Yesterday I heard a fantastic presentation in Yarmouth, Maine, by teacher Amy Sanders about her Arab Spring Project. I took notes and shared links during her presentation, and also recorded the presentation with permission using my iPhone and the free iOS app/service Cinch. Unfortunately there was a loud heater fan running in the classroom where Amy shared the presentation, which is pretty distracting in the “raw” recording. This evening I used the free/home version of WavePad software to “Apply Spectral Subtraction.” This was a two part process. After opening the raw mp3 audio file in WavePad I selected a small portion of the recording (about 2 seconds) in which no one talked and ONLY the fan noise was audible.

WavePad - Grab Noise Sample from Selected Area

Then I chose “Apply Spectral Subtraction” from the EFFECTS – NOISE REDUCTION menus.

WavePad - Apple Spectral Subtraction

I saved the edited file in WAV format, normalized it using free Levellator software, and then converted it to a 32 kbps mp3 file using Switch software. I lastly uploaded it to my “Fuel for Educational Change Agents” podcast channel which is running free/open source Podcast Generator software.

I am not entirely pleased with the results, but it is better than the “noisy” original. Do you know of or use a better free (or inexpensive) software option for removing background noise? I tried Audacity‘s noise removal effect but didn’t get good results, WavPad worked better.

At MacWorld in 2007 I saw a vendor floor demonstration of Adobe Audition‘s background noise removal power and was totally blown away. It doesn’t appear Audition is available for standalone purchase, and I don’t really want to pay hundreds of dollars (or even thousands) for an Adobe Creative Suite bundle. I’d love to hear about other free/affordable noise removal audio editing programs besides WavPad, so please share a link as a comment if you’ve got suggestions.

If you’re interested in the techniques I used to normalize the audio file and compress it, I created a screencast of that process a couple of weeks ago you can check out.

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