Human hearing beats FFT Options

[ncdrawl]

http://phys.org/news/2013-02-human-fourier...-principle.html

[probedb]

http://phys.org/news/2013-02-human-fourier...-principle.html

A summary of the article would be useful.

[ncdrawl]

http://phys.org/news/2013-02-human-fourier...-principle.html

A summary of the article would be useful.

erm..

it is right in the first paragraph
For the first time, physicists have found that humans can discriminate a sound's frequency (related to a note's pitch) and timing (whether a note comes before or after another note) more than 10 times better than the limit imposed by the Fourier uncertainty principle. Not surprisingly, some of the subjects with the best listening precision were musicians, but even non-musicians could exceed the uncertainty limit. The results rule out the majority of auditory processing brain algorithms that have been proposed, since only a few models can match this impressive human performanc

Read more at: http://phys.org/news/2013-02-human-fourier...nciple.html#jCp

[lvqcl]

From the comments:

The Fourier uncertainty principle doesn't set a limit on how accurately, say, the centre of a gaussian wavepacket, and the central frequency of a wavepacket, can be simultaneously be determined. There's no theorem in mathematics that says this is so and this experiment clearly demonstrates there is no such limit. So the title is a bit misleading.

[greynol]

That title? What about the title of this discussion?!?

This post has been edited by greynol: Feb 9 2013, 18:43

[Alexey Lukin]

Love the title

[greynol]

...with a blunt stick.

[Woodinville]

Ad the Gabor limit does not address known frequencies, either. Geeze.

[Kees de Visser]

Ad the Gabor limit does not address known frequencies, either. Geeze.

JJ, does this study add anything new to the current understanding of how our auditory system works ?

[Woodinville]

Ad the Gabor limit does not address known frequencies, either. Geeze.

JJ, does this study add anything new to the current understanding of how our auditory system works ?

It does show, again, the value of extensive training. It settles what had been claimed anecdotally, which I suppose is some new understanding. It does not break the Gabor bound or do anything astounding, however it does confirm something that has been pretty much taken at face value.

[Porcus]

does this study add anything new to the current understanding of how our auditory system works ?

The authors themselves give a yes-and-no answer to whether they are surprised, the “no” part due to indications from as far back as the 70's that the auditory system does not work as they would have if the hypotheses of the uncertainty principle were applicable. This does not answer the “anything” part of your question, but the authors certainly acknowledge that it isn't unheard of.

[probedb]

it is right in the first paragraph
For the first time, physicists have found that humans can discriminate a sound's frequency (related to a note's pitch) and timing (whether a note comes before or after another note) more than 10 times better than the limit imposed by the Fourier uncertainty principle. Not surprisingly, some of the subjects with the best listening precision were musicians, but even non-musicians could exceed the uncertainty limit. The results rule out the majority of auditory processing brain algorithms that have been proposed, since only a few models can match this impressive human performanc

Read more at: http://phys.org/news/2013-02-human-fourier...nciple.html#jCp

Yes, but posting a link to another web page is not a thread is it. I don't want to go to another website just to find out what your post is about.

[2Bdecided]

Is it worth spending $25 to read this in full?

This kind of thing fascinates me, though I think this is beyond the limits of my understanding.

I understand time/frequency uncertainty, but I think you have to draw a distinction between knowing exactly what's there (in an absolute analytical way), and knowing something is different from something else without knowing (in an absolute analytical way) what either actually is. To put it another way, the FFT has an analytical time/frequency limit, but it can be lossless and reversible - meaning that any differences are preserved and therefore detectable. e.g. A computer can do a mathematical ABX test on the output of an FFT just as well as on the input audio signal. It will get both right every time. The FFT does not force you to lose information.

In the ear, it is one thing to be able to hear an arbitrary signal with no prior knowledge and say "ah, that's three notes, the second one is higher than the first, the third one is really high, and oh wow all their durations are so short and they're so close together that I shouldn't be able to tell that". It's quite another to listen to lots of signals of a certain pattern, learn their sound, and then be able to identify another of that pattern.

Training gives you that latter ability.


I know the ear doesn't transduce sound using an FFT. But I think you have to be really careful saying "this proves it's not subject to the limitations of an FFT, because just an FFT couldn't do this" when, in fact, an FFT followed by a clever computer (brain anyone?) could do pretty much anything.


I'd be interested to hear more from people who understand this better. Have you got any relevant slides JJ?

Cheers,
David.

[Kees de Visser]

I just stumbled upon this blog. Are we heading towards another "Kunchur" discussion ?
http://tapeop.com/blog/2013/02/06/human-he...inty-principle/

More pointedly: until scientists devise and conduct more tests like this one, we may need to continue with a skeptical stance toward the application of mathamatical formulas and AB/ABX testing as the end-all of our windows into human perception.

It's been a long time (80's) since I learned auditory basics at (rec.eng.) school. Lots of Blauert. But even the simplified models always emphasised the importance of time information. I still fail to see what's new in this study.

[Porcus]

More pointedly: until scientists devise and conduct more tests like this one, we may need to continue with a skeptical stance toward the application of mathamatical formulas and AB/ABX testing as the end-all of our windows into human perception.

Impressive ...

