BS ISO 5130:2019 pdf download – Acoustics — Measurements of sound pressure level emitted by stationary road vehicles
In connection with each measurement session and at least at the beginning and the end of each measurement day, where possible, check the impact of residual sound levels on measured results to determine their potential impact on the measurement results.
4.1.3 Verification Conformance of the sound pressure level measuring instrument including microphone, the filters and the sound calibrator with the relevant requirements of IEC 61672-1, IEC 61260-1 and IEC 60942, respectively, shall be verified by the existence of a valid certificate of conformance from the manufacturer. Conformance testing in accordance with IEC 61672-3, IEC 61260-3 and IEC 60942:2017, Annex B, respectively, is required for verification. If applicable, random incidence response of the microphone shall be verified by a procedure from IEC 61183. All conformance testing shall be conducted by a laboratory meeting the requirements of ISO/IEC 17025 and the maximum-permitted uncertainty defined in IEC 61672-1, IEC 61260-1 and IEC 60942.
The sound calibrator should be calibrated at intervals not exceeding one year, the conformance of the instrumentation system with the requirements of IEC 61672-1 should be verified at intervals not exceeding two years, and the conformance of analog filters with the requirements of IEC 61260-1 should be verified at intervals not exceeding two years.
NOTE Testing in accordance with IEC 61672-3 does not fully verify conformance with the requirements of IEC 61672-1, unless it has been pattern approved in accordance with IEC 61672-2  .
4.2 Instrumentation for engine-speed measurement The rotational speed of the engine shall be measured with an instrument meeting the specification limits of at least ±2 % or better at the engine speeds required for the measurements being performed.
5 Acoustical environment, meteorological conditions and background noise
5.1 Test site A suitable test site shall be outdoors and consist of a flat surface of level concrete, dense asphalt with no appreciable level of porosity or similar hard material surface. It shall be free from snow, grass, loose soil, ashes or other sound-absorbing material. It shall be in an open space free from large reflecting surfaces, such as parked vehicles, buildings, billboards, trees, shrubbery, parallel walls, people, etc., within a 3 m radius from the microphone location and any point of the vehicle. As an alternative to outdoor testing, a hemi-anechoic chamber may be used.
The hemi-anechoic chamber shall fulfill the acoustical requirements given above. In addition to the 3 m distance criteria described above, the testing facilities shall have a cut-off frequency below:
— one-third-octave band below the lowest fundamental frequency of the engine during test, or
— 100 Hz (whichever is the lower). For a source located at the projection of the reference point on the reflecting plane, the broadband qualification criteria given in ISO 26101:2017, Annex A shall be met within a volume having a radius of at least 3 m.
In addition, the radius of the qualified volume, and the height of the hemi-anechoic chamber shall be at least two times the height of the measurement reference point.
NOTE The noise performance of indoor testing facilities is specified in terms of the cut-off frequency (Hz). This is the frequency above which the room can be assumed to act as a hemi-anechoic space. 5.2 Meteorological conditions The tests shall not be carried out if the wind speed, including gusts, exceeds 5 m/s during the sound-measurement interval. Tests shall not be carried out during periods of precipitation. 5.3 Background noise Readings on the measuring instruments produced by ambient noise and wind shall be at least 10 dB below the A-weighted sound pressure level to be measured. A suitable windscreen may be fitted to the microphone, provided that account is taken of its effect on the sensitivity of the sound level meter.BS ISO 5130 pdf download.