The purpose of this lab is to find out what the reverberation time (RT60; Rossing ch. 23) is in the lecture hall. This was measured with the room both empty (8Am Nov. 6) and full (class time, same day), at five frequencies: 100, 200, 1000, 5000, and 10000 Hz.

Your assignment, due Thursday Nov. 13, is to measure the reverberation time ("RT60") of the room in each of these cases. Did increasing the frequency increase or decrease the reverberation time? What was the effect of having people in the room?

NOTE: the textbook gives formulas for estimating reverberation time based on room volume and other parameters -- you won't need these for measuring an actual reverberation time. All you need is the graphs and the definition of "RT60" which is the time it takes the sound level to drop 60 decibels.

Here are the runs:

100 Hz, empty room

200 Hz, empty room

1000 Hz, empty room

5000 Hz, empty room

10000 Hz, empty room

100 Hz, during class

200 Hz, during class

1000 Hz, during class

5000 Hz, during class

10000 Hz, during class

In each graph, the horizontal axis is tenths of a second, and vertical axis is decibels.

(The graphs are printed upside down, for some reason -- maybe I can figure out how to fix this, but meanwhile, time runs from right to left and loudness increases downward -- beware!)