BackSound (Questionnaire Files)
Play a wave (.wav) or mpeg (mp3) sound file in the background when the current item is presented.
Any sound file with a .wav or .mp3 extension
In Questionnaire Files, all items support the Backsounds field. If the item is a movie or sound file that already has sound content, then the content of the Backsounds field will be superimposed. If you would like a sound played in the background as another item is presented, simply type in the name of the sound file in this field.
Keep in mind that MediaLab will play files in the Backsounds field their completion. This allows for files in the Backsounds field 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 duration parameter for the questionnaire item using the Backsounds field and specify the length of the sound clip in seconds. For example, to play the sound file in the Backsounds field for 30 seconds type
in the Parameter(s) field of the Questionnaire File item. 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 using the Backsounds field in other items. Note that Sound items end automatically when the next item in the questionnaire file starts, even if the sound file has not yet completed. In contrast, files in Backsounds field continue until completion (overlapping subsequent items) or until another file in a different Backsounds field is encountered. Thus Sounds items and the Backsounds field in other items can be used strategically to accomplish different effects. Note that if you need to stop a file in the Backsounds field upon item completion, you can simply insert "silence.wav" from the Utilities folder in the MediaLab program files in the Backsounds field for the subsequent item. It is a short silent sound file that will cancel any currently playing BackSound.