Question

(a) What is the frequency range of hearing in humans ?
(b) Which of the following sound frequencies cannot be heard by a human ear ? (i) 10 Hz
(ii) 100 Hz
(iii) 10,000 Hz
(iv) 40,000 Hz

Answer 1

Answer:

1. The frequency range for hearing in humans is from 20 Hz to 20000 Hz .

Sound having frequency lesser than 20 Hz is called infrasonic sound and cannot be heard by humans.

Similarly, sound having frequency greater than 20,000 Hz is called ultrasonic sound. It also cannot be heard by humans.

2. Keeping the above range in mind, (i)10 Hz and (iv) 40000 Hz cannot be heard as they fall in the infrasonic and ultrasonic sound groups respectively.

Additional facts about frequency:

1. Frequency determines the pitch or sharpness of the sound.

2. Even though we cannot hear infrasonic or ultrasonic sounds, BATS can produce and perceive ultrasonic sound. They use reflection of the ultrasonic sound wave to navigate their path of motion.

Answer 2

$\bold{\large{\underline{\underline{\sf{AnsWer:}}}}}$

(i)10 Hz and (iv) 40000 Hz cannot be heard as they fall in the infrasonic and ultrasonic sound groups respectively.

________________________

Frequency :-

The number of complete waves produced in one unit is called frequency.

The SI unit of frequency is Hertz.

Frequency = compression by time.