Bosch Security Systems | 2007-06 | F.01u.073.053
Hemi-directional loudspeaker
| Installation and User Instructions
| 27
5
Listening area and related mounting height
How to define a listening area?
1 Define the height between the loudspeaker and the
floor.
2 What is the desired maximum SPL variation from
centre to the edge of the listening area?
3 Look in the row for the specified height and in the
column for the specified SPL variation.
4 At the intersection of the row and column the
diameter and the surface is given of the listening
area.
Remarks:
•
The listening area is 1,5 m above the floor and has a circular shape.
•
The
centre
is the point where the loudspeaker perpendicular is positioned above the listening area.
•
The
height
is the distance in meters between floor and loudspeaker.
•
The total sound pressure contains the direct sound plus the first reflection of the sound on the floor measured in
dB SPL.
•
By use of the loudspeaker in indoor applications the sound pressure variation from centre to the edge of the
listening area will be equal or less. This depends on the amount of absorption and the dimension of that room.
•
The sound pressure at the edge of the listening area is the
MAX SPL centre
minus the chosen
sound
pressure variation from centre to the edge
.
•
MAX SPL
is the sound pressure level at the centre of the listening area with the loudspeaker mounted on the
specified height.
•
The
diameter
is the line in meters from edge to centre to edge of the circular listening area.
•
The
surface
is the dimension in square meters of the listening area.
•
X
in the table indicates that the total sound pressure drops below 75 dB SPL.
•
When two edges of listening areas reach each other, approxi3 dB may be added to the sound pressure at
that edge region.
fig. 5.1
Listening area
Height
1,5 m
Centre
Diameter
3 dB
6 dB
12 dB
9 dB
Maximum sound pressure variation from centre to the edge of the listening area
Height
[m]
Max SPL
centre
[dB SPL]
3dB
diameter
[m]
(+/-0,5dB)
surface
[m
2
]
6dB
diameter
[m]
(+/-0,5dB)
surface
[m
2
]
9dB
diameter
[m]
(+/-0,5dB)
surface
[m
2
]
12dB
diameter
[m]
(+/-0,5dB)
surface
[m
2
]
15dB
diameter
[m]
(+/-0,5dB)
surface
[m
2
]
18dB
diameter
[m]
(+/-0,5dB)
surface
[m
2
]
4,5
97,8
3,90
12
7,16
40
10,40
85
14,86
173
20,00
314
28,22
625
5,0
96,6
4,54
16
8,34
55
12,12
115
17,00
227
23,10
419
32,54
832
5,5
95,6
5,20
21
9,54
71
13,86
151
19,60
302
26,56
554
36,00
1018
6,0
94,7
5,84
27
10,72
90
15,58
191
21,70
370
30,00
707
39,66
1235
6,5
93,8
6,50
33
11,92
112
17,32
236
24,16
458
32,70
840
44,00
1521
7,0
93,1
7,14
40
13,10
135
19,06
285
26,20
539
35,98
1017
48,00
1810
7,5
92,4
7,80
48
14,00
154
20,78
339
28,28
628
39,06
1198
X
X
8,0
91,8
8,44
56
14,96
176
22,52
398
30,62
736
42,00
1385
X
X
8,5
91,2
9,10
65
16,10
204
24,24
461
32,98
854
44,00
1521
X
X
9,0
90,7
9,74
75
17,26
234
25,98
530
35,34
981
48,00
1810
X
X
9,5
90,2
10,40
85
18,40
266
27,20
581
37,70
1116
50,00
1963
X
X
10,0
89,7
11,04
96
19,56
300
29,44
681
40,04
1259
X
X
X
X
10,5
89,2
11,60
106
20,70
337
30,60
735
42,40
1412
X
X
X
X
11,0
88,8
11,88
111
21,86
375
32,00
804
43,88
1512
X
X
X
X
11,5
88,4
12,50
123
23,00
415
33,68
891
46,12
1671
X
X
X
X
12,0
88,0
13,12
135
24,16
458
35,34
981
48,00
1810
X
X
X
X
13,0
87,3
14,38
162
26,46
550
38,28
1151
52,26
2145
X
X
X
X
14,0
86,6
15,62
192
28,76
650
41,60
1359
X
X
X
X
X
X
