 In the early 21st century, compact digital storage media – Bluetooth-enabled devices, thumb drives, memory cards, and dedicated hard drives – came be accommodated by vehicle audio systems.The automobile sound system may be part of an active noise control system which reduces engine and road noise for the driver and passengers.One or more microphones are used to pick up sound from various places on the vehicle, especially the engine compartment, underside or exhaust pipes, and these signals are handled by a digital signal processor (DSP) then sent to the loudspeakers in such a way that the processed signal reduces or cancels out the outside noise heard inside the car.