[2Bdecided]

More pointedly: until scientists devise and conduct more tests like this one, we may need to continue with a skeptical stance toward the application of mathamatical formulas and AB/ABX testing as the end-all of our windows into human perception.

Impressive ...

Especially as psychoacoustic tests, by definition, are blind tests.

Can you imagine a sighted version?
Tester: "OK, I'm going to play you three very short notes - a low one, a slightly higher one, and a very high one, in that order."
beep beep beep
Tester: "Did you hear what I just described?"
Test subject: "Yes"
Tester: "It's amazing - your hearing is far better than humanly possible"



Cheers,
David.

This post has been edited by 2Bdecided: Feb 11 2013, 12:22

[db1989]

Given that the writer misspelled mathematical and uncertainty, I think it’d be fairly safe to ignore whatever they say.

This post has been edited by db1989: Feb 11 2013, 16:39

[greynol]

Would someone mind correlating the article with the concept of the FFT? The original poster, perhaps?

[ojdo]

Is it worth spending $25 to read this in full?

Access for free here: arxiv.org/pdf/1208.4611.pdf
(Link found in a comment by user AlexDSP in the otherwise highly off-topic discussion below the phys.org article.)

[benski]

Off the top of my head. I might be wrong. But part of the time/frequency uncertainty for FFT is the requirement to save the phase information so that it is reversible. If we replaced the FFT with a bank of IIR bandpass filters, would we not be able to measure frequency magnitude per bin as well as timing information? But this would be at the expense of losing precise phase information.

This post has been edited by benski: Feb 11 2013, 18:35

[2Bdecided]

By taking an FFT, you are performing an (approximate, with issues) time/frequency analysis. You can picture is as a time/frequency grid. Click on "spectral view" in your favourite audio editor, and there it is (but only the amplitude is visible; FFT phase is vital too).

If you use a short FFT, you have fine time resolution, but wide frequency bins.
If you use a longer FFT, you have fine frequency resolution, but longer time bins.

e.g. sampling at 44.1kHz:
a 64-point FFT gives you blocks 1.5ms apart, and 689Hz apart.
a 1024-point FFT gives you blocks 23ms apart, and 43Hz apart.
a 65536-point FFT gives you blocks 1.5 seconds apart, and 0.7Hz apart.

The analysis limit claimed for FFT in that paper (and derived right at the start), is 4*pi better than just hitting the nearest block in this spectral grid would give you.

The human auditory system is doing 10x better than this.

The human auditory system is stunningly good at picking out the start of sharp-onset notes - it amplifies the onset greatly.
IIRC the human auditory system doesn't use the (fairly poor) frequency resolution of its filterbank to determine pitch. There are a couple of different models of how pitch perception probably works, but counting cycles and/or tracking harmonics are the simplest (not entirely accurate) ones. They barely need the filter bank at all.

I'm hoping someone will explain this better though.

Cheers,
David.

[Ethan Winer]

Given that the writer misspelled mathematical and uncertainty, I think it’d be fairly safe to ignore whatever they say.

There's plenty of other reasons to ignore what Allen says. If you follow the link in his current blog to his older Neil Young blog (in the 3rd paragraph, hard to spot), you'll see enough belief to choke a religious cult.

This morning a poster in Lynn Fuston's 3dAudio forum summarized it nicely:

Posted by Andreas Lassak: So, I'm not saying that the headline of the article in question ("Human hearing beats the Fourier uncertainty principle") is wrong, but it could easily be interpreted the wrong way. The problem is, that people, who have no clue about the background of this study, may only be able to understand or, in the worst case, may only be willing to read the headline. They may read it like "New finding about human hearing renders current scientific knowledge worthless" or "Human hearing is much more accurate than previously assumed”.

IMO this exactly describes that Tape Op blog post. All wishful thinking, with no evidence or even a credible theory.

Edit: BTW, I've seen this article put forth in at least two hi-fi forums as evidence that previous knowledge about audio and hearing is now proven wrong. Sigh.

--Ethan

This post has been edited by Ethan Winer: Feb 11 2013, 23:08

[krabapple]

Here's what the audiophilosphere reliably takes away from articles like this, regardless of the actual content:

-- see, sighted claims of difference are valid, and blind testing is unnatural and misleading
-- see, we do need higher sample rates and wordlengths
-- see, analog is better. Especially vinyl.

This post has been edited by krabapple: Feb 12 2013, 07:19

[knutinh]

Is not some wavelet/filterbank transform more relevant than the FFT for comparing with human hearing? If the time-frequency space is sparse, would it not be possible to guess at time/frequency speculatively (incorporating knowledge about the waveform), and produce better results than a general approach could ever do?

I attended a speech by Richard Lyon on models of human hearing. He was very critical of our tendency to approximate it using linear systems, when non-linear components seems to be integral to the whole thing.

-k

[scuttle]

I thought it would be fun and informative to poke Allen by posting a comment:

>>> but I can see that this study shows that the assumed limits of human auditory perception as figured by the Fourier Uncertainty Principle were too narrow - especially when expert listeners (a pro musician and an electronic music producer) are tested<<<

What limits were so "figured"??? Very few people did believe that human auditory processing was FFT based, so these experiments are just confirming mainstream opinion. And what limits relevant to an ABX test would ever have been affected???

It really sounds to me as if you are using something you don't understand as an excuse to justify believing something that you want to believe is true....