Refer to figure. 
The human ear is responsible for two functions, sound reception (senses air vibrations) and balance-acceleration detection (senses accelerations of our body). To achieve these functions the human ear consists of three parts, outer, middle and inner ear.

INNER EAR 
The inner ear is divided into two parts:

1. Cochlea: The cochlea has a sensitive membrane that senses sound vibrations and produces the nerve impulses that the brain then interprets as sounds. This part of the inner ear is responsible for sound reception.
2. Vestibular Apparatus: The vestibular apparatus is the part of the inner ear responsible for balance-acceleration detection with a purpose to provide to the brain a model of spatial orientation and help it control other systems of the body. The vestibular apparatus consists of the following:
   • Otoliths: The otoliths are tiny chalk-like particles embedded in a soft substance that contains hair cells. The otoliths consist of the utricles chambers that senses linear accelerations and the saccules chambers that sense gravity (vertical acceleration).
   • Semicircular canals: The semicircular canals of the inner ear are three canals filled with fluid that are perpendicular to each other. Inside the canals there are fine hair-like cells which bend during angular accelerations. The superior canal senses acceleration in the pitch axis, the posterior canal measures acceleration in the roll axis and the horizontal canal measures acceleration in the yaw axis.

Vestibular Apparatus:

• Otoliths ⇒ Linear acceleration and gravity
• Semicircular canals ⇒ Angular acceleration (roll, pitch, yaw)