What is the name of the strings in the human voice box which vibrate 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.

Fill in the following blanks with suitable words :

(a) Sounds are produced by .............. objects.

(b) The human voice box is called ..............

(c) Sound cannot travel in ....................

(d) A set of three tiny............in the middle part of ear passes on sound vibrations from the eardrum to the liquid in cochlea.

(e) The unit of frequency is ..............

(f) The time taken by an object to complete one oscillation is called............

(g) The shrillness of a sound is determined by the ...........of vibration.

(h) Unpleasant sound is called...................

(i) Sound which is pleasing to the ear is called................sound.

(j) A person having partial hearing loss can hear properly by wearing a device called hearing ...............on the ear.

What makes these strings vibrate?

Describe how sound is produced by the human voice box (or larynx).