5 ms·

Very interesting. I wonder how it would cope with some noise -- for example playing the resultant file and recording it with a microphone for example. I suspec

by naggie 11y ago

Very interesting. I wonder how it would cope with some noise -- for example playing the resultant file and recording it with a microphone for example. I suspect there will be content lost at the bottom and the top of the image depending on the frequency response of the microphone/speaker.

wrigby 11y ago
I would expect to see the frequency response of the speaker + mic combination show up as darker and lighter horizontal bands in the image (since these spectrograms are plotted with frequency on the y axis). It might look really cool! Edit: depending on the time alignment / phase response of the speakers, you might see the low frequency parts of the image get distorted to the right.
- kylophone 11y ago
  Give it a try! The output file contains both very low frequencies and also frequencies up to Nyquist, in this case 24kHz.
  - wrigby 11y ago
    I'll try to give it a shot! What are you using to generate the spectrograms?
    - kylophone 11y ago
      sox -c 1 -r 48000 -b 32 -e float -t raw out.raw -n spectrogram
      - _lce0 11y ago
        please post your results! science is fun
KeytarHero 11y ago
If it's just through a cheap speaker and mic, you'll probably lose a lot of the image. This uses a linear frequency scale (which is just the nature of Fourier transforms), whereas our ears are sensitive on a log frequency scale. In other words, the information that's most important to our hearing, which is what a mic & speaker will preserve the best, is in the bottom 10% of the image. A cheap speaker & mic will probably lose a lot of content above about 10 kHz - which is the entire top half of the image. Even though this wouldn't be that huge a difference to our ears, it would sure look bad in the image. As for background noise, the difference would probably look like the difference here: http://www.sweetwater.com/insync/media/2010/09/RXAdv-e-xlarge.jpg http://www.sweetwater.com/insync/media/2010/09/RXAdv-e-xlarg... (that's a screenshot of audio restoration software that removes noise, so it's technically doing the opposite process as best it can, but the difference would be similar).
dktbs 11y ago
This isn't exactly related (as it doesn't produce a spectrogram), but the software pixivisor plays around with this idea: http://warmplace.ru/soft/pixivisor/ http://warmplace.ru/soft/pixivisor/ The software can act as a transmitter or receiver. In trasmitter mode, you can provide it a static image or animated gif, which it will convert into audio which plays continuously. In receiver mode, pixivisor listens via the mic or line-in (depending on hardware platform and whats attached) and reconstructs the image from the audio. You can then manipulate the audio however you want. This demo uses a korg monotron's low pass filter and LFOs to mangle an animated gif of a cat: https://www.youtube.com/watch?t=63&v=g2W1W4fwEkg https://www.youtube.com/watch?t=63&v=g2W1W4fwEkg Its really interesting to me to see how the audio modulation is represented in the receiver's output.

by naggie 11y ago

wrigby 11y ago

I would expect to see the frequency response of the speaker + mic combination show up as darker and lighter horizontal bands in the image (since these spectrograms are plotted with frequency on the y axis). It might look really cool! Edit: depending on the time alignment / phase response of the speakers, you might see the low frequency parts of the image get distorted to the right.

kylophone 11y ago
Give it a try! The output file contains both very low frequencies and also frequencies up to Nyquist, in this case 24kHz.
- wrigby 11y ago
  I'll try to give it a shot! What are you using to generate the spectrograms?
  - kylophone 11y ago
    sox -c 1 -r 48000 -b 32 -e float -t raw out.raw -n spectrogram
    - _lce0 11y ago
      please post your results! science is fun

KeytarHero 11y ago

If it's just through a cheap speaker and mic, you'll probably lose a lot of the image. This uses a linear frequency scale (which is just the nature of Fourier transforms), whereas our ears are sensitive on a log frequency scale. In other words, the information that's most important to our hearing, which is what a mic & speaker will preserve the best, is in the bottom 10% of the image. A cheap speaker & mic will probably lose a lot of content above about 10 kHz - which is the entire top half of the image. Even though this wouldn't be that huge a difference to our ears, it would sure look bad in the image. As for background noise, the difference would probably look like the difference here: http://www.sweetwater.com/insync/media/2010/09/RXAdv-e-xlarge.jpg http://www.sweetwater.com/insync/media/2010/09/RXAdv-e-xlarg... (that's a screenshot of audio restoration software that removes noise, so it's technically doing the opposite process as best it can, but the difference would be similar).

dktbs 11y ago

This isn't exactly related (as it doesn't produce a spectrogram), but the software pixivisor plays around with this idea: http://warmplace.ru/soft/pixivisor/ http://warmplace.ru/soft/pixivisor/ The software can act as a transmitter or receiver. In trasmitter mode, you can provide it a static image or animated gif, which it will convert into audio which plays continuously. In receiver mode, pixivisor listens via the mic or line-in (depending on hardware platform and whats attached) and reconstructs the image from the audio. You can then manipulate the audio however you want. This demo uses a korg monotron's low pass filter and LFOs to mangle an animated gif of a cat: https://www.youtube.com/watch?t=63&v=g2W1W4fwEkg https://www.youtube.com/watch?t=63&v=g2W1W4fwEkg Its really interesting to me to see how the audio modulation is represented in the receiver's output.