What name is given to sound waves of frequencies higher than 20 kHz?

What happens to the loudness of a sound if its amplitude decreases?

What happens to the loudness of a sound if its amplitude decreases?

Fill in the following blanks with suitable words:

(a) An echo is simply a ………. Sound.

(b) Pitch od sound depends on ………

(c) Loudness of sound depends on ……….

(d) Quality of sound depends on ……….

(e) Echoes are caused by the …………of sound.

On which day, a hot day or a cold day, an echo is heard sooner? (Give reason for your answer.