midterm 2 Flashcards
how do lifestyle assessments assist audiological recommendations
gives us an idea of the patients everyday life
-it helps give us information regarding the level of technology
8 warning signs of ear disease that should be referred or a medical evaluation
visible congenital/traumatic deformity, history of active drainage from ear within previous 90 days, history of sudden/rapidly progressive HL within previous 90 days, acute or chronic dizziness, unilateral HL of sudden/recent onset, audiometric ABGs equal to or greater than 15 dB at 500, 1000 and 2000 Hz, visible evidence of significant cerumen accumulation and pain/discomfort in the ear
heuristic decision making
making decisions based on experience and trial/error with previous patients
-proceeding to a solution by trial and error or rules that are loosely defined
HA technology level recommendation is based on
activity level, hours of use, patients age and speech discrimination
-increased technology with increased participation
-more use of HA will result in more benefit from premium technology
-entry level recommendations increase for patients over 70
-good speech discrimination were recommended premium technology more frequently
patient preference decision making
looking at what the patient wants and what they think they may want
-ranking of features that they can deem of importance will vary from patient to patient
degree of HL decision making
mild : more likely to rate visibility as extremely important, more likely to rate additional technology features as important
severe : function over visibility!
evidence based research decision making
benefits of premium technology improving intelligibility and localization did not translate into real world benefit
-however, individuals with poor ANL scores and individuals that regularly communicate in large groups or demanding settings benefited from premium technology
what is a recommendation based on evidence based research
multi level demonstration level technology during device trials will then allow patients to compare entry level to premium level within a realistic environment
frequency shaping bands
specific range of frequencies that are adjusted together
how many frequency shaping bands are needed to optimize HA fitting
only 4 to 7 bands were found to be sufficient
-with flat or sloping HA, 4 provided flexibility
-with steeply sloping loss, 7 bands allowed output adjustments
compression shaping channels
channels adjusting the compression ratio to shape the output within the individuals dynamic range
-number of bands needed varies based on configuration
how many compression shaping channels are needed to optimize a HA fitting
around 9 channels should accommodate most audiograms
-increasing bands from 3 to 18 improved speech audibility for a sloping HL but increasing above 18 provided little benefit
RE
real ear measures
U
unaided
O
occluded
A
aided
G/R
gain/response
-gain is the difference between output and input
-response is the absolute measure of SPL arriving to the TM
real ear unaided response (REUR)
measurement of the absolute SPL (output) of the open ear canal measurement at the tympanic membrane
-measuring input, gain and resonance across all frequencies with no mold or HA, just the ear
importance of measuring the REUR
by knowing the ear canal resonance, it can help with prescriptive fitting
-pediatric has tiny ears so volume will be smaller and the SPL will increase
-with age, the resonance will change because you have reflection and resonance changing in the ear
real ear unaided gain (REUG)
measurement of gain increase resulting from pinna, ear canal and head diffraction effects
-calculation of the difference between the input arriving to the TM and the output leaving the TM
real ear occluded response (REOR)
measurement of the attenuation of an input signal, across all frequencies, when a HA is inserted and turned off
-input that arrives to the TM when it is occluded
importance of measuring the REOR
to see if the vent effect is releasing the lows as it should be, if the open dome is truly open or if the closed vents or power domes supply the needed LF gain
-also can show if the vents introducing the standing wave effect
real ear occluded gain (REOG)
measurement of gain reduction, across frequencies, when the HA is inserted and turned off
-looking at insertion loss!!
