Category C - full version without watermark 720x576 (check terms and conditions at www.teledesign.de) The embed version with watermark is free of charge. - Description: Sound waves make the eardrum vibrate; the ear bones amplify these oscillations and transmit them as pressure waves to the inner ear. They set in motion about 15.000 minute sound receptors within the fluid filled cochlea -- the so called hair cells. These hair like structures "bow" when they follow the movement of the liquid. This is the way they "detect" the stimuli and then convert the oscillations to electrical impulses. The sound pitch is determined by the localization of the hair cells in the cochlea. All hair cells are connected with up to twenty neurons that converge to form the auditory nerve. The number of neurons activated with an arriving stimulus depends on the sound volume. The auditory nerve transmits the incoming information to the auditory center in the brain, where it will be interpreted as an acoustic event -- this is as speech, noise or music.