Audiometry Exam I Study Set Flashcards
Frequency of Hearing Loss
Children: 56,000 experiencing hearing loss below the age of 6.
Adults: 35 million experiencing hearing loss.
Impacts of Hearing Loss
Children: Lack of social, academic, and emotional development. Speech impairments can occur.
Adults: Economic and mental health burden (ex. Anxiety, depression, etc.)
Definition of Audiology
A sector of science that investigates hearing and its disorders. Within this sect, some processes include identifying, and evaluating hearing issues. As well as accessing the manner individuals with hearing issues could be aided.
Raymond Carhart
The founder of audiology who established training for students involved in Otology and Speech Pathology to become professors, clinical specialists, and research scientists for audiology.
Definition of Audiologist
Individuals in health care who are concerned with identifying, treating, and aiding people who possess hearing disorders. Individuals in this field require a doctorate degree and certification typically from the American Academy of Audiology (AAA) or American Speech-Language-Hearing Association (ASHA).
Service Delivery Models
Medical Model: Authoritative and assumes that clinician knows all.
Rehabilitation Model: More interactive and involves patient collaboration.
International Classification of Functioning, Disability and
Health (ICF) Framework
This evaluates how an individual’s health condition along with environmental and personal factors relate to their impairment, activities, and participation.
Ear Divisions
Outer ear-Middle Ear-Inner Ear-8th Canial Nerve-Brain
The peripheral auditory system is only the outer ear, middle ear, and outer ear.
Outer Ear Components
There are three main parts of the outer ear including the pinna (composed of cartilage and skin), the ear canal (this leads to the eardrum, external auditory meatus, and concha), and the tympanic membrane.
Parts of the Pinna
Tragus, Anti-tragus, Helix, Anti helix, Concha (Cymbal and Cavum), and Triangular Fossa.
Pinna Function
The Pinna localizes and funnels sound while creating a distinctive unique imprint.
Other names for Pinna
Auricle and Outer Ear
Parts of the External Auditory Meatus (Ear Canal)
The EAM is composed of two portions being the outer portion, which is cartilaginous portion that is filled with ceruminous glands (ear wax) and har folluculs to push out ear wax, and the inner portion, which is the Osseous portion (bone). The EAM extends from the Pinna to TM.
EAM Function
Provides protection for the eardrums
EAM Pathologies
Atresia: Ear canal absence
Stenosis: Narrowing of the EAM
Infections Caused by Bacteria and Fungus: Swimmer’s Ear and Impaction of Wax
Purpose of Cerumen
The does multiple things for the ear including: Trapping particles, moisturizing the epithelium, repelling insects with odor, prevention of water, and cleaning the ear with anti properties.
Parts of the Tympanic Membrane
The tympanic membrane (TM) can be split into three sections Annulus, Pars Flaccida (Top of TM), and the Pars Tensa (Bottom of TM).
There are also three layers of the memembrane including: Cutaneous stratum, Fiberous stratum, and Mucosa Stratum
Structures/Functions of the TM parts
Annulus: This is the tissue in the shape of a ring that holds TM in place.
Pars Flaccida: Consists of mucous and epidermal layers
Pars Tensa: Gives Ear drum its cone shape and contains malleus and umbo (Concave arrangement causing light reflection/refraction)
TM Layers
Outer layer: Skin that covers the osseous meatus (Epithelial Layer)
Middle Layer: Connective tissue that is made up of radial and concentric fibers ( fibrous layers)
Inner Layer: Membranous Layer
Tympanic Membrane Function
Regulates pressure within the middle ear. Apart of the transformer system within the middle ear.
Sound Resonance
Each structure helps to increase sound to about 10 to 12 dB. The main structures of the outer ear contributing to this are the Concha and ear canal. The final amplification is 20dB of sound at 3000Hz. Hearing aids can disrupt resonance.
Parts of the Middle Ear
There are several parts of the middle ear including: Incus, stapes, malleus, tensor tympani, stapedial muscle, and eustachian tube.
Middle Ear Cavities
Air filled and mucous membrane lined.
Middle Ear Function
The ossicles form a mechanical link that prevents displacement of he oval and round windows. The middle ear is an equalizer.
Middle Ear Muscle Function
Facial nerves trigger the stapedius muscle and it contracts with loud sounds. Trigeminal nerves trigger the tensor tympani and contracts with a change in air pressure of the EAM.
Middle Ear Muscles and Ligaments
Connect ossicles to the middle ear
Eustachian Tube Function
Enables air to go into the middle ear, and equalizes air pressure in the eardrum. It also allows drainage of fluids into the nasopharynx.
Eustachian Tube Facts
This tube is cartilagineous and remains closed but opens during swallowing to allow for air exchange. Smaller in children which causes draining issues.
Lack of Eustachian Tube Occurrences
Oxygen absorbed through ear, lower pressure, Retraction of TM, fluid entering, thick fluid, and cellular changes.
