Noise cancelling headphones can: block out auditory distractions, provide sounds that support focus AND act as a clue to the outside world that you are busy and not to be disturbed. I haven't personally used these Bose headphones but they seem to be well-reviewed. Like many other examples, they are also available refurbished for a cheaper price, and there are many other options on the market too. Let me know if you have any favourites to recommend to others, and why!