
Sine-wave speech audio encoding - pero_p
https://mobile.twitter.com/BrianRoemmele/status/1263583401677746176
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ssfrr
I love this demo. It’s a good example of how much our perception is affected
by our priors.

This is a other great example, where speech is synthesized with an acoustic
piano (though the keys are controlled digitally, the sound is just from the
hammers and strings). Without the subtitles you probably couldn’t understand,
but it sounds pretty clear when you know what it’s saying already.

[https://youtu.be/muCPjK4nGY4](https://youtu.be/muCPjK4nGY4)

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hprotagonist
you hit it on the nose here. This is a stellar example of priming.

Have you also done your fair share of psychophysics? :-D

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garaetjjte
Source: [https://www.mrc-cbu.cam.ac.uk/people/matt.davis/sine-wave-
sp...](https://www.mrc-cbu.cam.ac.uk/people/matt.davis/sine-wave-speech/)

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gwbas1c
???

All sound is a sum of sine waves. The term "sine wave speech" makes as much
sense as "wet water."

The demo is cool, but pick a name that makes sense.

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dragonwriter
> All sound is a sum of sine waves.

No, it's not, though that's a popular way of encoding sound data. A square or
triangular wave will still be a sound, with a distinct character to a sine
wave of the same frequency.

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kaoD
A square or triangular wave is a sum of sine waves.

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jdiez17
As far as I know, any arbitrary waveform can be represented by an _infinite_
sum of sine waves, and approximated by a finite sum of sine waves. However, I
don't know if you can assert that a sine wave is the only fundamental building
block for sound that exists. Is there a physical reason for that statement?

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hrydgard
There's an infinite number of different sets of orthogonal bases that you can
construct any signal from. Sine waves (with phase) are a quite natural and
convenient choice though, for mathematical reasons (for example, the
efficiency of the Fourier transform).

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jdiez17
Sure, but there may be a reason why non-sinusoidal sound waves cannot exist in
practice. For example, if I try to generate a square wave by applying +5V and
-5V to a speaker, the diaphragm does not move instantaneously so the resulting
pressure wave is not discrete. However, a triangle waveform may be physically
realizable. But I'm not sure about that either, because a speaker is
ultimately an inductor and hence the current flowing through it is non-linear.

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hatsunearu
I did a deep dive into this, but this just seems to be the case about
sinusoids. technically any well behaved periodic functions can be the basis
function for all fourier-related stuff (there actually is a FT where a square
wave is the basis function, but I can't seem to find it) but there seems to be
something special about sin(x) and cos(x) that makes it more convenient to
analyze our physical world. They seem to be the result (and the only result)
for some class of very simple linear differential equations, which because of
its simplicity, happens very often in nature. That's why FT uses sin(x) and
cos(x).

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exmadscientist
>there actually is a FT where a square wave is the basis function, but I can't
seem to find it

Haar transform? Technically that's a wavelet transform, but that's a
distinction without tremendous difference.

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hatsunearu
i meant the walsh transform, but that's also neat

