There’s one in every building: It might be the swinging bachelor, dutifully reenacting his favorite scenes from The Marquis de Sade Reader, or the Manolo-clad fashionista clickety-clicking across her parquet floors each morning, or, worst of all, the screaming newlyweds, whose every querulous interaction gets broadcast through your air vents. When you can’t take it anymore, call Alan Fierstein at Acoustilog in SoHo. Fierstein and his team of acoustic experts have helped New York residents and businesses keep quiet for 25 years. (They’ve even visited Savion Glover in his East Village pad – suggesting, among other things, a custom spring-loaded floor.) You can spend an hour consulting with Fierstein at his office for $250, or he’ll come to you for a site visit, and produce a complete written report for $850. Then he’ll put you in touch with contractors who can do the work, whether it’s blowing insulation into your ceiling, laminating your walls, or caulking spaces where sounds creep in.