though light n sound consist of particles then why it is not considered as a matter
Light and sound are not regarded as forms of matter.Light is another name for electromagnetic radiation. Light is interesting in that it has a dual nature to it in that it behaves both like waves and particles. The “particles” of light are called photons and have no mass. In contrast, matter is made up of particles that do have mass.
Sound is a little different in that it is the propagation of a pressure wave through a medium of particles. Since it is a wave, it is not considered a form of matter.