ABSTRACT
The ear senses energy from the outside world in the form of pressure waves in the air and converts these into nerve impulses, which the brain integrates into a psycho acoustical perception of the sound environment. Sound may be transmitted through bony structures, but this requires very high intensities to be effective. After travelling through the ear canal, a sound wave arriving at the eardrum makes it vibrate according to the frequency of the sound. The inner ear contains the receptors for hearing. The Eustachian tube connects the middle ear to the pharynx. Sound is a vibration that stimulates an auditory sensation. One of the most noticeable effects of noise is its interference with spoken communications and hearing of signals. Understanding verbal communications is a psychological process that requires suitable acoustical conditions. The intensity of a speech signal relative to the level of ambient noise is a fundamental determinant of the intelligibility of speech.
