Physiological acoustics is the study of the transmission of sound and how it is heard by the human ear. Sound travels in waves, vibrations that cause compression and rarefaction of molecules in the air. The organ of hearing, the ear, has three basic parts that collect and transmit these vibrations: the outer, middle and inner ear. The outer ear is made of the pinna, the external part of the ear that can be seen, which acts to funnel sound through the ear canal toward the eardrum or tympanic membrane. The membrane is highly sensitive to vibrations and also protects the middle and inner ear. When the eardrum vibrates it sets up vibrations in the three tiny bones of the middle ear, the malleus, incus and stapes, which are often called the hammer, anvil and stirrup because of their resemblance to those objects. These bones amplify the...