Moo box

The Moo box is a toy or a souvenir. When it is turned upside down, a noise is produced that resembles the mooing of a cow. The toy can be configured to create other animal sounds such as the mewing of a cat, the sound of a bird, or the bleat of a sheep.

The toy can be used to perform the Moatti test, conceived by doctor Lucien Moatti. It uses four boxes calibrated to reach sixty decibels at two metres. The test can be used to screen the hearing of children aged from six to 24 months.

The tester knocks down the boxes out of sight of the child. If the child hears the sound, they will turn their head in the direction of the sound. Each box tests different frequencies.

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Wikipedia