Hearing 2

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Outer Ear: Composed of two parts: 1. Pinna (funnels sound to ear and helps localize sound) 2. External auditory canal (2.5 inches long and â€œsâ€ shaped)
Cerumen: Wax secreted by special cells. It lubricates and cleanses the canal, protects the ear from fungi, bacteria, and small insects
Middle Ear: Air-filled cavity with the ossicular chain and opening of the Eustachian tube
Tympanic Membrane: Elastic, thin and cone-shaped. Flexile and tough and vibrate in response to sound pressure
Ossicular Chain: Parts: Suspended in the middle ear by ligaments, it is composed of three tiny bones: the malleus, incus, and stapes
Ossicular Chain: Vibrations of the tympanic membrane are transferred to the malleus (which is connected to it), which is then transmitted to the incus, then the stapes. The footplate of the stapes rocks in and out of the oval window that leads to the inner ear. Transmits sound efficiently with no distortion. Amplifies sound by 30dB
Muscles of the Ear: Two small muscles in the middle ear dampen the vibrations of the tympanic membrane and ossicular chain: the tensor tympani and the stapedius muscle (smallest muscle in the body.)
Tensor Tympani: tenses the tympanic membrane so the vibrations are reduced
Stapedius: stiffens the ossicular chain so that its vibrations are reduced
Acoustic Reflex: The middle ear muscles contract in a reflexive action when a person hears very loud noises that could damage the ear
Eustachian Tube: Connects the middle ear with the pharynx. It helps maintain equal air pressure within and outside the middle ear. Yawning and swallowing open the Eustachian tube, letting fresh air in
Tensor Veli Palatini & Levator Veli Palatini: Open the end of the eustachian tube. Infants eustachian tubes and more horizontal, making them more susceptible to infections
Inner Ear: A system of interconnecting tunnels called labyrinths within the temporal bone. They are filled with a fluid called perilymph. The oval window is a small opening in the temporal bone through which the movement of the footplate of the stapes in the oval window allows the inner ear to receive mechanical vibrations of sound
Inner Ear: There are two major structures: "1. Vestibular System: Related to movement, balance, and body posture. Contains the semicircular canals that are responsible for equilibrium 2. Cochlea: Snail shaped and resembles a coiled tunnel. Filled with endolymph, a type of fluid
Inner Ear: Basal Membrane: Floor of the cochlea which contains the organ of Corti. The organ of Corti is bathed in endolymph and contains several thousand (15,500) hair cells, or cilia, which respond to sound vibrations
Inner Ear: Functioning: Nerve fibers carry the sound (neural impulses) to the brain (which does not respond to mechanical vibrations, only electrical vibations)
Auditory Nervous System: Cranial nerve 8, the acoustic nerve, is the nerve that picks up the neural impulses from the movement of the hair cells. It exists the inner ear through the internal auditory meatus
Auditory Nervous System - function: The auditory or acoustic branch supplies the hair cells and conducts electrical sound impulses from the cochlea to the brain; The nerve impulses are carries by the left and right auditory pathways to the brain. Up to the brainstem they are peripheral, past it they are central; At the cerebellopontine angle, the auditory nerve exits the temporal bone through the internal auditory meatus and enters the brain stem; At the level of the brain stem, most auditory nerve fibers decussate forming contralateral pathways. Some fibers continue on the same side, forming ipsilateral pathways. This helps the brain localize and in interpret sounds; The fibers project the sound to the temporal lobeâ€™s primary auditory area, which is responsible for receiving and interpreting the sound stimuli
Acoustics: the study of sound as a physical event
Vibrations: occur in cycles
Frequency: The number of cycles per second
Pure tone: A single frequency
Simple harmonic motion: A single tone that repeats itself
Complex Tone: Two or more sounds of differing frequencies
Periodic: Vibrations have a pattern that repeats itself at regular intervals
Aperiodic: Vibrations occur at irregular intervals
Sound Waves: Displaced air molecules. The swinging back and forth of air molecules that disturb adjacent air molecules causing compression and rarefaction
Pitch: Changes in frequency
Intensity: Changes in loudness. Expressed in terms of decibels, at SPL
Amplitude: The extent of displacement of the molecules in their to-and-fro motion. The greater the displacement, the greater the amplitude, and intensity.
