Audiology test 1 study guide
Audiology test 1 study guide CDS 290LEC
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This 8 page Study Guide was uploaded by Alicia Notetaker on Sunday February 21, 2016. The Study Guide belongs to CDS 290LEC at University at Buffalo taught by Wei Sun in Spring 2016. Since its upload, it has received 151 views.
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Date Created: 02/21/16
CDS 290 Audiology: Diagnosis and Management Lecture 2: The profession of audiology Eardrum: sealed membrane, nothing can go in unless a hole in eardrum Middle ear space: ossicles carry vibration in inner ear Hearing and balance within the ear Cause of dizziness: damage of organ in inner ear Damage of inner ear: deaf Inner ear is inside of brain (can’t see it) Audiologist: diagnoses, treats, and manages those with hearing loss/balance problems Treatment options: dispensing and fitting hearing aids, vestibular rehab treatment, etc. Hearing damage can be due to the air or brain Assessment and rehab (peripheral and central hearing loss/ vestibular disorders), prevent, prevent, research, education, intraoperative monitoring(prevent damage during surgery), dispensing hearing aids ENTS & Audiologist = partners ENT: physicians for medical and surgical treatment (ear, nose, throat, head and neck) Audiologist: not technician, can have own practice **ear infection = most common prob in kids can affect learning & speech development Statistics of hearing loss 1. 278 million people worldwide have moderate - profound hearing loss in both ears 2. 28 mill Americans have hearing loss 3. 6 in every 1,000 infants have moderate – severe hearing loss at birth 4. 15% school –aged children may have ear infection 5. close to 8 mill people between 18-44 have hearing loss 6. 14% between 45-64 have hearing loss 7. > 30% of people over 65 have hearing loss Audiologists work in: hospitals, medical doctor office/department(ENT), private practice, schools, universities, factories >60% work in medical facility primary employment setting is private practice Specialists: Medical audiology, education audiology, pediatric audiology, industrial audiology, dispensing audiology, research audiology 1. Medical audiology: (largest specialty), medical environment, assessments to see location of hearing/balance problems, non-invasive for newborns (if they can’t hear speech, they can’t produce speech), monitor ototoxicity induced hearing loss (ear poisoning due to due exposure of chemicals or drugs in inner ear), intraoperative hearing monitoring in brain surgery, works with SLP, otologist, neurologist, physical therapist, occupational therapist Pure Tone Test – Audiogram: air conduction = produce sound through ear phone, soft sound @ top, loud sound @ bottom, produce sound through bone oscillator, they can hear (deficit from ear to skill – conductive hearing loss, common for children) damage middle ear When losing hearing for aging, lose part of hearing first (only miss part of word or hear you but don’t know what you’re saying) 2. Educational Audiologist: support children w/ hearing loss (public schools), routine screenings, rehab service, counsel, appropriate referrals 3. Pediatric Audiologist: infants and children (very challenging), pediatric hospitals, rehab centers, newborn screenings, cochlear implants, Central Auditory Processing Disorders (easily distracted or difficult following directions), for newborns after evaluation come back 3 months for another evaluation to see if still a prob with hearing loss or fluid in ear Newborn hearing screenings: non-invasive, for babies make noise & if brain reacts you see response on screen, important to test babies early 4. Industrial Audiology: noise is too loud, can damage cells, if cells are damaged they will never come back, noise induced hearing loss is most common occupational disease 5. Dispensing/Rehabilitative Audiology: open fit hearing, more on management than diagnosis, patients of all ages, excellent counseling skills 6. Research Audiology: universities, hearing aid companies, cochlear implant makers, hospitals/ ENT department Training: State license & ASHA certificate (requirements: education, experience, exam) Lecture 3: Acoustics ** sound intensity very important for audiology tests sound: vibration of substance (may or may not produce sensation in ear) sound source: generator (tuning fork, vocal fold, piano, guitar) sound medium: transmit sound( air, water, wires, steel rails, bone) if no medium after vocal fold – can’t hear it * higher mass = lower vibrating rate, lower mass = higher vibrating rate (tuning forks have diff sizes bc vibrating is diff) Sound medium: vibration of air molecules, vibration creates pressure changes (compression = higher pressure, rarefactions = lower pressure), sound vibrations along longitudinal wave Sound waves: vibration speech, amplitude, pattern, travel speed, diff sounds have diff patterns ( y axis: pressure, x axis: time) Amplitude: size displacement from rest position Frequency: number of cycles per second (Hertz) (1 kilohertz = 1000 Hz) Period: how long it takes to make one complete cycle, INVERSELY related to frequency (F = 1/T, T = 1/F) (1 microsecond = .001 milliseconds) Wavelength: length of 1 cycle (λ = vT = v/F) (v: velocity) Lecture 4: Sound intensity and