Abstract Chapter 2 explores the fundamental building blocks of musical sound, the “Lego bricks” with which music is constructed. Readers engage with the most basic elements of sound through pairs of opposites: sound vs. silence, noise vs. music, loud vs. quiet, beats vs. durations, consonance vs. dissonance, tension vs. resolution. They learn how to modify the qualities of sound elements by changing their variables. The chapter also discusses overtones and how they impact our culturally constructed perceptions of “harmonious” or “discordant” qualities of sound, governed by the principle of “valence,” or positive/negative emotional responses to experiences. The concept of timbre is introduced and explored. A two-dimensional representation of sound is described that features a vertical component associated with pitch and frequency, and a horizontal component associated with time and rhythm.