Active noise control (ANC) system based on adaptive algorithm is an effective technique for acoustic noise reduction. FxLMS is a fairly robust algorithm but it gives inferior performance when secondary path is time varying, as a result, online secondary path modeling has been used. A variable step-s... Read more
Muzo removes unwanted sounds, stick it on your window, looks great.
Active noise control (ANC) system based on adaptive algorithm is an effective technique for acoustic noise reduction.
Active Noise Control (Cancellation)
Ford use this to quieten things down in cars. Not sure if it works for sirens though.