Get the microphone out of your pocket!
April 5, 2014 8:18 PM   Subscribe

I've been asked to write summaries of some recordings of meetings. Problem is, whoever recorded it had the microphone in his shirt or his pocket or something, and there's impossible rustling preventing me from hearing what they're saying half the time! Especially when someone asks a question and they start explaining details. Is there any software I can run these sound files through to reduce some of that?
posted by saysthis to Computers & Internet (7 answers total) 2 users marked this as a favorite
Best answer: My install of Audacity has a 'Noise Removal' filter under the 'Effect' menu. You load your audio file, select a snippet that's just the noise you want removed, then tell it which parts of the file to remove it from (IE select the whole track, or just this minute's worth). Haven't tried it myself, but it's worth a shot. And free.
posted by carsonb at 8:36 PM on April 5, 2014 [1 favorite]

Best answer: In short, no. Noise removal is meant to work well with noises that are consistent in features - for example, a noisy hum that has specific frequency characteristics the same throughout the whole recording. Noise removal works well for things that are regular. Impulse noises, like the ones from the recordings in the pocket, are unpredictable and so noise removal doesn't work well in these situations.

When professionals are phonetically transcribing voice samples, they typically listen 3 times and then mark that section as unintelligible if that section can't be understood at that point. Listening to something more than three times is going to A - unproductive and B - make you hear things that aren't there. Do your best and move on.

If you have money and time to spend on this, have a look at iZotope RX 3. It might be a good idea to read the manual to see what noise removal products are actually capable of - it's not just a matter of select wave form and then hitting enhance.
posted by Brent Parker at 9:01 PM on April 5, 2014 [4 favorites]

Response by poster: Yeah, I'm trying to run this through Audacity and trying every setting on the noise removal feature they'll let me adjust on multiple sections of the file (some pure noise, some noise + voice), but all I'm succeeding in doing is taking the VOICE out, the one consistent thing in the file. A for effort I guess.
posted by saysthis at 10:45 PM on April 5, 2014

Best answer: saysthis: "… but all I'm succeeding in doing is taking the VOICE out …"

If this isn't just hyperbole, and you are actually taking a significant amount of the voice out - well, then you can simply subtract that result from the original & be left with maybe enough voice to be intelligible.

Though having fscked around with this sort of thing for hours, multiple times in the past, with varying degrees of success, I'm going to heartily recommend the "listen 3 times, then mark as 'unintelligible'" rule.
posted by Pinback at 11:15 PM on April 5, 2014 [2 favorites]

Response by poster: Trying to isolate the voice might be something to try when I'm not under deadline pressure, but this is a repeat client, and at this point if they don't know to take the recorder out of their pocket, or shave, or whatever is constantly brushing up against the microphone, I don't feel compelled to help anymore. Audio, even surreptitious audio: can it be so hard?
posted by saysthis at 12:10 AM on April 6, 2014

Depending on how much you want/need the content of the recordings, it might be worth it to post this as a transcription gig on eLance and see if the bids for the job are affordable. Professional transcriptionists have the software and sharp ears to make out what people are saying in these sorts of recordings, and many of them are in parts of the world where a livable wage is much lower so it might be cheaper than you think.
posted by Jacqueline at 1:33 AM on April 6, 2014

If the cloth is filtering out certain frequencies, you can try running it through a band pass filter and boosting the output at the appropriate frequency.
posted by empath at 7:46 AM on April 6, 2014

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