Sound direction and field type change perceived loudness at a fixed level.

Evidence

Equal-loudness contours are normally drawn for a frontally-incident plane sound field. However, in many cases the sound field is not a plane sound field but similar to what is known as a diffuse sound field, in which the sound comes from all directions. Our hearing system is not equally sensitive to sounds coming from different directions and the direction dependence depends also on frequency. For this reason, the equal-loudness contours for a plane sound field and contours for a diffuse sound field are different. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1173

Categorization

• XREF: Connects to room acoustics and head-related transfer function research from psychoacoustics chapters on spatial hearing.