Hi, I''m using Audacity for sound editing and I was wondering if anyone knows how to make a sound file loop seamlessly? I cut a chunk out of the centre of a rain sound file but there is a little static sound when it loops from the end to the beginning. Is there a way to fix this? http://audacity.sourceforge.net/

I suggest you take the entire sound clip, and duplicate it. Have the first clip overlap the second by about 10 percent, and crossfade the two. Now crop the entire clip from the middle of the first subclip to the middle of the second subclip, such that the cropped region starts and stops in exactly the same point of the original clip. ''course, I''ve never actually done this; it just seems to make sense.

"Sneftel is correct, if rather vulgar." --Flarelocke

The reason why you get a blip on a loop is because the wave is having to jump. If you zoom in a hell of a lot on a wave file, you can see where the individual samples go up and down from the zero line. If the end of the file is starting to go down, whilst the beginning is starting to go up (or vice versa), you get a blip.

The best way that I know of to remove it is to make the start and the end of the file to be on the zero line. Also, the end part is (say) travelling up to the zero line, and the start is travelling up from the zero line. You then get a continuous wave, and (fingers crossed) no blip.

Barry Ryerson
Head of Audio Development
Ryerson Sound Solutions
URL:http://www.ryerson-sound.com

Be careful that you don''t start to get more subtle beats - which are very prevalent in ''pitchless'' tracks like rain. ("Wind" sounds are another classic culprit) They give me a headache.

A way around this is to take both of the suggestions above in combination:

-Make one file that (effectively) starts at zero and ends at zero - as Baz describes. (That way you know the ends tie up)
-Copy it
-Take a chunk of the end of the copy and insert it into the beginning
-That way, your two ''manufactured'' zero''s match up and you get a smooth(ish) wave, plus the loop point will be based on a continuous piece of your original recording, so that too will work by default. You will also have two files of identical length, so you have no issues with combining them.
-Combine the two tracks
-Repeat until you cannot hear a beat, taking Nurofen as and when required

Hope that helps
Tom