This document provides an overview of an audio content analysis module about intensity and loudness. It discusses human perception of loudness and how it relates to physical measurements of intensity and magnitude. It then describes several common low-level features used to represent intensity in audio signals, including root mean square (RMS), peak envelope, weighted RMS, and models of loudness like the Zwicker model. The goal is to discuss intensity and loudness from both a perceptual and technical feature extraction perspective.