Since ICS, Google has decided to link the volume of ringer and notification volume together. This Xposed module can separate the two streams as they were before ICS.
1. Your phone must be rooted
2. Xposed framework must be installed first http://forum.xda-developers.com/showthread.php?t=1574401
** MTK devices are not compatible **
- Install the module
- Run Xposed Installer and enable the module Separate ringer & notification volume link in ICS/JB
- Reboot the phone