Sound frequency refers to the number of vibrations or cycles that sound waves complete in one second, measured in hertz (Hz). Higher frequencies produce higher-pitched sounds, while lower frequencies result in lower-pitched sounds. For example, a piano note can have a frequency of 440 Hz, which is known as the standard pitch for the musical note A above middle C. The frequency of sound affects how we perceive it and is crucial in various fields, including music, acoustics, and audio engineering. Different frequencies can create distinct sounds, and understanding them helps in designing better speakers and improving sound quality in recordings.