4 ms·

> Using FFT to decompose someones speech, I'm getting peaks at 300Hz, 600Hz, 900Hz etc.. My crude understanding is that those are all related to one another, th

by qb45 10y ago

> Using FFT to decompose someones speech, I'm getting peaks at 300Hz, 600Hz, 900Hz etc.. My crude understanding is that those are all related to one another, though I can't quite fathom why. This is not a quirk of FT but a result of the way physical things actually vibrate. You get this output from FT because your input consists of 300/600/900/...Hz sinewaves superimposed on each other. https://en.wikipedia.org/wiki/Harmonics https://en.wikipedia.org/wiki/Harmonics

edblarney 10y ago
There is a person talking - that's it. The peaks at 600Hz and 900Hz are higher than 300Hz. Humans can't make speech at 600 and 900Hz, is my understanding. Listening to it, I don't hear those frequencies. So it's hard for me to understand how they are there.
- ww520 10y ago
  Where do you get your information about human voice frequency range? 600Hz and 900Hz are certainly within the frequency range of human voice.
  - nkurz 10y ago
    I would have all these frequencies were in range, but when I search I find several sources suggesting that 600 and 900 Hz are indeed greater than the fundamental frequencies of human voices: Baby cries have a fundamental frequency (hereafter referred to as Fo) of around 500 Hz (roughly corresponding to the note B4). Child speech ranges from 250-400 Hz (notes B3 to G4, adult females tend to speak at around 200 Hz on average (about G3), and adult males around 125 Hz (or, B2). http://www.ncvs.org/ncvs/tutorials/voiceprod/tutorial/influence.html http://www.ncvs.org/ncvs/tutorials/voiceprod/tutorial/influe... My guess at this point would be that while the "fundamental frequencies" are lower for vowels, higher frequencies are still required for the consonants?
    - ww520 10y ago
      Fundamental frequency is the lower bound of the frequency range. That's the floor.
    - edblarney 10y ago
      900Hz is way out of range for human speech. Now - maybe humans create some higher frequencies, but the dominant frequency you speak at is much lower. Maybe I can understand some 'peaks' at higher ranges ... but the 'big peak' should be at the frequency that is obviously the loudest, which is 100-200Hz. That's the range you speak at. But I also read that those are in fact the 'same frequencies' - simply at different phases. I also read that without 'windowing' (apparently an extremely complicated process) you get wierd results. I did a test with a 'pure' 300Hz tone - and I got a nice peak at 300Hz, but some other, rounded peaks at other ranges. Anyhow - I don't think I'm doing something wrong - I do think that FFT in the real world definitely has some weird artifacts that require interpretation, and they are non-obvious.

by qb45 10y ago

edblarney 10y ago

There is a person talking - that's it. The peaks at 600Hz and 900Hz are higher than 300Hz. Humans can't make speech at 600 and 900Hz, is my understanding. Listening to it, I don't hear those frequencies. So it's hard for me to understand how they are there.

ww520 10y ago
Where do you get your information about human voice frequency range? 600Hz and 900Hz are certainly within the frequency range of human voice.
- nkurz 10y ago
  I would have all these frequencies were in range, but when I search I find several sources suggesting that 600 and 900 Hz are indeed greater than the fundamental frequencies of human voices: Baby cries have a fundamental frequency (hereafter referred to as Fo) of around 500 Hz (roughly corresponding to the note B4). Child speech ranges from 250-400 Hz (notes B3 to G4, adult females tend to speak at around 200 Hz on average (about G3), and adult males around 125 Hz (or, B2). http://www.ncvs.org/ncvs/tutorials/voiceprod/tutorial/influence.html http://www.ncvs.org/ncvs/tutorials/voiceprod/tutorial/influe... My guess at this point would be that while the "fundamental frequencies" are lower for vowels, higher frequencies are still required for the consonants?
  - ww520 10y ago
    Fundamental frequency is the lower bound of the frequency range. That's the floor.
  - edblarney 10y ago
    900Hz is way out of range for human speech. Now - maybe humans create some higher frequencies, but the dominant frequency you speak at is much lower. Maybe I can understand some 'peaks' at higher ranges ... but the 'big peak' should be at the frequency that is obviously the loudest, which is 100-200Hz. That's the range you speak at. But I also read that those are in fact the 'same frequencies' - simply at different phases. I also read that without 'windowing' (apparently an extremely complicated process) you get wierd results. I did a test with a 'pure' 300Hz tone - and I got a nice peak at 300Hz, but some other, rounded peaks at other ranges. Anyhow - I don't think I'm doing something wrong - I do think that FFT in the real world definitely has some weird artifacts that require interpretation, and they are non-obvious.