Question

When two sound sources of the same amplitude but of slightly different frequencies $\upsilon_{1}$ and $\upsilon_{2}$ are sounded simultaneously, the sound one hears has a frequency equal to.

• A. $\left| \upsilon_{1} - \upsilon_{2} \right|$
• B. $\left\lbrack \frac{\upsilon_{1} + \upsilon_{2}}{2} \right\rbrack$
• C. $\sqrt{\upsilon_{1}\upsilon_{2}}$
• D. $\left\lbrack \upsilon_{1} + \upsilon_{2} \right\rbrack$

Answer 1

Answer: (B)

$\left\lbrack \frac{\upsilon_{1} + \upsilon_{2}}{2} \right\rbrack$

Answer 2

The resulting sound wave has a frequency equal to half the sum of the individual frequencies. Note that the resulting intensity varies at the beat frequency equal to difference of the individual frequencies.