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Unformatted text preview: Hearing Aids Review
Components of a hearing aid microphone, amplifier, receiver, battery Modern day hearing aids ITE aids, programmable, digital Hearing aids vs. assistive listening devices (amplification at ear vs. at source) vs. implants Who benefits and how? Auditory Development
Every day, 33 babies (or 12,000 each year) are born in the United States with permanent hearing loss? 3 of every 1,000 newborns have a hearing loss Hearing loss is the most frequently occurring birth defect. Auditory Development: Physiology Auditory Development re: Rat
Human child has long period of hearing vulnerability. Cochlear maturation
Sensory cell differentiation Onset of function End of maturation Auditory CNS development Ear 3 mos. (in utero) 4-6 mos. (in utero) Birth ... 6 yrs. Vulnerable period PUJOL R., and HILDING D. Anatomy and physiology of the onset of auditory function. Acta Otolaryngol (Stockh) 76:1-11, 1973 Auditory Development
Critical Period Best outcomes for cochlear implants at early age Normal cortical auditory evoked potentials 3-6 months after implant up to age 3.5 yrs, not after age 7 years (Sharma & Dorman, 2006) In mice, hamsters and rats, the exposure to intense sound is more traumatic in the developing ear than in the adult ear (Saunders & Chen, 1982) Auditory Developmental Abnormalities
Acoustic neuroma tumor on auditory nerve Cochlear hypoplasia incomplete development of the cochlea (e.g. absence of hair cells) Middle ear cholesteatoma abnormal skin growth (tumor) in middle ear Ossicular discontinuity detached bones of the ossicular chain Microtia (small ear) congenital deformity of the pinnae Anotia (no ear) absence of the pinnae Atresia absence of the ear canal Auditory Developmental Abnormalities Congenital Hearing Loss
Occurs During Fetal Development Causes: In utero infections Ototoxic medications e.g. aspirin Asphyxiation Cranio-facial anomalies Genetic Anotia/Atresia Middle ear cholesteatoma Microtia Acoustic neuroma Fishing for genetic factors for hearing loss
Zebra fish used as animal model for determining genetic and drug factors for hearing loss Auditory Development: Early Problem Signs Does not startle, move, cry or react in any way to unexpected loud noises. Does not awaken to loud noises. Does not turn his/her head in the direction of a parent's voice. Language Development and Hearing Loss Auditory Development and Deafness
Cochlear Implants: Surgery Restore hearing Variability in success Need auditory-verbal training Cost ($40,000) Deaf: Sign language Community support Less risky & expensive Mainstreaming? Future `cure' Great variability in language development (Audiogram not good predictor) Factors underlying variability: age of onset, age of identification, age of amplification, degree hearing loss... Risk factors: Social interaction, babbling different -> speech delayed, same but stages prolonged, Limited incidental learning Early Hearing Detection and Intervention (EHDI) Screening 1st month -> Confirmation 3rd month -> Intervention 6th month Communication Approaches: Deaf Culture (ASL), Oralism (English), Total Commun. (MCE+Oral), Bilingual/Bicultural (ASL->English) Definitions: Deaf, deaf, hearing-impaired vs. hard-of-hearing Auditory Development: Behavior
How can hearing be measured in infants? Can't ask them to tell you about the sound. Have to elicit a behavior and measure a response What do infants do?
Birth Measurable Behaviors at Different Ages Startle response to loud sounds Increase sucking in response to sound 5-months Turns head in search of sound Reaches with hands 1-2 years Mobile; doesn't sit still 3-5 years Talks & understands simple instructions Plays games / computers Likes to please adults (?) Can measure these behaviors Hard age to study Good age to work with Auditory Development
Startle and Sucking Response, Birth-5 mos
light Visual Reinforcement Audiometry
Conditioned Head Turn Response
Infant learns that an animated toy appears after a sound or after a change in the sound. Infant turns head in direction of toy to be reinforced by the sight of the toy. The sound is a conditioned stimulus, the head turn is a conditioned response. Gold Standard other measures don't test hearing sound Kid Parent
Masking Noise Auditory Development
Visual Reinforcement Audiometry What has been studied? Frequency & Intensity Discrimination Perception of Pitch Sound Location Speech perception How do babies learn language?
Problem of Segmentation: Must first learn where words begin and end. Children as Citizens of the World
Infants are born "citizens of the world" with regard to language. They can distinguish sounds from languages around the world, even if they've never heard them before. By the end of the first year of life, however, they become "language-specialists," and the ability to attend to sounds from foreign languages greatly diminishes. Patricia K. Kuhl, Ph.D. Babies appear to do this by learning likely patterns within words. e.g. "pret-ty ba-by" more likely than "pret ty-ba by" Aslin Exp.: 7-8 mo old infants listen longer to novel combinations of nonsense syllables ...
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This note was uploaded on 03/21/2012 for the course COM DIS 110 taught by Professor Weismer during the Fall '08 term at Wisconsin.
- Fall '08