Testing the Human
Ear
Chris Burns
Johari Wiggins
Frequency Recognition
The purpose of this portion of the project is to see how many
wavelengths of a tone it takes for a human ear to recognize that
it is a tone.
Subjects were played 3 related tones for five seconds each. Then
they were played selected number of wavelengths of those tones
and asked if they could identify them. The test tones began at 1
wavelength and got increasingly longer.
Frequency Recognition
Results:
For the low range, the average was 9 wavelengths. For the middle
range, it was 6. For the high range, it was 15.
Overall, the average number needed was 11 wavelengths.
Frequency Recognition
18
16
Wavelengths needed
14
12
Low Range
Middle Range
High Range
10
8
6
4
2
0
James
Matt
Mike W.
Tom
Carroll
Subjects Tested
Max
Josh
Ian
Mike D.
Time Delay with Ears
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Distance between ears is about 9-14 cm
.12m / 340m/s = .0035 sec
Used Audacity to simulate this time delay
between ears
Time delay creates the illusion of the sound
being louder in one ear.
Time Delay with Ears
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Slowly increased the time delay starting from
zero to find the threshold for the recognition of
this time delay for the human brain.
Found that the brain is extremely sensitive to
time delay.
Time Delay with Ears
Did extensive studies on
three individuals.
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Perceived Intensity Difference vs. Time Delay
4.5
4
3.5
3
2.5
59 cm
2
63 cm
61 cm
1.5
1
0.5
0
-0.5
0
0.002
0.004
0.006
0.008
Time delay
0.01
0.012
0.014
0.016