Active bass trap is an type of bass trap that uses electronic sensing and actuation to reduce low-frequency sound energy and room mode resonances. Unlike conventional passive bass traps, which dissipate acoustic energy through porous materials or resonant structures, active bass traps use microphones, loudspeaker-type transducers and electronic control systems to modify the acoustic impedance presented to the surrounding air.
Further reading Everest, F. Alton. The Master Handbook of Acoustics, McGraw-Hill, 2000 (ISBN 0-07-136097-2). Kinsler, Frey, Coppens and Sanders, Fundamentals of Acoustics, Third Edition, John Wiley & Sons, 1999 (ISBN 978-0471847892), Section 10.8: “The Helmholtz Resonator”.
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