The high levels of noise generated during launch can destroy sensitive equipment on space craft.
Passive damping systems, like acoustic blankets, work to reduce the high frequency noise but do
little to the low frequency noise (<400 Hz). While wall mounted transducers can reduce the low
frequency noise during a launch, they also can create areas of higher increased sound pressure in
the payload fairings. Ferroelectret cellular polymer foams with high piezoelectric coupling
constants are being used as new types of actuators and sensors. Further impedance control
through the inverse piezoelectric effect will lead to a new "semi-active" approach that will reduce
low frequency noise levels. Combining layers of conventional nonpiezoelectric foam and
ferroelectret materials with a multiple loop feedback system will give a total damping effect that is
adaptable over a wide band of low frequencies. This paper covers the manufacturing methods that
were used to make polarized polypropylene foam, to test the foam for its polarized response and
its noise shielding ability.