There are plenty of fancy earphones on the market. Not too many of them can track your concentration level though. Mindset is a pair of headphones that connects to your smartphone via Bluetooth and provides you with active noise cancellation. Its spring-loaded electrodes sit gently on your head, tracking your focus to alert you when your concentration drops.
Mindset has 5 EEG sensors to measure brain activity. It helps train your brain to stay focused for longer periods of time. Expected to ship in December.[where to get it]