Soundore is a web app that helps you block out distracting so you can stay focused on your work.
Silenz is an app dedicated to headphones users who listen to music as a way to keep focused.
It monitors the sounds of your surrounding in a smart way; once it detects a significant sound (e.g. human speech), it reacts by pausing or adjusting the volume of media players.
The app also allows you to hear surrounding sounds mixed with your music.