Edison style phonograph

Making a microphone using two cups

Working Principle: The vibrations created by the Kid's voice (differences in air pressure) are captured by the paper cup and transferred to a needle that “scars” the plastic cup as it spins, creating tiny grooves/channels.

Then, to play the sound back, the process is reversed: the needle is placed at the start of the groove and the plastic cup (the medium onto which the groove was created) is spun in the opposite direction. By running along the groove, the needle follows the pattern it had cut previously and creates vibrations. These vibrations are then amplified by the paper cup and voila!