Question

What difference would a person feel on hearing two sounds of same speed, but the first sound having a wavelength of 1.3 m and the second 3.9 m?

• A. First sound is heard with a higher pitch.
• B. Second sound is heard with a higher pitch.
• C. First sound is louder.
• D. Second sound is louder.

Answer 1

The correct option is A First sound is heard with a higher pitch.

Speed (v) of the wave is the product of frequency (f) and wavelength ($\lambda$),

$v=f\times \lambda$

Since speed of $1^{st}$ and $2^{nd}$ sound is the same,

$v_1=v_2$

$f_1\times {\lambda }_1=f_2\times {\lambda }_2$

${\lambda }_1=3.9$
${\lambda }_2=1.3$

$\frac{f_1}{f_2}=\frac{1.3}{3.9}=3$

As $f_1$ is $3$ times of $f_2$, first sound is pitched higher than the second one.
{$pitch\propto frequency$}
On the other hand, loudness of sound depends on amplitude which is unaffected by the change in wavelength.