Transfer Functions of Middle Ear (Impedance Matching)
The middle ear recoups for energy lost between sound exchanges between air and fluid. This is done from the ratio of area from the TM to Stapes foot plate (recovers 25dB) and the ossicles lever action (recovers 2 dB).
Impedance Matching
-30dB of sound is lost as a result of an air-to-fluid impedance mitch match but, the middle ear recoups for this loss by increasing the pressure of sound. (This all depends on signal frequency)
Middle Ear Contraction
A decrease in sound pressure causes the middle ear to contract. This is done through the tightening of the ear drum which stops sound propagation.
Acoustic Reflex
Muscles are activated by loud sounds which reduces the danger of ear damage from them.
Inner Ear Parts
The overal inner ear is an ossesus labryinth containing: Smicircular canals, cochlea, round window, vestibule, oval window, perilymph, and endolymph.
Vestibule
This is where the oval and round windows are located. The oval window is the cochlea’s entrance and the round window is the cochlea’s exit.
Inner Ear Function
Helping the brain with hearing and balance hrough the conversion of sound waves to nueral impulses.
Inner Ear Balance
Two Systems control balance within the inner ear. These systems are Utricle/Saccule (linear motion) and semi-circular canals (angular motion).
Cochlea Function
Turns complex sounds into simple parts, amplifies soft sounds, and sends information to the CANS for perception.
Cochlea Main Parts
Parts of the Cochlea include: Modiolus, Scala Vestibuli, Scala Tympani, Scala Media and Organ of Corti.
Cochlea Parts in the Main Parts
Helectroma: Perilymph and connects Scala Tympani and Scala Vestibuli.
Scala Vestibuli: Perilymph, oval window, and Resiners membrane.
Scala Media: Endolymph, Tectorial membrane, organ of corti, basliar membrane, stria vascularis.
Scala Tympani: Perilymph and round window.
Organ of Corti
Within the organ of Corti (hering organ) are hair cells which act as sensory receptors. There are inner hair (1 row) cells and outer hair cells (3 rows). This organ is bordered by the basilar (below) and tetorial membrane (above)
Inner Ear Membranes
The Resiners membrane separates SM from SV and is attached to a spiral ligament. The spiral Ligament connects the cochlear duct to the outer wall. Stria vascularus is fixed opposite of the spiral ligament. The tectorial membrane overlays organ of corti.
Traveling Wave Theory
This is the pattern in which the basilar membrane is displaced as a result of sound transmission. Waves occur to the right at lower frequenceies and to the left at higher frequencies.
Stiffness Gradient
This is within the basilar membrane. This decides which direction the traveling wave will progress in.
Shearing
When the Basilar membrane is being displaced a shearing force occurs on the outer hair cells of the tectorial membrane this then activates auditory nerve fibers that are embedded in the base of a hair cell.
OHC and IHC Function
Mechanical input is amplified by outer hair cells to inner hair cells, and the inner hair cells send this information to the brain.
Outer hair cells are motor (efferent)
Auditory Nerve Anatomy
This nerve runs from the cochlea to the internal auditory nerve canal. This nerve also carries the vestibular part of the 8th cranial nerve. The vestibular portion includes the utricle, saccule, and semicircular canals.
Parts of the Auditory Nerve
There are two portions aranged cylindrically-
Outer portion: Fibers coming from the basil turn of the cochlea (higher frequencies).
Inner portion: Fibers coming from the apical turn of cochela (lower frequencies).
Acoustic Neuroma
This is a tumor that occurs in the internal auditory canal.
Auditory Pathway
The order goes:
Auditory branch of VIII th nerve > Cochlear Nuclear Complex > Superior Olivary Complex > Lateral Lemniscus > Inferior Colliculus > Medial Geniculate Bod > Primary Auditory Cortex
Auditory Pathway Parts
Superior Olivary Complex: regulates reflexes, receives both inputs, and determines direction.
Lateral Leminiscus: Lower brainstem impulse pathway.
Inferior Colliculus: Gets stimulation from both SOC’s.
Auditory Pathway Parts Continued
Medial Geniculate: The third part of the system.
Primary Auditory Context: Located in temporal lobes. Represents preserved frequency.
Parts of Auditory Nerve
Dendrites: Gains nerve impulses from other cells. Projection from hair cells.
Axon: Impulses are transmitted along neurons. Projection within the brainstem to sensory cells.
What is the auditory system?
This system is primarily afferent or sensory but has motor/efferent aspects.
Parts of Neurotransmitters
Synaptic Cleft: Location of meeting of nerve fibers through dendrites or cell bodies. Where neurotransmitters are released.
Chemical-based substances that can activate or inhibit adjacent neurons.
Spike Rate
A single nerve can fire up to 30-40dB without the help of other nerve fibers.
Characteristic Frequencies
High characterisitc frequency fibers originate from hair cells at cochlea base. Low characteristic frequency fibers supply the apex. The auiditory nerve has a tonotpic organization.
Whole Nerve AP
The whole nerve action potential is measured in terms of amplitude. Amplitude increases with intensity.
