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© FANTECH
2016
NOISE CONTROL PRODUCTS
GENERAL ACOUSTIC INFORMATION
INTRODUCTION
GENERAL
Since 1991, Fantech under the Q-Tech Acoustic Products brand has continuously
invested in research and development programs. The investment in this program
results in Fantech continuously testing new designs and materials in its own
ISO7235:2003 and BS4718:1971 acoustic attenuator test rig. The results of this
program include the first published test data for a range of attenuators based on
Australian sourced materials and the advent of the unique Q-Seal range of specialised
attenuators. Our continued investments in the research and development of acoustic
products results in the most accurate and dependable data for acoustic products,
unrivalled by any other supplier in the industry.
Fantech maintains strong relationships with universities, testing houses and the industry
to ensure that the experience gained from the use of our products in the real world
feeds back into the design of our new products. We will continue to be involved in the
latest acoustic technology and innovation and we will continue to provide our
customers with products they can rely upon.
The following pages, incorporates a glossary of acoustic terms to assist the user of the
Fans By Fantech catalogue in understanding the depth of technical information
supplied for our fans and attenuators.
SOUND POWER LEVEL
The sound power is defined as the rate at which a sound source emits energy. Since
sound energy in everyday situations ranges from 10
-12
Watts to 1000 Watts, a
logarithmic scale is used for practicality; this provides us with a sound power range
from 0 to 150 dB, which is a lot more manageable.
The sound power level is denoted as L
w
and is defined as:-
and is expressed in decibels, dB
Where:
W = Watts and
pW = 10
-12
Watts
SOUND PRESSURE LEVEL
The sound pressure is what you actually hear and is the effect of the sound power in
the hearing environment. It will be a function of the volume of the space, its acoustic
absorption qualities and the distance of the listener from the sound source.
Sound pressure level is also expressed in dB and is relative to the quietest sound which
a healthy young person can hear at 1kHz; 2 x 10
-5
N/m
2
(or Pa).
The sound pressure level, like sound power is expressed on a logarithmic scale and
denoted as L
p
. It is defined as:
INFORMATION ON
FAN NOISE TEST STANDARDS
Where noted in the product data pages within this catalogue fan noise levels are tested
to BS848 Part 2: 1985 “Fans for general purposes. Methods of noise testing”.
This test standard describes methods that may be applied to calculate the sound
power level of fans. That is, the In-Duct method, the Reverberant Room method and the
Free Field method. The sound pressure level of a product is measured using one of
these test methods. A calculation is then used to convert the measured sound pressure
levels to sound power levels.
L p
=
20 log
10
(s
, Pa)
(
, 2 10 )
ound pressure
reference pressure
Pa
-5
L w = 10 log
10
(
, W)
(
, 1 W)
sound power of source
reference power
p
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