For frequent travelers, a quality pair of noise-canceling headphones can transform an in-flight experience. Right now, three traveler favorites are deeply discounted: the Sony WH-CH720N is 48% off at $92.95, the flagship Sony WH-1000XM5 is 38% off at $248, and the Sennheiser Momentum 4 is 51% off, dropping to just $222. Here's how to score these limited time deals.