APPLY SOUND TRANSMISSION
TO SOUNDPROOFING
KOSHI HIGH SCHOOL 2ND GRADE TOMOHIRO IWATA YUTO OCHIAI TAKAKI SAITO KYOHEI YAMAMOTO
When our school is under construction, the noise will have a bad influence on our class. We considered how we can reduce the noise and studied how the thickness of a material affects sound transmission. In the end, we want to find the cheapest and easiest way to reduce sound transmission.
Motivation
透過音エネルギー
吸収音エネルギー (熱に変換)
Incide
nt so
und
energ
y
Reflected sound energy
Transmitted sound energy
Absorbed energy
What is sound transmission?
12mm 48mm
Use 1-6 boards 12mm or 5.5mm thick
Experiment
device Speaker
PCConstant-frequency oscillator
Experiment equipment
speaker
microphone
Front view
0 12 24 36 48 60 72
Thickness(mm)
Loud
Quiet
Transm
ission loss(
dB
)
We thought sound gets smaller and smaller by adding boards.
Expectation
FFT (FAST FOURIER TRANSFORM)N
oise ( outside the area of m
easurement)
percentage of frequency occurring sound
percentage of frequency
frequency
-20
-40
-60
-80
-100
dB(sound
level)Experimental landscape
percentage of frequency
frequency
percentage of frequency
frequency
FFT(FAST FOURIER TRANSFORM)representing sound in terms of the frequencies of the waves that make up that signal
Experiment result
Red 0mm green 12mm blue 24mm yellow 36mm light blue 48mm pick 60mm white 72mm
As the number of boards increases, we don`t see sound insulation effect.
Experiment result
0 10 20 30 40 50 60 70 800
5
10
15
20
25
Thickness (mm)
Transmission loss
(dB)
Contrary to expectations, the sound didn’t increases in proportion.
Consideration Ⅰ
0 10 20 30 40 50 60 70 800
5
10
15
20
25
Thickness (mm)
Transmission loss
(dB)
Asymptote
It seems that this graph has an asymptote.
Consideration Ⅱ
0 10 20 30 40 50 60 70 800
5
10
15
20
25
Thickness (mm)
Transmission loss
(dB)
There will never be a point where sound isn’t transmitted at all.
Consideration Ⅲ
Thickness of board(mm)
Transmission loss (dB
)
Consideration Ⅳ
transmission loss (dB
)
Thickness of board(mm)
Consideration Ⅳ
TRUSS STRUCTURE
Incident sound
Reflected sound
Transmitted
sound
OUR NEXT CHALLENGE
1. MEASURE SOUND TRANSMISSION USING A TRUSS STRUCTURE (WHICH LOOKS LIKE THE CROSS SECTION OF CARDBOARD).
2. MAKE SPACE BETWEEN THE BOARDS, AND STUDY THE DIFFERENCE FROM WHEN THE BOARDS ARE ATTACHED.
3. CONFIRM THE ASYMPTOTE OF THE GRAPH.
THANK YOU FOR LISTENING !
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