Hearing or audition

A. Hearing begins with sound 1. SOUND - mechanical energy typically caused by vibrating objects 2. SOUND WAVES - vibrations produce movement of air molecules 3. ACCOUSTICAL TRANSDUCTION: conversion of sound waves into neural impulses, in the hair cells of the inner ear

Characteristics of sound FREQUENCY - corresponds to perceptual term PITCH in which sounds are described as high or low due to the change in pressure created by sound waves (length of wave) AMPLITUDE - corresponds to perceptual term LOUDNESS/VOLUME is the dimension of sensory experience and amount of energy in a wave COMPLEXITY- corresponds to perceptual term TIMBRE or quality

Frequency (Pitch)

Intensity, Amplitude (Loudness)

Decibels (dB) A standard unit for measuring a sound’s LOUDNESS Every increase of SIX decibels DOUBLES a sounds intensity a. example – a 40 decibel sound is twice as intense as a 34 decibel sound Noise related to 80 decibels or higher can cause PROLONGED hearing loss if heard over prolonged periods of time.

Loudness of Sound Richard Kaylin/ Stone/ Getty Images 120dB 70dB

Structures of the ear: PINNA - external (visible) flaps of skin and cartilage AUDITORY CANAL - part of the outer ear that tends to tympanic membrane EARDRUM or TYMPANIC MEMBRANE - separates outer ear from the middle ear and vibrates with receiving sounds OSSICLES - the three bones in the middle ear that are set in motion by the eardrum

COCHLEA - part of the inner ear that contains fluid and receptors a. BASILAR MEMBRANE - subject to pressure changes in the cochlear fluid b. HAIR CELLS - belong to organ of conti which is triggered by fluid movement

Outer ear Inner ear Auditory nerve cochlea sound eardrum Middle ear Bones of Middle ear Auditory nerve cochlea sound eardrum Auditory canal Auditory cortex of temporal lobe anvil stirrup hammer eardrum

Auditory theories PLACE THEORY - differences in pitch result from stimulation of different areas of the basilar membrane

FREQUENCY THEORY - differences in pitch are due to rate of neural impulses traveling up the auditory nerve

Localization of Sounds Because we have two ears, sounds that reach one ear faster than the other ear cause us to localize the sound. OBJECTIVE 14| Describe how we pinpoint sounds.

Experiment Test your partner’s hearing. One of you will need to the put the blindfold on. Your partner will snap his/her fingers (use both hands and snap in different directions.) From right, left, front, back, etc.

Hearing Loss Conduction Hearing Loss: Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea. Sensorineural Hearing Loss: Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve, also called nerve deafness. OBJECTIVE 15| Contrast two types of hearing loss, and describe some of their causes.

Hearing Deficits Older people tend to hear low frequencies well but suffer hearing loss when listening for high frequencies.

Deaf Culture Cochlear implants are electronic devices that enable the brain to hear sounds. Wolfgang Gstottner. (2004) American Scientist, Vol. 92, Number 5. (p. 437) OBJECTIVE 16| Describe how cochlear implants function, and explain why Deaf culture advocates object to these devices. Where these implants are pertinent for hearing parents with deaf children, deaf culture advocate not using them especially on children deafened before learning to speak. Deaf Musician Cochlear Implant