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The author explains that it's a psychoacoustic model and then demonstrates how various artifacts in various waveforms are the result of compromises within this

The author explains that it's a psychoacoustic model and then demonstrates how various artifacts in various waveforms are the result of compromises within this model. As an aside, I don't understand why people take the position that lossy transcodes are indistinguishable from one another when, right out of the gate, it's well-understand that compromises are being made in the highs, well within the range of human hearing. In fact, CDs can only replicate frequencies below 22kHz and even that's within the hearable range of many (mostly younger) people. I just really don't understand this widespread need to believe "lossy" doesn't really mean "lossy." It's a psychoacoustic model and people are different, and further you can (as demonstrated by the article) even show where various encoding artifacts are feasibly audible to plenty of people. I just don't get it.

tchaffee 8y ago
I used to believe these things were audible until I got into A / B testing with people claiming to hear the difference. The vast majority cannot. I barely ever can. And that's when I'm focusing to try to detect a difference. It's not something I'll notice when listening for enjoyment. YMMV, but I highly suggest doing listening tests yourself.
- joegahona 8y ago
  Same. NPR Music published a quiz of this sort a few years ago (https://www.npr.org/sections/therecord/2015/06/02/411473508/how-well-can-you-hear-audio-quality https://www.npr.org/sections/therecord/2015/06/02/411473508/...), and I failed pretty hard. I learned to play piano by ear too, so it's not like my ear is crap.
  - enilakla 8y ago
    This was fun, thanks for this.
  - tom_ 8y ago
    Ha. That was interesting. I got 1/6, though out of the 5 I got wrong, I picked the 320Kbps MP3 for 4 of them. This backs up a few blind tests I did when I was younger, though then with music I was familiar with: 320Kbps MP3 and uncompressed WAV were typically indistinguishable to me, and, when they were audibly different, I still couldn't say which was better and which was worse. The one I got completely wrong was the Jay Z track. Even re-listening knowing which is which, I still can't tell the difference :( - but this is a style of music I rarely listen to, and maybe that's the reason. It's also a fair few years since I was 30, and that could be an alternative explanation. (I'm actually quite surprised I did as well as I did, as the 128Kbps versions weren't obviously worse, and it did take a few listens on headphones. I should probably do another blind test with a 2003 build of LAME or whatever, not so much to compare MP3 vs WAV, but more to measure how much my hearing has deteriorated over the years...)
  - darkerside 8y ago
    Ha, I just picked 5/6 the 128Kbps tracks. Maybe my ear has become accustomed to the compression artifacts and misses them when they're not there!
    - 33degrees 8y ago
      This is apparently a thing, that people will prefer what they’re used to and these days that’s low bitrate audio played through phone and laptop speakers...
      - deleted 8y ago
        [deleted]
      - tchaffee 8y ago
        I question how often people regularly listen to music through laptop speakers. Isn't it mostly through earphones or headphones?
        33degrees 8y ago
        Not necessarily, lots of students don’t speakers hooked up to their laptops, abd I see kids listening to music on their phone speakers all the time
  - seattle_spring 8y ago
    Doesn't that test just intentionally choose bits of music that are hard to discern?
  - ken 8y ago
    These aren't songs I normally listen to, but I did this quiz just now and even with laptop speakers I picked 3x uncompressed, 2x 320kbps MP3, and 1x 128kbps MP3. 128 is usually pretty easy to pick out, once you know what to listen for. There's no soundstage. They just sound flat. The tricky part is distinguishing between 320 and uncompressed. 320 is pretty darn good. Even when I can hear the difference, if it's not a song I'm familiar with, I can't tell which one is better. It's just different.
- amgutier 8y ago
  I've conducted several A/B tests back when I had nothing better to do and it was a very education experience. I used a recording of a harpsichord, using lame V5 mp3s, and came away with a statistically significant result (I remember taking 14 trials, though I don't remember what my actual true positive rate was) After all of that, though I had double blind evidence I could hear a difference, I knew I didn't really care about that difference. I couldn't even describe the difference - it was almost subliminal. And that was with a harpsichord, which is a known difficult sound to encode. I've been a lot more comfortable knowing lossy encoding isn't destroying my music enjoyment since those tests.
  - glandium 8y ago
    There are different things that could be found through tests, but I don't think I've seen tests being really extensive. The interesting questions to me: - Can a difference be heard? - If yes, are people able to reliably identify A vs B (as in, can people identify whether it's A or B rather that whatever they listen now is not the same as the last they heard) - If they can identify a difference, which sounds better to them? - Do different headphones give different results? - Same question with headphones vs speakers?
    - TheOtherHobbes 8y ago
