Conversation so far:
What are the different forms of energy?
Examples of these are: light energy, heat energy, mechanical energy, gravitational energy, electrical energy, sound energy, chemical energy, nuclear or atomic energy and so on.
How can energy be stored?
Batteries, gasoline, natural gas, food, water towers, a wound up alarm clock, a Thermos flask with hot water and even pooh are all stores of energy. They can be transferred into other kinds of energy.
What type of energy is used in motion?
Motion energy – also known as mechanical energy – is the energy stored in moving objects. As the object moves faster, more energy is stored.
Tell me about mechanical energy.
Mechanical energy is the sum of kinetic and potential energy in an object that is used to do work. In other words, it is energy in an object due to its motion or position, or both.
Give me some examples of mechanical energy.
A few examples are: a moving car possesses mechanical energy due to its motion(kinetic energy) and a barbell lifted high above a weightlifter's head possesses mechanical energy due to its vertical position above the ground(potential energy).

Question: Why is sound a form of mechanical energy?
Self-contained rewrite: Why is sound a form of mechanical energy?