Question

why sound heat and magnetism not considered to be a matter

Answer 1

sound is not considered to be matter because its has waves that can be feel and cant be seen. so sound is not matter and doesn't take space.

matter takes up space but heat is energy and it's not dense, so it doesn't take up space.

also magnetism is considered to be matter because its also has waves that cant be seen and only we can see is its effects .so magnetism is not matter and doesn't take space.

hope this will help you

Answer 2

Because all three types you mentioned are the forms of energy which has no dimensions.And matter is anything that occupies space has mass and can be perceived by our six senses and of course has dimensions. Heat ,Magnetism and Sound are the form energy which creates a wave motion in matter .In other words these forms of energies affects the matter but themselves they not  are matter. I hope you understand.