Decibel: Measure of sound pressure
Sound pressure level (SPL): Measures intensity
Hearing level (HL): Lowest intensity of a sound necessary to stimulate the auditory system. It is the decibel level used on audiometers. The human ear is most sensitive to sounds between 1000 -4000 Hz. The SPL needed to stimulate the human auditory system at different frequencies is considered 0dB HL
Air conduction: Sound waves strike the tympanic membrane to the middle & inner ear
Bone conduction: The lager bones of the skull vibrate to produce movements in the inner ear fluid
Hearing Impairment: Can be very mild to severe to profound
Hearing Impaired: Being heard of hearing or deaf
Hard of Hearing: Loss between 16-75 dB in children, 25-75 dB in adults
Deaf: Loss exceeds 75 dB, and in many cases, 90 dB
Hearing Loss (Children & adults): Up to 15 dB (25 dB) = normal hearing; 16 (25) to 40 dB = mild hearing loss; 41 to 55 dB = moderate hearing loss56 to 70 dB = moderately severe hearing loss; 71 to 90 dB = severe hearing loss; 91 + dB = profound hearing loss
Conductive Hearing Loss: Sound conducted to the middle or inner ear is diminished. In a pure conductive hearing loss, the inner ear, acoustic nerve, and auditory centers of the brain are working normally. Bone conduction is working normally. A conductive hearing loss is never profound because there is always some hearing left with bone conduction. Thus, people can hear their own speech well, and speak too softly, especially in background noise
Conductive Hearing Loss: Causes: Birth defects, diseases, foreign bodies blocking the external ear canal
Aural atresia: external canal is completely closed
Microtia: pinna is very small and deformed
Stenosis: extremely narrow external auditory canal
External Otitis: Infection of the skin of the external auditory canal, frequently found in swimmers
Otitis Media: Infection of the middle ear associated with upper-respiratory infections and eustachian tube dysfunction. Frequently in infants and children but rarely in adults. Creates a conductive loss of 20-35 dB HL
Otitis Media: Type 1: Serous: Middle ear is inflamed and with watery and thick liquid. The eustachian tube is blocked. Increased air pressure outside pushes the tympanic membrane inward. Treated with antibiotics or PE tubes
Otitis Media: Type 2: Acute: Sudden onset due to infection. Quick buildup of fluid and pus creates moderate pain. May have fever and vertigo. Tympanic membrane may burst from built up pressure in middle ear. Treated with medical and surgical procedures: myringotomy-incision made in the tympanic membrane to relieve the pressure
Otitis Media: Type 3: Chronic: Permanent damage to middle ear structures. Erosion of the ossicles, cholosteotoma, or atrophy or perforation of the tympanic membrane (which can be permanently ruptured.) Painless, foul-smelling discharge from the ear. Treated with antibiotics and surgery
Otosclerosis: May be inherited, more common in women and whites. A new, spongy growth starts on the footplate of the stapes. The stapes becomes ridged and does not move enough into the oval window to create pressure waves in the inner ear
Carhartâ€™s Notch: Found in patients with otosclerosis, reduced bone conduction predominately at 2000 Hz
Otospongiosis: Stapes becomes to soft to vibrate. Stapedectomy: Stapes is surgically removes and replaced with a synthetic prosthesis
Ossicular discontinuity: Disarticulated ossicular chain
Sensorineural Hearing Loss: "Damage to the inner ear, such as the hair cells or acoustic nerve. Permanent, and mild to profound. Bone and air conduction is impaired, thus they have a hard time hearing themselves and speak too loudly. Not the same across frequencies
Sensorineural Hearing Loss: Recruitment: disproportionate increase in the growth of perception of the loudness of the sound when it is presented with liner increases in intensity. Makes a person hypersensitive to intense sounds
Sensorineural Hearing Loss: Causes: Prenatal causes: Drugs taken during the 6th and 7th week of pregnancy; Ototoxic drugs; Noise; Birth defects; Viral and bacterial diseases: Siphilis, toxoplamosis, rubella, cytomegalovirus, and herpes simplex; Tumor called an acoustic neuroma; Presbycusis: impairment in older people resulting in a sloping high frequency loss.; Meniereâ€™s Disease: fluctuating loss from excessive endolymphatic pressure causing a distended Reissnerâ€™s membrane. Hearing loss, dizziness or vertigo, fullness of the ear, tinnitus. No cure
Mixed Hearing Loss: When neither the middle or inner ear is functioning properly
Central Auditory System: includes the brain stem, where the auditory nerve terminates, fibers that project sound to the auditory centers of the brain, and those brain centers themselves
Peripheral Hearing Problems: Results from problems in the oter, middle, or inner ear
Central Auditory Disorders: Refers to hearing losses due to disrupted sound transmission between the brainstem and the cerebrum as a result of damage or malformation.
