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Loud sounds presented to the ear cause the stapedius muscle attached to the stapes bone and the tensor tympani attached to the hanlde of the malleus to contract (ossicular chain stiffens) Measure with impedance testing unit
The decibel difference between the air conducted threshold and bone conducted threshold for same frequency and same ear. Present in mixed or conductive loss, not present in sensorineural loss.
Air Conduction Pathway
(aucoustic energy)Auricle/Pinna->TM->Malleus/Incus/Stapes->Oval Window->Inner ear fluids->Hair cells->Spiral Ganglions->Brain
Bone Conduction Pathway
(vibration) Skin->Fatty Tissue->Skull->Inner Ear Fluids of Cochlea->Hair Cells->Sprial Ganglion->Brain
- A yellowish waxy substance produced by a combination of secretions (sweat and sebum) by ceruminous and sebaceous glands, mixed with dead epidermal cells. pH 6.1
- 1. Keeps ear canal pliable
- 2. Kills bacteria (some strains eg S.aureus, E.coli)
- 3. Waterproofing
- 4. Traps forgein bodies: eg. dust and fungi (inhibits but does not kill fungal spores)
- 1. Wet - yellow/brown & moist, 50% lipid
- 2. Dry -gray & flaky, 30% lipid
- (recessive) Often in first nations and asians.
- Specialized sudoriferous glands (modified apocrine sweat glands) found in the cartilaginous outer third of the external auditory canal.
- Produce a specialized sweat that mixes with sebum and epithelial cells to produce cerumen.
- Capable of developing benign and malignant tumors.
Branch of Cranial Nerve VII (facial nerve) that lies exposed in the middle ear. Provides the sensation of taste to the anterior two-thirds of the tongue.
Tumor which starts in tissues of ear drum
- Small snail shell like structure which contains peripheral hearing mechanisms and in which hydraulic energy is tranduces into neural energy. Human cochlea turns 2 1/2 rotations (dogs turn 3 1/4)
Band of fibres connecting lobes of the anterior portion of the brain.
Hollow next to ear canal. Cavum consha
Conductive Hearing Loss
Outer or middle ear obstruction in the pathway of sounds
Thick band of fibres which connect the right and left hemispheres and is the primary site for binaural hearing
Contralateralization of Sounds
Stimuli presented to one ear crosses the head and is heard by the other
Measurement made with master hearing aid unit indicating the frequency response needed for the hearing aid as measured in dB/octave roll-off in the amplifier
- Contained in the membranous labyrinth. Interior fluid in which the sensory cells of both the auditory and vestibular mechanisms are located.
- Secreted by the stria vascularis
- Low Na+, high K+ electolyte, filtrate of cerebrospinal fluid. High positive potential (80–120 mV ).High potassium content allows K+ to be carried as depolarizing current into the hair cells. This is known as the mechano-electric transduction (MET) current. Because the hair cells are at a negative potential of about -50 mV, the potential difference from endolymph to hair cell is on the order of 150 mV, which is the largest electrical potential difference found in the body.
If enlarged (endolymphatic hydrops) is linked to Meniere's disease.
Connects nasopharynx to middle ear.
Functional Hearing Loss
Nonorganic Hearing Loss
Exaggerated Hearing Loss
An exaggeration in the degree of hearing impairment.
The measurement of the client's ability to hear simple words without hearing instruments. Requires no equipment.
Genetic Hearing Loss
Hereditary Hearing Loss
Hearing loss due to defects in the chromosomes
Site on temporal lobe where primary auditory area is located
Opening located at the apex of the 2 3/4 turns of the cochlea. Through this opening the wave motion passes.
- To reduce.
- Impedance tests measure many physical properties of the ear including ear drum mobility and stapedial reflex levels. Provide:
- 1. Tympanograms (Fluid in middle ear;TM scarring; TM retraction; stapes fixation; Eustachian tube abnormality;middle ear infection)
- 2. Acoustic Reflex test (functioning of middle ear muscles and tendons)
- 3.Relative Physical Volume test (integrity of TM)
Major synapse of the auditory pathway between the lateral lemniscus and the medial geniculate bodies, which generates wave V.
The engery loss in a sounds as it travels from one ear to another.
