz frequency if it's fundamental is 10kHz You are going to have to provide me with a citation to back that up because that goes against everything I've learned and experience in 17 years of working in acoustics.
  - cmer 15y ago
    Humans will hear the impact > 20kHz frequency has on the lower frequencies, not the 30kHz frequency itself. That's been proven a million times.
    - surrealize 15y ago
      Note the lack of citation

colanderman 15y ago

That data doesn't back your point at all. That data concerns what frequencies are present, not what frequencies can be heard.

amouat 15y ago

I'm no sound engineer, but as far as I can tell, the main point of that paper is that some instruments produce harmonics at frequencies greater than 20kHz, not that these frequencies matter to humans. However, section X references other papers that apparently make this claim. Just because it is difficult to record a triangle does not necessarily mean it is impossible to accurately recreate the sound (to human ears) using 48kHz.

cmer 15y ago
The only "good sounding" triangles you'll hear are those buried in a mix. Alone, it always sounds weird and "muted". EDIT: Listen to the triangle at the beginning of Rush's YYZ. It's an old recording, but it sounds significantly worse than the analog version. It's been digitally mastered some time ago so if it was mastered today, it would probably sound better, but still not great. I heard a rumor that Rush is remastering all their albums "for iTunes" at the moment, so hopefully we'll be able to compare soon!
- TylerE 15y ago
  Not a very good example, because that's a Crotale (A Flat, ~4" cymbal, basically), not a triangle.
  - cmer 15y ago
    Wow! I didn't know that! All these years I was convinced it was a triangle just like pretty much everybody I guess. Thanks :)
    - FrankBooth 15y ago
      It's not like it has been a secret: http://en.wikipedia.org/wiki/YYZ_%28instrumental%29 http://en.wikipedia.org/wiki/YYZ_%28instrumental%29
glassx 15y ago
> I'm no sound engineer, but as far as I can tell, the main point of that paper is that some instruments produce harmonics at frequencies greater than 20kHz, not that these frequencies matter to humans. However, section X references other papers that apparently make this claim. Yes, you're right. In fact, some of the section X references don't even mention hearing, they talk about "alpha-EEG rhytms" (in this case "listeners explicitly denied that the reproduced sound was affected by the ultra-tweeter") and "bone-conducted ultrasonic hearing" trough the "saccule" ("organ that responds to acceleration and gravity and may be responsible for transduction of sound after destruction of the cochlea"). -- In fact, most of the claims of the article are around the fact that there is energy over 20khz and how it can affect recording process. This is a well known fact, and this is exactly why engineers filter out sub-sonic and super-sonic frequencies, especially today: stuff that you can't hear (or feel) will just suck your headroom and make you lose the loudness war.

leephillips 15y ago

The linked article was accurate. You are confused. "I'm an ex-audio engineer" Hard to believe. "The distinct sound of the triangle constitutes of a high fundamental frequency, ballpark 10kHz" That's a pretty high note - higher than the top key on the piano. But an "audio engineer" would know that. "many very high-pitch harmonics" Since the next harmonic after the fundamental would be at 20khz, which only young people can hear, and none of the others are audible to any human, I don't understand what you are talking about. "Most of these harmonics are 20kHz." OK, you don't either. "it can hear the influence of the very high pitch harmonics on a lower frequency." Sure....

leif 15y ago
You clearly have little to no musical background, and think that your basic math skills are a substitute. The overtones present in a cymbal or triangle are not straight multiples of the fundamental, they are chaotic, and are very important in determining the timbre. Anyone (and I mean that) can easily tell the difference between a cymbal with and without a low-pass filter with the threshold around 22kHz, because these "inaudible" frequencies are lost.
- cmer 15y ago
  This is a much more polite response than what I had in mind. Better this way I guess :)
- mortil 15y ago
  If anyone can hear it, then surely it must have been verified through a double-blind test. Can you provide a citation?
  - leif 15y ago
    I don't know of any to point you to. They probably exist, but I haven't read them. Let me know if you stir some up.
- leephillips 15y ago
  1: He said "harmonics", not overtones. 2: You can not hear inaudible frequencies. Because they are inaudible.

