Final Exam (New Material) Flashcards
what is SII
Calculates % of speech info that is audible and usable to the listener
SII of 50%
50% of speech cues supporting intelligibility are audible in a quiet setting
Increase in # of dots
frequency region with higher contribution to intelligibility (HF)
Decrease in # of dots
frequency region with reduced contribution to intelligibility (LF)
purpose of measuring LDL
needed to ensure amplified output doesn’t exceed the individual’s loudness tolerance
interpretation of LDL
normal is between 100-105
purpose for ANL
Quantifies a listener’s willingness to listen to speech in the presence of background noise.
Identifies those who will have more difficulty adapting to amplification
how to score ANL
MCL value – BNL value = ANL score
low anl score
difference <7
Indicates the patient ACCEPTS a lot of noise background noise w/o issues
This patient is likely to wear hearing aids on a regular basis
high anl score
difference > 13 dB
Indicates the patient LACKS TOLERANCE for background noise
This patient is less likely to wear hearing aids regularly
Premium technology
ANL scores b/w 8-12 dB
equivocal
May require extra post-fitting counselling or adjustment period
purpose of SNL
Speech intelligibility in noise remains the #1 improvement patients seek with hearing aids
Each patient will need tailored technological recommendations based on their individual “signal-to-noise loss.”
0-2 snr
normal
omni or may benefit with directional mic
2-7 snr
mild loss
recommend standard directional mics
7-15 snr
moderate
beamforming as well as standard directional mics
> 15 snr
severe
requires remote mic in addition to beamforming and directional mics
rem ref mic
monitor and calibrate the soundfield speaker output, maintaining the desired signal intensity at the measurement point
retention cord
to stabilize and maintain the reference microphone’s position
Blue stretchy coard
probe tube
measure the intensity of the signal arriving to the TM
prob mic
collects and measures sound from the probe tube attached to it
Stem
Aided output of 15dB in needed to achieve binaural benefit
true
type I signal
brief puretone signal swept over variety of frequencies
verifies MPO
DFS can attenuate this signal
doesn’t show the affect of compression or channel interactions on output signal
type II signal
complex speech like signals
BB signal over different intensities
mimics speech
might not show all spectral issues because we cannot capture every little detail
types of type II signal
standardized
nonstandardized
standardized speech signal
calibrated
repeatable
verifies device can reach prescriptive targets
ex: speech map, ISTS, ICRA
nonstandardized signal
not used for programming
good for counseling
less repeatable
speech envelope
Visual representation of modulated speech sounds
LTASS
long term average speech spectrum
Measured by averaging a measured signal for 10 seconds
what are factors that impact its average value
will change with varying vocal effort, mic position, and language
vocal effort influences
mid frequency LTASS avg
mic position influences
HF LTASS avg
tonal languages influence
LF LTASS avg
Speech envelope has a crest factor of +____dB (louder speech signals) & valleys of - ______ dB (soft speech signals)
12 18
crest factor and valleys define the representative ______ of normal convo speech over time
dynamic range
The difference between the valleys (softest signal) and peaks (loudest signal) of speech is
~30dB SPL
Difference bw threshold & LDL represents
dynamic range
what is room mean squared error
how close the measured output is to the prescribed target
what is RMSE criterian
5dB
what are the calibration methods
substitutioin method of soundfield equalization
modified pressure methdos
substitution method equalization
Done before the PT arrives, placed at where subject’s head would be, stored as a reference point, used to calibrate the reference mic and probe
Impacts results if the subject changes location or moves
modified pressure concurrent equalization
reference mic monitors test signal throughout test to equalize and adjust, calibration signal replays every 10 seconds (pink noise segment)
modified pressure stored equalization
probe is calibrated one time on PT’s ear & stored for fitting process
Used to avoid ref mic contamination (stops it)
what is ref mic contamination? what is used to stop it?
happens when amp output escapes ear canal through open dome
Modified pressure “stored equalization”
Probe tube Calibration & Acoustic Transparency
probe microphone module cannot be physically located in the ear canal; the probe tube serves as an extension to the probe microphone
Probe tube tip is placed directly over the reference microphone during calibration. This protocol accounts for the different intensities arriving to the probe microphone module’s reference mic and through the probe tube.
