A moo box ( moo box), also called a cow or humming box, humming or tilting voice, is a mechanical sound generating instrument that is used as a toy, souvenir or as a component of a humming teddy bear . It consists of a reed pipe and a bellows, which is weighted down. As soon as the device is turned over, the weight pulls the bellows open, which releases the air to the pipe when it changes position.
In addition to amusement or entertainment, the animal voice cans are used for the hearing test of small children . This test was developed by the French doctor Lucien Moatti. He uses four cans with the voices of cow, sheep, cat and bird set to sixty decibels at two meters. The different frequencies (250 Hz, 500 Hz, 1000 Hz and 2500 Hz) of the animal voices allow conclusions to be drawn about the hearing ability of the bass, baritone, alto and soprano.