untangle 15y ago

> In theory, it's true that the human hear can't hear above ~18kHz, but it can hear the influence of the very high pitch harmonics on a lower frequency. That may well be true. But those mixed-down harmonics that are heard "live" would then be captured by the 16/44 (or whatever) sampling. IOW, the recording captures what you heard. Those upper harmonics have no emergent properties. Their effect is captured. Bob

eatmyshorts 15y ago

Yes, but our ears only hear 20Hz-20KHz. So, according to Nyquist theory, you can recreate the entire signal that the human ear hears by recording those sonic artifacts that result from interference between supersonic harmonics. So while it's true that the human ear can't hear well above ~18KHz, and the interference between high order harmonics are audible, it's also true that a properly recorded signal, sampled at 44.1KHz, oversampled, and filtered, can reproduce the exact signal the human ear is capable of hearing. At least according to theory. The human ear is capable of detecting sound pressure as well as sound intensity, and while playback of the interference between harmonics can be reproduced faithfully in the sound intensity realm, the sound pressure levels will differ, and it is theorized that people may be able to tell the difference between the two. However, as far as I am aware, nobody has been able to demonstrate this reliably in practice.

tzs 15y ago
What about sound outside 20-20k that affects us via mechanisms other than being directly sensed in the air by our ears? For instance, consider frequencies below 20 Hz that we can feel with our feet as vibrations in the floor, instead of hear with our ears? Or what about the possibility of sound above 20k causing a vibration in something other than our ears, which could have a subharmonic in 20-20k that gets conducted to our ears via bone? I'd prefer recording technology to err on the side of capturing what we need to reproduce all of that, even if we aren't sure that we need it.
- panacea 15y ago
  >I'd prefer recording technology to err on the side of capturing what we need to reproduce all of that, even if we aren't sure that we need it. Again, this article is about distribution, not recording.
jwatte 15y ago
Nyquist is true for static signals. Music is not static. Brick wall at 20 kHz and get audible phasing artifacts! (Even if your filter is phase linear)

retrogradeorbit 15y ago

I'm an audio engineer, too, and I agree that this has been debated to death. And I agree that frequencies above the threshold of hearing are more important than standard dogma (based on Nyquist theory combined with Pure tone audiometry) allows. It helps explain how audio gear with a 100kHz bandwidth sounds clearer than gear with a 20kHz bandwidth even when they measure the same in the audible band. Have you read the Audio Technology magazine interview with Rupert Neve? Greg Simmons: Geoff Emerick, the famous British Producer ? Rupert Neve: Yes, he started me off on this trail. A 48 input console had been delivered to George Martin's Air Studios, and Geoff Emerick was very unhappy about it. It was a new console, made not long after I had sold the Neve company in 1977. George Martin called me and said, "please come and make Geoff happy, while he's unhappy we can't do any work". They'd had engineers from the company there, and so on. The danger is that if you are not sensitive to people like Geoff Emerick, and you don't respect them for what they have done, then you are not going to listen to them. Unfortunately, there was a breed of young engineers in the company ( I hasten to say this was after I sold it !) who couldn't understand what he was bitching about. So they went back to the company and just made a report saying the customer was mad and there wasn't really a problem. Leave it alone, forget it, the problem will go away. They were acting like used car salesmen. I was very angry with it. So I went and spent time there, at George Martin's request, and Geoff finally managed to show me what it was that he could hear, and then I began to hear it, too. Now Geoff was The Golden Ears - and he still is - and he was perceiving something that I wasn't looking for. And it wasn't until I had spent some time with him, as it were, being lead by him through the sounds, that I began to pick up what he was listening to. And once I'd heard it, oh yes, then I knew what he was talking about. We measured it and found that in three out of the full 48 channels, the output transformers had not been correctly terminated and were producing a 3dB rise at 54kHz. And so people said, "oh no, he can't possible hear that". But when we corrected that problem, and it was only one capacitor that had to be added to each of those three channels, I mean, Geoff's face just lit up ! Here you have the happiness/ unhappiness mood thing the Japanese were talking about. copy here: http://poonshead.com/Reading/Articles.aspx http://poonshead.com/Reading/Articles.aspx

deleted 15y ago
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