Active sound transmission control for windows using carbon nanotube based transparent thin film actuators

The continued growth in urban population has led to high-density housing close to airports and highways. This has increased the exposure of the population to noise from a variety of sources, increasing the need to provide better sound insulation for the homes. For homes close to airports and highway, windows constitute the primary path through which noise enters a home. This project explores the development of double-glazed windows with embedded active control systems to achieve significant reduction in noise transmission.; Two fundamental challenges need to be addressed in order to make the development of such noise blocking windows feasible. These are the need for a distributed actuation system that is optically transparent and the unavailability of a real-time reference signal that can be used by the active control system and that can provide advance information on the noise affecting the window. To address the first challenge, a transparent thin film actuator (speaker) is first developed for the control system, which consists of a piezoelectric poly(vinylidene fluoride) (PVDF) thin film coated with compliant carbon nanotube (CNT) based transparent conductors on both sides. The developed thin film speaker shows excellent acoustic response over a broadband frequency range, and has the advantages of being flexible, transparent, thin, and lightweight. To address the second challenge of providing a time-advanced reference signal from a moving noise source, a small microphone array distributed around the home is used. New noise source identification algorithms are employed, by which an appropriate microphone from the array can be chosen to provide a reference signal.; The effectiveness of the control system is experimentally tested in a laboratory test rig with a moving impacting noise source. Experimental results show that over 12 dB reduction in sound transmission is achieved globally in the case of broadband sound, which demonstrates the viability of the active sound transmission control systems for windows.