Central Auditory Disorder: Causes: Tumors, TBI, HIV, asphyxia during birth, genetic disorders, infections such as meningitis and encephalitis, metabolic disturbances, central degenerative diseases such as Alzheimerâ€™s, and demylinating diseases such as MS
Central Auditory Disorder: characteristics: Poor auditory discrimination, integration, sequencing skills, closure, attention, memory, and localization; Difficulty listening in background noise; Difficulty understanding rapid speech; Difficulty following melodic and rhythmic elements of music; Difficulty learning to read aloud due to inability to learn correct association of visual and auditory sounds
Central Auditory Disorder: Treatment for Children: 1. Direct intervention or remediation techniques aimed at improving auditory skills 2. Helping the child use compensatory strategies to manage the deficit 3. Modification of the environment to minimize adverse learning conditions 4. FM Units
Retrocochlear Disorders: Damage to the nerve fibers along the ascending auditory pathways from the internal auditory meatus to the cortex. Usually involves the cerebellopontine angle or cranial nerve 8
Retrocochlear Disorders: causes: Acousitc neuromas (unilateral tumors). Often has a unilateral high frequency loss that may be accompanied by dizziness, tinnitus, and a feeling of disequilibrium. Acoustic reflexes are absent or at elevated levels. May also have alterations of facial sensation and movement because the facial and trigeminal nerves may be affected. There may be pain and headache in the ear and mastoid region, and a feeling of fullness in the ear. May have problems with balanceMay be confused with Meniereâ€™s disease. Another cause may be von Recklinghausen disease, an inherited disease where numerous small tumors grow slowly and occur along various peripheral nerves
Audiometer: An electric instrument that generates and amplifies pure tones, noise, and other stimuli for testing
Threshold: An intensity level at which a tone is faintly heard at least 50% of the time it is presented. Each tone is presented several times
Bone conductions testing: Assesses the sensitivity of the sensorineural position of the auditory mechanism. A bone vibrator is placed on the forehead or behind the test ear. It is difficult to which ear heard the sound
Masking: Noise is set through a headphone at a level that is strong enough to mask the tone in the opposite ear
Speech audiometry: Measures how well a person understands seech and discrimination between speech sounds
Speech reception threshold: The lowest level of hearing at which a person can understand 50% of the word presented (spondee word lists.)
Spondee words: Two syllable words with equal stress (ie. hotdog, baseball).
Word discrimination/word recognition Test: Establishes how well a person discriminates between words having the person repeat monosyllabic words such as cap and day. Presented at a comfortable loudness
Acoustic immitance: Transfer of acoustic energy. When sound stimulus reaches the external ear and strikes the tympanic membrane
Impedance: Resistance
Admittance: The amount of energy that flows through the system. Both very low and very high impedance suggest pathology within the auditory system
Tympanometry: Procedure in which acoustic immitance is measured with an electroacoustic instrument called an impedance meter. It can also measure the acoustic reflex
Electrophysiological audiometry: Measure of auditory mechanism functioning by measuring electrical impulses
Auditory-evoked potentials: electrical changes produced by sound stimuli
Electrochleography: Measurement of the electrical activity of the cochlea in response to sound.
