- Real Ear Measurement is the only way to ensure
that you receive the maximum amount of benefit
from your hearing aids, but performing Real Ear Measurement
and performing it well, are two completely different things.
That's why in this video I'm gonna show you
how I utilize Real Ear Measurement to maximize
hearing aid performance, coming up.
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This video is sponsored by Natus formally Otometrics,
the preferred diagnostic equipment supplier
of Dr. Cliff AuD.
Since the 1950's Otometrics has been one of the most
innovative manufacturers of hearing aid fitting equipment,
and diagnostic hearing and balance equipment
in the industry.
When it comes to testing and treating
my patients I only want to work with the best.
This is why I use Natus in my clinic.
Chances are if you're watching this video
you already know from my other videos
just how critical Real Ear Measurement
is to verify that your hearing aids
are programmed correctly to provide you
with the maximum amount of aided benefit.
After all even the best hearing aids are only as good
as they are programmed.
That's why I wanted to create this video,
so I could show you exactly how I'm using
Real Ear Measurement to maximize performance
outcomes with my patients,
so the next time that you go in
to see your hearing care provider,
you too can understand what they're trying to accomplish
by using these verification measures.
Now let me clear something up right off the bat.
There are definitely wrong ways
to performing Real Ear Measurement
and by no means is my way the only
correct way of performing Real Ear Measurement.
You will typically find small variations
between hearing healthcare providers
and how they choose to employ Real Ear Measurement
to maximize your performance benefit with hearing aids.
That being said I'm going to take you through a complete
hearing aid fitting for a mild to moderately severe
hearing loss that you see here in this audiogram.
First, we need to create a prescription
for the hearing loss that we are treating.
Now because my Astera 2 Audiometer that I use
for hearing testing and my Aurical Freefit
Probe Microphone measurement system
that I use for Real Ear Measurement
are linked together in the OtoSuite software,
it makes transferring
over the audiogram extremely streamlined.
The part that takes a little more thought is deciding
which prescriptive method to use
for this particular patient.
Now there are several different prescriptive methods
out there and deciding which one to choose
can depend on what you're trying to accomplish.
Now I won't get into the specifics
of these following prescriptive methods,
but I just want to give you an idea
of the three most common ones.
You have the NAL-NL1, the NAL-NL2 and the DSL v.5.
The first two are typically used for adult fittings
and DSL can be used for an adult fitting,
but is also frequently used for children.
For this individuals fitting I'm going to be utilizing
the NAL-NL2 prescriptive method with the goal
of maximizing speech intelligibility and not exceeding
overall normal loudness for a range of inputs.
The next step in this process is to set up
the probe microphone tubes that are responsible
for measuring the amount of amplification
that the hearing aids are giving you
inside of your ear canals.
For a female ear canal,
I set these for a depth of 27 millimeters
and for a male ear canal I set them
for a depth of 30 millimeters.
This ensures that the tip of the probe tubes
are close to the eardrum which helps
to ensure an accurate measurement.
My Aurical Freefit also has a Probe Tube Assistant
that helps guide the probe tube inside of the ear canal
to ensure the proper depth for accurate measurements.
It's important to understand that this entire process
is about precision.
If we make one mistake it can have a negative
impact on your overall performance.
Before I place the probe tubes inside
of the patient's ear canals along with their hearing aids,
I perform a feedback management test to determine
if the dome or ear mold that I'm utilizing
for their fitting is appropriate.
As the person wearing the hearing aid
you'll perceive this as a series of beeps,
whistles, or static sounds.
If this feedback measure indicates that there is little
to no risk of feedback or whistling while still allowing us
to meet amplification targets,
then I'm able to proceed with the fitting.
If not I need to change the dome or the ear mold venting
until this measure is acceptable.
Next I need to place the probe microphone tubes
inside of the patient's ear canals
along with their hearing aids making sure to keep
the probe tube in the same position.
Then I need to ensure the speaker
is in front of the patient.
This speaker will play calibrated speech like signals
that will be picked up by the patient's hearing aids
and amplified to the levels
that we set in the programming software.
I like to use the International Speech Test Signal
often referred to as the ISTS which uses six
different languages all mixed together.
Here's an example of what the ISTS sounds like.
(speaking in foreign language)
Now it's time for the exciting part
which is actually programming your hearing aids.
Typically I recommend measuring first fit settings,
which are the amplification estimates
in the hearing aid manufacture software.
I also like to measure amplification levels
for average level speech at 65 dB SPL.
Amplification levels for loud level speech at 80 dB SPL.
Amplification levels for soft level speech at 50 dB SPL.
The maximum power output or MPO of the hearings aids.
I also then like to complete a few additional measurements
such as actual speech to gage perceived clarity perception
and user volume preference to provide an understanding
of how far below prescriptive targets a patient
is at their initial fitting before they've had a chance
to adapt to that amplification.
All right, now that we know what we're going to measure,
I'd like to start with first fit settings.
I like to do this because it gives me an understanding
of how far off the hearing aid manufacturers estimates are
from a patients actual hearing loss prescription.
As I start these measurements
let me explain what we're looking at here.
