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That's kind of the key theory behind why JPEG (and other lossy encodings) work at all. A perfect being would see a JPEG next to a PNG or TIFF and find the first

That's kind of the key theory behind why JPEG (and other lossy encodings) work at all. A perfect being would see a JPEG next to a PNG or TIFF and find the first repugnantly error-ridden. But we tend to ignore high-frequency data's specifics most of the time, so it psychologically works. I often wonder though, what do my cat and dog hear when I'm playing compressed music? Does it sounds like a muddy phone call to them?

jdiff 3y ago
No, audio compression doesn't filter out high frequencies, that's just what computer audio as a whole does. And I don't think there's enough of those high frequency components in what humans typically record for a cat or dog to notice the difference. As far as compression, the tricks that work on us should work on them.
- LordDragonfang 3y ago
  >MP3 compression works by reducing (or approximating) the accuracy of certain components of sound that are considered (by psychoacoustic analysis) to be beyond the hearing capabilities of most humans. -via Wikipedia This holds true for most other audio compression as well. Now, it's true that max recording frequency is bounded by sample rate via the Nyquist theorem, but that doesn't mean we're incapable of recording at higher fidelity - we just don't bother most of the time, because on consumer hardware it's going to be filtered out eventually anyway (or just not reproduced well enough, due to low-quality physical hardware). Recording studios will regularly produce masters that far exceed that normal hearing range though.
- a-dub 3y ago
  the early xing mp3 codec famously cut everything off above 18khz, but that was out of spec. :) instead perceptual audio compression typically filters out frequencies that neighbor other frequencies with lots of power. deleting these neighbors is called perceptual masking and to the best of my knowledge, we do not actually know if it works the same way in animal auditory systems.
bob1029 3y ago
> Does it sounds like a muddy phone call to them? Likely no. Audio is decidedly less "compressible" in human perceptual terms. The brain is amazingly skilled at detecting time delay and frequency deviations, so this perceptual baseline likely extends (mostly) to your pets. You can fool the eyes a lot more easily. You can take away 50%+ or more of the color information before even a skilled artist will start noticing.
- a-dub 3y ago
  while work has been done to characterize frequency sensitivity across species (which does vary quite a bit, especially in the higher ranges (>20khz)), i haven't seen any work that has been done to explore frequency domain perceptual masking curves in a cross species context. since some species use their auditory systems for spatial localization, i would guess that the perceptual system would be totally different in those contexts.
- sdenton4 3y ago
  There are real differences in audio perception, though. Frequency range and sensitivity to different frequencies is a big difference in other animals; I would expect cats (who chase rodents, which often have very high pitched or even ultrasonic vocalizations) to be more sensitive to high frequencies than humans, and thus low passed / low sample rate audio could sounds 'bad.' Another aspect is time resolution. Song birds can have 2-4x the time resolution of human hearing, which helps distinguish sounds in their very fast, complex calls. This may lead to better perception of artifacts in lossy coding schemes, but it's hard to say for sure. Edit: reference on cat hearing: https://pubmed.ncbi.nlm.nih.gov/4066516 https://pubmed.ncbi.nlm.nih.gov/4066516 The hearing range of the cat for sounds of 70 dB SPL extends from 48 Hz to 85 kHz, giving it one of the broadest hearing ranges among mammals.
  - xenadu02 3y ago
    True but hearing is logarithmic in both volume and frequency domains. Double the power does not equate to anything near double the loudness. Similarly each doubling of frequency is only one octave higher. Hearing up to 80khz doesn't mean hearing 4x more than humans... 10 octaves for humans, 12 octaves for cats. In a musical sense it probably isn't noticeable.

jdiff 3y ago

No, audio compression doesn't filter out high frequencies, that's just what computer audio as a whole does. And I don't think there's enough of those high frequency components in what humans typically record for a cat or dog to notice the difference. As far as compression, the tricks that work on us should work on them.

LordDragonfang 3y ago
>MP3 compression works by reducing (or approximating) the accuracy of certain components of sound that are considered (by psychoacoustic analysis) to be beyond the hearing capabilities of most humans. -via Wikipedia This holds true for most other audio compression as well. Now, it's true that max recording frequency is bounded by sample rate via the Nyquist theorem, but that doesn't mean we're incapable of recording at higher fidelity - we just don't bother most of the time, because on consumer hardware it's going to be filtered out eventually anyway (or just not reproduced well enough, due to low-quality physical hardware). Recording studios will regularly produce masters that far exceed that normal hearing range though.
a-dub 3y ago
the early xing mp3 codec famously cut everything off above 18khz, but that was out of spec. :) instead perceptual audio compression typically filters out frequencies that neighbor other frequencies with lots of power. deleting these neighbors is called perceptual masking and to the best of my knowledge, we do not actually know if it works the same way in animal auditory systems.

bob1029 3y ago

> Does it sounds like a muddy phone call to them? Likely no. Audio is decidedly less "compressible" in human perceptual terms. The brain is amazingly skilled at detecting time delay and frequency deviations, so this perceptual baseline likely extends (mostly) to your pets. You can fool the eyes a lot more easily. You can take away 50%+ or more of the color information before even a skilled artist will start noticing.

a-dub 3y ago
while work has been done to characterize frequency sensitivity across species (which does vary quite a bit, especially in the higher ranges (>20khz)), i haven't seen any work that has been done to explore frequency domain perceptual masking curves in a cross species context. since some species use their auditory systems for spatial localization, i would guess that the perceptual system would be totally different in those contexts.
sdenton4 3y ago
There are real differences in audio perception, though. Frequency range and sensitivity to different frequencies is a big difference in other animals; I would expect cats (who chase rodents, which often have very high pitched or even ultrasonic vocalizations) to be more sensitive to high frequencies than humans, and thus low passed / low sample rate audio could sounds 'bad.' Another aspect is time resolution. Song birds can have 2-4x the time resolution of human hearing, which helps distinguish sounds in their very fast, complex calls. This may lead to better perception of artifacts in lossy coding schemes, but it's hard to say for sure. Edit: reference on cat hearing: https://pubmed.ncbi.nlm.nih.gov/4066516 https://pubmed.ncbi.nlm.nih.gov/4066516 The hearing range of the cat for sounds of 70 dB SPL extends from 48 Hz to 85 kHz, giving it one of the broadest hearing ranges among mammals.
- xenadu02 3y ago
  True but hearing is logarithmic in both volume and frequency domains. Double the power does not equate to anything near double the loudness. Similarly each doubling of frequency is only one octave higher. Hearing up to 80khz doesn't mean hearing 4x more than humans... 10 octaves for humans, 12 octaves for cats. In a musical sense it probably isn't noticeable.