That's the sound of changing configuration from descent to landing. Involves increasing power to the engines which is the main source of the sound involved.

Properly executed landing in airliner doesn't use airbrakes until touchdown (where they are used among other things to ensure airplane doesn't accidently lift from runway and are triggered by pressure sensors on main gear).

To quote a certain pilot's response to ATC: "Air brakes are for when I fuckup, not for your fuckups"