- In this video, I'm gonna show exactly how we can identify
where sound in coming from, comin' 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 make you a better informed consumer.
So if you're into that,
make sure you hit that Subscribe button,
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At least once a week I lose my phone somewhere in my house
and I have to have my wife call it
so I can carefully listen to it vibrate,
and after about three or four times,
I eventually am able to locate exactly where my phone is.
Obviously, your hearing plays a huge role
in identifying where sound is coming from,
and this requires the use of both ears,
and this process is called localization.
To understand exactly how localization works,
we need to know about interaural timing differences,
interaural level differences, and pinna effects.
First, let's talk about interaural timing differences,
otherwise known as ITDs.
This is the difference in timing that it takes
for sound to reach one ear and then reach the other ear.
So imagine that you have a friend calling you
from the right side of your head.
Their voice is going to hit your right ear
before it ends up hitting your left ear,
and the difference in timing tells your brain
that that sound is coming from that direction.
Second, let's discuss interaural level differences,
otherwise known as ILDs.
This is the difference in intensity of sound
between your ears
caused by the head shadow effect and distance.
The head shadow effect is a phenomenon that happens
when sound has to travel through and around your head
before it can be heard by your opposite ear.
By the time the sound reaches the opposite ear,
it is typically six to seven decibels softer
than it was in the ear that was on the side
of the sound source.
In that same situation that I described before,
where your friend is calling your name
from the right side of your head,
by the time that sound gets around to your left ear,
it is actually softer in that ear
than it was in the right ear.
Again, triggering your brain to understand
that that sound is coming from your right-hand side.
This is why having two functioning ears
is required to be able to determine
where sound is coming from.
So if you're someone who has single-sided deafness,
even if you receive treatment for that single-sided deafness
using CROS or BiCROS,
you're not gonna be able to identify
exactly where sound is coming from.
Now, in some cases
with AmpCROS or with a Cochlear implant
for a unilateral-sided deafness,
you may be able to get a little bit of localization back.
And I will have a video in the description
discussing these different treatment options
if you do have single-sided deafness.
Third, let's talk about pinna effects.
So normal-hearing individuals are really good
at identifying where sound is coming from
in the horizontal plane,
and they're also really good at identifying
where sound is coming from in the vertical plane.
Now, if you actually have something in your vertical plane
that is completely centered with your head,
you're not gonna have a whole lot of timing
or level differences between both of your ears.
This is where the unique size and shape of your pinna
comes into play.
The shape of your pinna is something that helps you
identify where in your vertical plane
sound is coming from,
and your brain is attuned to this over the course
of your entire life.
Now, there is a easy way to demonstrate this
if you can actually get a friend to jingle
a set of car keys at somewhere in your vertical plane,
with your eyes closed, you can usually identify
very accurately where that sound is coming from.
But if you actually take your ears and contort them
and kinda squish them around,
and then try to do the same thing,
it becomes increasingly difficult to understand
where in your vertical plane that sound is coming from.
Now, if you're having issues in identifying
where sound is actually coming from,
then you absolutely have to go in
and get your hearing evaluated,
because that is what is controlling your ability
to actually perform localization.
All right, there you go.
Now you know how we use timing differences,
level differences, and pinna effects
to determine where sound is coming from.
Now that you know, here's a piece of advice,
never leave your phone on silent mode.
Where is my phone anyway?
That's it for this video.
If you have any questions,
leave them in the comments section below.
If ya like the video, please share it.
If you wanna see other videos 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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