- Hey, guys, welcome back to the Dr. Cliff AUD vlog.
This is vlog number 42,
and today I want to talk about noise reduction co-efficients
or NRC's.
Now, before you just go ahead and skip past this video
because you just know it's going to be incredibly boring,
just know that the noise reduction coefficient or NRC value
of different objects inside of an environment,
that you are trying to communicate in,
will have a significant impact
on how well you can actually hear.
Now, the reason that I'm bringing this topic up
is because I went to Prescott, Arizona this last week,
with my wife and with some family,
and we went to a restaurant called The Local,
and when I looked up at their ceilings,
they had acoustic panels hanging on them.
Now, acoustic panels, and I'll just go ahead
and show you this photo right now, 'cause I took a photo
when I was in there,
but these acoustic panels will actually absorb sound
and prevent that sound from reverberating
off of the ceiling, back into the restaurant,
into the dining area where everybody's sitting
and eating and talking and all of that.
The reason that this is so important
is because of something we call critical distance.
Now, very simple, critical distance is the distance
at which the amplitude of a direct sound
and the amplitude of noise and reverberation are the same.
As long as you stay within the critical distance,
the amplitude of a direct speech source will be louder
than its reverberation,
which means that you will understand speech
significantly better.
Critical distance is very important
but the thing that will dictate
how far that critical distance is,
or how short that critical distance is,
are the acoustics of the environment that you're in.
So when you start looking at these restaurants, now,
if you've noticed this, I know I've noticed this
and I know COVID's going on,
so you haven't been in a restaurant probably
in quite some time, but when you start looking
at the acoustics of these restaurants,
you know that they're getting bad.
These restaurants are being built
to be aesthetically pleasing from a visual perspective,
and they're actually, from a noise perspective,
it's almost more favorable for a restaurant
to have a lot of noise,
because it seems like it's a happening place
and it's exciting to be there,
but they are definitely doing this at the detriment
of being able to communicate effectively.
So anytime that I find a restaurant
that is actually paying attention to the acoustics,
and they're trying to cut down on this reverberation,
that gets me excited.
So let's talk a little bit about NRC values,
and different objects have different NRC values.
So for instance, a really, really hard surface
that reflects all sounds, so it doesn't absorb any sound,
it just reflects all sound back into a room,
think of something close to concrete,
because concrete has a very low NRC value.
You would have anywhere between 0.0, which is very bad,
or it means it reflects a lot of sound,
all the way up to 1.0,
which means that whatever that object is
or whatever that surface is, absorbs 100% of sound,
and so when you start looking at,
like harder objects are closer to 0.0,
you start looking at really, really soft objects.
They tend to be up closer to 1.0.
Now, when you start looking at these acoustic tiles,
now you can see here, we're in my studio.
I have acoustic tiles up on this wall
because I want it to absorb a lot of the sound,
and I'm a loud talker, but I want it to absorb a lot
of my sound and not let that bounce off the walls
and come back into the room and get into my audio recording.
So I went ahead
and purchased a bunch of these acoustic tiles.
Now, these acoustic tiles have an NRC value of 0.95,
which means that 95% of sound is absorbed by these tiles.
If you look at my carpeting,
I think carpeting is something like 0.3, which means 30%,
or 0.4, which is 40% of sound is absorbed with the carpet.
You look at dry wall.
It's usually 0.15, which means only 15% is absorbed
by the drywall, with the paint on it.
A couple of months ago, I think I put up a little question
with some photos about different tiles, acoustic tiles,
that we would have on our ceiling, inside of the new clinic,
and they had really great designs.
They looked really, really sharp.
The problem was they had a very low NRC value,
which means that they were going to reverberate
a lot of the sound, from me talking,
from my patient talking, from the acoustic measures
that we do inside of our treatment rooms,
and it would not have been a positive sound environment
for someone to be in.
So we actually had to make the switch,
going from those more decorative ceiling tiles,
to an actual acoustic ceiling tile that has an NRC value
of 0.55, which means they'll absorb 55%
of the sound information that hits them,
so it doesn't reflect all of that sound back into the room.
Now, yes, it would be better if it had a 1.0 value,
but you need to start looking at different things
inside of a room.