Psychoacoustics Sound intensity: amount of solid energy transmitted per second over an area (Watts/m2) Sound pressure: amount of force distributed over a surface area (Force/ Area) (pascal) Force: capacity to do work or cause physical change (Newton) (1 Pa = 1 N/m2) Decibel: expresses relative difference in power/ intensity (dB = 10 log10) (comparing kimball tower to house, Kimball is 100 times higher than house) dB IL: intensity level, (10^-12 watt/ m2) aB SPL: sound pressure level (20 uPa) Sound loudness: intensity Sound pitch: frequency Sound masking: two sounds interfere 1. Loudness: subjective experience, related to intensity, every time level raised 10 dB the loudness level doubles Normal conversation: 60 dB-110 dB 2. Psychoacoustics: (audiologists need to know how sound perceived by patient) subjective human perception of sound Loudness varies with frequency Loudness: (phon) = number to intensity in decibels of a 1000 Hz Sensation level: level of sound relative to threshold of subject (same sound could have diff perception to 2 diff people) (dB SL) Pitch: subject impressions of “highness” and “lowness” of a sound, relates to frequency (mel, 1000 mels = pitch of a 1000 Hz tone at 40 Db above listeners threshold) Sound localization: ability to tell direction of sound w/ out seeing source, requires bilateral ears, hearing loss can affect sound localization, bilateral hearing aids can improve sound localization ability Masking: 2 sounds heard at the same time, intensity of 1 sound may cause the otherndo be inaudible, change in threshold of sound caused by 2 sound = masking, used in hearing evaluation when want to separate each ear’s hearing (pure tone test, auditory brainstem response, etc) Lecture 5: Anatomy & Physiology of the outer and middle ear Outer ear: Pinna (auricle), external auditory canal (meatus), ear drum (tympanic membrane) Pinna: collects sound o Helix: outer frame of pinna (rolled up edge) (can always see it) o Antihelix: folded “y” shaped part of ear o Concha: hollow bowl like portion of outer ear next to canal o Lobe: fleshy lower portion of ear o Tragus: small projection in front of ear canal External Auditory canal: can only see a small portion, canal is not straight, outer portion is very soft, outer portion: elastic fibrocartilaginous canal & skin creates ear wax or cerumen, inner portion: bone covered by thin skin and no hair follicles or glands Should only use water to get wax out of ears, but not recommended to do by yourself b/c you need a certain temp, etc. Tympanic membrane: (ear drum) @ end of canal, irregular cone, very thin, rich blood supply, efficient vibrating surface, 3 layers: lateral epidermal (skin of external auditory canal), intermediate fibrous layer (outer radial and inner circular layer, tough fibrous tissue), inner layer (mucosa) Function of outer ear: cerumen protects tympanic membrane & middle ear from foreign objects, pinna changes spectral components of sound & brain interprets changes to assist in localizing, pinna: funnels sound down ear canal, ear canal closed @ one end so resonates like tube, vibrating air particles enter canal and resonate w/ greatest amplitude @ specific frequency (resonant frequency) Middle ear: in mastoid process of temporal bone(hardest bone in body), cavity is filled with air, several small bones called ossicles that look connected but there is cartilage separating them, contains: 3 ossicles, ligaments, muscles, Eustachian tube Middle ear ossicles: Malleus (head, neck, manubrium), Incus (short process long process lenticular process), Stapes (head, neck, anterior and posterior crus, footplate) Middle ear ligaments and muscles: hold ossicles in place, movement is very flexible, muscles: Tensor tympani (attaches to malleus, branch of trigeminal nerve), Stapedius (attaches to stapes, branch of facial nerve) Eustachian Tube: connects middle ear space to through, runs from anterous wall of the ME to posterior of nasopharynx, function: maintain air pressure in middle ear equals to external auditory canal, @ rest tube is closed, tensor palatine activated (yawning) allows tube to open, tube fails to open properly leads to build up of negative pressure in middle ear Low impedance: air, High impedance: fluid Sound in air must enter fluid in ear, when sound hits fluid most will be reflected back b/c of difference in acoustic resistance, if no ossicular chain air is not efficient to move fluid Lever effect: malleus is slightly longer than incus, when malleus moves during vibration, exerts force on incus by factor of 1.3 Physiology of middle ear: function: impedance matching, transfer vibration from one medium to another, sound travels down ear canal pushes against TM then TM vibration causes ossicles to vibrate so ossicles transmit vibration to oval window and sets fluid in cochlea into motion (it’s a pathway of sound), 3 main functions: impedance matching, protection, pressure equalization Lecture 6: Anatomy and Physiology of the Inner ear Inner ear is not flat, it is inside of the middle ear, vestibular and cochlear are connected, vestibular: movement & 3 circuit canal, cochlear: tube (snail shape), inside coil = 2 membranes Inner ear: located in petrous part of temporal bone, consists of vestibular (balance) and cochlear (hearing) components, cochlea: tube coiled into