Document ID: chunk:federal_register_of_legislation:F2024L00089:reg:800:p7
Version: federal_register_of_legislation:F2024L00089
Segment Type: reg
Provision Reference: reg 800 (pt 7/16)
Character Range: 46780–50084

evaluation on the microphone transverse line;
(f) The one third octave bands used to establish hemi-anechoic qualification shall be defined to cover the spectral range of interest.
              The test facility shall have a cut-off frequency, as defined in ISO 26101:2012, lower than the lowest frequency of interest. The lowest frequency of interest is the frequency below which there is no signal content relevant to the measurement of sound emission for the vehicle under test.

               In the vicinity of the microphones, there shall be no obstacle that could influence the acoustic field and no person shall remain between the microphone and the noise source. The meter observer shall be positioned so as not to influence the meter reading. Microphones shall be located as specified in Figures 2 of the Appendix to this annex.

              2.2. Meteorological conditions

              2.2.1. For outdoor facilities

              Meteorological conditions are specified to provide a range of normal operating temperatures and to prevent abnormal readings due to extreme environmental conditions.

              The meteorological instrumentation shall deliver data representative for the test site and shall be positioned adjacent to the test area at a height representative of the height of the measuring microphone.

              A value representative of temperature, wind speed, relative humidity, and barometric pressure shall be recorded during the measurement interval.

              The measurements shall be made when the ambient air temperature is within the range from 5 °C to 40 °C.

              The ambient temperature may of necessity be restricted to a narrower temperature range such that all key vehicle functionalities that can reduce vehicle noise emissions (e.g. start/stop, hybrid propulsion, battery propulsion, fuel-cell stack operation) are enabled according to manufacturer's specifications.

              The tests shall not be carried out if the wind speed, including gusts, at microphone height exceeds 5 m/s, during the measurement interval.

              2.2.2. For indoor facilities

              Meteorological conditions are specified to provide a range of normal operating temperatures and to prevent abnormal readings due to extreme environmental conditions.

              The meteorological instrumentation shall deliver data representative for the test site and values of temperature, relative humidity, and barometric pressure shall be recorded during the measurement interval.

              The measurements shall be made when the ambient air temperature is within the range from 5 °C to 40 °C.

              The ambient temperature may of necessity be restricted to a narrower temperature range such that all key vehicle functionalities that can reduce vehicle noise emissions (e.g. start/stop, hybrid propulsion, battery propulsion, fuel-cell stack operation) are enabled according to manufacturer's specifications.
              2.3. Background noise

              2.3.1. Measurement criteria for A-weighted sound pressure level

              The background, or ambient noise, shall be measured for a duration of at least 10 seconds. A 10 second sample taken from these measurements shall be used to calculate the reported background