- In this video, I'm talking about the occlusion effect
and why it may cause hearing aids to make your own voice
sound hollow or loud to yourself.
Coming up.
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Hi, guys, Cliff Olson, doctor of audiology
and founder of Applied Hearing Solutions
in Phoenix, Arizona.
And on this channel, I cover a bunch of
hearing-related information
to help you make a better informed consumer.
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make sure you hit that subscribe button,
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One of the first comments that new hearing aid wearers have
when they're first being fit with hearing aids is,
"Why does my own voice sound so much different
"with these hearing aids on?"
And there are two possible answers to this question.
First is your voice is actually being amplified
by the hearing aids themselves,
and the second is the occlusion effect.
Let's go ahead and take a look at
the first possible culprit,
which is your own voice being amplified
by the hearing aid themselves.
Now this is exactly what hearing aids are designed to do,
is to amplify speech,
and this includes your speech.
And since you probably haven't heard your own voice
at the proper levels for quite some time,
it's probably going to sound a little bit different
once you get it all back.
Fortunately, this is something that new hearing aid users
get used to pretty quickly.
However, the second culprit, the occlusion effect,
is an entirely different story.
The occlusion effect occurs when the vibration of sound
that's being created when you talk or when you chew on food
is being bone conducted
through your jaw and through your skull
and it can't escape through your ear canals
because they're being blocked by something,
like a hearing aid.
When this sound is trapped inside of your ear canals,
it can cause your ear drums to vibrate,
giving you a variety of different auditory perceptions,
anything from a booming loud sound, to a hollow sound,
to a sound of you talking in a barrel,
or a sound of you talking in a tunnel.
You can actually give yourself
the occlusion effect right now.
If you actually take your fingers
and plug your ears with them and you talk,
that is the perception of the occlusion effect
that's actually your own voice vibrating
inside of your ear canals.
So how do we determine if you have the occlusion effect?
Well, this is a pretty easy thing to determine
usually when fitting you with hearing aids.
We can actually mute the hearing devices
when we're going through your programming with you
and actually have you talk.
If your voice ends up returning back to a normal level
or it even sounds a little bit muted
then you are not experiencing the occlusion effect.
The second way would be to objectively
measure the occlusion effect
by using probe microphone measures,
by using some of the same verification equipment
that we would use to perform real ear measurement.
Typically though occlusion effect is often experienced
more by individuals who have good low frequency hearing,
but bad high frequency hearing thresholds,
like you see illustrated on this audiogram.
That is because the occlusion effect
is typically experienced below 500 hertz.
And the better your hearing at thresholds
below 500 hertz,
the more you'll perceive this bone conducted vibration.
If you have bad hearing at the frequencies
below 500 hertz, like you see in this audiogram,
you typically won't experience the occlusion effect,
because the vibration of your own voice
inside of your ear canals
won't be loud enough for you to perceive.
So the question then becomes,
if you do experience the occlusion effect,
is there a way to get rid of it?
And the answer is yes.
There are two different ways to reduce the occlusion effect.
The first way is to increase the venting
on your hearing aids.
So whether you have a dome inside of your ear canal,
or whether you have a custom ear mold
inside of your ear canal,
if you can actually increase the venting of that,
it will allow your voice that's being bone conducted
to escape outside of that venting,
reducing your perception of occlusion.
This table illustrates the recommended vent size
to optimize amplification
and to reduce the occlusion effect.
You can see that the better your hearing thresholds are
at 500 hertz, the more open the venting should be.
Give someone with lower than 20 dBHL hearing thresholds
a .5 millimeter vent diameter,
and they are virtually guaranteed
to experience the occlusion effect.
The second way that you can reduce the occlusion effect
is to get an ear mold or a hearing aid
that fits deeper inside of your ear canals.
If you take away the space between your ear drum
and the beginning of that hearing aid,
it reduces the amount of space
that your own voice can vibrate in.
The less vibration of your own voice
and the less you perceive the occlusion effect.
Well, there you go, seems pretty simple, right?
Just increase the vent size and have that hearing aid
go further inside of your ear canal.
Well, it's not actually that simple.
In fact, this turns into quite the balancing act.
The larger that you make vent,
the less that you can actually amplify outside sounds
before they actually leak out of your ear canal
and recycle back through the hearing aid
causing a whistling, otherwise known as feedback.
On the other hand, the deeper you go inside of an ear canal,
the more sensitive that it become.
So you can't necessarily just make
a deeper seated hearing aid or a deeper seated ear mold.
It might not be comfortable to the user.
That being said, your hearing care professional.
Should be able to identify the optimal balance
between acceptable occlusion and optimal amplification
by adjusting vent size and depth of hearing devices.
At the end of day, occlusion is always something
that's on the mind of your hearing care provider.
And the better your hearing care provider,
the better they will be
at making sure that the occlusion effect is a non-issue.
That's it for this video.
If you have any questions,
leave them in the comment section below.
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Also feel free to check out my website, drcliffaud.com.
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