Sunday, April 29, 2018

Audio Noise Reduction - 3 small steps are better than 1 big step

I needed to digitise music from a cassette tape.
I was recording with the software "Adobe Audition 2017"
I first tried "Noise Reduction". That reduced the background noise but I had the feeling that it had also made a small change to the music.
I then tried using 2 x simple low impact treatments then finishing off with "Noise Reduction". This gave a much better and IMO usable result:

  1. "De-Hummer" - 50Hz for where I live - otherwise using the default settings.
  2. "De-Hisser" - "Noise Floor" stay with the default of "8 dB". "Reduce by" 18 dB
  3. "Noise Reduction" settings "60%" and "-12 dB"
What I was thinking was that the "Noise Reduction" might work better if I could get the noise level down first by simpler means. It worked first time for this example. I am sharing it here in case the  general principle can work for others.

Music is "Walled City" composed by Ian Eccles-Smith for our film "Walled City" made in 1987. Recovering the music is part of my current project of digitising this movie.
The tape is a chrome tape. Player is a Panasonic SA-PM21 which is a domestic mini home system. I was using an audio cable with 3.5mm plugs to run from the headphone jack to the line input (blue) socket of a desktop computer. Noise in silent passages was about -40 dB which is a "good" as in low value in theory but it sounded unacceptable to me. The above 3-step process got it below the measurement scale ie below -60 dB and silent passages sounded completely silent.