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Using Audacity for Sound Design

By • Oct 5th, 2008 • Category: Backstage, ShowBizRadio

Last summer, I promised you an article detailing how I mixed together various sounds to create new sound effects. Sorry about the delay, but here’s the promised article.

For The Least Offensive Play in the Whole Darn World, a sound effect was needed for the machine that renders all objectionable content out of scripts. I talked with the show’s director to get an idea of what he was looking for. He wanted it to sound computerish, only last a few seconds, and to sound like something was happening.

So I first looked around the house to simply brianstorm ideas for what could make appropriate sounds. Simply go into a room, and close your eyes and listen. Or look at an object, and have it make noise. (Closing your eyes is important, because the sound will be used in a different environment. If you tell the audience they’re hearing a machine cleaning a playscript, that’s what they’ll believe. They don’t need to know it’s actually your vacuum cleaner.) I tried a shredder, but it didn’t sound quite right. Nothing in my home quite worked out the way I thought it would, so I turned to the web looking for the equivalent of clip art: sound effects.

I searched the web, and found many collections of sound clips. I tested a lot, but couldn’t find one that was exactly what I was looking for. I did find two though that if I put together would be a nice effect. I started with a computer sound, plus a nice sound effect.

I decided I simply wanted to add the “effect” to the end of the “computer” sound. I used the free Audacity Sound Editor for this project. Then In Audacity I opened both files.

The sampling rate for each clip is to the left of each clip, as the first line of text in the largest gray box. Notice that the sampling rate of the two files is slightly different. What that means is if I were to combine the two files by simply copying and pasting, you would end up with a squeeky sound, or chipmunks, since the combined file would be playing at different rates. For example, here’s the computer sound from above when pasted into a sound clip with a rate of 22.050Khz. And here’s the computer sound when it is incorrectly pasted into a clip at the rate of 8Khz, when the original flie was 22Khz.

To change the sampling rate of an audio file, open the file in Audacity. Then look in the lower left corner of Audacity’s editing window. You should see “Project rate” then a number. Simply click on the number and you’ll get a list of choices. Then choose the rate you’d like the file to be. Finally, choose the File menu, and then “Export to AIFF…”. Enter a filename and press the Save button. You can then close the file.

So I now have two audio files, one a computer beeping noise, the other a cool sound effect. Open both of them in Audacity. The “computer” file I want to be in front of the effect sound. So I highlight the computer file waveform, and choose Copy from the Edit menu. Then change to the other open document and position the cursor just at the beginning of the waveform for the effect. Once the cursor is in the correct place, choose Paste from the Edit menu.

Now look at the waveform, especially where the two different sound effects have been joined. Zoom in if you need to (Apple-1 or click on the zoom-magnifying glass in the toolbar). Is there a flatline between the two sounds? The flatline is silence. If so, you can highlight the silence and delete it by pressing the delete key (Apple-K, or Edit menu, Delete). You may want to have the end of effect fade to silence, simply select the last quarter second or so, and choose the Effect menu, and “Fade Out.” If you’d like a few seconds of silence at the end of the track, simply position the cursor and choose Silence from the Generate menu.

When the entire track sounds good, save the project (File menu, Save project As…). Then you can Export it as AIFF or MP3. Listen to the final sound effect.

If you have any questions or suggestions for articles on sound in theatre, just leave a comment here or email me.

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This article can be linked to as: http://washingtondc.showbizradio.com/goto/2520.

started ShowBizRadio in August 2005 because they love live theater. They each have both performed in and worked behind the scenes in DC area productions, as well as earned a Career Studies Certificate in Theater from Northern Virginia Community College. Mike & Laura are each members of the American Theatre Critics Association, and Mike is a member of the Online News Association.

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