a 2 and ¾ turn spiral filled with fluid, 2 membranes: Reissner’s membrane and basilar membrane, divided tube into 3 parallel partition Cochlear fluid: outside of cell, 3 fluid filled chambers: Scala vestibuli ( perilymph like cerebrospinal fluid or extracellular fluid), Scala tympani ( perilymph), Scala media ( endolymph, likes the intracellular fluid) size of fluid is not compressible: cannot be changed, stapes pushes against oval window & sets perilymph into motion, fluid is dense & cannot compress therefore round window bulges out Inner ear physiology: cochlear can vibrate based on diff frequencies, tunning of basilar membrane, Basilar membrane: movement pattern of basilar membrane depends on stimulus of frequency, Basal turn: low mass (narrow) high stiffness & represents high freq, Apical turn: high mass (wider) low stiffness & represents low freqs, like guitar strings OHC & IHC function: hair cells were there when born & cannot be regenerated, most important structure for hearing***, basilar membrane: 2 types of sensorial cells, Outer hair cells (OHC): cylinder shape, Inner hair cells (IHC): pear shape, tectorial membrane Physiology of Hair cells: ions flow from positive end to negative end, inner hair cells send most info to brain**, movement of BM causes Organ of Corti to move up and down, upward movement of BM (peak of wave) causes stereociliar to bend outward which activates HCs, HCs are sensorial cells that transfer vibration to electrical signal received by auditory system o Outer hair cells (OHC): make cochlea sensitive to low level sound o Inner hair cells (IHC): most info in cochlea was sent by IHC Source of active amplifier in cochlea : OHC, when hair cells depolarize they release neurotransmitters When you produce a sound, a lot of activity in cochlea Electrical response from hair cells o Cochlea microphonics (CM): alternating current (AC) generated by hair cells, has same frequency w/ sound stimuli o Summating potential (SP): direct current (DC) component generated by hair cells Auditory nerves: (aging – first target = outer hair cells) Afferent nerves: Type 1- each fiber synapses on a single IHC, Type 2- fibers branch and contact Physiology of auditory nerves: produce electrical potentials when receive neurotransmitters from hair cells, these are called compound action potentials (CAP) Lecture 7: Anatomy & Physiology of Central Auditory System Outer hair cells: increased sensitivity of vibration Positive cell ions come into cell depolarize Afferent: ear to brain Efferent: brain to ear Auditory system is like a microphone, have to transfer voice w/ mechanical movement intro electrical signals Sensory cells: hair cells, lose them- brain won’t receive any signals (most hearing loss is b/c of cells) Tumor: can feel the signal (cochlea is functioning but can’t hear anything) When you have a problem in only one ear, there might be something wrong b/c when people have congenital hearing loss or due to sound exposure, its usually in both ears Outer ear & middle ear: sound conduction Inner ear: transduce vibration to neuron activity Central auditory system: hearing perception most speech perception is in auditory cortex (memory center) limbic system: perception of sound (the way you react to sound, what sounds you like & don’t like) Auditory cortex: can control what sounds you suppress Longer duration from peak 1 to peak 5, the sound comes to cochlea but has trouble reaching position Auditory nerve (AN, peripheral), Cochlea nucleus (CN), superior olivary complex (SOC), inferior colliculus (IC), medial geniculate body (MGB), auditory cortex (AC) Each neuron is tuned to a specific frequency: only responds to one frequency sound stimulus Auditory nerves produce electrical potentials when they receive neurotransmitters from hair cells – compound action potentials (CAP) Efferent: nerve is bigger for outer hair cells & direct contact to outer hair cells, projection from lateral and medial olivary complex to hair cells – protecting hair cell damage from loud sound Cochlea outputs send to olivary complex on contralateral side – hair cells receive efferent nerves from both sides of olivary complex Cochlear Nucleus: located in brainstem, two primary divisions: Dorsal CN (DCN) & ventral CN (anterior & posterior, AVCN & PVCN) , tonotopic organization, primary functions: monaural processing, important for coding & timing info Superior olivary complex (SOC): located in brainstem, 3 divisions: Lateral (LSOC), Medial (MSOC), Medial nucleus of trapezoid body (MNTB) SOC organization: primary function: binaural processing (sound localization), LSOC and MNTB localize high frequency, MSOC localizes low frequency Inferior Colliculus (IC): located in midbrain, tonotopic organization, primary function: integration of ascending monaural & binaural pathways, almost all ascending and descending auditory cortex pathways synapses are in IC Medial geniculate body: located in thalamus, tonopic organization, primary function: auditory attention, auditory arousal Auditory cortex: located in temporal lobes- superior temporal gyrus, tonopic organization, high level processing: assigning meaning to sound, process complex signals (speech), complex sound localization, many connections to other parts of brain
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