降噪

降噪	jiàng zào	to reduce noise (e.g. in a device, signal or environment)
降	jiàng	to drop / to fall / to come down / to descend
降	xiáng	to surrender; to capitulate / to subdue; to conquer; to tame
噪	zào	(literary) (of birds or insects) to chirp / (bound form) to make a cacophonous noise
噪	zào	variant of 噪