Question

What characteristics of sound would change if there is a change in its: (i) amplitude (ii) wave form.

Answer 1

Sound is a form of energy which gives us sensation of hearing.

a]If amplitude of sound wave changes then Loudness changes.

The loudness of sound depends upon amplitude of sound wave.
If amplitude is more then sound is loud.
It is expressed in decibel [dB]

b]If wave form changes then it effects its pitch 
The pith of sound depends on the frequency of vibration.If frequency of vibration is higher than we say sound is shrill. 

Answer 2

amplitude will result in the changes in the loudness of sound whereas wave form would affect the pitch of the sound