Uconnect 8.4A Owner's Manual Supplement page 46

Uconnect® 8.4A 45
audio volume with variation to vehicle speed. Volume
increases automatically as speed increase to compensate
for normal road noise.
Surround System (If Equipped)
Touch the On soft-key to activate Surround Sound. Touch
3
Off to deactivate this feature.
When Surround Sound is On, you can hear audio coming
from every direction as in a movie theatre or home
theatre system.