The pink hashmark line is the prescription of amplification
for average level speech at 65 dB SPL
which stands for Decibels in Sound Pressure Level.
The pink solid line is the measurement
of the speech signal after it's been amplified
inside of the patient's ear canal.
Ideally we'd want the solid line to overlap
with the hash mark line as closely as possible.
Anywhere the solid line is below the hash mark line,
the patient is under amplified.
Anywhere the solid line is over the hash mark line,
they are over amplified.
Running this measurement
before making any custom adjustments gives us an idea
of just how off prescription the patient is
with first fit manufacturer settings.
If we let them leave our office at these settings,
they would not be maximizing
their performance with hearing aids,
and hearing aids are too expensive
not to be programmed correctly.
All right, once we get our base line
now we can go in to the programming software
and start making adjustments to the amount of amplification
coming through the hearing aids
so we can match these prescriptive targets.
I like to do this on a separate curve.
In this case I'm using a purple hash mark line
for the 65 db SPL prescription
and a solid purple line for the output curve.
As I make programming adjustments
inside of the hearing aid manufacturer software
we can start to see just how well we can match
the NAL-NL2 prescriptive targets for this patient.
The reason I love the Otometrics Aurical Freefit
for probe microphone measurements so much,
is that it allows me to obtain a very high level
of precision with these measurements
compared to other Real Ear Measurement equipment
that I have used over the years.
I am a firm believer that the closer we can get
to a patients prescription the better they will perform
with their hearing aids.
Now there are a variety of factors that contribute
to how well we can match targets
such as frequency bandwidth of the hearing aid,
the power of the receiver being used,
if we are going to use a generic open dome
or a custom vented dome, all of which can make or break
a great hearing aid fitting.
Sometimes a decision has to be made whether or not
sacrificing a perfect prescriptive match
is worth it or not based on patient perception.
But that is a topic for another video.
All right once we get this average level speech
at 65 dB SPL, it's time to start adjusting
the compression inside of the hearing aids.
I do this by adjusting the amplification levels
for a 80 dB SPL input which we would consider
a loud level sound.
That prescriptive target is indicated
by the red hash mark line.
Think of an 80 dB SPL signal
as someone talking very loudly to you.
Naturally because this sound is already louder,
we wouldn't want to over amplify this sound,
so we need to make sure that the output of your hearing aids
keeps this within your comfortably audible range.
When we get this measurement as close as possible
to the prescriptive targets, we are ready
to move onto soft level speech.
This measurement is indicated by the turquoise hash mark
and solid lines on the screen.
Now we are still using compression when adjusting
a 50 dB SPL soft level speech input by compressing
these soft level sounds up
into the audible range of the patient.
Soft level speech requires the most amount of amplification
to ensure adequate audibility.
Once we get the hearing aids program correctly for average,
loud and soft level inputs we need to consider measuring
the maximum power output or MPO settings
of the hearing aids.
We can see the uncomfortable levels
that we measured during the audiogram for this patient
at the top of the screen.
By measuring an 85 dB SPL pure tone sweep
across the frequency range, we want to make sure
that we limit the MPO of the hearing aid
to be below these UCL measures.
This will ensure that we are not over amplifying the sound
past the patient's comfort levels.
I do caution limiting on how much you lower MPO,
because you can inadvertently restrict a hearing aid wearers
ability to understand speech and background noise
by lowering it too much.
After this MPO measurement I like to determine the patients
perceived speech clarity for soft level speech.
For the soft level input I use a standard recorded passage
about rainbows spoken by a male in English at 50 dB SPL.
The rainbow passage is a common reading passage
used for a assessing language recognition.
I'm not really paying any attention
to the curves on the screen for this.
I'm primarily using it to gain an understanding
of a patient's perception of soft speech,
using a calibrated signal.
After determining a patient's soft level speech perception,
I then go ahead and ask them if my voice was the sound
of the TV would they be inclined to increase it,
leave it alone or decrease it,
and for most first time hearing aid users
they actually request that I lower down the volume.
And so once I get it down to a level where it's relatively
comfortable for them, I will go ahead and take another
measurement to see where they're at.
I run that measurement using the pink curve.
This will let us know how far below prescription
this patient is after their initial fitting.
This is why adaptation is critical
when being treated with hearing aids.
What sounds good to the patient at the fitting
is usually not where the patient
needs to be to hear their best.
And because we know exactly how far we had to reduce this
patient to get them down to a comfortable level
we now know exactly where we need to go
in the hearing aid programming over time
to get them up to their full prescription indicated
by the solid purple curve.
This typically takes 30-45 days for most individuals.
Now I know you're probably thinking,
"wow, there's a lot of different stuff going on here",
and it just goes to show
how technical probe microphone measurement is,
especially if you're going to use
an Aurical Freefit probe microphone measurement unit
to be as precise as possible.
Like I said before, performing Real Ear Measurement
and performing it really well
are two completely different things,
and now that you've seen this tutorial video,
you now probably know more about Real Ear Measurement
than about 60% of hearing care professionals.
That's it for this video, if you have any questions
leave them in the comments section below.
If you like the video please share.
If you wanna see other video's just like this one
go ahead and hit that subscribe button.
Also feel free to check out my website drcliffaud.com.
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