Ears:
Ears are part of the auditory system, which is the system that enables animals to detect sound. Ears are not only important for hearing, but are also essential for the sense of balance.
Sound waves enter the outer ear (the part we can see) and pass through the middle and inner ear before they are sent to the brain for processing (that’s a lot of traveling for sounds to do!)
The brain can determine the location of a sound by analyzing differences of the sound waves between the two ears. If we had only one ear, this would not be possible.
The smallest bones in the human body are found in the middle ear, or ear drum- they are called the ossicles.
Only vertebrates have true ears, but other species also have organs to detect sound. For example, some insects, such as spiders and caterpillars, are able to “hear” through hairs on their body.

Click on the other five senses (and don't forget the brain!)