How does a sound wave’s shape reveal its pitch, loudness, and timbre?

A sound wave’s shape provides a visual representation of its physical properties, which correspond to how we perceive sound:

• Pitch: This is determined by the wave's frequency, or the rate at which the pressure cycles repeat. A higher frequency—meaning more cycles per second (measured in hertz)—results in a higher perceived pitch. Conversely, lower frequencies correspond to lower pitches.12
• Loudness: This is determined by the wave's amplitude, which is the magnitude of the pressure fluctuation above and below atmospheric pressure. Larger amplitudes, representing greater pressure variations, are perceived by the ear as louder sounds.32
• Timbre: Often described as tone color, timbre is determined by the wave form. This shape is created by the combination of the fundamental frequency and the presence, number, and relative intensities of overtones (or harmonics). Because different instruments or voices emphasize different overtones, they produce unique, complex wave shapes even when playing the same fundamental pitch.452

In essence, while frequency and amplitude define the basic "height" and "speed" of the wave, the specific complexity of the wave's shape—its timbre—is what allows us to distinguish between different sources of sound.42