BS EN ISO 2922:2020 pdf – Acoustics — Measurement of airborne sound emitted by vessels on inland waterways and harbours.
5 Measuring equipment 5.1? Equipment? specifications The instruments for measuring sound pressure levels, including microphone(s) as well as cable(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. A wind speed anemometer with a maximum permissible error of ±10 % shall be used. An engine speed tachometer with a maximum permissible error of ±50 r/min shall be used. 5.2 Windscreen A suitable windscreen shall be used to reduce the influence of the wind on the reading. When it can be expected that the wind-induced signal will be within 10 dB of the average sound level induced by the vessel under investigation, windscreens shall be used which, together with the sound level meter, meet the requirements of a class 1 instrument according to IEC 61672-1. 5.3 Operational check/Calibration 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, the impact of residual sound levels on measured results shall be checked to determine their potential impact on the measurement results.
6? Test? site? specifications? and? environmental? conditions 6.1 Test conditions Two classes of test conditions are considered, namely: — moving vessels – when the vessel is under way, the requirements of 6.2.1, 6.3 and 6.4 shall apply; — stationary vessels – when the vessel is alongside a wharf or at anchor, the requirements of 6.2.2, 6.3, 6.4 and 6.5 shall apply. 6.2? Test? site? specifications 6.2.1 Moving vessels Within 30 m around the vessel under test and the microphone, there shall be no large surfaces (e.g. retaining walls, building façades, rocks, bridges) from which sound can be reflected back to the microphone. In the vicinity of the microphone, there shall be no obstacles which can disturb the sound field. Therefore, no person shall be between the microphone and the sound source, and any observers shall be in such a position that any influence on the meter reading is avoided. The area between the vessel under test and the measurement microphone shall be open water, free from any sound absorbing or sound reflecting objects. 6.2.2 Stationary vessels The surroundings of the microphone up to 30 m shall be free of large, sound-reflecting objects like barriers, hills, rocks, bridges or buildings. 6.3 Environmental conditions 6.3.1 At wind velocities above 7 m/s, the sound propagation can be disturbed and measurements shall not be performed unless the user has a method for adjusting the measurements for high wind. 6.3.2 Tests shall be avoided in conditions of rain or other precipitation, and/or when the wave heights are greater than 0,1 m (World Meteorological Organization (WMO) Sea State 1).
6.4 Background noise 6.4.1 Acceptance tests The maximum AS-weighted sound pressure level, the A-weighted sound exposure level and/or the time-averaged sound pressure level due to other noise sources (e.g. waves splashing on the measuring boat or ashore, other vessels, local industry or other machinery) and due to wind shall be at least 10 dB below the maximum AS-weighted sound pressure level, the A-weighted sound exposure level and/or the time-averaged sound pressure level of the sound of the vessel. The background noise shall be measured for a period of 5 min. If the background noise is frequency-analysed, the difference shall be at least 10 dB in the required octave or one-third-octave bands.