This chapter includes frequency, velocity, intensity, Ultrasound production, Piezo electric effect, Vocalization and hearing (Hearing, deafness, test of hearing, Tinnitus, Hearing aid, Audiometer), Medical use of ultrasound (A-mode, M-mode, B-mode, Doppler ultrasound), Noise pollution, Noise control measure and Application of Sound in nursing (Heart sound, Fetus sound, ultrasonics in physiotherapy, uses).