The unit mathematically adjusts the intensity differences removing the tube’s resonance effects.
This procedure makes the probe tube “acoustically invisible”
ANSI Recommendations & Working Distance
Distance allowed bw PT and speaker (18”-36”)
Reflective surfaces & tester: 2 x WD (about 34-36 in away)
Ambient noise in the room must be 10dB lower than REM signal
Horizontal plane: 0º azimuth: greatest reliability
Vertical plane: speakr should be level to the PT’s ear in order to accurately measure HF output
RE
real ear
r
response
g
gain
what is R
absolute measure of SPL output arriving to the TM
what is gain
diff bw output intensity and input intensity
output - input = gain
REUR
measurement of the absolute SPL level of an open ear canal response, across all frequencies, at the tympanic membrane (input + gain + resonance = output)
REUG
the measurement of gain increase resulting from pinna, ear canal, and head diffraction effects, as measured from an open ear canal
REUR - input = REUG
REOR
A measurement of insertion loss occurring because of the presence of a mold/dome in the ear canal
why do we do REUR
Knowing a patients ear canal resonance improve accuracy of prescriptive fitting
REUR changes due to
ear canal differences
Size, texture, shape, or presence of abnormal anatomy
Age: pediatric, adult, elderly
One person can have 2 different REUR’s
REOR
A measurement of insertion loss occurring because of the presence of a mold/dome in the ear canal
why do we do REOR
Lets us see if the vent effect is performing as expected
To identify which low frequencies are released due to the vent effect
To determine if the vent introduced undesired standing waves
REAR
absolute aided output and frequency response when a hearing aid is turned on
why do we do REAR
To view devices absolute aided output in a unique ear canal (if you don’t measure it, you don’t know if you’ve met your objective)
Measures intensity of the output signal arriving at the TM, when the input signal is sufficiently intense to drive the device to its maximum power output level
REAR 85/90
REIG
The difference between the AIDED response and the UNAIDED response of the ear canal
REAR- REUR = REIG
RECD
difference between the SPL resonance of a 2cc coupler and the SPL resonance of the real ear
why do we measure RECD
accurately converts HL thresholds using inserts to SPL values creating a personalized conversio factor for precise conversions
predicts the real ear output when HA measurements are made in the test box
the natural resonance resulting from the pinna and ear canal effect that the patient walked in the door with
REUR
the insertion loss that results from the mold/dome
REOR
the output arriving to the TM when aid is turned on
REAR
the amount of gain added to the input signal when the aid is turned on
REIG
the MPO that’s arriving to the TM
MPO/RESR/REAR85/90-
difference between the SPL resonance of a 2cc coupler and the SPL resonance of the real ear
RECD
How does an SPL-ogram differ from an audiogram. Why will measurement of the RECD improve the accuracy of the conversion?
SPL-o-gram is in dB SPL (physical sound level), while an audiogram is in dB HL (normalized against normal hearing thresholds).
Audiograms are used for diagnosing hearing loss, whereas SPL-o-grams are more common in hearing aid fitting because they show the actual sound level being delivered to the ear.
It creates a customized conversation to create accurate fitting targets for the patient.
RECD ANSI standards
Can be made with a custom earmold or foam insert
The same coupler must be used for both measurements - ANSI requires the use of HA-1 coupler
pink line in RECD
real ear measurement
green line in RECD
green
dots in recd
HA-1 RECD avg
blue line in recd
actual ha-1 recd measurement
if RECD is above avg
smaller ear canal than avg
if RECD is below avg
larger ear canal than avg
If RECD is negative in LFs below 1000
slit leak