What happens to the eardrum when sound pressure waves reach it?

When sound pressure waves reach the eardrum, it vibrates with alternating pressure. This is a crucial part of the auditory process, as the eardrum acts as a barrier between the outer ear and the middle ear, converting sound waves in the air into mechanical vibrations.

The alternating pressure of the sound waves causes the eardrum to move back and forth, which in turn initiates the chain of events that leads to the perception of sound. These vibrations are transferred to the ossicles (the tiny bones in the middle ear), which amplify the sound before it is transmitted to the inner ear.

The other options do not accurately describe the function of the eardrum. While it does not absorb sound, it must vibrate to allow sound transmission. It also does not translate sound into electrical signals, as this function occurs later in the auditory pathway, particularly within the inner ear and auditory nerve. Reflections of sound waves to the outer ear are not a primary role of the eardrum; rather, its main function is to vibrate in response to incoming sound waves.