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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 $%&s#ola
Speech intelligibilit8 with diAerent ceilings!
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Recordin&s 'ith different ceilin&s
Speech intelligibility
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1() ()0 )00 1000 (000 *000 +$-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 +$-0
0,(
0,*
0,6
0,.
1,0/lass
/lass
/lass /
/lass 2
/lass 3
C - A
Speech intelligibility
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1() ()0 )00 1000 (000 *000 +$-0
0,(
0,*
0,6
0,.
1,0/lass
/lass
/lass /
/lass 2
/lass 3
C - A
Speech intelligibility
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/lass 0,) sec7/lass / !
Speech intelligibility
Sound absorber RT
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/lass 0,) sec7/lass / 0,6 sec7
Speech intelligibility
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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