During the past decade, tangible sensor technologies have matured and become less expensive and easier to use, leading to an explosion of innovative musical designs within video games, smartphone applications, and interactive art installations. Interactive audio has become an important design quality in commercially successful games like Guitar Hero , and a range of mobile phone applications motivating people to interact, play, dance, and collaborate with music. Parallel to the game, phone, and art scenes, an area of music and health research has grown, showing the positive results of using music to promote health and wellbeing in everyday situations and for a broad range of people, from children and elderly to people with psychological and physiological disabilities. Both quantitative medical and ecological humanistic research show that interaction with music can improve health, through music’s ability to evoke feelings, motivate people to interact, master, and cope with difficult situations, create social relations and experience shared meaning. Only recently, however, the music and health field has started to take interest in interactive audio, based on computer-mediated technologies’ potential for health improvement. Here, we show the potential of using interactive audio in what we call interactive musicking in the computer-based interactive environment Wave. Interactive musicking is based on musicologist Christopher Small’s concept “musicking”, meaning any form of relation-building that occurs between people, and people and things, related to activities that include music. For instance, musicking includes dancing, listening, and playing with music (in professional contexts and in amateur, everyday contexts). We have adapted the concept of "musicking" on the design of computer-based musical devices. The context for this chapter is the research project RHYME. RHYME is a multidisciplinary collaboration between the Centre for Music and Health at the Norwegian Academy of Music, the Oslo School of Architecture and Design (AHO), and Informatics at the University of Oslo. Our target group is families with children with severe disabilities. Our goal is to improve health and wellbeing in the families through everyday musicking activities in interactive environments. Our research approach is to use knowledge from music and health research, musical composition and improvisation, musical action research, musicology, music sociology, and soundscape studies, when designing the tangible interactive environments. Our focus here is interaction design and composition strategies, following research-by-design methodology, creating interactive musicking environments. We describe the research and design of the interactive musicking environment Wave, based on video documentation, during a sequence of actions. Our findings suggest some interactive audio design strategies to improve health. We base the design strategies on musical actions performed while playing an instrument, such as impulsive or iterative hitting, or sustainable stroking of an instrument. Musical actions like these can also be used for musicking in everyday contexts, creating direct sound responses to evoke feelings that create expectations and confirm interactions. In opposition to a more control-oriented, instrument and interface perspective, we argue that musical variation and narrative models can be used to design interactive audio, where the audio is seen as an actor taking many different roles, as instrument, co-musician, toy, etc. In this way, the audio and the interactive musicking environments will change over time, answering with direct response, as well as nose-thumbing and changing response, motivating creation, play, and social interaction. Musical variation can also be used to design musical backgrounds and soundscapes that can be used for creating layers of ambience. These models create a safe environment and contribute to shared meaning.