Sound field control systems have been widely used for personal audio, telepresence, and spatial audio applications. In this overview article, we review current advances in sound field control systems and associated control algorithms. In particular, personal sound systems for reproducing independent audio programs at different passenger seats of a car are introduced with system design examples. Current practical limitations in building loudspeaker systems are reviewed and possible directions to overcome those limitations are addressed. The novel concept of smart sound systems is introduced with an aim to control a sound field in a de-centralized way using sparsely distributed sound devices connected via wireless network. As an exemplary application of the smart sound system, automatic coordination, and user tracking functions are demonstrated.