Members of the class were asked to listen
to 20 pairs of white-noise sounds from a recording.
The first was of reference intensity, and the second
was of greater or lesser intensity by 5, 10, 15, and 20
decibels. The class was asked to assign the reference
sound a loudness of 100; if the second sound sounded
twice as loud they should record a value of 200 and if it sounded
half as loud they should record 50. The data
table below gives the responses to this test. The
answers for each sound intensity level were averaged
and plotted with standard errors on the graph below.
Because the decibel scale is already a logarithmic scale,
the data were fit to an exponential. The
coefficient B came very close to the standard (B=0.07)
value found in text books.
The measured B is somewhat lower, most likely
because the small speakers used are not linear in
sound intensity reproduction.
dB A B C D E F G H I J K L
15 300 300 200 300 250 200 300 250 150 200 180 200
-5 75 50 80 50 70 75 80 80 75 75 70 80
-20 40 25 40 20 20 25 20 35 25 50 60 30
0 110 100 100 100 90 105 110 100 100 100 100 110
-10 60 50 50 20 40 80 60 50 50 75 70 80
20 400 400 300 400 270 250 350 300 200 200 200 350
5 150 150 130 40 140 110 130 180 115 125 120 120
10 200 200 150 150 130 140 190 200 180 150 150 150
-15 70 20 30 10 60 25 40 20 80 50 40 30
0 110 80 90 100 110 95 95 95 90 95 100 100
-10 70 35 40 50 80 50 70 40 40 60 40 50
15 200 300 130 200 200 200 200 225 220 175 160 250
20 300 400 200 250 300 250 250 300 250 200 170 300
-5 90 45 70 40 75 80 90 75 75 90 100 70
10 170 200 150 150 150 150 140 160 125 150 130 40
-15 50 35 50 10 40 30 35 20 25 50 80 50
-5 80 50 70 20 80 70 85 70 35 75 90 80
-20 40 20 40 10 10 20 15 10 15 50 40 20
5 130 125 140 110 140 130 110 120 120 125 110 140
15 180 300 200 200 240 190 180 200 220 200 160 200
