Active control of payload fairing noise

This work presents adaptive feedforward control using advanced structural–acoustic actuators to reduce the low-frequency acoustic transmission in a sub-scale composite fairing. The actuators, referred to as distributed active vibration absorbers, are multi-resonance devices specifically designed to produce high output forces over a large bandwidth as necessary for payload fairing noise control. Single- and multi-channel control configurations were implemented using external acoustic disturbance levels as high as 130 dB. Design parameters such as sample frequency, control filter length, reference source, and causality/delay were examined to determine impact on performance. The active control system reduced the broadband interior noise levels by up to 5 dB between 70 Hz and 200 Hz, and 10 dB at specific resonances.