Noise-canceling headsets
The best known are made by Bose® and may fit on the ears or surrounding the ears.

Sony® makes a much more compact set of noise canceling earplugs. They may be plugged into your music player or used without the audio. They're powered by a single AAA battery.

For most ears, the ‘in-the-ear types’ are best because they seal against the ear canal and block the drone of the engines.
--From The Air Travel Handbook.