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How the cochlea computes (2024)

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Re: How the cochlea computes (2024)

#151

Post by kulahan »

didroe wrote: post #140
kulahan wrote: post #120

Earlier quoted context omitted.

It's about filling open niches. City birds were an open niche for a long time. The ones who adapted to handle that better are thriving in better population numbers than those which can only survive with 13 specific types of trees. Even still, among the populations of birds not adapting to the city, they are being forcibly adapted in other ways. If the reach is too big, they die. This is how evolution works, and has a…

The problem is that evolution works on a much longer timescale than the pace of change to the environment that humans cause.

Only if our explicit goal is to preserve the exact environment that was in place when humans showed up and gained enough knowledge to decide change wasn't allowed anymore

Re: How the cochlea computes (2024)

#152

Post by fluoridation »

antognini wrote: post #149
dr_dshiv wrote: post #142

Earlier quoted context omitted.

Neither this article nor this book discuss the fact that hair cells phase lock to sound pulses. While individual neurons can fire no more than 200hz, populations of neurons are capable of phase locking to frequencies up to thousands of hertz. Because cochlear implants only rely on stimulating the places in the cochlea related to particular frequencies but do not play the actual frequencies themselves (for reasons unk…

Yes this is another important difference between human auditory perception and classical signal processing algorithms. Typically when processing audio we take a Fourier transform and then throw away the phase information. Mostly the amplitude information is all you need to understand a sound, but the ear actually is capable of picking up phase information. (I thought this was discussed at some point in Lyon's book bu…

What does that mean, though? If you invert the sign of a waveform it sounds the same, so if it's not picking that up, what phase and relative to what does it pick up?

Re: How the cochlea computes (2024)

#153

Post by fluoridation »

paulgerhardt wrote: post #146
didroe wrote: post #140

Earlier quoted context omitted.

The problem is that evolution works on a much longer timescale than the pace of change to the environment that humans cause.

While I understand the spirit of this comment, if you look at the fossil record you’ll see that’s objectively not true. Roughly half of the shifts in the last 11 evolutionary periods, over the last 500 million years, were caused by changes that occurred in a-few-hours-to-a-few-thousand-years with 75%-90% species lost. Evolution did not fail to work then.

I think GP meant "evolution without catastrophic biodiversity bottlenecks". Of course evolution will "work" as long as a single species survives.

Re: How the cochlea computes (2024)

#154

Post by jibal »

kulahan wrote: post #120
jibal wrote: post #109

Earlier quoted context omitted.

The dying out of birds "in nature" and the adaptations to cities are largely independent as they occur in different populations.

It's about filling open niches. City birds were an open niche for a long time. The ones who adapted to handle that better are thriving in better population numbers than those which can only survive with 13 specific types of trees. Even still, among the populations of birds not adapting to the city, they are being forcibly adapted in other ways. If the reach is too big, they die. This is how evolution works, and has a…

I know very well how evolution works ... and your comment in no way refutes or even responds to my point about your previous comment about "trade offs". As I pointed out, there are multiple populations of birds, and there's no zero sum game such that what happens to one population determines what happens to another ... that sort of thinking is behind the "if monkeys evolved into humans then why are there still monkeys" confusion of creationists.

Re: How the cochlea computes (2024)

#155

Post by jibal »

paulgerhardt wrote: post #146
didroe wrote: post #140

Earlier quoted context omitted.

The problem is that evolution works on a much longer timescale than the pace of change to the environment that humans cause.

While I understand the spirit of this comment, if you look at the fossil record you’ll see that’s objectively not true. Roughly half of the shifts in the last 11 evolutionary periods, over the last 500 million years, were caused by changes that occurred in a-few-hours-to-a-few-thousand-years with 75%-90% species lost. Evolution did not fail to work then.

You are tautologically saying that massive shifts resulted from massive changes, but that doesn't contradict the statement about evolution--which is about far more than such "shifts" (not an aspect of nature but rather changes large enough for humans to perceive)--operating over long time periods. Every single instance of offspring is a "shift" from its progenitors.

Also talking about evolution failing to work is a category mistake--evolution is an ongoing process that is the inevitable result of imperfectly replicating biological mechanisms and there's no "succeed" or "fail" about it.

Re: How the cochlea computes (2024)

#156

Post by antognini »

fluoridation wrote: post #152
antognini wrote: post #149

Earlier quoted context omitted.

