For humans, speech, music, and other environmental sounds form the basic elements of language, social relations, and adaptive response to environmental stimuli. Our auditory system can detect rapid changes of sound intensity (measured in decibels, dB) and frequency (measured in hertz, Hz). In humans, sound intensity and frequency roughly correspond to loudness and pitch.
The task of the auditory system is to convert changes in air pressure in the environment into the neural activity that permits our brain to perceive and attach meaning to the sounds that we hear.
Each part of the ear performs a specific function in hearing. The external ear captures, focuses, and filters sound. The middle ear concentrates sound energies. Finally, the inner ear transduces mechanical energy into neural activity.
In this tutorial we have seen how the ear captures sound energy and transduces this mechanical energy into nerve impulses. The external ear captures, focuses, and filters sound. The bones (ossicles) of the inner ear focus the sound energy onto the oval window, generating pressure waves that sweep along the basilar membrane of the cochlea. The structure of the basilar membrane allows it to respond to vibrations of different frequencies. The organ of Corti contains the sensory hair cells (about 15,000 in humans) that convert the mechanical energy into action potentials that are transmitted to the cerebral cortex.
Textbook Reference: Concept 34.4 Sensory Processes Provide Information on an Animal’s External Environment and Internal Status