Page 1 : ‘Two sound waves of equal amplitude A but different frequencies fj and f arrive at your ear. If the frequencies, are close to each other, you can hear a variation in loudness, which is called a deat., , ‘Two sound waves, with slightly, different frequencies, , , , , , , , YAK, é, Fi 1.005, $, a, & Time, “The two waves interfere ~ Beat ~, , , , vhen they are in phase, and destructively when they are « half-cycle out of phase, The, resultant wave rises and falls in intensity, forming beats.