1 Data as ‘transitional object’. 1 Peter Nelson University of Edinburgh, UK. The sonification of data has provided a new resource for the understanding of complex phenomena, as well as anchoring a certain creative practice in the representation of those phenomena as a sort of alibi for the material consequence of the work created. In this paper, data are conceived of as forming a sort of ‘transitional object’ as theorised by Donald Winnicott. This places data between subjects and their observations as a force for subject formation and processes of attachment. The work of the Greek composer Iannis Xenakis is taken as a case study to explore ways in which an aesthetics of attachment might allow art, and sound in particular, a role in creating a more wholesome relationship between human (or non-human) subjects and the mysteries of their situation in a living universe. Keywords: data, sonification, transitional object, Xenakis, aesthetics Douglas Kahn, in his book Earth Sound Earth Signal 2 , surveys the historical record of accounts of the sounds registered by telephone lines, radio antennae, seismic monitors, and electrical devices. An early example he gives comes from the 1893 manual entitled Practical Information for Telephonists in which different sorts of line noise are categorised in a manner strikingly similar to the aesthetic categorisation of mechanical and industrial sounds attempted by Luigi Russolo in his manifesto of 1913, The Art of Noises. These historical accounts of sound, in their mundane as well as their artistic manifestations, give us a narrative of a new common understanding in relation to sound that developed through the end of the 19 th and into the 20 th century: they register the beginning of the sort of co-creation of a listening-sense – what Brian Kane 3 calls an ‘audile technique’ developed within a ‘community of listeners’ - that allows us insight into traditions of social intercourse and social meaning around sounds that seem to emanate from the earth or the heavens. The technical configuration of the experience of these sounds is consistent, and presents a critical context for the appearance in the 1940s and 1950s of concrete, electronic, radiophonic, and electroacoustic works that develop a sound world with a radically different consistency to traditional notions of music: first, there is the presence of an apparatus - usually a metal cable, reflecting dish, or stylus attached to some registering 1 This paper was presented to the panel D3.7 Dialogues Between Space Science and Art, at Committee on Space Research: 44th COSPAR Scientific Assembly, 16 - 24 July 2022, Athens, Greece. 2 Kahn, Douglas. 2013. Earth Sound Earth Signal: Energies and Earth Magnitude in the Arts. Berkeley, CA: University of California Press. 3 Kane, Brian. "Sound studies without auditory culture: a critique of the ontological turn." Sound Studies 1.1 (2015): 2-21.