Question

What beat frequencies (in Hz) result if a piano hammer hits three strings that emit frequencies of 127.6, 127.8, and 128.7 Hz? (Give your answers from smallest to largest.)

_____Hz

_____Hz

_____Hz

Answer 1

The sound of a beat frequency or beat wave is a fluctuating volume caused when you add two sound waves of slightly different frequencies together. If the frequencies of the sound waves are close enough together, you can hear a relatively slow variation in the volume of the sound. A good example of this can be heard using two tuning forks that are a few frequencies apart. ince the frequencies of the two sounds are so close, you would hear a sound that is an average of the two. But you would also hear the modulation of the amplitude as a beat frequency, which is the difference between the initial frequencies: fb = | f1 − f2 | where fbis the beat frequency f1 and f2 are the two sound frequencies | f1 − f2 | is the absolute value or positive (+) value of the difference & hence beat frequency. 128.1-127.8= 0.3Hz 129.1-128.1= 1.0Hz 129.1-127.8= 1.3Hz