Like other speakers, an iDog changes digital signals into analog signals. In other words, it translates a computer’s language of ones and zeros into a wave that human ears can hear. Unlike other speakers, an iDog also dances in response to music. It moves its head and ears and flashes lights on its face.

When you plug an MP3 player into the iDog’s input, your music travels to several locations inside. It moves through wires to a small speaker located in the iDog’s back. A diaphragm inside the speaker moves back and forth very quickly, creating a pressure wave. The wave moves through the air until it reaches your ear. Then, it moves your tympanic membrane, or eardrum, which is your body’s first step in hearing the sound. In addition to music, this speaker plays the iDog’s own sounds, like barks and whimpers.

Signals also travel from the input to a printed circuit board (PCB) in the iDog’s head. The PCB’s circuitry receives the signals and tells the rest of the iDog how to respond. There are also seven light-emitting diodes (LEDs) mounted to the PCB. When the LEDs light up, you can see them through the plastic surface of the iDog’s face. A rubber dome switch on the PCB lets you turn the iDog on and off by pressing its nose. A similar switch under the dog’s back lets you pause the iDog by pressing its tail.

An iDog uses battery power. Next to the battery compartment is a small power supply. The power supply sends the right amount of electricity from the batteries to the parts that require it. This includes the speaker, the PCB and an electric motor. The motor also receives signals from the PCB that tell it when to turn on and off.

The motor spins several gears, which turn other gears. In this way, motion travels from the spinning motor to the iDog’s head. Gears in the iDog’s neck and ears cause these parts to move in time with the music.