This research project combines a theoretical intervention into sound ontology, with an empirical investigation into listening experience, in parallel with two technologically focused, research-led creative practice projects. The design follows an iterative cycle of research and creative practice that integrates theory, practice and empirical approaches. The research makes an initial contribution to the field of sound studies by re-appraising the work of pioneers in the field—Pierre Schaeffer and R. Murray Schafer—in light of the concept of the sonic effect. This concept is developed as an effective tool for both sound studies and sound design. This theoretical work attempts to critically and creatively examine the ontology or mode of existence of sonic phenomena and is informed by the post-structural theory of the effect. The theory of the sonic effect is empirically investigated by examining verbal accounts of listening experience elicited by semi-structured interview. Finally, having deconstructed sonic phenomena in terms of their potential to be actualised in diverse contexts, sonic effects are interrogated as a creative strategy in the field of sound design for performance and installed sonic art. Two projects are documented. One is a hybrid live performance installation utilising a novel software design for sound composition and projection. The other is a sound installation work demonstrating a novel loudspeaker design for the creation of very dense sound fields. In this context, design occurs as an effect at the intersection of new technologies of sound production and the production of audible sense. This approach enacts a radical pragmatism that underlies the radical sound design strategy outlined in the thesis.