- One of the most underrated and underutilized
pieces of diagnostic equipment
inside of a hearing aid clinic
is the hearing instrument test box.
Never heard of one?
Well, in this video, I'm gonna explain why it's so critical
to have your hearing care professional use a test box
to ensure that your hearing aids are functioning properly.
Coming up.
(fun upbeat music)
This video is sponsored by Natus, formerly Otometrics,
the preferred diagnostic equipment supplier
of Doctor Cliff, AuD.
Since the 1950s, 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.
When you take your vehicle into the shop,
what is the first thing that the mechanic does
other than asking you what you feel is wrong with your car?
That's right, they hook it up to a computer
and they run a diagnostic test on the car
so they can identify exactly which areas are having issues.
Well, did you know that your hearing care professional
can run a very similar test on your hearing aids
inside of a hearing instrument test box?
We call this electroacoustic analysis
or more simply test box measures.
When performing these test box measures,
we can objectively evaluate your hearing aids
to see if they're meeting manufacturer specifications
for things like output, gain, distortion,
and the input noise of those devices.
And we can do this with a higher level of precision
than we can if we just listen to those hearing aids
and try to determine with our own ears
what's going on with them.
In fact, best practices indicate
that every brand new hearing aid
from a hearing aid manufacturer
should be tested inside of a test box
to see if it's actually meeting manufacturer specifications.
Not only that, but every hearing aid that comes back
from repair from the manufacturer should be tested
to see if it's meeting those same specs as well.
Some hearing aid industry data suggest
that up to 12% of brand new hearing aids
that come from a hearing aid manufacturer
do not meet the manufacturer specifications.
On top of that,
it's estimated that up to 18% of repaired hearing aids
that come back from a manufacturer
are not meeting manufacturer specifications.
I mean, can you imagine going and buying a brand new car
and that car has a 12% chance of something
not functioning correctly on it?
And on top of that,
can you imagine taking your car into a mechanic
and 18% of the time he's gonna give you your car back
and it's not actually gonna be functioning properly?
That is exactly the same thing that we're talking about
with your hearing aids.
It's also a good idea to have these hearing aid diagnostics
tested inside of a test box about once a year
just to ensure that they're meeting specs still
and to identify potentially anything
that could cause a bigger issue down the road.
All right, now that you know how important
these diagnostic measurements are,
I'm gonna go ahead and take you through the testing process
and show you what we're looking for.
In order to perform these measures,
we need to prepare a hearing aid for testing
in the Aurical HIT box.
This requires that we program the hearing aid in question
to manufacturer test settings.
The whole concept here is that we're going to use
the HIT box to present calibrated signals to the hearing aid
that is programmed to these manufacturer test settings
and then record the output, gain, distortion,
and noise level of the hearing aid
to ensure it is actually functioning
within the manufacturer specifications.
These measurements from the HIT box
are represented in graph form and in numerical values.
Every new hearing aid
comes with a manufacturer specification sheet
that shows the technical data of that hearing aid.
Here is an example of what one of those sheets looks like.
This is what we use to compare the diagnostic readings
that are recorded using the test box.
The curves in the Otosuite software
should resemble the curves
on the manufacturer specification sheet
for the specific hearing aid and receiver power
that we are testing.
If we see something out of the ordinary here,
it can indicate that the hearing aid
is not performing correctly.
Next, let's take a look at the numerical values.
These values should be within a certain tolerance range
of the numerical values presented
on the manufacturer specification sheet.
These allowed tolerance levels are standardized
by the American National Standards Institute
which is often abbreviated A-N-S-I or ANSI.
If these values are within those specified tolerance ranges,
then the devices are considered within specs
and are functioning properly.
All right, so now that you know what we're looking for,
let's take you through a few measurements of a hearing aid
that I recorded inside of my test box
so you can see how it works.
First, I'm gonna start with a hearing aid from a patient
who just feels like they're hearing performance
isn't as good now as it was a few months ago.
And after doing a listening check on the device myself,
it really sounded fine,
but that prompted me to do a diagnostic check
on this hearing aid to see if there's something objectively
that we could measure to identify what the problem is.
As I set up the device in the HIT box
and ran it through the test sequence,
performing full on gain and reference test gain measures,
things started off well,
but some of these measures looked like they could be
outside of the allowed tolerance ranges.
As we compare the HIT box measures
to the manufacturer specifications,
we can start to see why the patient felt
that their hearing has not been as good lately.
Staring with the shape of the curves,
we can see that the red curve is looking okay,
but their turquoise curve is not as smooth
as we would expect to see as indicated by the spec sheet.
This is our first red flag about this hearing aid.
When it comes to the numerical values with the OSPL 90 max,
we should have an output value
that is no higher than 114 dB SPL
due to an ANSI tolerance of plus three dB
so we're good there.
However, the OSPL 90 HFA should be
between 102 and 110 dB SPL
so this is our second red flag
that this device is not meeting specs
even though it is not significantly
outside of the tolerance range.
Next, we need to look at the amount of gain
the device is producing for a 50 dB SPL input.
And for this, we look at the FOG 50 HFA gain
which has a value of 33.6 dB,
but should be between 34 and 44 dB
which is our third red flag.
Where things get really crazy
is when we look at the distortion levels of the hearing aid.
The specs sheets indicate that we should be no higher
than 4.5 to 5% distortion at 500, 800, and 1,600 hertz.
We can clearly see that we are exceeding those ranges
with distortion percentages of 22.9, 22.5,
and 37.5% respectively.
Even though our equivalent input noise,
which is the amount of noise a hearing aid generates
when it's turned on,
is within manufacturer specifications at 19.9 dB SPL,
the diagnostic test clearly indicate
that this hearing aid is not functioning properly.
Okay, so now that we've identified that this hearing aid
is clearly not meeting manufacturer specifications,
even though it really sounded good to me
before running it through these diagnostic tests,
let's go ahead and see how it performs in the test box
after I repaired this device.
Here is a direct side-by-side comparison
of the HIT box measures.
We have the device when it was outside
manufacturer specifications on the left
and the new measures after repair on the right.
The turquoise curve for the repaired hearing aid
in the right has been smoothed out.
The OSPL 90 max has been increased,
but it's still within the tolerance range of 114 dB SPL.
The OSPL 90 HFA has improved to 104.7 dB SPL
which is now within specs.
The FOG 50 HFA gain has increased significantly to 38.3 dB
which is also now within specs.
Distortion levels of the hearing aid have decreased greatly
and are now well below the allowed
tolerance ranges of 4.5 and 5%.
And the equivalent input noise
continues to be within specifications as well.
So you see, without using a hearing instrument test box,
it's really impossible to determine
if a hearing aid actually is performing the right way.
And you could actually be having
a hearing aid in your ears right now
that is not meeting manufacturer specifications
and the crazy thing is is that you may not even notice
that you're not performing at your highest level possible.
If you want to ensure that you're receiving
the maximum amount of benefit from your hearing aids,
you need to do more than just buy the best hearing aids
or even have those hearing aids fit perfectly
by your hearing care professional.
You need to make sure that they're still functioning
within manufacturer specifications.
After all, you wouldn't want to drive a car around
that isn't functioning properly,
so why would anything be different with a hearing aid?
That's it for this video.
If you have any questions,
leave them in the comments section below.
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Also feel free to check out my website drcliffaud.com.
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