Analog audio is the representation of a series of sounds through the use of signal that can continuously change (analog). This analog signal indicates the level and frequency information within the audio signal. Audio signals can be transmitted through air by sound pressure waves and through wires via electrical signals. Sound pressure waves are converted to electrical signals by a microphone.

Sound Pressure (Volume) - Sound pressure level - SPL - is a measure of acoustic wave force. SPL is the force a sound can exert against an object, measured in decibels.

Frequency Range (Dynamic Range) - ABC

Filtering - ABC

Pre-Emphasis and De-Emphasis - ABC

Companding and Expanding - ABC

Noise Reduction - ABC

This figure shows a sample analog signal created by sound pressure waves. In this example, as a microphone detects the sound pressure from a person’s voice, it is converted to its equivalent electrical signal. This diagram shows analog audio signals continuously vary in amplitude (height, loudness, or energy) as time progresses.