Audition (Hearing)

Audition (Hearing) We hear via sound waves Amplitude (height) of wave = loudness Loud sounds have high amplitudes Softer sounds have low amplitudes

Pitch – a tone’s experienced highness or lowness, depends on frequency Frequency – number of wavelengths that pass a point in a period of time Low pitch/frequency sounds = bass High pitch/frequency sounds = high ringing

Outer Ear Pinna – outer ear/lobe Auditory canal – channels sound waves to the eardrum

Middle Ear – Eardrum, 3 bones Eardrum – thin membrane that vibrates when a sound waves hits it Vibrations felt by 3 small ossicle bones – hammer, anvil, and stirrup – and sent to inner ear

Inner Ear Cochlea – a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses Vibrating fluid in cochlea → moves hair cells in the basilar membrane – the inner lining of cochlea → Auditory nerve – sends neural impulses from the cochlea to the temporal lobe for processing.

Place Theory We hear different pitches because different sound waves trigger activity at different places along the cochlea’s basilar membrane.

Frequency Theory The brain reads pitch by monitoring the frequency of neural impulses traveling up the auditory nerve. If a sound wave has a frequency of 100 waves per second, then 100 pulses per second travel up the auditory nerve.

Volley Principle Place theory best explains how we sense high pitches. Frequency theory best explains how we sense low pitches. A combination of the two handles pitches in the intermediate range.

Hearing disorders

Tinnitus A chronic ringing in the ears. Caused by damage to and loss of the tiny sensory hair cells in the cochlea Tends to happen as people age. Can also result from prolonged exposure to excessively loud noise.

Conduction Hearing Loss Caused by damage to the mechanical system that conducts sound waves through the outer and middle ear to the cochlea. Typically caused by damage to the tiny bones in the middle ear, the hammer, anvil, and stirrup.

Sensorineural Hearing Loss Caused by damage to the cochlea’s receptor cells or to the auditory nerves. Cochlear implant: a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.

Locating Sounds The placement of our ears allows us to hear stereophonic (multidirectional) hearing. A sound to your right hits our right ear more intensely and receives sound slightly sooner than your left ear.