Test 2 Audiology Flashcards
what is the tiny hairs on top of a hair cell called?
stereocilia
where are the stereocilia embedded into?
the tectorial membrane
what fills the scala media and what is it high in?
endolymph and it is high in potassium ions (K+)
when the stereocilia are sheared towards the tallest stereocilia (during rarefaction of a sound wave) what happens?
the potassium channels are opened and potassium from the endolymph rushes into the hair cell
what do the channels near the bottom of the cell allow into?
Ca++ ions
what charge happens when the potassium and Ca++ ions enter the cell?
the charge becomes positive (depolarization)
what happens when there is a positive charge in the hair cell?
a neurotransmitter is released to the neighboring synapse of an auditory nerve fiber
what happens when stereocilia are sheared the other way during the compression phase of the sound wave?
the excess K+ and Ca++ ions are pushed out of the ion channels
what is hyperpolarization?
the inhibition portion of the process (no neurotransmitter is released)
what happens when the neurotransmitters are released?
this caused the nerves to fire, this is the electrical impulse
What is the order of the central auditory pathway?
- cochlear nerve (auditory nerve)
- cochlear nucleus
- superior olivary complex
- lateral lemniscus
- inferior colliculus
- medial geniculate body
- auditory cortex a. Heschl’s gyrus b. wernicke’s area
where does the cochlea coil around?
the modiolus, which is where the bundle of auditory nerve fibers are contained
the _____ nerve fibers code for ____ frequency sounds
outer, higher
the _____ nerve fibers code for the _____ frequency sounds
innermost, lowest
cochlear nucleus
only receives input from one ear, and this is where the auditory info begins to get broken down, the tonotopic info from the cochlea is duplicated 3 times here
why is the tonotopic info from the cochlea duplicated 3 times?
to create redundancy (redundancy of info gives your brain more opportunities to eventually make sense of the info)
superior olivary complex
receives info from both ears, first time the left ear crosses to the right, vice versa
lateral lemnicscus
more of a pathway than a structure, largest tract of auditory nerves in the brainstem
inferior colliculus
located in the midbrain, the uppermost structure in the brain stem
medial geniculate body
located in the thalamus, form here, the info is sent to the auditory complex
auditory cortex
housed within Heschl’s gyrus in the temporal lobe is the primary auditory cortex, where auditory info is processed
With ABR we can see the pattern of
action potentials electrical activity represented by waveforms
what are neuro-generator sites?
few places along the pathway where big bundles of neurons are firing
auditory pathway:
cochlear nucleus>superior olivary complex>lateral lemniscus>inferior colliculus>medial geniculate body>auditory cortex
ABR is used to get…
information about how these neural centers in the brainstem are functioning
How to avoid interference for the signal of an ABR:
-turn off the lights
-have the patient turn their phone off
-try not to do the procedure right next to where there are a lot of things plugged into the wall
what should a patient do during an ABR?
they should lie down and be as relaxed as possible, sleeping is encouraged
stimulus rate
the rate per second at which the acoustic signal is delivered to the ear
latency
the timing aspect of the waveform and waves, measured in milliseconds
interpeak/wave
the latency differences between the waves l-lll, lll-V, l-V
interaural
any differences between the ears (latency, amplitude)
amplitude
the magnitude of the response, measured in microvolts
what do the waves represent on an ABR?
certain points along the pathway
what waves do we focus on when we analyze ABR?
waves l, lll, V
neurodiagnostic ABR
uses a loud click stimulus. the click stimulates a broad portion of the cochlea, which results in more neural firing and gives better waveforms.
to find retrocochlear disorders.
what does a neurodiagnostic ABR look for?
retrocochlear disorders and abnormalities in the lower brainstem
threshold ABR
uses frequency specific stimulus called tone-bursts or chirps, lower stimulus level until you can’t see waveforms anymore. looks at lowest intensity that wave 5 can obtain.
preferred method for assessing infants hearing?
threshold ABR
what frequency specific stimuli does threshold ABR use?
tone-bursts or chirps
what thresholds are tested in threshold ABR?
500, 1000, 2000, and 4000 Hz
what wave do we only focus on threshold ABR?
wave V
if the lowest dB they could get on a threshold ABR was 20 this is not their actual threshold because
you would need to do correctional factors
effects of hearing loss on development
-language development academics
-social/emotional development
-everything
why is it important to catch hearing loss and intervene as early as possible?
to minimize the negative effect of hearing loss on a child’s development
what is the critical window for speech development?
birth to 3 years
Behavioral observation audiometry
behavioral assessment of infants’ (ages 0-6) hearing sensitivity by way of observing startle reflex behavior in response to auditory stimuli presented. does NOT provide true auditory thresholds
-BOA requires a subjective and time-locked response from the child each time a sound is heard
how is BOA accomplished in a sound field?
different sounds are presented through calibrated speakers, auditory stimuli may include warbled tones, noise, music stimuli
babies typically do not respond to sounds at threshold level so we record….
minimum response levels
for BOA responses are typically reflexes in response to sound like
eye blinks, startle, suckling
BOA methodology
-boa is accomplished in a sound field with different sounds being presented through calibrated speakers
-auditory stimuli must include= warbled tones, noise, music stimuli
-with boa we record minimum response levels
-responses are typically reflexes in response to sound like: eye blinks, startle, suckling
-boa requires a subjective and time-locked response from the child each time a sound is heard
BOA is not a reliable way to test a baby’s….
hearing thresholds, but it can give us some idea of their ability to hear
Time-locked
response occurs within a reasonable amount of time after the stimulus. we must try to differentiate random behavior from behaviors in response to sound
what must we keep in mind for BOA?
not a reliable way to test a baby’s hearing thresholds
what do we use boa results in conjunction with?
