When two harmonic sound waves of close but not equal) frequencies are heard at the same time, we hear

Options

A. a sound of similar frequency
B. a sound of frequency which is the average of two close frequency which is the average of two close frequencies
C. audibly distinct waxing and waning of the intensity of the sound with a frequency equal to the difference in the two close frequencies
D. All of the above

Answer

D

Explanation

When two harmonic sound waves of close (but not equal) frequencies are heard at the same time, we hear a sound of similar frequency (average of two close frequencies)
The intensity of the sound heard is waxing and waning (varying) with a frequency `= |v_(1) - v_(2)|`, where `v_(1) and v_(2)` are the individual frequencies of the waves.