Page 30 - Volume 8, Issue 1 Winter 2013
P. 30

                                         ACOUSTICAL STANDARDS PLAY A KEY ROLE
Stephen J. Lind
Building 12-1
La Crosse, Wisconsin, 54601
Acoustical standards are important “Providing accurate, how accurate or repeatable the tests are
to heating, ventilation, and air
conditioning (HVAC) system manufacturers. Our participation in developing standards helps us by:
1. getting the right information to our customers;
2. avoiding conflicts between man- ufacturers and other organiza- tions; and
3. preparing for changing system requirements.
Getting the right information to customers
Our company’s mission is to provide safe, comfortable, and efficient environments. Part of the comfort offering includes appropriate acoustical conditions such as sound lev- els that are due to system operation. Customers that specify acoustics as a design parameter range from those with very little exposure to those who
are very knowledgeable
acoustical professionals. To
apply our systems correctly,
information needs to be pro-
vided about our solutions.
However various customers
ask for different information.
Some customers desire information about sound power levels while some want information about sound pressure levels. Different fre- quency ranges are often requested. Some demand sin- gle number descriptors and some want data presented in one-third octave bands. It takes time to convince cus- tomers that the values we pub- lish are correct, educate them on what the information means and show them how it can be used in their applica- tion. Standards help to deter- mine what information needs to be published and how to collect that information. Some standards educate the users about what is included in the standard, why it matters, and
appropriate acoustical
information for our systems
helps ensure that the solutions
are applied correctly.”
that determine published values.
In general, our industry prefers to provide sound power levels since it is a direct output of the systems. Sound pressure is usually controlled by factors beyond our control. We have to under- take a very large number of measure- ments to adequately describe our solu- tions, so the measurements need to be fast. Our systems are often large and generate significant lev- els of low frequency sound. The information we provide needs to be used by customers to design spaces that meet the acoustical requirements, without excessive controls, so it
must be accurate.
Customers who have experienced untested systems and
the headaches they may create have demanded check tests, so our measurements must be repeatable. To use our published information in the design process, either octave band or one-third octave band levels are needed. We have found that using qualified reverber- ation rooms to determine sound power meets these requirements. Furthermore, having standardized sound measurements allows for comparisons between differ- ent manufacturer’s systems.
(See Fig. 1)
In the 1960s and 1970s,
reverberation room stan- dards1 were developed with considerable input from the HVAC and computer indus- tries. The equipment specific standards have been undergo- ing improvements ever since.
As new methods and sys- tems become available, the standards evolve. Those who write the standards are influ- enced significantly by the problems they face. Those who focus on small easily movable devices that primari- ly emit high frequency noise have different perspectives
  Fig.1. Qualified reverberation room with system ready for sound power meas- urements.
Acoustical Standards Play A Key Role 29

   28   29   30   31   32