Internal Auditory Canal
Canal within skull which house the VIII Cranial Nerve, the Hearing and Vestibular Nerve.
Columnar cells on the side (rising superiorly) in the brainstem which generate wave IV.
- Lowest curved setion of the incus.
- (where it attaches to the head of the stapes)
Long process or "handle" of the malleus
The use of noise in the non test ear to preclude that ear from assisting the ear under test.
- Removal of infected tissue within the mastoid bone behind the ear.
Medial geniculate body
- The major synapse at the upper margin of the auditory brainstem at the level of the thalamus, between the inferior colliculus and the auditory radiation fibres which go "out" to the temporal lobes and which generate wave VI.
Portion of brain that attaches to pons and the junction into which afferent branch of the VIII Cranial Nerve enters the brainstem.
- Inner ear disease.
- Over production of endolymph.
- 1. Hearing Loss
- 2. Tinnitus
- 3. Vertigo
Mixed Hearing Loss
Hearing loss with both conductive and sensorineural problems of the same ear.
Conical shaped, central structure of the cochlea consisting of spongy bone. Supports the 2 3/4 turns of the cochlea and through which the nerve fibres (spiral ganglion) pass.
Hearing with one ear.
Monitored Live Voice (MLV)
Speech hearing tests given with a live voice instead of a recorded voice. The voice level is controlled b monitoring a volume units meter (VU meter).
Most Comfortable Level
The intensity which the client judges to be the most comfortable; not too loud or too soft.
- Electrically insulating sheath covering nerve fibres, usually around the axon. Outgrowth of glial cells.
- 1.increase the speed at which impulses propagate
- 2. sheath provides a track along which severed peripheral nerve fibres can regrowth
- Open ear drum to remove fluids in the middle ear.
Noise Induced Hearing Loss
Noise Induced Permanent Threshold Shift
Hearing loss that results from exposure to noise which is sufficiently intense to damage the delicate tissues within the cochlea
Malleus Incus Stapes
- Inflammation in middle ear structures.
- Disease/Disorder - Middle ear
- Pathology affecting the bones in the middle ear. Bones start becoming spongy then later harden. Footplate of stapes fixates in the oval window creating a conductive hearing loss.
Flaccid upper third of tympanic membrane.
- Lower 2/3 rds of tympanic membrane, stiffened with radiation fibres.
- Integral part of the impedance matching transformer action of the middle ear.
Phonetically balanced words
Monosyllable words used to measure word recognition ability. Equal frequency of occurence of test word phonetics and real life. eg. the /f/ occurs in test words the same frequency as it does in speech.
Low Potassium, high sodium electrolyte that is also a filtrate of cerebrospinal fluid and fills the membranous labyrith of both cochlea and vestibular mechanism.
Contained within the osseus labyrinth, surrounding and protecting the membranous labyrinth (within the scala tympani and scala vestibuli).
- Most dense.
- The petrous portion of the temporal bone is the site of the cochlea, internal auditory meatus and semicircular canals.
Area between the medulla oblongata and the brainstem.
Pure Tone Average
The average of 500, 1000, and 2000 Hz hearing thresholds.
Hearing deterioration due to aging.
The abnormal growth of loudness within the ear due to damage in the cochlear tissues. Associated with sensorineural loss. Hypersensitivty to loud sounds.
Separates the scala vestibuli and the scala media
Tendency of a system to oscillate with greater amplitude at some frequencies.At these frequencies, even small periodic driving forces can produce large amplitude oscillations, because the system stores vibrational energy.
Retrocochlear Hearing Loss
- Disease/Disorder - Inner Ear
- Any hearing loss as result of a pathology medial to the cochlea (between the cochlea and the auditory complex of the brain)
- Portion of cochlear membranous labyrinth that contains Organ of corti, filled with endolymph.
Portion of cochlear membranous labyrinth from the helicotrema to the round window. Contains perilymph.
Portion of cochlear membranous labyrinth from the oval window to the helicotrema.
A gland of the skin which secretes an oily substance, sebum, usually into a hair follicle near the surface of the skin. Located in the outer 1/3 of external auditory canal.
Sensorineural Hearing Loss
Hearing loss within the sensory hearing unit (inner ear. ie the hair cells within the cochlea; and auditory nerve.
