BS ISO 5130-2019 pdf free download.Acoustics — Measurements of sound pressure level emitted by stationary road vehicles
4 Instrumentation
4.1 Instrumentation for acoustical measurement
4.1.1 General
The instruments for measuring sound pressure levels, including microphone(s) as well as cable(s),windscreen(s), recording devices and other accessories, if used, shall meet the requirements for a class 1 instrument according to IEC 61672-1 for free field or random incidence application, as appropriate.
Filters shall meet the requirements for a class 1 instrument according to IEC 61260-1.
The measurements shall be made using the frequency-weighting A and the time-weighting F.
4.1.2 Operational check
At the beginning and at the end of every measurement session, the entire sound pressure level measuring system shall be checked at one or more frequencies by means of a sound calibrator meeting
the requirements for a class 1 instrument according to IEC 60942. Without any further adjustment, the difference between the readings of two consecutive checks shall be less than or equal to 0,5 dB. If this value is exceeded, the results of measurements obtained after the previous satisfactory check shall be discarded. 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.
4.1.3Verification 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 [5] .
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.BS ISO 5130 pdf download.