This article traces the history of the use and reception of field recordings on radio, in France and Britain, outside the categories considered as art or music such as hörspiel or musique concrète. It shows that radio producers had diverse reactions to the use of sonic ambiences recorded in the field. There was an opposition between a ‘Pure Sound School’, which promoted the use of field recordings instead of voice to depict the environment where the reporter was, and a school that privileged voice. If the use of recordings of sonic ambiences was not new, their utilisation on radio as elements autonomous in themselves was. They were falling between categories: they were not reports (because of the absence of voice), they were not musique concrète (because sounds were not modified and were presented within their context, that is, not as sound objects), they were not sound effects (because they lasted several minutes and could be composed through editing), and they were not wildlife recordings (because wildlife could be absent). Sonic ambiences were new sonic objects that took time to digest. This time also represented a listening mutation, and this will be analysed through the beginnings of radio documentaries and the works of sound hunters.