A periodic increase and decrease in loudness heard when two notes of slightly different frequency are sounded at the same time. If a note of frequency n is heard at the same time as a note of frequency m, the resulting note will have a frequency of about (n + m)/2. However the amplitude of this note will vary from the difference to the sum of the amplitudes of the m and n notes and the frequency (called the beat frequency) of this variation will be (m – n). The beating sound produced occurs as the waves successively reinforce and oppose each other as they move in and out of phase. Beating also occurs with radio-frequency waves and is made use of in heterodyne devices. See also interference.
Subjects: Physics — Mathematics.