I have a large number of audio files, each of which contains the pronounciation of a certain word. I need to batch process these files such that they all sound equaly loud when I'm finished with them. I also wish to remove the short pauses that occur at the start and end of each file.

I am working on Mac Os X Mavericks but I can also do this on Windows 7.

Please state if your solution involves software which must be purchased.

Also, I can program using Python so if there is a command line solution which does not have a batch mode, I can probably program the batch part.

  • What's the format of audio files?
    – gronostaj
    Dec 14, 2013 at 21:13

2 Answers 2


Two options spring to mind:

  1. Audacity (free/open source + multiplatform) - provides batch processing of audio files using something called Chains. You can select from a list of effects, filters and edits. Here's a video example of the process. Check the Audacity docs for further information. MP3 support is provided as a separate (free) install depending on your OS - e.g. LAME encoder.

  2. Adobe Audition (paid + Windows/OSX) - Supports batch processing of audio files with multiple effects, filters, etc. More features and slicker interface than Audacity. Called Favourites in Audition this video gives a quick introduction to the system and this guide may help too.


You can batch trim silence at the beginning and the end with Amadeus Pro for Mac OS (need to purchase). You can also normalize (make the same loudness) with Amadeus, but normalization is much more complicated process. There is normalization by the actual loudness of the file and perceived loudness. Amadeus can only provide 'actual loudness normalization'. For perceived loudness you better use Platinum Notes or JRiver Media Center. Need to purchase both. I work with such kind of software every day and, unfortunately, didn't find anything free good enough. But, if you can program, you can try to find something free with Replay Gain algorithm (it's used in JRiver). Not sure, but you might find something. But you should have in mind that most of the players using Replay Gain can not save the files normalized. Only play them.

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