Embodiments herein relate generally to changing spatial audio fields that are defined for audio sources. In the embodiments, the spatial audio fields are indicated to a user performing audio mixing, for instance by displaying them as polygons on a touch screen. The spatial audio fields move as the related audio sources move, and/or as the position of a notional consumer changes. Apparatus of the embodiments is configured to detect whether at any time (initially, or after movement) there is overlapping of two spatial audio fields. If an overlap is detected, this is indicated to a user performing audio mixing The apparatus then responds to a user input (e.g. a gesture on the touch screen) by detecting the nature of the user input and then moving or sizing one or both of overlapping spatial audio fields and such that overlapping is avoided or reduced.