Is it true that we hear a sound our eardrum sends a message to our brain?

Yes, it's true. When sound waves enter the ear, they cause the eardrum to vibrate. These vibrations are transmitted through the ossicles (tiny bones in the middle ear) to the cochlea in the inner ear, where they are converted into electrical signals. These signals are then sent to the brain via the auditory nerve, allowing us to perceive sound.