Since February 2009 the working group ISO/TC 43/SC 1/WG 54 “Perceptual assessment of soundscape quality”, of the International Organization for Standardization (ISO), has been working on a draft of the first international standard on soundscape. It was submitted as a new work item proposal to ISO in November 2010, and may become the first part of the new ISO 12913 series on soundscape. This first part of the series provides a definition of the term ‘soundscape’ and a conceptual framework of soundscape perception. It explicates background factors relevant for soundscape perception and the measurement of soundscape quality. By providing a standard reference, the working group aims at international consensus in order to avoid confusion in regard to the definition, and to accelerate progress in soundscape research. Subsequent parts of the ISO 12913 series will deal with minimum reporting requirements in soundscape research, and methods for measuring soundscape quality.