And it turns out that there's the this Sabine Frankler, Franklin-Jaeger Theory

of Room Acoustics. and basically it's, it's It's based upon

the statistical energy-based approach of, of measuring the decay of sound in a

room. And so for any given listener in a room

or if you were to place a microphone in the room.

Then the sound pressure level is going to decay and t60 is defined to be the time

required for the sound to decay by 60 dB. And that's something we're interested in

because at that point the direct sound is going to dominate what you hear.

as opposed to that portion of the decayed sound so if you would clap your hands in

a room you will be able to hear this. This expression is six times the natural

log of 10 times the, 4 times the volume of the of the room.

And then C is the speed of sound, and A is the equivalent area of an open window

so that sound could escape. typically, basically, it's a way of

measuring the amount of damping that's in a room.

So, you know, if you were to put sofas, and drapes, and carpet, and things in a

room. It would basically there'd be some co,

there's be some constant that would represent an equivalent area of an open

window that corresponded to that for sound absorption.

Now this is a pretty good point to go back to one more demonstration from our

colleagues web page at Penn State. And in particular, he has a demonstration

of reverberation in a small room. And I thought it would be interesting

because what he did is he's taken a room that's empty and then he's actually

placed carpet in the same room. So let's listen to the reverbent

characteristics of the room. So here's the empty room [SOUND].

And here's [SOUND] the carpeted room. You can hear how much more quickly the

sound pressure level dissipates. If you you can hear him speaking.

>> I am standing in a very reverberant room.

>> Okay. And then with carpet.

>> I am now standing in the same room, now, the carpet has been.

>> All right, so, you know, again, feel free to explore the website.

it's a, it's you know, a very effective demonstration.

He actually gives the Sabine equation for estimating the the t60, the re-, the

reverberation time required for the response to decay by 60 db here.

and talks about how you would calculate absorption coefficients and such for

rooms. and here you can kind of see a difference

in the measured reverberation time. the red curve being for the empty room,

and the black curve for a room with carpet on the floor.

and so the effect of the carpet's just reduced the reverberant characteristics

of the room. So, this expression can be used to to

calculate this rever, the, the amount of decay.

And it's it's a useful expression and, and this is one of the keys in, in, in

room acoustics. And, and it's typ-, traditionally applied

by acousticians.