Outer ear 

● Auricle (Auricula auris) 

● Outer auditory canal (Meatus acusticus externus) 

Middle ear 

● Eardrum (tympanic membrane) – diameter 9-10mm 

● Hammer (Malleus) 

● Anvil (Incus) 

● Stapes (Stirrups) – the smallest bone in the human body 

● Tympanic cavity (Cavum tympani) 

Inner ear 

● Cochlea 

○ hair cells: mechanical stimuli are transformed into nerve activity 

● Vestibulocochlear nerve (auditory vestibular nerve)

● Semicircular ducts (Ductus semicirculares) 

Transmission of stimuli to the brain 

● The vestibulocochlear nerve (auditory vestibular nerve), known as the eighth cranial nerve, transmits sound and equilibrium (balance) information from the inner ear to the brain. 

The auditory nerve transports the sound to the brain and thus becomes peceptible:

● Brain stem / auditory cortex 

Audible range of humans and animals:

• Infrasound < 16 Hz 

• Audible sound 16 Hz to 20 kHz

• Ultrasound 20 kHz to 1,6 GHz

• Humans (approx. 25 years): 16 to ca. 18000 Hz 
• Humans (approx. 65 years): 16 to ca. 14000 Hz 
• Cat: 60 to 65000 Hz 
• Dog: 15 to 50000 Hz 
• Bat: 1000 to 150000 Hz 
• Dolphin: 100 to 200000 Hz 
• Blue whale: 10 to 30000 Hz