real ear aided response (REAR)
absolute aided output and frequency response when a HA is turned on
-the increasing gain in the output that is arriving to the TM
importance of measuring the REAR
to view devices aided output and some prescriptive targets use these points
-this will change based on depth of the coupler
real ear insertion gain (REIG)
measures amount of gain needed to overcome the insertion loss and restore audibility of the signal
-difference between aided and unaided response
-showing difference between the input arriving to the HA and the output arriving to the TM
importance of measuring the REIG
gain will be adjusted based on this in order to meet targets
REAR 85/90 (MPO)
measures the intensity of the output signal arriving to the TM when the input is sufficiently intense to drive the device to its maximum power output level
importance of measuring the MPO
documents the MAX SPL that the HA can deliver to the users ear for loud sounds and to ensure that MPO settings do not exceed loudness discomfort levels
what type of signal do we use with real ear measurements
pink noise
what is the ideal depth of the probe
within 2-5 mm of the TM
reference microphone
monitoring and calibrating the soundfield speaker output and maintaining the desired signal intensity at the measurement point
-making sure the intended intensity is that of the intensity arriving to the test spot
retention cord
stabilizes and maintains the reference microphone position
probe tube
measures the intensity of the signal arriving to the TM
probe microphone
collects and measures sound from the probe tube attached to it
what is the output requirement to achieve binaural benefit
aided output must be within 15 dB to achieve binaural benefit
type 1 test signals
pure tone signal swept over a variety of frequencies
-drives a higher output and used to measures maximum loudness
-however this does not show effect of compression or channel interactions and DFS signals attenuate them
type 2 test signals
complex speech like signals that are broadband signal consisting of random frequencies occurring at different intensities
-changing amplitude mimics speech
-however rapid gain changes may not truly show a devices response to different spectral shapes in the succeeding sounds
what are non-calibrated signals helpful with
counseling but NOT for fittings
-i.e. can use live voice of a communication partner to show audibility compared to non-audibility
long term average speech spectrum (LTASS)
frequency dependent measure of time average sound pressure level of speech
-this is a calculated average within the speech envelope from a measured signal for around 10 seconds
importance of the LTASS
important when determining how much gain to add to the input signal
-useful with the process of fitting HAs
peaks and valleys of the speech envelope in relation to the LTASS
peaks are 12 dB louder than the LTASS and valleys are 18 dB softer than the LTASS
factors that can change the LTASS
vocal effort, microphone positions and language
why does probe module calibration result in acoustic transparency
the probe tube acts as an extension to the probe microphone
-since the tube is placed directly over reference microphone during calibration and this accounts for different intensities arriving
-the unit adjusts the intensity differences removing the tubes resonances effects
methods of calibration
substitution method and modified pressure method
substitution method of soundfield equalization
measurement microphone is placed at the point where the subjects head will most likely be located at and the calibration is stored and used as a reference point
-however, the absence of the head or body reduces precision and any changes in location impacts results
modified pressure methods
both concurrent and stored equalization are varying methods
modified pressure using concurrent equalization
reference microphone constantly monitors the test signal throughout testing to equalize and adjust signal intensity
-every 10 seconds there will be a reference check
-we can be sure that what we are measuring is correct by waiting the 10 seconds for the calibration signal to play then record
modified pressure using stored equalization
probe is calibrated one time on the patients ear and it is stored for the fitting process
-stimulus will be on a loop however we will only hear one calibration signal and the signal will continue to loop
-used when amplified sound can lead out of open domes and interact with reference microphone
-any head movement can impact the final recording
reference microphone contamination
occurs when the amplified output escapes the ear canal through open domes
-reference mic measures and reacts to the intensity of the HAs output signal lowering the intensity
what calibration method can overcome microphone contamination
modified pressure stored equalization
what does ANSI mean by working distance
allowable distance between the patient and the speaker
-nearest reflective surfaces and the tester should be 2x farther than the working distance during testing
what should the ambient room noise be like for real ear measures
must be 10 dB lower than the REM signals to minimize effect on test results
how do standing waves occur within REUR and REAR measurements
placement that is more than 5 mm from the TM creates acoustic nulls resulting in these standing waves
-you can pull the probe out and reinsert watching for the standing waves
how can standing waves impact our measurements
the nulls attenuate measured SPL tricking you into believing the HF output is lower than it actually is
-underestimating the actual output of the device
what are the three methods for probe insertion
constant depth method, acoustic method and geometric method
when the HF are higher than the LF, this indicates that the probe is …..
close to the TM
when the HF are lower than the LF, this indicates that the probe is …….
