For the past year I’ve been using a service called Focus@Will, which plays special music to help you concentrate for longer periods of time. They claim that the music they output is superior to a regular study playlist. While they are not too transparent about the exact mechanics behind the service, they explain that the service was developed in connection with doctors and neuroscience researchers.
I’m normally quite skeptical of opaque claims like these, but I have been very impressed with how well the service works. So impressed that I forked over $45 for an over-priced annual subscription. I haven’t done any sort of quantitative assessment of it’s efficacy, but I have noticed subjectively that when I’m using Focus@Will I get into “the zone” much more easily. This mental state is known as flow, and you usually only notice it when you snap out of it and are surprised by the rapid passage of time.
You might want to look into Focus@Will if you are looking to improve your concentration, perhaps in conjunction with something like The Pomodoro Technique. The 30-day free trial should be sufficient to evaluate whether or not it makes a difference for your concentration. This service has become an indispensable part of my toolkit for focused work (along with caffeine and l-theanine).
Of course there are a number of free alternatives if you are willing to spend a bit more time figuring out what works for you. 8tracks has a massive collection of study playlists, however since they are user-made, you may need to spend some time testing out various playlists until you find one that works well for you. I’ve also found that Songza has some pretty good ambient playlists. They also have an in-house music curating team, which sometimes leads to a more consistent experience than user-generated playlists.