Microphones: From Analog Air to Digital Data

You speak. Air molecules vibrate. A computer chip hears you. How?

The Eardrum (Diaphragm)

Inside every mic is a super-thin membrane (Diaphragm).

• When a sound wave hits it, it wigges.
• The wiggle moves a magnet inside a coil of wire.
• Faraday’s Law: Moving magnet = Electricity.
• The louder you yell, the higher the Voltage.

The ADC (Analog to Digital Converter)

This voltage is a smooth wave (Analog). Computers hate smooth waves. They need steps (Digital). The ADC takes a snapshot of the voltage 44,100 times a second (Sample Rate).

• Snapshot 1: 0.1 Volts
• Snapshot 2: 0.5 Volts
• Snapshot 3: 0.9 Volts This list of numbers is the audio file.

Robot Ears

We use this for Audio Analysis.

• In some years, robots have to listen for a specific “Start Signal.”
• The code listens to the microphone stream.
• It runs an FFT (Fast Fourier Transform) to break the sound into frequencies.
• “I hear a strong spike at 4000 Hertz. That’s the whistle! GO, ROBOT, GO!”