The term "20 kHz" refers to a frequency of 20,000 hertz, which is the upper limit of human hearing. Frequencies are measured in hertz (Hz), with one hertz equating to one cycle per second. Sounds at this frequency are often associated with high-pitched noises, such as the chirping of certain birds or the sound of a dog whistle, which is inaudible to humans. In audio technology, 20 kHz is significant because it represents the maximum frequency that standard audio equipment, like speakers and headphones, can reproduce. Many audio formats aim to capture sound within the range of 20 Hz to 20 kHz, ensuring a full representation of audible sound for listeners.