Complaining about kids blasting loud music and wearing headphones is the epitome of crankiness.
But loud music and headphones — along with the other sources of loud noise in modern society — are slowly driving us deaf.

between 10 and 26 million americans suffer from noise-induced hearing loss
While age-related hearing loss has plagued humans for generations (ever since our lifespans grew long enough to be an issue), noise-induced hearing loss is a growing problem.
Somewhere between 10 and 26 million Americans suffer from it, and many of them are teenagers or kids: some researchers estimate that as many as 12.5 percent of those between 6 and 19 years old already have degraded hearing due to excessive noise exposure.
http://www.vox.com/2014/9/18/6334205/hearing-loss-headphones-noise