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  The KidsRoom uses a simple audio trick to detect the loudness of the screams of children in two different parts of the story. The first time is when the children yell the "magic word" to transform the bedroom into the forest. The second time is when the children yell "be quiet!" when they first encounter the monsters in the MonsterLand.  

Scream DetectionImage of the microphone and position with respect to the floor

The scream detector is a simple amplitude detection program running on one of the SGI Indy workstations. There is a single microphone placed in the room between the screens that is monitored for a few seconds at the appropriate time. If the loudness of the scream goes above a set threshold, the control program accepts the scream and moves on in the story.


If the scream is below the threshold, the narration encourages the children to scream a second time. If they fail to achieve this second, slightly easier, threshold, then the narration lets them know that it wasn't a very loud scream but that they can continue anyway (e.g. "Well I can't say that was a very loud shout, but perhaps the monster will figure it out!")


The effect is that when the children yell loudly, they get immediate positive feedback from the system, but when they fail to yell, the system acknowledges that it knows they didn't yell loudly but keeps the story moving.

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The KidsRoom - Perceptual Computing Group - MIT Media Laboratory