These vibrations are transmitted to the fluid of the inner ear. In turn, this fluid vibrates the hair cells that line the inner ear. These hair cells are connected by neurons to the auditory nerve. The auditory nerve carries the signal to our brain where the sound is translated into information. The volume of the sound is determined by the number of hair cells stimulated and the pitch is determined by the distribution pattern of stimulated cells.
Water is an ideal medium for the transmission of sound.
The speed of sound in water is 5 times faster than it is in air. This speed can be altered depending on the salinity, temperature and depth of the water. Early marine scientists were not aware of this property of water and originally the ocean was considered a vast and silent realm. However, when the first hydrophone was dropped in the water, they realized the level of ambient noise underwater was incredible. As water is such an efficient transmitter of sound, many marine animals have adapted to use sound as a tool.