The frequency of a wave in sound is referred to as the sound's pitch. Frequency, measured in hertz (Hz), indicates the number of wave cycles that pass a given point per second. Higher frequencies produce higher pitches, while lower frequencies correspond to lower pitches. The human ear typically perceives sound frequencies ranging from about 20 Hz to 20,000 Hz. Musical notes are defined by their frequencies, and the relationship between different frequencies results in harmony and dissonance in music. Understanding frequency is essential in fields like acoustics, music production, and audio engineering, as it affects how we perceive and interpret sound.