本标准规定了一个程序，用于计算典型听者在以下条件下经历的响度:漫射场或自由场。听者可能处于漫反射声场或自由声场中。在漫反射场中，声音基本上从各个方向到达听者的耳朵。在自由场中，假设声源位于听者正前方至少一米处（正面入射）。在声学坚硬的房间中，声音在被显著吸收之前被多次反射，其声场近似于漫反射场。消声室内或室外相对无障碍环境中的声场近似于自由场。2003年11月19日重申。

This standard specifies a procedure for calculating the loudness experienced by a typical listener under the following conditions:Diffuse Field or Free Field. The listener may be in either a diffuse sound field or a free sound field. In a diffuse field, it is asumed that sound reaches the listener's ears from essentially all directions. In a free field, the sound source is assumed to be located at least one meter directly in front of the listener (frontal incidence). The sound field in an acoustically hard room where the sound is reflected many times before being significantly absorbed approximates a diffuse field. The sound field in an anechoic chamber or outdoors in a relatively obstruction-free environment approximates a free field.Reaffirmed 19 November 2003.