This paper reports on emotions felt by users manipulating a computationally and acoustically augmented artifact. Prior studies have highlighted systematic relationships between acoustic features and emotions felt when individuals are passively listening to sounds. However, during interaction with real or computationally augmented artifacts, acoustic feedback results from users' active manipulation of the artifact. In such a setting, both sound and manipulation can contribute to the emotions that are elicited. We report on a set of experimental studies that examined the respective roles of sound and manipulation in eliciting emotions from users. The results show that, while the difficulty of the manipulation task predominated, the acoustical qualities of the sounds also influenced the feelings reported by participants. When the sounds were embedded in an interface, their pleasantness primarily influenced the valence of the users' feelings. However, the results also suggested that pleasant sounds made the task slightly easier, and left the users feeling more in control. The results of these studies provide guidelines for the measurement and design of affective aspects of sound in computationally augmented artifacts and interfaces.