too far from the TM
frequency shaping band adjustment
selecting a frequency range for ALL input levels (soft, moderate and loud)
-objective is to verify audibility of a speech signal by maximizing the SII
-changing the top and bottom of the speech envelope
compression shaping channel adjustment
selecting a frequency range for only ONE input level (soft or loud)
-objective is to adjust compression ratio to optimize detection of soft input signals or reduce loud input signals for increased comfort
-changing either the top or bottom of the speech envelope
what does the measured speech map REAR representing
shows the output of the speech envelope and aided audibility
loudness normalization prescriptive approaches
strives for an output that is audible and comfortable for the patient
-theorizes aided loudness perception should be the same as normal loudness perception
-how much output that needs to arrive to the TM to be perceived as soft, moderate and loud
loudness equalization prescriptive approaches
increases intensity of the mid and high frequencies until their energy equals the lows
-recognizes audibility of mid and high frequency cues are critical for intelligibility
-based on threshold and audibility to determine how much gain to add
_________ is loudness normalization
DSL
_________ is loudness equalization
NAL
DSL formula
maximizes audibility to assist with language development
-TKs are based on degree of loss
-expansion is applied to the low input levels
-multi stage WDRC is applied to input signals to expand the dynamic range
NAL formula
focusing on the higher frequencies as these support the most speech intelligibility
-recommendation based on SII
-provides gain targets for non tonal and tonal languages
-calculates for A/B gaps
what is a good formula for someone who has severe to profound HL
NAL-RP
-preferred more gain and less HF emphasis
what is a proprietary formula
ones that are produced by the manufacturer
-be considerate as these may not give as much gain as needed
root mean squared (RMSE)
considers how close the measured output is to the prescribed target
-checking to see how close our measured output was to the center of a target
-difference between the probe measured output and the prescriptive targets
+/- 5 dB for target criteria and changing the prescription in relation to this
it is a good rule when fitting patients however we can move away from this target zone based on what the patient is experiencing
-based on patients loudness or sound quality perception’s as long as the output follows the prescriptive contours
PITFALL : don’t disregard targets falling below thresholds
these targets are there for a reasons even if it is just to hear the top of the speech envelope
-remember that the LTASS represents an averaged signal so the upper intensities of speech may be audible even when the targets fall below the threshold
verification protocol
1: maximize audibility by adjusting bands first
#2: adjust soft gain values to 55 dB input signal
#3: adjust loud gain values to 75 dB input signal
PITFALL : only adjust a frequency shaping band for one input frequency
just ensure that after matching targets with the 65 dB signal with frequency bands that intensity channels are the only thing being adjusted
PITFALL : adjusting the moderate input channel for a 65 dB input signal
avoid this adjustment during the initial fit and just focus on changing the soft and loud channel
PITFALL : using too small a frequency range when adjusting to target
begin by selecting the broadest range possible
-only select a narrower frequency when you’re close to completing an intensity
PITFALL : if you increase gain without observing an increase in REM, stop adding gain!
