MMA Project; Real Time Spectrograms; Mic-Input Jack Oscilloscope

I really hope to start posting/reading about projects.

The project I am working on right now is a microphone data-logger.

I recently discovered that a friend was interested in a spectrograph for studying Mandarin pronunciation.

I tried 3 leads:

  1. microcontrollers — this idea died after I discovered their internal memory was really limited (couldn’t do a good sampling for very long.  I’m still looking for an embedded/portable solution.
  2. The Mic-Input Jack of the computer (would have simultaneously solved my high speed data-logger problem and this problem).
  3. Praat Speech Analyzer — a quick open-source solution to the problem.  This can take such samples and fix the problem if you can install it.

While unable to find a suitable program to do real time spectrograms for sound input, I was able to find an analog for mac’s “say” command in linux: espeak.  It is pretty good and used like this:


echo hello world | espeak

I think I will just need to learn more about the audio input card for computers (current and voltage limitations and sample rates), then I will just use it and “Audacity” for my datalogging (I think that many audio formats can actually record raw data).

After that, it is a simple step to record a voltage divider in real time.  Afterwards I could pull some fancier circuits from Franco’s Op-Amp design text.