The loudness of a sound depends upon its intensity, which is determined by the amplitude (or height) of the sound waves. The greater the amplitude, the more energy is carried by the sound waves and the louder the sound is. Distance can also affect how loud a sound appears, as sound waves spread out and become less intense as they travel farther from the source. Hertz refers to the frequency of sound waves and is related to the perceived pitch of a sound, but not directly to its loudness. Watts refer to the rate at which energy is transferred, but are not a primary factor in determining the loudness of a sound.
