Document ID: chunk:federal_register_of_legislation:F2024L00089:reg:800:p9
Version: federal_register_of_legislation:F2024L00089
Segment Type: reg
Provision Reference: reg 800 (pt 9/16)
Character Range: 52583–56867

the representative background noise A-weighted sound pressure level over a defined time period   Sound pressure level of j-th test result minus background noise level  Correction in dB(A)
∆Lbgn, p-p in dB(A)                                                                                                                   ∆L = Ltest,j - Lbgn                                                    Lcorr
                                                                                                                                      in dB(A)
-                                                                                                                                     ∆L > 10                                                                no correction needed
< 2                                                                                                                                   8 ≤ ∆L <10                                                             0,5

6 ≤ ∆L <8                                                                                                                             1,0
4.5 ≤ ∆L <6                                                                                                                           1,5
3 ≤ ∆L <4.5                                                                                                                           2,5
∆L < 3                                                                                                                                no valid measurement
                                                                                                                                      can be reported

If a sound peak obviously out of character with the general sound pressure level is observed, that measurement shall be discarded.
              As an aid for measurement correction criteria see flowchart in Figure 5 of the appendix to this annex.

              2.3.3. Background noise requirements when analysing in one-third-octave bands

              When analysing one-third octaves according to this Regulation, the level of background noise in each one-third octave of interest, analysed according to paragraph 2.3.1., shall be at least 6 dB(A) below the measurement of the vehicle or AVAS under test in each one-third-octave band of interest. The A-weighted sound pressure level of the background noise shall be at least 10 dB(A) below the measurement of the vehicle or AVAS under test.

              Background compensation is not permitted for one-third octave band measurements.

              As an aid for background noise requirements when analysing in one-third-octave bands see flowchart in Figure 6 of the Appendix to this annex.

              3. Test procedures for vehicle sound level

              3.1. Microphone positions

              The distance from the microphone positions on the microphone line PP' to the perpendicular reference line CC' as specified in Figure 1 and 2 of the Appendix to this annex on the test track or in an indoor test facility shall be 2,0 m ± 0,05 m.

              The microphones shall be located 1,2 m ± 0,02 m above the ground level. The reference direction for free field conditions as specified in IEC 61672-1:2013 shall be horizontal and directed perpendicularly towards the path of the vehicle line CC'.

              3.2. Conditions of the vehicle

              3.2.1. General conditions

              The vehicle shall be representative of vehicles to be put on the market as specified by the manufacturer in agreement with the Technical Service to fulfil the requirements of this Regulation.

              Measurements shall be made without any trailer, except in the case of non-separable vehicles.

              In the case of HEVs/FCHVs, the test shall be carried out in the most energy efficient mode so to avoid the restart of the ICE, e.g. all audio-, entertainment-, communication- and navigation-systems shall be switched off.

              Before the measurements are started, the vehicle shall be brought to its normal operating conditions.

              3.2.2. Battery state of charge

              If so equipped, propulsion batteries shall have a state-of-charge sufficiently high to enable all key