Due to this high prevalence, vertebral artery hypoplasia (VAH) has not yet been considered an independent risk factor for ischemic stroke [1,2].
How to use your own headphones on Americanâs new 777-300ER. Passengers traveling in First and Business Class on Americanâs new 777-300ER are provided with Bose QuietComfort 15 Acoustic Noise Canceling headphones to use during the flight.
Noise-cancelling headphones are headphones that reduce unwanted ambient sounds using active noise control engineering. This is distinct from passive headphones which, if they reduce ambient sounds at all, use techniques such as soundproofing. Noise cancellation makes it possible to enjoy music without raising the volume excessively. It can also help a passenger sleep in a noisy vehicle such as an airliner.