Acoustic feedback controllers (AFCs) are typically applied to solve feedback problems evident in applications such as public address (PA) systems, hearing aids, and speech applications. Applying the techniques of AFCs to different contexts, such as musical performance, sound installations, and product design, presents a unique insight into the research of embodied sonic interfaces and environments. This paper presents techniques that use digital acoustic feedback control algorithms to augment the sonic properties of environments and discusses approaches to the design of sonically playful experiences that apply such techniques. Three experimental prototypes are described to illustrate how the techniques can be applied to versatile environments and continuous coupling of users' audible actions with sonically augmented environments. The knowledge obtained from these prototypes has led to Acoustic Feedback Ecology System (AFES) design patterns. The paper concludes with some future research directions based on the prototypes and proposes several other potentially useful applications ranging from musical performance to everyday contexts.