Dave Legeret silently fumed as the man seated beside him on the plane blasted techno music on his iPod at full volume. It was kind of rude, recalled Legeret, 38, a jewelry designer from Sandy Hook, Conn., who was forced to listen while flying from New York City to Disney World with his wife and 8-year-old son. Listen to it at a level that just you can hear it, he admonished.

iPod Noise a Nuisance to Neighbors