Locating a sound sequence within a sound file

Audacity Help Forum Windows
1

Windows 7 Home Premium
Audacity 2.0.3
Audacity .exe installer obtained from the homepage.

Hi and thank you in advance for your help.
I have a set of lectures in mp3 format that include 2 or 3 actual lectures per file, and I’d like to split the files so each lecture is a separate mp3. The “audio bar” alone (sorry for the poor lingo) doesn’t provide enough information to determine when the lectures stop and start within a file, and I don’t know content of the lectures to be able to distinguish between lectures; which means I can’t narrow down the end point of two lectures by bouncing back and forth in the audio until I find the point of intersection.

I do have one idea, though, which could help me solve the problem, but I’m not sure if it’s feasible. Each lecture begins with an intro ‘tune’ like an episode of a tv show or a podcast. If I could select that section of audio in the beginning of the first file and find everywhere it repeats throughout the rest of the file I would be able to easily locate the start of each lecture and split them accordingly. Is this possible with Audacity? If not, do you know of any other tools that may help me?

Thank you very much for your time, and have a great day.

Warm regards,
Alex

2

Is there a small silent gap between the two lectures? You may be able to use Analyze > Silence Finder.

You do know some pieces of this. The gap is likely to be in the middle third of the file, right? Nobody is likely to stop talking five minutes into the show and break for lunch.

I know of no pattern recognizer. Someone may be able to press one of the other tools into doing this.

If you used the musical passage as the “Profile” in Noise Reduction, would Noise Reduction put a big hole in any other occurrence of the same music?

Koz

3

Here’s a radio show that uses music bumpers. They’re frequently lower than the regular show. This example happens at 35. The full screen display of this show is 53 minutes and I have no trouble finding both bumpers by looking.

Koz
Screen shot 2013-07-23 at 12.35.06 AM.png

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One at 17 and one at 35.
Screen shot 2013-07-23 at 12.39.47 AM.png

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Even if you find the splits you will lose quality by re-encoding the MP3 in Audacity. Just another point to bear in mind. See this page Missing features - Audacity Support for some direct MP3 editing tools.


Gale