24 August 2010

The basic noise removal left something to be desired, so I worked through documentation to come up with a more thorough cleaning process in Audacity.

  1. Use Analyze > Plot Spectrum to identify any specific whine frequency. The example below was based on an 800 Hz frequency.
  2. In Effect > Nyquist Prompt, remove the offending frequency:
    (setf freq 800)
    (setf q .7)
    (if (arrayp s) (vector (notch2 (aref s 0) freq q) (notch2 (aref s 1) freq q)) (notch2 s freq q))
  3. Effect > Leveller, with settings "Moderate" and "-55 dB"
  4. Effect > Amplify (adjust the volume as necessary)
  5. Effect > Noise Removal (same process as before)

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