when we continue to add gain and do not see changes, this is probably due to a slit leak
-if we make a change and see no change, use the back arrow to where you cam from
-making changes and see what happens
PITFALL : not realizing MPO headroom limitations can result in unintentionally high compression ratios
increase bands and channels but sometimes channel interaction may occur
-meaning changes in one results in the changing of another channel and CRs become adjusted
pitfalls with more channel interaction
frequency ranges overlap one another and adjustments made to one frequency pulls adjacent frequencies up or down too
-each range overlaps slightly with one another so one frequency range can change the parameters outside what they are intending to do
recommendation to help with channel interaction
select a narrower frequency range for adjustment knowing the adjacent frequencies will adjust too
PITFALL : ignoring compression ratios within each frequency range
maintain similar compression ratios across all frequencies
PITFALL : trusting the default fitting MPO is right
can lead to consequences if too high or too low
-too high can result in turning down of gain, patients only wearing HA in quiet settings and the initial experience may be negative
-too low can result in distorted speech, peak clipping or the range of loudness perception will be limited
fitting HAs with supporting binaural advantage
in order to support binaural benefits we need to ensure that output arriving to the TM is within 15 dB
-wanting to pay attention to soft, moderate and loud output
-allows for interaural level and timing differences
high frequencies supply interaural __________ differences and low frequencies supply interaural __________ differences
level ; timing
asymmetrical threshold loss
3 adjacent frequencies are more than 20 dB apart from each other OR is 1 frequencies is greater than 25 dB
-can be asymmetrical speech intelligibility, SNR loss or discomfort level
unilateral vs. bilateral devices fitting options
looking at individual ear factors and consider the amount of audibility attainable in each ear
-is audibility realistic and verifiable using objective REM
CROS verification set up
probe tube placed on the better ear and the patient is positioned to 45 degrees azimuth
-better ear is the test ear and enters thresholds to start the test
3 NIHL configurations
type 1, type 2 and type 3
type 1 NIHL
represents the configuration after a few years of exposure
-normal or near normal to 2000 Hz
-special fitting strategies aren’t necessary
type 2 NIHL
represents many years of excessive exposure to noise
-threshold loss extend into the low frequencies
-use of fitting strategies may help if output supplies HF audibility
type 3 NIHL
represents the extreme case in which hearing is near normal for the low frequencies only
-threshold loss shows a precipitous slope into the high frequencies
-special fitting strategies are needed to support success
type 2 and 3 NIHL challenges
-outer hair cell damage in the cochlea leads to abnormal loudness growth (recruitment)
-damaged or absent inner hair cells can cause potential distortion
-high frequency output is limited by feedback
-full HF audibility is not reasonable goal due to comfort
-WRS assessments may not accurately be assessed
what do we do when high frequency output is limited by feedback
there needs to be the balance between vent size and output
explain how WRS are changed with type 2 and 3 NIHL
-may not accurately reflect impact of reduced audibility of critical speech cues
-may not show cochlear distortions resulting from frequency resolution or temporal resolution
-may not show central auditory nervous system deficiencies or deficits in cognitive processing
what is the old idea of fitting strategies with cochlear dead regions
assuming that any threshold greater than 70 dB has the presence of a dead region and any frequency slopw that is greater than 20 dB you can assume that there are dead regions
-would make the fitting based on these
-adding gain in the area of dead regions results in degraded frequency resolution
what is the new idea of fitting strategies with cochlear dead regions
new ideas contradicts the old idea because dead regions were found to be present within quieter levels as well as in smaller slopes
management of cochlear dead regions
special fittings may be needed when dead regions are present
-but do not assume that the individual needs reduced high frequency output
-do not take away the HF gain at the beginning
with cochlear dead regions, we should focus on adding gain to ________ areas of the cochlea
healthier
-within low and mid frequencies
fitting strategy for type 3 NIHL
add gain to thresholds below 85 dB HL
-strive for a balance of audibility from 500 to 3000
-add 5 to 8 dB of gain to normal thresholds before precipitous drop
-enable expansion to reduce mic noise
-if threshold is near LDL, apply no gain or 1/5 of threshold
frequency lowering
the theory is shifting HF output to healthier cochlear regions will improve intelligibility
-what is recommended is to verify audibility of high frequency signals at the time of initial fitting and then do not enable frequency lowering at the initial fitting (suggested at 4-6 weeks of use)
review : what are the types of frequency lowering
frequency compression, frequency transposition and spectral warping
usage guidelines for frequency lowering
steeply sloping loss and severe to profound loss
programming steps for frequency lowering
-find the MAOF with FL turned off
-assess FL candidacy
-enable FL to verify if audibility of a calibrated s signal is achievable
-ideally a SH signal is 100 Hz lower than the S
maximum audible output frequency (MAOF)
region where audibility ends
-lower limit is the frequency where LTASS becomes inaudible
-upper limit is the upper range frequency where speech envelope becomes inaudible
why is too much audibility with frequency lowering a bad thing
this can result in a poor sound quality
