In biology we study about the ear and its functions ,but ineed to know in detils,how such fenomena occurs and which parts of the ear involved?

This should cover everything you are looking for: Howstuffworks "How Hearing Works" (http://health.howstuffworks.com/hearing.htm)

Short answer: Sound waves hit the ear drum ("tympanic membrane"), which transmits the impulse through the three bones of the middle ear, which transmit the sound wave impulses to the inner ear, which "transduces" the signal into a sort of electrical signal the brain can interpret.
Cheers,
Asking