BS EN ISO 17201-2:2006 pdf – Acoustics — Noise from shooting ranges — Part 2: Estimation of muzzle blast and projectile sound by calculation.
1 Scope This part of ISO 17201 specifies methods for estimating the acoustic source data of muzzle blast and explosions and the source data of projectile sound on the basis of non-acoustic data for firearms with calibres less than 20 mm and explosions less than 50 g TNT equivalent. This part of ISO 17201 addresses those cases where no source measurements exist or where the data necessary to calculate projectile sound according to ISO 17201-4 are unknown. An example of this situation would be measuring projectile sound from shot guns pellets. This part of ISO 17201 can also be used as an interpolation method between measurements of muzzle blast. Source data are given in terms of spectral angular source energy covering the frequency range from 12,5 Hz to 10 kHz and can be used as data input for sound propagation calculation. This part of ISO 17201 is not applicable to the prediction of sound levels for the assessment of hearing damage and cannot be used to predict sound pressure levels or sound exposure levels below a specific distance where linear acoustics does not apply. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 17201-1:2005, Acoustics — Noise from shooting ranges — Part 1: Determination of muzzle blast by measurement ISO 17201-4, Acoustics — Noise from shooting ranges — Part 4: Prediction of projectile sound 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 17201-1 and the following apply. 3.1 General 3.1.1 air density ρ density of air for the estimation conditions NOTE The air density is expressed in kilograms per cubic metre (kg/m 3 ).
3.1.2 angular frequency ω frequency multiplied by 2π NOTE The angular frequency is expressed in radians per second (rad/s) in all formulae. 3.1.3 coordinate system (x, y) plane coordinate system describing geometry, where the x-axis denotes the line of fire with x = 0 at the muzzle, and the y-axis measures the perpendicular distance from the line of fire in any plane around the line of fire NOTE 1 The sound field of projectile sound is rotational symmetric around the line of fire. NOTE 2 The coordinates are given in metres (m). 3.1.4 cosine-coefficients c 1,2…N coefficients of the cosine-transform used to describe the directivity of the angular source energy 3.1.5 deceleration angle ε difference between the radiation angle at the beginning and end of a part of the trajectory NOTE The deceleration angle is expressed in radians (rad) in all formulae. 3.1.6 specific chemical energy u specific chemical energy content of the propellant NOTE The specific chemical energy is usually expressed in joules per kilogram (J/kg) 3.1.7 line of fire continuation of the axis of the barrel See Figure 1. NOTE Ballistic trajectories can be described as a sequence of straight lines. Then the methods apply to each segment. Corrections of the aiming device are ignored.
3.1.15 divergent area S S size of the area at a certain distance from the trajectory through which the sound radiated from the respective path of the trajectory is propagating NOTE The divergent area is expressed in square metres (m 2 ). 3.1.16 propagation distance r S distance between the source point of projectile sound, P S , and the receiver point, P R , NOTE The propagation distance is expressed in metres (m). 3.1.17 Weber radius R W radius of an equivalent radiating sphere of the “simple model of explosion” NOTE The Weber radius is expressed in metres (m). 3.1.18 Weber pressure p W sound pressure at the surface of the Weber sphere NOTE The Weber pressure is expressed in pascals (Pa). 3.2 Directivity 3.2.1 correction factor due to source directivity c S correction taking into account that different orders of Fourier functions contribute differently to the energy 3.2.2 directivity factor Y( α ) directivity function in the direction of α 3.3 Energy 3.3.1 effective angular source energy distribution Q Y ( α ) effective energy radiated into the direction α , weighted by directivity NOTE The effective angular source energy distribution is expressed in joules per steradian (J/sr). 3.3.2 total acoustic source energy Q e total acoustic energy after integration of Q Y ( α ) over the whole sphere NOTE The total acoustic energy is expressed in joules (J).