Which of the following frequency of sound can be heard by a dog but not by a man?

(a) 50,000 hertz

(b) 15,000 hertz.

What is the name of very high frequency sounds which cannot be heard by the human ear?

Why do we not hear the screams of a bat ?

Name the substance which vibrates in a flute to produce sound.

State whether the following statements are true or false:

(a) Sound cannot travel in vacuum.

(b) The number of oscillations per second of a vibrating object is called its time-period.

(c) If the amplitude of vibrations is large, sound is feeble.

(d) The lower the frequency of vibration, the higher is the pitch.

(e) If the amplitude of vibrations is doubled, the loudness of sound also gets doubled.

(f) When the amplitude of vibrations is halved, the loudness of sound becomes one-fourth.

(g) Unwanted or unpleasant sound is termed as music.

(h) Noise pollution may cause partial hearing impairment.