Auditory brain stem response: Techniques used to record the electrical activity in the auditory nerve, the brain stem, and the cortical areas of the brain. Helpful in testing the hearing of newborns infants
Localization audiometry: Used with older infants, presenting a sound and seeing of the infant will turn their head toward it
Operant audiometry: A childâ€™s hearing is tested by conditioning voluntary responses to sound stimuli. Used for more challenging children
Audiologists make recommendations based on: A case history and interview; A comprehensive speech and language assessment; Otological records from the patientâ€™s olologist; Any general medical records that include information relative to the patientâ€™s hearing and overall health; For children, reports from regular and special education teachers
Audiograms: Graphs that display the results of air & bone conduction tests in dB
Air-bone gap: Indicates a conductive loss when the differences in air and bone frequency average 10 dB or more
People with hearing impairment manifest the following speech problems:: Distortion of sounds, especially fricatives and stops; Omission of initial and final consonants; Consonant cluster reduction; Substitution or voiced consonants for voiceless; Omission of /s/ in almost all positions in words; Substitution of nasals for oral consonants; Increased duration of vowels; Imprecise production of vowels; Epenthesis
Language Problems in the prelingually deaf: Limited variety of sentence types; Reduced length and complexity of sentences; Providing insufficient background info to listener; Limited oral communicationDifficulty understanding proverbs, metaphors, and other abstract utterances; Slower acquisition of grammatical morphemes; Poor reading comprehension; Writing reflect oral language problems
Hearing Problems: Associated problems with Voice and Fluency: Hypernasal on non-nasal sounds; Hyponasal on nasal sounds; Abnormal rhythm; Lack of intonation; Improper stress; Restricted pitch range; Rate of speech too slow or fast; Inappropriate pauses; Hoarseness or harshness
Aural rehabilitation: Educational and clinical program implemented primarily by audiologists to help people with hearing losses achieve their full potential. Focus on hearing aid fitting and orientation, the environment and communications within the environment, and early identification and intervention
Amplification: Three types: Hearing aids, cochlear implants, and auditory trainers
Hearing Aids: Amplify sound and deliver it to the ear canal
Hearing Aids types: Eyeglass variety; Body aids; Behind the ear model; In the canal model; Completely in the canal model; In the ear model; Disposable hearing aid
Analog Hearing Aids: Create patterns of electrical voltage that correspond to the sound input. Has a microphone, amplifier, power source (batteries), & volume control
Digital Hearing Aids: Samples the input signal and converts it to into a binary systems of zeros and ones. Those numbers are processed by a computer housed in a unit worn on the body
Digital Hearing Aids: Adventures: 1. More ability to adapt it to the clientâ€™s needs; 2. Amplify certain frequencies for which loss is greater; 2. Amplify certain frequencies for which loss is greater 3. More effective reducing irritating loud noises like vacuums; 4. Better signal to sound ratio, separating speech from background noise
Cochlear Implants: Electrical device surgically implanted in the cochlea and other parts of the ear and deliver sound directly to the acoustic nerve endings in the cochlea. Hearing aids deliver amplification, cochlear implants deliver electrical impulses, converted from sound, directly to the auditory nerve. Cochlear implants replace the nonfunctioning inner hair cell transducer system. Microphone in the ear canal, processor worn on the body, external transducer worn on the skull, and the implanted receiver.
Auditory training: Teaches a person with hearing impairment to listen to amplifies sounds, recognize their meaning, and discriminate their sounds from each other
Auditory Trainers: Amplifies speech
Fm Auditory Trainer: Wireless system that can be used with a group or individual treatment sessions
Lipreading/Speech reading: Deciphering speech by looking at the face of the speaker and using visual cues to understand what the speaker is saying
Cued Speech: Speech produced with manual cues that represent the sounds of speech.
Nonverbal communication: ASL, Seeing essential English (breaks English morphemes down), Signing exact English, fingerspelling, and te Rochester Method (combo of oral and fingerspelling.)

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