| The test track shall be such that the conditions of a free sound field between the sound source and the microphone are attained to within 1 dB(A). These conditions shall be deemed to be met if there is no large sound reflecting objects, such as fences, rocks, bridges or building within 50 m of the centre of the measuring section. The surface of the test track and the dimensions of the test site shall be in accordance with ISO 10844:2014. Until the end of the period indicated in paragraph 12.8. of this Regulation the specifications for the test site may be in accordance with Annex 4 to this Regulation. | a0c0 |