The Sony MDR-NC500Ds aren't as mobile or as unobtrusive as more compact designs, but they're not unduly heavy and many people will find them more comfortable than in-ear products.
Intelligent circuitry selects the mode most effective for the environment you're in. It's not clear how these modes work and what advantages are offered by digital processing, but the end result is impressive, with some types of noise disappearing entirely. Although ANC circuitry degrades audio quality, the reproduction is good and far better than cheap in-ear headphones.
The internal Li-ion batteries give 15 hours' listening time and come with a charger. You can use a pair of AA batteries in an external box, but if they go flat then you lose all audio, not just the noise-cancelling.
Overall, the MDRNC500D cans are impressive – but the reduced noise cancellation offered by other ANC headphones for a more affordable price may win you over.
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