You're going to have different types of surfaces,
so you just have to pay attention to it.
So inside of a treatment room, for instance,
we're going to have carpeting,
we're going to be having different acoustic tiles like this
on the wall,
and we're going to have the acoustic ceiling tiles as well,
and you start looking at all of those surfaces
having some form of absorption of sound,
then it's going to make the acoustics inside of that room
significantly more favorable.
Now, that is going to be a theme
throughout the entire office
because there are a lot of hard surfaces.
There's glass. There is the vinyl flooring.
There is, of course, all of the dry wall that's in there.
All of those surfaces reflect sound back into a room,
so we need to make sure
that we're selectively putting different things like this
inside of the office.
But it doesn't just stop at the office.
This stuff comes down to your homes as well.
If you happen to have a home
that has a bunch of tile floors,
has a bunch of glass windows,
has really, really tall ceilings,
the NRC values of all of those things are bad.
They're really low, which means you go into different rooms
in your house and someone's talking to you,
but you're getting a ton of reverberation,
and it makes it significantly more difficult
for you to hear them, and I usually tell people that.
I know that people say background noise is the worst thing.
I think reverberation is the worst thing,
when it comes to hearing,
because you can have a bunch of people
in a restaurant talking,
but if they have really good acoustics in that restaurant,
you'll still be able to hear the person
that you're talking to.
However, if they have a ton of reverberation,
then all of the sound from everybody's getting all mixed in
and reverberated off of everything
and into your hearing aids,
which is going to make it to where your hearing aids
don't know what the heck to pick up and amplify for you,
and you are not going to do well
in that particular environment.
Now, one way that you can get by with bad NRC,
or noise reduction co-efficients,
on different surfaces in an environment
is to use a remote microphone,
where you clip a microphone onto someone's shirt,
the person you're talking to,
and then their voice goes right into that,
sends it wirelessly into your hearing aids,
and you can hear them significantly better,
because their voice is right there,
and I don't care if your critical distance is super short,
where the reverberation is hitting your hearing aids really,
really soon, it doesn't matter, 'cause you're getting that,
their voice, at a such high volume level,
that you're not going to be worrying about reverberations,
so that's why having these assistive listening devices
helps significantly in these really,
really noisy environments.
Now, one other thing that you can do inside of your home
is to actually go to a company like audimute.com,
which is actually where I got these tiles from,
and you don't have to get tiles like this
inside of your home.
I don't think a lot of people would like having walls
looking like that.
But you can actually get photos put onto different types
of acoustic panels and put up on your wall,
and it looks really, really nice,
but it also serves the dual purpose
of absorbing sound waves,
so it makes the acoustic environment inside of that room
much more favorable to be able to hear better.
Now, when you go to restaurants,
it's great to find a restaurant
that has those acoustic panels, like The Local does,
up in Prescott,
but not every restaurant's going to have those,
so what you need to start thinking about is eating outdoors.
When you go outside, the NRC value of outside is 1.0,
which means there is there's no reverberation of sound.
All of that sound, wherever it wants to go, it can go.
So when you go outside and eat at a restaurant,
you probably noticed that you hear significantly better.
Of course, if that outside means that you're sitting
right next to a busy road, where there's a lot of traffic,
you're still gonna run into issues,
because you're going to have a lot of noise from the road.
But if you can find restaurants
that either have good acoustics inside
or you can have an outdoor seat,
you're going to be able to hear significantly better
in those environments.
All right, so hopefully I haven't bored you significantly
at this point.
What I would say is that if you're trying to improve
the acoustics inside of your environment,
go ahead and go online and just type in NRC values,
and when you're starting to pick out different things
to put inside of your home, keep in mind,
if they're hard surfaces or if they're soft surfaces,
if there are different things that you can do,
and get your NRC values as high as you possibly can,
it is going to help you hear better.
All right, guys, hopefully I haven't bored you enough,
talking about NRC values.
It is a very important thing that you understand
if you're trying to make your environment easier to hear in,
and it can definitely help you understand
why hearing in a really acoustically unfriendly environment
is so bad for you, but that being said,
I hope you enjoyed today's video, and as always,
I'll see you next week.
(upbeat music)