The Acoustics Office
is responsible for ensuring safe, healthy and habitable
vehicle acoustic environments, in which astronaut
crews can live, communicate, and work. This means
ensuring that space vehicle environments are not too
noisy, do not have irritating audible sounds (except
when trying to get the crew's attention), and do not
have startling bursts of acoustic energy.
In order to control the
noise of the environment, one must control the noise
of the flight hardware. And, to help the hardware
developer community meet this challenge, the Acoustics
Office was established with the following charter.
Flight hardware noise is controlled through a comprehensive
set of requirements where acoustic noise levels are
limited based on the type and complexity of the hardware.
Compliance to the requirements must be verified for
the hardware to be approved for flight. See the following
link for guidance with respect to requirements
and compliance.
Knowing the acoustic
requirements is only the first step. In order to meet
the requirements the hardware must be designed to
be quiet. The mistake is often made of waiting until
the hardware has been built before thinking about
the noise it makes, and many times this leads to additional
expense and schedule difficulties. To assist the hardware
developer with designing quiet hardware, information
pertaining to basic acoustics, noise control, and
also contains valuable experience in the section containing
lessons learned are provided on this webpage. As part
of hardware noise control, it must be emphasized that
only flight certified acoustic materials are allowed
to be used on flight hardware. To provide hardware
developers with assistance in this area, flight materials
with noise control applicability are specifically
addressed.
Finally, to verify compliance
with acoustic requirements, acoustic emissions testing
is required for all flight hardware. This testing
may be performed in different classes of facilities;
however, performing this testing in a facility with
poor acoustic quality may increase the measured noise
of the hardware. Also, the background noise in the
testing facility must be substantially lower than
the noise of the hardware being tested at all test
frequencies. Many places in the country have dedicated
acoustic testing facilities and some of these, those
with whom we have experience, are included at testing
and facilities.
