How the cochlea computes (2024) • Hacker News Board

Re: How the cochlea computes (2024)

#31

Post by jacquesm » Thu, Oct 30, 2025, 6:09 PM UTC

TheOtherHobbes wrote: post #28

jacquesm wrote: post #9

Earlier quoted context omitted.

It's even more complex than that. The low notes are hard to tune because the fundamentals are very close to each other and you need to have super good hearing to match the beats, fortunately they sound for a long time so that helps. Missing fundamentals are a funny thing too, you might not be 'hearing' what you think you hear at all! The high notes are hard to tune because they sound very briefly (definitely on a pia…

See also, psychoacoustics. The ear doesn't just do frequency decomposition. It's not clear if it even does frequency decomposition. What actually happens is lot of perceptual modelling and relative amplitude masking which makes it possible to do real-time source separation. Which is why we can hear individual instruments in a mix. And this ability to separate sources can be trained. Just as pitch perception can be tr…

Yes, indeed, to think about the ear as the thing that hears is already a huge error. The ear is - at best - a faulty transducer with its own unique way of turning air pressure variations into nerve impulses and what the brain does with those impulses is as much a part of hearing as the mechanics of the ear, just like a computer keyboard does not interpret your keystrokes, it just turns them into electrical signals.

Re: How the cochlea computes (2024)

#32

Post by xeonmc » Thu, Oct 30, 2025, 6:09 PM UTC

bobmcnamara wrote: post #24

TheOtherHobbes wrote: post #19

Earlier quoted context omitted.

Pretty much, but phase is also included. Which matters for some things.

But mostly not for ears it turns out! Phase matters for some wideband signals, but most folks struggle to tell apart audio from hilbert-90-degree-shifted-audio

Phase is required if it is to be a reversible transform. Otherwise would just be a Functional.

Re: How the cochlea computes (2024)

#33

Post by SoftTalker » Thu, Oct 30, 2025, 6:10 PM UTC

edbaskerville wrote: post #21

To summarize: the ear does not do a Fourier transform, but it does do a time-localized frequency-domain transform akin to wavelets (specifically, intermediate between wavelet and Gabor transforms). It does this because the sounds processed by the ear are often localized in time. The article also describes a theory that human speech evolved to occupy an unoccupied space in frequency vs. envelope duration space. It mak…

Ears evolved long before speech did. Probably in step with vocalizations however.

Re: How the cochlea computes (2024)

#34

Post by rolph » Thu, Oct 30, 2025, 6:13 PM UTC

nakulgarg22 wrote: post #17

rolph wrote: post #5

Earlier quoted context omitted.

the closest i have been, was acoustic phase discrimination by owls. there appears to be no software for this, its all hardware, the signal format flips as it travels through the anatomy.

This might be interesting for you - https://nakulg.com/assets/papers/owlet_mobisys2021_nakul.pdf Owls use asymmetric skull structure which helps them in spatial perception of sound.

that was the start of it. the offset otic openings result in differential arrival times of the acoustic peaks, thus phase differential.

neurosynaptically, there is no phase, there is frequency shift corresponding to presynaptic intensity, and there is spatio-temporal integration of these signals. temporal integration is where "phase" matters

its all a mix of "digital" all or nothing "gates" and analog frequency shift propagation of the "gate" output.

its all made nebulous by the adaptive, and hysteretic nature of the elements in neural "circuitry"

Re: How the cochlea computes (2024)

#35

Post by adornKey » Thu, Oct 30, 2025, 6:14 PM UTC

This subject has bothered me for a long time. My question to guys into acoustics was always: If the cochlea performs some kind of Fourier transform, what are the chances, that it uses sinus waves as a base for the vector-space? - if it did anything like that it could just as good use any slightly different wave-forms as a base for transformation. Stiffness and non-linearity will for sure take care that any ideal rubber model in physics will in reality be different from the perfect sinus.

Re: How the cochlea computes (2024)

#36

Post by Sharlin » Thu, Oct 30, 2025, 6:14 PM UTC

SoftTalker wrote: post #33

edbaskerville wrote: post #21

To summarize: the ear does not do a Fourier transform, but it does do a time-localized frequency-domain transform akin to wavelets (specifically, intermediate between wavelet and Gabor transforms). It does this because the sounds processed by the ear are often localized in time. The article also describes a theory that human speech evolved to occupy an unoccupied space in frequency vs. envelope duration space. It mak…

Ears evolved long before speech did. Probably in step with vocalizations however.

Not sure about that; I'd guess that vibration-sensing organs first evolved to sense disturbances (in water, on seafloor, later on dry ground and in air) caused by movement, whether of a predator, prey, or a potential mate. Intentional vocalizations for signalling purposes then evolved to utilize the existing modality.

Re: How the cochlea computes (2024)

#37

Post by gowld » Thu, Oct 30, 2025, 6:14 PM UTC

Why is there no box diagram for cochlea "between wavelet and Gabor" ?

Re: How the cochlea computes (2024)

#38

Post by shermantanktop » Thu, Oct 30, 2025, 6:16 PM UTC

The thesis about human speech occupying less crowded spectrum is well aligned with a book called "The Great Animal Orchestra" (https://www.amazon.com/Great-Animal-Orchestra-Finding-Origin...).

That author details how the "dawn chorus" is composed of a vast number of species making noise, but who are able to pick out mating calls and other signals due to evolving their vocalizations into unique sonic niches.

It's quite interesting but also a bit depressing as he documents the decline in intensity of this phenomenon with habitat destruction etc.

Re: How the cochlea computes (2024)

#39

Post by cnity » Thu, Oct 30, 2025, 6:29 PM UTC

toast0 wrote: post #27

xeonmc wrote: post #26

Earlier quoted context omitted.

Analogy: when you knock on doors, how do you decide what rhythm and duration to use, so that it won’t be mistaken as accidentally hitting the door?

Shave and a haircut is the only option in my knocking decision tree.

Thanks for giving your two bits on the matter.

Re: How the cochlea computes (2024)

#40

Post by [deleted] » Thu, Oct 30, 2025, 6:30 PM UTC

jacquesm wrote: post #9

fallingfrog wrote: post #7

Earlier quoted context omitted.

I haven't noticed that effect, to be honest. Actually I think its the really low bass frequencies that are harder to tune- especially if you remove the harmonics and just leave the fundamental. Are you perhaps experiencing some high frequency hearing loss?

It's even more complex than that. The low notes are hard to tune because the fundamentals are very close to each other and you need to have super good hearing to match the beats, fortunately they sound for a long time so that helps. Missing fundamentals are a funny thing too, you might not be 'hearing' what you think you hear at all! The high notes are hard to tune because they sound very briefly (definitely on a pia…

[deleted]