Smart Listening by Adaptive Sound Control automatically detects your activity such as traveling, walking, and waiting, then adjusts ambient sound settings to you. You can customize them to your preferences with the Sony I Headphones Connect APP. 4 Truly authentic sound Hear music that stays true to the original recording with High-Resolution Audio. Optimized for High-Resolution Audio, S-Master HX™ reduces distortion and allows you to enjoy all the subtleties in your music. The 9mm dynamic driver maintains drive force for deep bass and clear mids without dropping off like other drivers, while the airtight Balanced Armature driver provides natural high frequency sound for longer. Both drivers work together to keep sound response steady across the frequencies.