      The answer to the last two questions is easy - yes to both. There are absolutely huge differences between budget consumer and high-end professional equipment. There are also huge differences between high-end audiophile and professional equipment - the former being designed to flatter and enhance the sound, the latter being as neutral as possible. A good few years ago a high-end audiophile CD/DAC maker was caught deliberately rolling off the top end on their equipment to make it sound smoother and "less digital." It wasn't accurate, but a lot of people liked the sound enough to pay five figures for the boxes they made. Professional audio has a different goal. The aim is to create a mix that "translates" - sounds good on as many different systems as possible, from budget earbuds to audiophile. For a long time studios used a pair of shitty Yamaha bookshelf speakers called NS10s next to their ultra-expensive reference speakers. NS10s were almost the worst speaker ever. But if a mix sounded good on the NS10s, it sounded good on anything.
- imhelpingu 8y ago
  I did these kinds of tests in my early 20s (not sure how it would go now) and completely destroyed them. (I shut many many people up doing these tests, actually.) > I barely ever can. > It's not something I'll notice when listening for enjoyment. Pretty much tell the story.
opencl 8y ago
Some of the numbers in the article are unsourced and highly questionable. 130-140dB dynamic range of hearing? That's the difference between an anechoic chamber (~10-20dB) and enough sound pressure to literally rupture your eardrums (~150dB). Maybe you can technically perceive that dynamic range... once. I certainly agree that artifacts in 128kbps MP3s are noticeable but the assertion that 320kbps AACs or MP3s created with modern encoders are audibly different from uncompressed audio really needs some evidence. Every single double blind test I have seen conducted between them has shown that nobody can tell.
- cogman10 8y ago
  128kbps aac or opus are going to be transparent. MP3 is such an old standard (1993). The fact that is still the reference and used is little crazy.
- rplst8 8y ago
  If you don't think there is a huge difference between 140 and 150db then you don't understand decibels. I can most certainly tell the difference between 320kbps lossy and red book audio on well done recordings.
  - Retric 8y ago
    The problem is people’s hearing range shrinks so much at low dB as to include it in ‘hearing range’ is meaningless. Similarly, people can detect pain at 140db, but they don’t differentiate sounds. Ex at 60db detecting 100hz sounds is easy, at 20db it’s outside of human hearing range.
chipotle_coyote 8y ago
The question isn't whether lossy means "lossy," the question is whether lossy means "audibly different." Years ago Stereophile published an article called "MP3 vs AAC vs FLAC vs CD" which was really meant to argue for the superiority of lossless compression, but actually does a pretty good job of explaining both subtle differences between AAC and MP3 at the same bit rate and how high bit-rate lossy encoding pushes artifacts down to inaudible levels. You can put up an AAC/MP3 frequency graph compared to a FLAC/CD frequency graph and have it look absolutely horrifying, until you notice that the junk on the AAC/MP3 chart is all at -100db and below. Unless your listening room is an anechoic chamber, you're just not going to hear it. (In most cases it's probably below the noise floor of your reproduction equipment.) I often think I can hear the difference between lossless and lossy, but IIRC, the last time I did ABX testing on that, there was only 1 out of 5 tracks I tried where I could tell the difference at a statistically significant rate. (And I'm not sure I'd be able to repeat that.) The best argument I have for storing music in FLAC (or ALAC or some other open lossless format) is analogous to the argument for storing images in a lossless rather than lossy format if you have the space: if you ever have to transcode the file to something else, start with the highest quality possible.
- imhelpingu 8y ago
  > 1 out of 5 tracks I tried where I could tell the difference at a statistically significant rate. Hate to sound like a broken record, but what are you arguing with me about?
ovao 8y ago
> The author explains that it's a psychoacoustic model and then demonstrates how various artifacts in various waveforms are the result of compromises within this model. The explanations aren’t themselves incorrect — there’s certainly low-pass filtering, pre- and post-echo artifacting and so on, and these reflect in the waveforms — but to reference a waveform and to say “this sounds bad because it looks like this” doesn’t really hold water. Visual differences are not necessarily audible differences, which is the fact psychoacoustic encoding leverages. If an encoder’s design goal was to produce visually-comparable waveforms, a different approach would be used. > In fact, CDs can only replicate frequencies below 22kHz and even that's within the hearable range of many (mostly younger) people. There is no useful or meaningful content above ~18 kHz (aside from dither) on most recordings. There may be exceptions, but by and large, on real music recordings, the information above that frequency isn’t valuable, and is the among the easiest things to discard.
- imhelpingu 8y ago
  Again, I have no idea what you think we disagree about. Your reply, like most of the replies, is premised on the idea that yes you can hear the difference in some cases.

