Chapter 14 Test Audiology hearing Loss 1 Incidence and Prevalence of Hearing Loss 10 of U S population has hearing los o one of the most common birth defects 3 in 1 000 births result in child with hearing loss most common birth defect loss 1 in 1 000 births result in child who is deaf 83 in 1 000 children in the US has educationally significant hearing 95 of babies are screened within 1 month Failure to identify hearing loss and provide early intervention can lead to many difficulties 2 Hearing Loss through the Lifespan Psychosocial aspects of hearing loss o Psychological social emotional consequences o 95 of children with hearing loss are born to hearing parents must educate parents to come up with a plan o Kubler Ross grief cycle o Professionals must Stages shock denial anger depression acceptance Explore psychosocial issues Determine full impact of hearing loss Classification of Impairment Disability and Handicap o Impairment Loss of structure or function We want to understand is hearing loss due to outer or inner ear problem Etc o Disability Functional consequences of impairment How does hearing loss limit types activities that the person can participate in Psychosocial consequences of impairment How does society respond to the person with hearing o Handicap loss o All experience impairment most experience disability not all experience handicap Deaf Community Chapter 14 Test Audiology hearing Loss o Group who views deafness with a sense of pride sense of belonging Does not see their hearing loss as a handicap Distinguishes itself w own language ASL o Deaf vs deaf BIG DIFFERENCE deaf loss of auditory signal Deaf capital letter deaf culture community Means one is part of Deaf Culture o American Sign Language ASL The language of the Deaf Fosters cohesion and identity Schools for the Deaf allow for interactions using ASL Those who are part of Deaf community often marry others with similar cultural ideals Many desire children who are deaf Communication with nonsigning people can be inhibited Some view speech language pathology and audiology negatively o SLPs have a negative perception in Deaf community 3 What is Audiology Discipline involved in o Prevention and assessment of auditory vestibular and related impairments as well as habilitation rehabilitation and maintenance the ASHA defines audiology as the definition above hearing and balance issues Audiologists o Provide counseling prescribing and fitting amplification various therapies Amplification technology such as hearing aids cochlear implants and assistive listening devices that improve access to sounds by electronically increasing their intensity Work in healthcare settings schools universities Recommend different types of treatments 4 Fundamentals of Sound Must be an energy source and a receptor Chapter 14 Test Audiology hearing Loss Series of compressions and rarefactions that move outward from vibrating source Sound wave propagates to the ear o There are molecules that bounce around and create vibrations that become sound waves o Distance a vibrating object travels determines intensity measured in decibels DB Amplitude Frequency o Cycles per second measured in Hertz Hz o How many vibrations per second how high or low a sound is Extra notes from class follow in this order o Sound wave outer ear pinna ear canal mid ear inner o Then sound waves are converted to neural impulses that are ear cochlea transported Audibility the ability to detect the presence of a given sound Intelligibility the ability to recognize and understand what is heard o HEARING LOSS affects both audibility intelligibility 5 Anatomy and Physiology of the Auditory System The outer ear o PINNA Enhances sound Aids localization localization is the process of determining where sound originates in space o External Auditory Meatus Elliptical tube lined with skin Extends from concha to tympanic membrane Concha the deep bowlike depression on the pinna Tympanic membrane basically eardrum the thin cone shaped structure composed of three layers of tissue located at the end of the external auditory meatus It is set into vibration as acoustic energy strikes its surface Cerumen a substance produced by glands in the ear canal that provides lubrication and protects the ear from the invasion of insects and other foreign objects Glands that produce cerumen Resonator The Middle Ear Chapter 14 Test Audiology hearing Loss o Tympanic membrane Vibrates in response to sound 3 layers o Middle ear space tympanic cavity The Inner Ear o Cochlea Air filled lined with mucous membranes housed in temporal bone o Eustachian tube Connects middle ear with nasopharynx o Ossicles in Ossicular chain Malleus incus stapes Malleus the largest of ossicles It is fastened to the eardrum and articulates with the incus the next bone in the chain Incus The middle bone of the ossicular chain Articulates the malleus at the top and has a projection that is joined to the stapes at the bottom Ossicular chain allows the eardrum to move back and fourth o Footplate of stapes rests on oval window o Stapedius muscle Provides auditory input to the central auditory system Pea sized coiled structure Two concentric labyrinths Outer bony filled with perilymph Inner membranous filled with endolymph In cochlea when fluid moves through energy is created If none is made person suffers from deafness o Organ of Corti the part of the inner w hair cells and auditory cells Tectorial membrane Basilar membrance These are the two acellular gels in the corti Tonotopically organized o The spatial arrangement of where sounds of different frequency are processed in the brain o Cochlea cont Hair cells Inner and outer Stereocilia Chapter 14 Test Audiology hearing Loss Bent through movement of basilar and tectorial membranes Chemical transmitters released Creates neuroelectic energy Auditory fibers of VIIIth cranial nerve innervates hair cells o Vestibular System Information regarding balance and spatial orientation Dizziness vertigo imbalance Semicircular canals Sense angular acceleration Otolith System Two membranous sacs Senses linear acceleration Nerve fibers form the vestibular branch of CN VIII o The Vestibulocochlear Nerve CN VIII Travels through the internal auditory meatus Joins brainstem Cerebellopontine angle Juncture of peripheral and central auditory systems o The Central Auditory System Ipsilateral and contralateral ascending pathways Superior olivary complex Lateral lemniscus Inferior colliculus Medial geniculate