The pitch of a sound is determined by its .

Sounds, of frequency more than $20 \mathrm{kHz}$, are known as _____.

An irregular, irritating sound is referred to as a _____.

Human beings, as well as animals, have a voice box for producing their characteristic sounds.

Of the three mediums, solids, liquids and gases, sound propagates fastest in liquids.

Sound can not propagate through vacuum.

Light propagates, through vacuum, with a speed that is nearly a million times more than the speed of sound in air.

The frequency of a given sound determines its 'shrillness' or 'flatness'.

Irregular non-periodic vibrations generally produce musical sounds.