The Workshop on 'Sonic Interaction Design and its relation to Film and Theatre Sound Design' was organised as part of the European COST project on Sonic Interaction Design (COST-SID). The aim of the workshop was to explore how existing practices in theatre can inform the design and evaluation of sonic interfaces. In this paper we describe the process of creating the sound design for a short theatre scene and the process of directing and creating the final performance, which involved a high degree of improvisation. We also describe the listening process constructed for the workshop. The scene was played to the audience in the dark and they were asked for responses regarding understandings of the scene, the sources of the sounds, the emotional content and their expectations based on the sounds alone. The sound design was then played again but this time with an accompanying performance in which the actor interacted with various objects. More feedback was gathered after this second performance looking at how the perception of the sounds, the audience expectations and the emotional content of the piece was changed. Finally the Sound Designer, the Theatre Director and the Actor explained their processes and a discussion gathered comments on this theatrical method for testing and evaluating sonic interaction designs. We finish with reflections on what we have learnt from this workshop about the ways that theatre can be used to experiment, prototype and sketch sonic interaction designs, and conclude with directions for future work.