Question

Our ear can hear sound waves of frequency between
A. $5 - 100cycles/sec$
B. $50 - 20000cycles/sec$
C. $20000 - 50000{\text{ }}cycles/sec$
D. $\;2000 - 3000{\text{ }}cycles/sec$

Answer 1

Frequency shows the rate of vibration of medium particles and the number of waves passing per second. Pitch is the sensation of frequency. The measure of the loudness or softness of a sound is determined by its amplitude. The amplitude of the sound waves are usually dependent on the force with which an object is made to vibrate.

Complete answer:
Children that are present beyond the age of five and some animals, such as dogs can hear up to 25 kHz$\left( {1{\text{ }}kHz = 1000{\text{ }}Hz} \right)$. As with time when people become older their ears become less sensitive to higher frequencies.
Sounds of frequencies below 50 Hz are called infrasonic sound or infrasound. If human beings could have heard infrasound, we would hear the vibrations of a pendulum just as we hear the vibrations of the wings of a bee.
Now let us match this with given options:

$5 - 100cycles/sec$: Rhinoceroses communicate using infrasound of frequency as low as 5 Hz. Whales kind of fishes and elephants generate sound in the infrasound range. It is found that some animals get disturbed before the occurrence of earthquakes. Earthquakes that occurs due to shaking of earth plates produce low-frequency infrasound before the main shock waves begin which possibly alert the animals
$50 - 20000cycles/sec$: The audible range of sound for human beings extends from about 50 Hz to 20000 Hz (one Hz = one cycle/s). Sound above this frequency can damage human ears.
$20000 - 50000{\text{ }}cycles/sec$: Frequencies higher than 20 kHz are called ultrasonic sound or ultrasound. Ultrasound is generated by dolphins, bats and porpoises Moths of some families have very sensitive hearing tools. These moths can hear the ultrasound noises of the bat and know when a bat is flying nearby, and are able to escape capture. Rats also play games by producing ultrasound.
$\;2000 - 3000{\text{ }}cycles/sec$: The frequency in this range provides information on consonant production, third formant for vowels, noise bursts and crust for plosives and affricates, turbulent noise of
voiced and unvoiced fricatives.

So, the correct option is B that is $50 - 20000cycles/sec$.

Note:
People with hearing loss may need a hearing aid. A hearing aid is electronic, in nature and is a battery operated device. The hearing aid receives sound through a microphone. The microphone converts the sound waves to electrical signals. These electrical signals are amplified by an amplifier. The processed electrical signals are given to a speaker of the hearing aid. The speaker is used to convert the processed electrical signal to sound and sends it to the ear for clear hearing.