BackSound (Questionnaire Files)

QuickInfo

Play a wave or mpeg (mp3) sound file in the background when the current item is presented.

Value

Any sound file with a .wav or .mp3 extension

Purpose

In questionnaires, all items support backsounds. If the item is a movie or sound file that already has sound content, then the content of the backsound will be superimposed. If you would like a sound played in the background when another item is presented then simply type in the name of the sound file in this field.

Hint

Keep in mind that MediaLab will play backsound files to their completion. This allows for a backsound to play through multiple items if you care to structure things that way. To have MediaLab wait for the duration of the sound file and then automatically proceed, use the delay parameter for the item and specify the length of the sound clip in seconds, e.g., for a 30 second sound clip, use (d30). You can find out the length of a sound clip by right clicking on the file in Windows Explorer and selecting Properties.

Note about Sounds versus BackSounds:

For flexibility in playing sound files, they can be presented as a Sound item or they can be presented as "BackSounds" to other items. Note that Sound items end automatically when the next item appears even if they have not yet completed. In contrast, BackSounds continue until completion (overlapping subsequent items) or until another backsound is encountered. Thus Sounds and BackSound can be used strategically to accomplish different effects. Note that if you need to stop a BackSound upon item completion then you can simply insert "silence.wav" as the backsound for the subsequent item. It is a short silent sound file that will cancel any currently playing BackSound. Silence.wav can be found in the Utilities folder.

Converting WAV files to MP3

Traditional WAV sound files can get rather large especially when they're of high sound quality. In contrast, MPEG (MP3) sound files are exceptionally small in their size while maintaining excellent sound quality. With mpeg compression, you can reduce the size of your sound files by up to 90% without a loss in detectable sound quality. MediaLab includes a freeware utility called CDex in the Utilities folder that allows you to convert your WAV files to mpeg MP3 format. Run CDex and select Convert -> WAV to MPEG from the main menu. The new MP3 version of your sound files will be copied to the OutputFiles folder of CDex.