1/ The size and arrangement of the three bones, the hammer, anvil and stirrup creates a mechanical advantage. That is the force applied to the first bone becomes larger by the time the stirrup strikes the oval window. In addition the ear drum, the tympanic membrane, is 15 times larger than the oval window, again magnifying the conversion of sound energy to mechanical energy and eventually electrical energy in the inner ear.
The conversion of sound energy to mechanical energy and eventually to electrical energy is also seen in the shape of the pinea. Since sound energy spreads out according to the inverse square law, the piƱa is large and shaped in such a way as to direct sound towards the auditory canal.
This is clearly seen in dogs who have 18 muscles responsible for the for the movement of the pinea to accurately determine the. origin of a sound.
In general, the larger the pinea (e.g rabbit) the greater the sensitivity of a mammals hearing. However on e needs to note the importance of ears with a large surface area in heat loss (homeostasis).
The ear magnifies the sound energy so that maximum intensity is obtained.
Since the hair cells in the organ of corti ( cochlea) are sensitive to individual frequencies, a wide range of sounds can be heard. This is important in evolution by natural selection as mice for example, can communicate to one another outside the hearing range of their predators. In addition different signals can be sent regarding different dangers.
One species of monkeys use one high frequency sound to warn of an eagle, (the monkeys rush to the tree) and another to warn of a snake, in which the monkeys leave the trees.
This variation in frequency allows animals to communicate fear or distress generally with a high frequency sound (e.g. Cry of a baby) and confidence or aggression with a low frequency sound (the raw of a lion).
Low frequency sounds (larger wavelength) in general travel a longer distance because the sounds waves encounter less interference, reflection and refraction.