Division 3.1.1

The surface of the test track and the dimensions of the test site shall be in accordance with ISO 10844:2011. The surface of the site shall be free of powdery snow, tall grass, loose soil or cinders. There shall be no obstacle which could affect the sound field within the vicinity of the microphone and the sound source. The observer carrying out the measurements shall so position himself as not to affect the readings of the measuring instrument.