# The Lawnmowers (Harmonization of Noise Emission Standards) Regulations 1992, Paragraph 6.3.4: Measurements indoors


The sound field inside the measurement room shall be similar to that of an acoustical free field, and the value of the constant C shall be determined in accordance with point 8.6.2.
The floor must be flat and horizontal. The test area, including the vertical projection of the microphone positions shall have the acoustical properties of concrete or non-porous asphalt and be covered by an artificial flooring in accordan ce with Annex A of this Schedule, the centre of which coincides with the geometric centre of the hemisphere mentioned in point 6.4 and the corners of which are aimed at the vertical axes of the microphone positions 2, 4, 6 and 8.
If the wheels of the lawnmower could cause a compression of the artificial flooring of more than 1 cm the wheels shall be placed on supports so that they are level with the artificial flooring before compression. The supports shall be made in such a way that they do not influence the measurement results.

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Source: https://www.legislation.gov.uk/uksi/1992/168/schedule/3/paragraph/6.3.4 (the official version)
Page: https://openlegislation.uk/lawnmowers-harmonization-of-noise-emission-standards-regulations-1992/schedule-3/paragraph-6.3.4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.