tchaffee 8y ago

I used to believe these things were audible until I got into A / B testing with people claiming to hear the difference. The vast majority cannot. I barely ever can. And that's when I'm focusing to try to detect a difference. It's not something I'll notice when listening for enjoyment. YMMV, but I highly suggest doing listening tests yourself.

joegahona 8y ago
Same. NPR Music published a quiz of this sort a few years ago (https://www.npr.org/sections/therecord/2015/06/02/411473508/how-well-can-you-hear-audio-quality https://www.npr.org/sections/therecord/2015/06/02/411473508/...), and I failed pretty hard. I learned to play piano by ear too, so it's not like my ear is crap.
- enilakla 8y ago
  This was fun, thanks for this.
- tom_ 8y ago
  Ha. That was interesting. I got 1/6, though out of the 5 I got wrong, I picked the 320Kbps MP3 for 4 of them. This backs up a few blind tests I did when I was younger, though then with music I was familiar with: 320Kbps MP3 and uncompressed WAV were typically indistinguishable to me, and, when they were audibly different, I still couldn't say which was better and which was worse. The one I got completely wrong was the Jay Z track. Even re-listening knowing which is which, I still can't tell the difference :( - but this is a style of music I rarely listen to, and maybe that's the reason. It's also a fair few years since I was 30, and that could be an alternative explanation. (I'm actually quite surprised I did as well as I did, as the 128Kbps versions weren't obviously worse, and it did take a few listens on headphones. I should probably do another blind test with a 2003 build of LAME or whatever, not so much to compare MP3 vs WAV, but more to measure how much my hearing has deteriorated over the years...)
- darkerside 8y ago
  Ha, I just picked 5/6 the 128Kbps tracks. Maybe my ear has become accustomed to the compression artifacts and misses them when they're not there!
  - 33degrees 8y ago
    This is apparently a thing, that people will prefer what they’re used to and these days that’s low bitrate audio played through phone and laptop speakers...
    - deleted 8y ago
      [deleted]
    - tchaffee 8y ago
      I question how often people regularly listen to music through laptop speakers. Isn't it mostly through earphones or headphones?
      - 33degrees 8y ago
        Not necessarily, lots of students don’t speakers hooked up to their laptops, abd I see kids listening to music on their phone speakers all the time
- seattle_spring 8y ago
  Doesn't that test just intentionally choose bits of music that are hard to discern?
- ken 8y ago
  These aren't songs I normally listen to, but I did this quiz just now and even with laptop speakers I picked 3x uncompressed, 2x 320kbps MP3, and 1x 128kbps MP3. 128 is usually pretty easy to pick out, once you know what to listen for. There's no soundstage. They just sound flat. The tricky part is distinguishing between 320 and uncompressed. 320 is pretty darn good. Even when I can hear the difference, if it's not a song I'm familiar with, I can't tell which one is better. It's just different.
amgutier 8y ago
I've conducted several A/B tests back when I had nothing better to do and it was a very education experience. I used a recording of a harpsichord, using lame V5 mp3s, and came away with a statistically significant result (I remember taking 14 trials, though I don't remember what my actual true positive rate was) After all of that, though I had double blind evidence I could hear a difference, I knew I didn't really care about that difference. I couldn't even describe the difference - it was almost subliminal. And that was with a harpsichord, which is a known difficult sound to encode. I've been a lot more comfortable knowing lossy encoding isn't destroying my music enjoyment since those tests.
- glandium 8y ago
  There are different things that could be found through tests, but I don't think I've seen tests being really extensive. The interesting questions to me: - Can a difference be heard? - If yes, are people able to reliably identify A vs B (as in, can people identify whether it's A or B rather that whatever they listen now is not the same as the last they heard) - If they can identify a difference, which sounds better to them? - Do different headphones give different results? - Same question with headphones vs speakers?
  - TheOtherHobbes 8y ago
    The answer to the last two questions is easy - yes to both. There are absolutely huge differences between budget consumer and high-end professional equipment. There are also huge differences between high-end audiophile and professional equipment - the former being designed to flatter and enhance the sound, the latter being as neutral as possible. A good few years ago a high-end audiophile CD/DAC maker was caught deliberately rolling off the top end on their equipment to make it sound smoother and "less digital." It wasn't accurate, but a lot of people liked the sound enough to pay five figures for the boxes they made. Professional audio has a different goal. The aim is to create a mix that "translates" - sounds good on as many different systems as possible, from budget earbuds to audiophile. For a long time studios used a pair of shitty Yamaha bookshelf speakers called NS10s next to their ultra-expensive reference speakers. NS10s were almost the worst speaker ever. But if a mix sounded good on the NS10s, it sounded good on anything.
imhelpingu 8y ago
I did these kinds of tests in my early 20s (not sure how it would go now) and completely destroyed them. (I shut many many people up doing these tests, actually.) > I barely ever can. > It's not something I'll notice when listening for enjoyment. Pretty much tell the story.

