ItemTransfunctionality: a compositional approach for expanding the horizons of acoustic instruments(University College Cork, 2019) Molloy, Richard; Godfrey, John; Weeter, JeffreyThis PhD in music composition explores a compositional approach referred to as 'Transfunctionality', where traditional acoustic instruments were paired with 'Expanded Instrument Systems' (EIS). These technological peripherals allow performers access to sonic expression in a live setting that would be inaccessible by other means. I've sought to classify such performance technologies not as 'add-ons' or 'performance elements', but as integral parts of that which is considered to be the 'instrument'. This aesthetic consideration has led me to work closely with musicians to create EIS that offer musically meaningful live interactions. Writing music for EIS is labour intensive, niche and a challenging musical balance to achieve. This convergence of the classical musician and performance software is perhaps unduly rare in today's concert halls. While seeing my work through to completion I've found myself pitted against barriers of both practicality and perception. The interplay between software and acoustic instrument can be fascinatingly varied, with both elements potentially serving to inform the other. This thesis consists of a written dissertation, audio recordings, scores and performance technology.