My approach for international flights is a pair of circum-aural[1] noise cancelling headphones, with disposable foam earplugs inside them, and the music playing just loud enough to distract me from anything that gets past both the earplugs and the noise cancellation.
Where I am (Australia) OH&S regulations say workplace noise louder than 85dB averaged over 8hrs requires the employer to provide hearing protection[2]. The cabin of a 747 in flight is often louder than that, and for me it's usually a 13 or 14hr flight, so not using some form of hearing protection is almost certainly doing damage. But the best reason to wear protection is that I get off at the end of a 12+hr flight much more relaxed than when I don't have earplugs.
[1] big "DJ style" headphones with the cushions that surround/seal around the entire ear.
[2] I've heard, but never seen any actual evidence, that airlines operating in Australia have negotiated exemptions from the standard OH&S rules which would require cabin staff to fly wearing hearing protection.