OAE, ABR, etc.
VRA
a behavioral assessment of hearing that relies on conditioning the child to make a head turn in response to auditory stimuli
what age ranges of VRA testing is used?
6-36 months
premise of VRA
child has a natural insisting to turn searchingly for an interesting sound when it’s heard, and the child will continue to do when “rewarded” with an appealing visual stimulus (such as lights, light animated toys, videos, etc.)
VRA setup
-can be performed in sound field with headphones or inserts to provide ear specific info
-visual reinforcers are situated on top of each of the speakers in the sound field
-VRS can be easily accomplished by having the child sit on their parent’s lap
CPA
a behavioral assessment of hearing sensitivity in which the child is given a play task to perform every time they hear the acoustic stimuli
what is the aim of CPA?
to obtain ear-specific and frequency-specific threshold info, primarily in the speech frequencies
what age is generally used with CPA?
36 mon(3 years) to 5 years of age
CPA methodology
-CPA is designed to gain audiological test results by making the evaluation process into a game
-the child is conditioned to play a game each time a sound is heard
-CPA is performed with using head phones or insert earphones and a bone conduction oscillator
-with CPA we are typically able to obtain info regarding the severity, type and configuration of hearing loss
testing SRT and WRS for slightly older kids, we can use…
word lists that are easier/more appropriate for children
what do we use for WRS for children?
PB-K
IDEA-individuals with disabilities education act
birth to 21 was changed to
made school system responsible for providing assistive technology (hearing aids, FM systems) if the child did not have access to them. provide service for infants and toddlers. this is where Early Steps came from
IFSP- individualized family service plan
for children with disabilities from birth to 3 years and their families
detailed document outlining: child’s current level of dev., family’s concerns, special services to be provided, progress monitoring
IEP-individualized education plan
for individs with disabilities from 3-21 years of age. similar to IFSP with a more specific focus on how the child will be educated
what type of hearing aid should babies and young children be fit for?
behing-the-ear
why BTE for children?
- can replace ear mold since children’s ears grow quickly
- earmolds can be replaced without having to replace the whole hearing aid
- reduces the possibility for injury
- most durable *they will last longer and endure more wear and tear
some pediatric-specific hearing aid features:
- tamper-proof battery doors
- indicator lights
- fun colors, stickers, and image options
auditory skill levels
- sound awareness: understanding the presence of sound
- sound discrimination: knowing that sounds are the same or different
- identifications: labeling or putting a name to sounds
- comprehension: understanding the speech and being able to act on it
sound awareness activities:
-have someone knock on the door and encourage them to look
-musical chairs
sound discrimination activities:
-can use speech sounds varying in pitch, length, and intonation EX: “are these sounds the same or are they different? moooooo vs mo and ee vs oo”
sound identification activities:
- have child pint to pictures of words/sounds you say
- “show me cow”
- “show me ‘nnn”
sound comprehension activities:
- follow directions
- simon says
- draw what i say
FM systems
devices that wirelessly route a speaker’s voice to a hearing aid
WE use FM to overcome:
-distance
-noise
-reverberation
what are the electrodes that are put on ABR?
middle of forehead=ground
on top of hear=non-inverting
on earlobes=inverting
wave 1
portion of the 8th nerve that is closest to cochlea
wave ii
portion of the 8th nerve closest to the brain
wave iii
cochlear nucleus
wave iv
SOC
wave v
LL and IC
Auditory pathway
auditory nerve, cochlear nucleus, superior olivary cortex, lateral lemniscus, inferior colliculus, medial geniculate body, auditory cortex
what makes up the auditory cortex?
wernicke’s area and heschl’s gyrus
what is action potential?
all or nothing events that are the framework for neuron to neuron communication that wakes up ABRs
what are some important steps to eliminate noise in the room?
turn off the lights and phones, away from outlet where things are plugged in, tell them to not talk. clench jaw. or chew gum, instruct the patient not to move
what is stimulus rate?
the speed at which the stimulus is presented
what is latency?
the timing of the waves measured in milliseconds
what are interpeak intervals?
the time in b/n the waves
what is interaural latency difference?
any difference b/n the ears in latencyw
what is amplitude?
the magnitude of the response
what kind of abnormalities that are found in ABR testing that are suggestive of some type of pathology?
-large interpeak latency
-abnormalities in latencies
-abnormal interaural latencies
- and if there is no waveform
What is it called when you need to find the right dB nHL for HA?
need to apply correctional factors, nHL to eHL
