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[street noise & music]
The ubiquitous, often disruptive, our constant everyday companion...
...noise.
It attacks us at home, at school, in the workplace.
It has become an integral part of our lives.
However, there are places where noise has no right to exist.
Welcome to the D1 building, which houses the Department of Mechanics and Vibroacoustics.
Here you can visit one of the most "deaf" places which exists in our university as well as in Poland.
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You'll see what research is being done in the most silent place in Poland.
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We'll demonstrate you the possibility of reverberation chamber,
and we gonna go down under the ground to show you unique construction of an anechoic chamber.
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AGH Explorer
Episode 1: Anechoic chamber
We are in the Laboratory of Technical Acoustics of Department of Mechanics and Vibroacoustics,
which operates since 1974.
We deal here with education by training students and academic staff.
The laboratory consists essentially of two test rooms.
This is a room called an anechoic chamber
and a room that is called reverberation chamber.
Both chambers have advanced instrumentation, which allows us to carry out research.
Mainly we have been here testing, designing and supervisors on execution of acoustically advanced interiors.
Such as the Lviv Opera House, where here we have some pictures visible, where last year we carried out renovation of the interior.
We have produced many such interiors.
In Krakow, Bagatela Theatre was also rebuilt according to our acoustic guidelines .
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At the moment we are in a large reverberation chamber at the Department of Mechanics and Vibroacoustics AGH in Krakow.
It is, apparently, a special room, where we want reverberation as big as possible.
[explosion]
[reverberation]
We obtained this by using non-parallel walls which can be seen here in the room,
by special wall painting with oil paint, which has a very low absorption coefficient
and by an adequately performing the floor.
[explosion]
[reverberation]
The main difference between the absorption coefficient measured in the chamber, which is called the reverberant absorption coefficient and coefficent measured in this impedance tube is
that in a reverberation chamber sound incident on the sample from all directions.
There we have a diffuse field situation .
The disadvantage of that method is that sometimes it's hard to make a sample with an area of 10-12 m2 as it is very cost-intensive.
It is much easier make a sample with a diameter of 10cm,
which we can measure the impedance tube.
In this tube we measure sound absorption coefficient for the sound incident perpendicular to the sample.
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Speaking of the Laboratory of Technical Acoustics we should especially mention the "heart" of the laboratory, where we are now.
This is the main room, which is used to control and perform measurements in both chambers in our laboratory.
As seen in the laboratory we work all the time.
In this moment, colleagues are working on a program that will be using the manipulator to measure sound power level of sound sources mounted on the rotary table, which can be remotely controlled.
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At the moment we are in a large anechoic chamber at the Laboratory of Technical Acoustics.
As you can see this is a completely different room.
It looks quite different than our reverberation chamber.
There is quite a different sound field.
Emitted sound , e.g. when I say something, it does not bounce off the wall.
It " goes" to wedges, there is diffused, absorbed and we have any reflected sounds.
With this feature, we can measure a lot of things here.
This chamber is a cube,
a big reinforced concrete cube, the exterior dimensions include a volume of about 1000 m3.
This is the largest anechoic chamber in Poland (of its kind, data as at the filming of the movie).
The weight of this chamber is estimated to be 600 tonnes (after weighing, we know that it is less than 500 tons),
and to make things even more interesting - the chamber have no ordinary foundations.
It is located on the 25 vibration isolators.
These are special springs, which in some way limit immission of vibration and noise from the street or the seismic activity, which unfortunately sometimes they interfere.
To prove this, let us see what is under the anechoic chamber.
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This is the anechoic chamber where we have been inside.
Here is the bottom of the anechoic chamber.
In a moment we gonna go under, to view these vibration isolators.
Here, you can see beam which is holding up the rest of the building.
The chamber itself is not in any way connected to the rest of the building.
Feel free underneath the chamber.
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Welcome under the anechoic chamber.
This is one of mentioned before vibration isolators.
Under the chamber we have 25 of this kind of vibration isolators.
Behind me is 12, on your side is another 12 units.
Inside, in this kind of "cube",
It is composed of two parts, top and bottom.
The bottom is attached to the foundation, the upper is attached to the chamber.
Here you can see the gap in the middle. Inside are special springs that result in reduced transmission of vibrations from the substrate to the chamber.
These vibrations can come from tectonic movements, as from the street that passes near.
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These 25 vibration isolators, are carrying 600 tons.
Above us is 600 tons, which have no foundation. This "hangs" on springs,
So it's pretty incredible thing.
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