Yes this is another important difference between human auditory perception and classical signal processing algorithms. Typically when processing audio we take a Fourier transform and then throw away the phase information. Mostly the amplitude information is all you need to understand a sound, but the ear actually is capable of picking up phase information. (I thought this was discussed at some point in Lyon's book bu…

What does that mean, though? If you invert the sign of a waveform it sounds the same, so if it's not picking that up, what phase and relative to what does it pick up?

The relative phase between the different frequencies. You're correct that the ear can't pick up a global phase change.

As an extreme example, consider a delta function: there is silence, then a brief spike, and then silence again. If you're just looking at the amplitudes of the various frequency components of this signal it is indistinguishable from white noise. The only thing that makes this signal look (and sound) different from white noise is the relative phase between the different frequency components. The ear's ability to detect these phase synchronicities helps it to pick out "peakiness" in waveforms more easily. (This is, in turn, important for understanding consonants in speech, which is extremely important for intelligibility, particularly in noisy environments.)

Re: How the cochlea computes (2024)

#157

Post by smolder »

fluoridation wrote: post #152
antognini wrote: post #149

Earlier quoted context omitted.

Yes this is another important difference between human auditory perception and classical signal processing algorithms. Typically when processing audio we take a Fourier transform and then throw away the phase information. Mostly the amplitude information is all you need to understand a sound, but the ear actually is capable of picking up phase information. (I thought this was discussed at some point in Lyon's book bu…

What does that mean, though? If you invert the sign of a waveform it sounds the same, so if it's not picking that up, what phase and relative to what does it pick up?

This doesn't directly answer your questions, but I can share one example where our sensitivity to phase information becomes apparent: when you play the sound of a pair of hands clapping. It's a great test case for hearing when a set of speakers has phase alignment problems, which is underappreciated as a metric for speaker systems. (It's rare even for experts to put a lot of effort into uniform phase response when designing speakers. It's one of the hardest things to manage. Frequency response, harmonic distortion levels, dispersion and even aesthetics usually take priority.)

Likewise, if you mess with the phase alignment of different frequencies in a hand clap sample and play it through an otherwise phase-coherent source like ear buds or headphones, the misalignment is really obvious.

Re: How the cochlea computes (2024)

#158

Post by kulahan »

jibal wrote: post #154
kulahan wrote: post #120

Earlier quoted context omitted.

It's about filling open niches. City birds were an open niche for a long time. The ones who adapted to handle that better are thriving in better population numbers than those which can only survive with 13 specific types of trees. Even still, among the populations of birds not adapting to the city, they are being forcibly adapted in other ways. If the reach is too big, they die. This is how evolution works, and has a…

I know very well how evolution works ... and your comment in no way refutes or even responds to my point about your previous comment about "trade offs". As I pointed out, there are multiple populations of birds, and there's no zero sum game such that what happens to one population determines what happens to another ... that sort of thinking is behind the "if monkeys evolved into humans then why are there still monkey…

In what world is it not a zero-sum game? You don't think that the human population has affected others? You are not aware of what keystone species are, like how wolves are so singularly important, they can literally force geographic changes to a region, which obviously has a massive effect on other species?

I think you might be a bit out of your depth here. You really seem to not know much about evolution.

Re: How the cochlea computes (2024)

#159

Post by jibal »

jibal wrote: post #154
kulahan wrote: post #120

Earlier quoted context omitted.

It's about filling open niches. City birds were an open niche for a long time. The ones who adapted to handle that better are thriving in better population numbers than those which can only survive with 13 specific types of trees. Even still, among the populations of birds not adapting to the city, they are being forcibly adapted in other ways. If the reach is too big, they die. This is how evolution works, and has a…

I know very well how evolution works ... and your comment in no way refutes or even responds to my point about your previous comment about "trade offs". As I pointed out, there are multiple populations of birds, and there's no zero sum game such that what happens to one population determines what happens to another ... that sort of thinking is behind the "if monkeys evolved into humans then why are there still monkey…

> I think you might be a bit out of your depth here. You really seem to not know much about evolution.

Wow, such rude projection, coupled with bizarre strawmen and an apparent complete lack of understanding of what "zero-sum" means even after I explained the sense in which I was using it.

It seems to be a thing with them, e.g., "In what world do you think our energy needs plateau? [total misrepresentation of what their correspondent said] I'm always so surprised to see this 1970s hippie attitude making a comeback, especially since it makes less sense today than ever before."

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