video..."Every sound is a SINE"

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#2
Every sound can be decomposed into sines or composed by sines. Even a square wave. It doesnt mean that "a sound" (i.e. something you hear) is a sine. A sound pressure or electrical signal carried by two wires can only hold one level at each instant iof time. If one ponder this and look at segment of a cats "mjauooo", you will see that the signal is indeed not, or very seldom, a sine. So, yet again, a happy tech video on the internets is not really true. At least not the title.

Every sound is NOT a sine.

I have to admit I didn't bother to watch it... ;-) If the video indeed described what I stated above, I recent it for the click bait title.

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#6
wiseoldtech said:
We hear in analog, we speak in analog.... all noises are analog.
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I agree and so does the vid in the first post. It says there are infinite sines and infinite harmonics in real sounds. The point is that SINES show up all over and how even just a few can make things very convincing. That is it. I get that the title is a bit too basic and incomplete. It is like saying all atoms are protons or something.
 
#8
TNT said:
So we seem to agree that the video title was really poor and dont reflect the content and message!?

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Yeah, it is not the best english. But from a math perspective, it is correct.

I have found a few posts related to sines and audio:
https://www.quora.com/Is-sound-a-sine-wave-or-cosine-wave
https://jackschaedler.github.io/circles-sines-signals/dft_introduction.html

That last link has lots of interactive graphs. From the posts:
The square wave in Figure 1 can be thought of as a compound waveform since it’s composed of three sinusoidal components. In fact, any waveform can be thought of as an aggregation of one or more sine waves. In this section we’ll utilize the dot product to construct a “detector” which is capable of measuring the presence or absence of a given sine wave within a compound waveform.
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https://jackschaedler.github.io/circles-sines-signals/sine_wave_properties.html


Really, all of this about sines is not what I found the most interesting. It was how many tiny phase shifts make up the harmonics. In the video when the sounds of buzzers and toys are recreated the phase shifts can be seen. I did not know the phase would change so much in a recording or for a simulation of a recording...


found one more paper on decoding signals from bats.. https://academic.oup.com/jmammal/article/81/4/927/2372896

The major disadvantage of the Fourier transformation is the inherent compromise that exists between frequency and time resolution. The length of Fourier transformation used can be critical in ensuring that subtle changes in frequency over time, which are very important in bat echolocation calls, are seen. It may be that no single length of transform is ideal for a particular signal; several transformations, each of a different length, may be required before a signal can be described adequately. In a signal that is masked heavily with noise, the start and end points of a call may be more obvious in a spectrogram, because the high-amplitude noise is often of lower spectral density and lower frequency than the echolocation call of interest. However, because of the windowing calculation of the spectrogram, it is less advisable to measure duration of a signal from a spectrogram. Such measurements contain some degree of imprecision, which can be compensated for only after elaborate calibration of a specific spectrogram setting (window size, window shift) against the time–amplitude display.
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#9
HeadShake said:
Hi. What about past 5khz?

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It is presented as great mystery that square wave and sine wave sound the same at higher frequencies, but its very logical. Lets say hearing limit is 15kHz. When you play 10kHz square or sine, they are identical for human, as nothing above 15kHz matters. So only the fundamental is heard, and no harmonics. Bats would hear clear difference.
 
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