Sound Absorption 2006-01-26 (Eng) R1

8/9/2019 Sound Absorption 2006-01-26 (Eng) R1

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Photographer: Peter Persson

The perfect sound environment


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What is sound?

What is sound absorption?

How do we measure sound absorption?

Sound absorption reverberation time

Solution for a good sound environment


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Our mission is to

contribute to a good

working environmentfor the eye,

the ear and the mind


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What is a good working environment ?


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Our ear

Our ears are made for natural sounds.

..in a natural environment.


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Outside


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Build a room


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What is sound?


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The Ear


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Freuency

" sec

number of oscillationstime #sec$

%number of H&


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!ound "ressure level#dB$

%&

%'%(

%)

%*

%+

%%

%

%-%.

&

'/&&&/&&&

(/&&&/&&&

)/&&&/&&&

*/&&&/&&&

+/&&&/&&&

%/&&&/&&& -/&&&/&&&

'&/&&&/&&&

0elative soundenergy

& '&,&&&&( 12m(


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What can we hear?

'hresholdof

hearing

'hresholdofpain

()*+,

d-

")*+,,, H&

3udiable

!ong2 4usic

!"eech


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F

T

!5B

4 06 7

O3

8 E 9


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100% loss of vowels

s:m: cl:ssr::ms h:v: "::r :c::st:cs


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/( ")

),),,

",,,,,,

0,,,

;i$


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1oudness #d-$

2re3uence #H&$

5ure tone

",,,


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2re3uence #H&$

1oudness #d-$

!ound 2 noise


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!ound absor"tion'ransmitted

4onverted

5e6ected

7ncidentenerg8

transmitted @ converted

incidentsound absor"tioncoeAcient


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!ound absor"tion'ransmitted

4onverted

5e6ected

7ncidentenerg8

: not to reect sound


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Wallace Sabine in the year1895


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The room methodC0andom2di


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") ), ),, ",,, ,,, 0,,, #H&$

,

,9

,90

,9/

,9+"9,

ab/result sound absor"tionp

7s this result good orbad?


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") ), ),, ",,, ,,, 0,,, #H&$

,

,9

,90

,9/

,9+"9,

lassiDcation of soundabsorbers

4lass !

4lass -

4lass 4

4lass :

4lass ;

p ;


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Four factors

=aterial

Surface

'hickness

Overall depth of s8stem #o.d.s.$


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") ), ),, ",,, ,,, 0,,, #H&$,

,9

,90

,9/

,9+

"9,open

semiopen

closed

p

alpha

beta

gamma

!urface

!bsorber thickness 0,mm 9o.d.s.

,,mm


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") ), ),, ",,, ,,, 0,,, #H&$,

,9

,90

,9/

,9+

"9,

Thickness

*& mm

(& mm

p


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") ), ),, ",,, ,,, 0,,, #H&$,

,9

,90

,9/

,9+

"9,

;i


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0everberation time

/, d-

' #sek$

'ime

#sec$

1oudness #d-$


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Volume of the room

Sound absorbtion amount

RT is created by:

RT factors

RT

room volume

sound absorbtion am.in theroom

x0,16

=


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Which factor is the most important ?

RT factors


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p

,

,9

,90

,9

/

,9+

"9,

") ), ),, ",,, ,,, 0,,,

oeAcients for di


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Is RT imortant for eole!


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Speech intelligibility

Research made by "unds Te#nis#a $%&s#ola

Speech intelligibilit8 with diAerent ceilings!


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Recordin&s 'ith different ceilin&s



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1() ()0 )00 1000 (000 *000 +$-0

0,(

0,*

0,6

0,.

1,0/lass

/lass

/lass /

/lass 2

/lass 3

SS435 IS 116)*

lassiDcation of soundabsorbers


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1() ()0 )00 1000 (000 *000 +$-0

0,(

0,*

0,6

0,.

1,0/lass

/lass

/lass /

/lass 2

/lass 3

C - A



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1() ()0 )00 1000 (000 *000 +$-0

0,(

0,*

0,6

0,.

1,0/lass

/lass

/lass /

/lass 2

/lass 3

C - A



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/lass 0,) sec7/lass / !


Sound absorber RT


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/lass 0,) sec7/lass / 0,6 sec7


Sound absorber RT


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Small changes in RT is important


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Reverberation Time is oneacoustic arameter

Sound environment is created by manyarameters

Room Acoustic Comfort


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Sound nvironment !ndoors

7n Schools9 OBces and Health 4are buildings

* @roblems with high Sound @ressure 1evels


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"ow do you lower the S#$

Suggestion from the acoustician is oftenC

'his doesnDt alwa8s solve the problem

* a shorter 5everberation 'ime


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&hat is reverberation time

e'actly(()


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Reverberation Time

Time +sec-

S8" +d-

4 timeit ta#es for the S8" to decrease 60 d

60 d

T


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4 an acoustic ceilin& is installed

0oom without an 3cousticeiling

7s the direct sound and all re6eEes in the room

S@1 in the room


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$i&habsortion factor in the ceilin& &ives lo'erS8"

"o'absortion factor in the ceilin& &ives hi&herS8"

0oom with an 3coustic eiling

7s the direct sound and weakerre6eEes

S@1 in the room


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Turn off the loudsea#er

0T is measured

i d


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$o' does the ceilin& effect the RT !

RT is created by allsurfaces in the room

Turn off the loudsea#er

0T is measured


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i< l


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class !

,

,9

,90

,9/

,9+

"9,

") ), ),, ",,,

,,,

0,,,

#H&$

p

;i


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RT class A

T

d

d-

+se#-


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C


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d-

d

T/

+se#-

RT class C

C i l A C


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d-Comparison class A - C

T/

T

? +se#-

class 4

class !

'e measure timefor sound ressure reduction 9 not S8"

T/T %

/,

d-

/,

d-

"o'er S8" 'ith class


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R A ti C f t


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4 'ill all'ays create a lo'er S8"

coustic ceilin&s 'ith hi&her absortion class

4 can sometimes create the same RT

coustic ceilin&s 'ith different absortion classes

Room Acoustic Comfort

One eGam"le


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easurement of RT and S8" reduction

One eGam"le

4 /lass room ;,) x .,0 x (,;

0everberation Time


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0everberation Time

(sek)

") ), ),, ",,,

,,,

0,,,

#H&$

,9"

,9

,9(

,90

,9)

,9/

,9F

,

class 3class

0T &,*-0T &,+( 0T &,+0T &,+


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Documents

Sound Absorption 2006-01-26 (Eng) R1