When musical instruments are played,they produced special type of sound or voice which is called music.
Well... I see some issue with this idea itself.... In my view, music is not the sound or voice alone. Music has lot to do with rhythm, melody and harmony of sounds. For example, if you play a wrong note, then it would be intolerable. So, I wish if you had given a better definition to describe music.
There are many kinds of music in this world like rock music,pop music and jazz music etc.
There are many forms of music such as classical, rock, pop, jazz etc.The answer of this question is,because ofthat having great interest and effect we need music
The answer is that music helps people to relax and enjoy; it soothes one's mind :)