The research on the perceived depth in a sound image mainly concerns the distance to the source. Observations on the three-dimensional environment, is generally of an anecdotal nature. In order to enhance the perceived spatial quality of reproduced sound, it is important to know more about how depth in recordings is perceived and generated. The aim of this study is to put focus on the concept of depth, i.e. define what sound engineers mean by depth in recordings. This has been studied through interviews with sound engineers. The most common thought is that depth is equal to the distance to the sound sources. This definition is still not enough to encompass the whole concept of depth. The experienced environment in front of the listener may also affect the perceived depth.