Sound treated enclosure which attenuates ambient noise by a fixed amount called the transmission loss. Compared to required standards.
The area close to a loudspeaker from which hearing testing signals are emitted. Sounds field tests are conducted a fixed distance from the speaker within a fixed area.
Spiral ganglion (pl ganglia)
Nerve cell bodies of neurons arranged in a spiral, strung along the bony core of the cochlea. Their axons (fibres) are sent into the CNS.
These bipolar neurons are the first in the auditory system to fire an action potential, and supply all of the brain's auditory input.
- Their dendrites make synaptic contact with the base of hair cells and their axons are bundled together to form the auditory portion of Cranial Nerve VIII. The number of neurons in the spiral ganglion is estimated to be about 35,000–50,000.
- Two apparent subtypes of spiral ganglion cells exist.:
- 1. Type I spiral ganglion cells comprise the vast majority of spiral ganglion cells (90-95% in cats and 88% in humans), and exclusively innervate the inner hair cells. They are myelinated, bipolar neurons.
- 2. Type II spiral ganglion cells make up the remainder. They are unipolar and unmyelinated in most mammals. They innervate the outer hair cells with each Type II neuron sampling many (15-20) outer hair cells.In addition, outer hair cells form reciprocal synapses onto Type II spiral ganglion cells, suggesting that the Type II cells have both afferent and efferent roles.
Speech Reception Threshold
The softest level at which spondee words (2-syllable words with equal stress) can be heard and repeated correctly 50% of the time
2 syllable words with equal stress on each syllable (baseball, greyhound)
- Removal and replacement of a non-mobile stapes to improve hearing.
- Small muscle that attaches to neck of stapes.
- Smallest skeletal muscle in body.
Stapedial Reflex Arc
Sounds passes through the outer-middle-inner ear into the cochlear nerve ("hearing nerve"). A small branch of the cochlear nerve crosses to the facial nerve within the brain. The facial nerve (Cranial Nerve VII) activates the stapedius muscle in response to loud sounds to contract which tightens the ear-drum by moving the ossicles.
Third, most medial ossicle. Full size at birth.
Vascular portion along the outer wall of the scala media which provides nutrients and electical charge to the cochlea.Produces endolymph.
- It is the only epithelial tissue that is not avascular(i.e. completely lacking blood and lymphatic vessels).
Superior olivary complex
- At the lowest levels of the brainstem the synapse is responsible for the generation of wave III.
The sudden (overnight) loss of hearing. Usually the loss is severe and sensorineural in nature.
The space (folded in upon itself) on which Heschl's gyrus is located in the temporal lobe. Site of primary auditory area.
The connection point of nerve fibres, at which axons connect to dendrites.
Speech test stimuli in sentence form but without meaning.
- "tongue shaped"
- Jelly-like membrane that lies atop the stereocilia in the cochlea and contributes to the shearing motion of the stereocilia.
- Thin bone at the top of the middle ear separating it from the floor of the brain.
Point of connection and articulation between the temporal bone and and mandible
Muscle that attaches to the manubrium "handle" of the malleus with a long tendon. Begins in the cartilaginous portion of the auditory canal, ajoins the great wing of the sphenoid and the osseous canal.
The softest level a tone or other test stimulus can be heard 50% of the time.
Ear noises not generated by an outside source.
- Speech test stimuli.
- Monosyllabic words which are grouped into five tonal categories:
- 1. low
- 2. low-middle
- 3. middle
- 4. middle-high
- 5. high
One to one representation.
Changing engergy from one kind to another.
The roughly triangular section of skin covered cartilage which is situatedin front of the opening to the external auditory canal.
V Cranial Nerve.
- Ear drum
Uncomfortable Loudness Level
Signals presented in increasing intensity until a client responds that the level is uncomfortable.
Process at the end of the malleus which is at the point of cone of the tm and along it's medial surface. Where skin grows from in EAM.
The decibels of amplification used by the client at a comfortable listening level
Dizziness resulting from a problem in the vestibular apparatus. Client reports spinning or severe imbalance sensations. (Not from standing up too fast, which is a blood pressure issue)
Word Recognition Score
The percentage correct of a word understanding test. PB words are used for evuluation (other words are also used for additional measurements)