opencl 8y ago

Some of the numbers in the article are unsourced and highly questionable. 130-140dB dynamic range of hearing? That's the difference between an anechoic chamber (~10-20dB) and enough sound pressure to literally rupture your eardrums (~150dB). Maybe you can technically perceive that dynamic range... once. I certainly agree that artifacts in 128kbps MP3s are noticeable but the assertion that 320kbps AACs or MP3s created with modern encoders are audibly different from uncompressed audio really needs some evidence. Every single double blind test I have seen conducted between them has shown that nobody can tell.

cogman10 8y ago
128kbps aac or opus are going to be transparent. MP3 is such an old standard (1993). The fact that is still the reference and used is little crazy.
rplst8 8y ago
If you don't think there is a huge difference between 140 and 150db then you don't understand decibels. I can most certainly tell the difference between 320kbps lossy and red book audio on well done recordings.
- Retric 8y ago
  The problem is people’s hearing range shrinks so much at low dB as to include it in ‘hearing range’ is meaningless. Similarly, people can detect pain at 140db, but they don’t differentiate sounds. Ex at 60db detecting 100hz sounds is easy, at 20db it’s outside of human hearing range.

chipotle_coyote 8y ago

The question isn't whether lossy means "lossy," the question is whether lossy means "audibly different." Years ago Stereophile published an article called "MP3 vs AAC vs FLAC vs CD" which was really meant to argue for the superiority of lossless compression, but actually does a pretty good job of explaining both subtle differences between AAC and MP3 at the same bit rate and how high bit-rate lossy encoding pushes artifacts down to inaudible levels. You can put up an AAC/MP3 frequency graph compared to a FLAC/CD frequency graph and have it look absolutely horrifying, until you notice that the junk on the AAC/MP3 chart is all at -100db and below. Unless your listening room is an anechoic chamber, you're just not going to hear it. (In most cases it's probably below the noise floor of your reproduction equipment.) I often think I can hear the difference between lossless and lossy, but IIRC, the last time I did ABX testing on that, there was only 1 out of 5 tracks I tried where I could tell the difference at a statistically significant rate. (And I'm not sure I'd be able to repeat that.) The best argument I have for storing music in FLAC (or ALAC or some other open lossless format) is analogous to the argument for storing images in a lossless rather than lossy format if you have the space: if you ever have to transcode the file to something else, start with the highest quality possible.

imhelpingu 8y ago
> 1 out of 5 tracks I tried where I could tell the difference at a statistically significant rate. Hate to sound like a broken record, but what are you arguing with me about?

ovao 8y ago

> The author explains that it's a psychoacoustic model and then demonstrates how various artifacts in various waveforms are the result of compromises within this model. The explanations aren’t themselves incorrect — there’s certainly low-pass filtering, pre- and post-echo artifacting and so on, and these reflect in the waveforms — but to reference a waveform and to say “this sounds bad because it looks like this” doesn’t really hold water. Visual differences are not necessarily audible differences, which is the fact psychoacoustic encoding leverages. If an encoder’s design goal was to produce visually-comparable waveforms, a different approach would be used. > In fact, CDs can only replicate frequencies below 22kHz and even that's within the hearable range of many (mostly younger) people. There is no useful or meaningful content above ~18 kHz (aside from dither) on most recordings. There may be exceptions, but by and large, on real music recordings, the information above that frequency isn’t valuable, and is the among the easiest things to discard.

imhelpingu 8y ago
Again, I have no idea what you think we disagree about. Your reply, like most of the replies, is premised on the idea that yes you can hear the difference in some cases.