Active noise mitigation with transparent piezoelectric film speakers

Noise disturbance among residence in urban areas is often generated from various external sources (road traffic, aircraft, etc). The building envelop particularly windows often constitutes to the primary path for external noise sources to travel into the buildings. Passive noise mitigation technologies have been used to improve the acoustic comfort in urban life today. However these passive technologies are not very effective at low frequencies of most noise present in urban areas, and they also cannot be applied when transparency is required. For active noise mitigation technologies, discrete bulky and non-transparent electromagnetic speakers are typically installed at selected locations, but with limited global noise cancellation effect over a large area. Implementation of the conventional speakers for window applications also has aesthetical acceptance issue. In this work, we have designed and produced transparent piezoelectric film speakers aiming at active noise mitigation effect over increased area for window applications. The performance properties of our transparent speakers, the active noise control method, and the simulation and experimental results of the effectiveness for active noise mitigation in a window sash structure are reported. The potential and challenges of applying large area transparent piezoelectric film speakers for noise mitigation windows are analysed.