That has to do with the acoustically very large room.
Sabine said the very large room can be
characterized by the reverberation time or period,
which is related with size of room and open area window.
Where and in the last lecture,
we found that the reverberation period of
this room was estimated by myself very roughly.
And then, we got about 0.9 second.
But our measurement system is very expensive.
Estimate reverberation period, 0.7 second.
Okay. And if you look at
the reverberation period of various famous room,
you can find that interesting number.
For example, the whole famous Vienna Symphony Hall,
that has a volume of
15,000 and reverberation unoccupied
is about three second.
Okay, so, the Vienna Hall reverberation period when it is occupied,
two second, unoccupied, three second.
And Birmingham Symphony Hall reverberation period
is about 2.5 and it is not occupy,
but if it is occupy,
it is about two second.
And Boston Symphony Hall is about 1.9 second when it is occupied.
When it is not occupied, it is 2.5.
Dallas case, 2.9 and 2.8. Stuff like that.
So, what you can see here,
the reverberation period of most of the Symphony hall is
ranging somewhat in 2.52 second.
So, it is more than we expected, okay?
If you go to the very old Catholic,
Cathedral, things like that,
it is more than sometimes three seconds.
So, you feel very revolved around a soundfield.
And this table was adapted from Beranek Concert Halls and Opera Houses,
which is published in 2004.
Okay. Now, in some cases,
most cases I believe,
we would like to increase reverberation period in most cases.
And then, we have to select the area that we wanted change, okay?
Can you move up this?