When people hear a sound, their ears turn the vibrations in the air into neural messages from the auditory nerve, which makes it possible for the brain to interpret the sound. this process is called: ?

The process is called Transduction. 
In physiology, transduction is the conversion of a stimulus from one form to another. Transduction in the nervous system typically refers to synaptic events wherein an electrical signal, known as an action potential, is converted into a chemical one via the release of neurotransmitters. Like vision and all the other senses, hearing begins with transduction. Sound waves that are collected by our ears are converted into neural impulses, which are sent to the brain where are integrated with past experience and interpreted as the sounds we experience.

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