http://nypost.com/2014/07/28/unruly-ferry-horns-driving-away-residents-in-battery-park-city/
I read on Downtown Express newspaper. Why are they complaining. First Greenwich Village complaints about tour guide in tour bus making noise, followed by plane noise and train noise near Sunnyside Yard.
Now, Battery Park City residents want to complaint about ferry horn?
Ferries were there first. Ferry horns to warn other ferry or sightseeing cruises warn each other.
I don't think there's no way to silence ferry horn.
It could be possible if they want to silence ferry horn, residents near East River Ferry and NY Water Taxi might want to do same and complain horn noise from ferry.
I don't mind noises because I live right under LGA Airport, and most of Hispanic-Spanish love to have loud noise party lot, especially in summer, even on school days.