Many
offices provide poor acoustics.
A common complaint is that conversations
are too easily overheard, and there
always seems to be too much noise.
Poor privacy and noisy conditions
can be controlled with good design
and today's technology. Ostergaard
Acoustical Associates has spent
two decades working with firms
to help achieve their office acoustical
goals, through design and technical
assistance.
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Speech Privacy Criteria |
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Ostergaard Acoustical Associates assists in
establishing acoustical criteria for offices
based on user information, experience, and
acoustical tests made in current offices or
mock-up areas. Privacy requirements are generally
determined after discussing with the client
trade-offs about privacy needs vs. the project
budget. Office environments can be designed
to provide any of three degrees of acoustical
privacy: confidential, normal, or minimal.
Under a confidential privacy condition, it
is not possible to understand what is being
said in an adjacent office. With normal privacy
it is possible to understand conversations
from adjacent areas if one uses concentrated
effort. Minimal privacy provides some control
of distracting noise, but conversations are
easily understood from one area to another.
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Predicting
Open Office Speech Privacy |
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The achievement of sufficient
speech privacy is critical to user productivity
and acceptance of an office installation.
Speech privacy depends on many elements in
the open office including: the ceiling; light
fixtures; furniture; office layouts; finishes
for floors, walls, and windows; and, the
degree of background sound control provided
by an electronic masking sound system or
the HVAC system. Because these elements are
procured from different suppliers, acoustical
product specifications and careful design
are needed to assure an acoustically efficient
combination.
Trying to use "overkill design" by
tightly specifying the acoustical
performance of certain elements of the environment, such as ceiling performance,
is unlikely to result in an acoustically successful installation. This is because
it is the weakest link in the acoustical chain that determines the degree of
speech privacy.
Utilizing
data from the new ASTM open office test standards
fostered by Ostergaard Acoustical Associates,
we are able to predict degrees of speech
privacy for open offices during the planning
stage. Acoustical measurements in existing
open offices and mock-up areas may also be
part of this effort. Based on these predictions,
Ostergaard Acoustical Associates works with
office planners to adjust the open office
design, specify acoustical performance, and
select constructions to achieve needed acoustical
performance. This process results in a high
success rate for open offices and reduces
the likelihood of expensive acoustical renovations.
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Testing
For Acoustical Privacy |
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Frequently there is an
advantage in knowing the actual degree of privacy
between open offices. The need may be to evaluate
a proposed office environment through a mock-up,
evaluate privacy in an open office where there
are user complaints, or verify the degree of
privacy between completed offices. Ostergaard
Acoustical Associates provides clients with
office privacy evaluations based on a method
developed by its staff and now incorporated
into ASTM Standard E-1130. This test method
provides Articulation Index values which are
speech-weighted signal-to-noise ratios measured
between selected talker and listener office
locations. The Articulation Index results translate
directly into speech privacy categories for
comparison with project criteria.
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Engineered
Electronic Masking Sound Systems |
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Electronically
generated masking sound is usually required
in quality open offices to increase speech
privacy and reduce the audibility of other
intruding office sounds. To be effective,
a masking sound system must be engineered
to complement the acoustical environment.
It must assure uniform coverage, and should
comprise components that facilitate tuning
to the appropriate level and frequency spectrum.
Ostergaard Acoustical
Associates designs and specifies electronic
masking sound systems encompassing the most
recent technical advances. These include
multi-channel systems with automatic attenuation
to make the system less apparent after hours.
Specifications are prepared to assure professional
quality systems while controlling cost.
The specifications include
equipment performance requirements and models
of previously tested and approved equipment.
Loudspeaker layouts are engineered to assure
uniform sound distribution. Ostergaard Acoustical
Associates reviews submittals for compliance
with the specification and visits the completed
installation to inspect and tune the electronic
masking sound system to the acoustically
optimum spectrum for effective masking for
the particular installation. State-of-the-art,
computer based systems, are used for the
tuning process.
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Closed
Offices |
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Although closed offices
have a higher potential for privacy than
open offices, frequently the needs of the
closed office users are not met. There
is often excessive audibility between offices,
either because intervening constructions
are acoustically inadequate or because
constructions were not correctly detailed
and built to control sound leaks. There
may also be inadequate background sound
control because ventilation sound levels
are often too low to mask intruding speech.
Supplemental background sound from a masking
sound system is often a benefit and easily
added when planned for adjacent open offices.
Ostergaard Acoustical
Associates is highly experienced in analyzing
closed offices to determine what measures
are needed to achieve sound privacy. The
firm provides feasibility analysis, performance
specifications, construction information,
testing, and inspections, to assure that
sound privacy and noise control goals are
met.
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