Ear Biology:
Pinna
Ear Canal
Inner Ear
Parts of the ear that vibrate when hit by sound waves: Small bones, cochlear hairs
The cochlea converts vibrations to electrical signals because the brain can only respond to electrical impulses, so it has to be converted.
An ultrasound is a noninvasive medical imaging test that uses high-frequency sound waves to capture real-time pictures or videos of the inside of your body. It can help people because it does not use any ionizing radiation; it is a very safe way for doctors to examine internal organs, tissues, and blood flow.
Headphones make sounds by translating electrical audio signals from the device into physical vibrations. These vibrations then enter the ear canal and react with the small bones, and once they vibrate, they send a vibration to the cochlea, which vibrates as well and hits the nerves, and the nerves alert the brain of a sound, and then the brain translates the waves into sound.