ISO 5129 pdf download.Acoustics — Measurement of sound pressure levels in the interior of aircraft during flight
1 Scope
1.1 This International Standard specifies requirements for instruments and test procedures for the measurement and reporting of sound pressure levels at crew and passenger locations in the interior of aircraft under steady flight conditions. The sound pressure levels may be used to determine various quantities for describing the acoustical environment in the interior of the aircraft. The procedures are intended to ensure uniformity in test results and to provide the basis for determination of measurement uncertainties. 1.2 This International Standard provides electroacoustical performance specifications for a complete measurement system from a microphone to the readout device. Various individual components of a measurement system may be selected so long as the total measurement system conforms to the specifications of this International Standard. 1.3 The preferred measurement procedure involves the recording of sound pressure signals with subsequent analysis into one-third-octave band sound pressure levels. Direct measurements may be made of one-third-octave- band sound pressure levels.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 31 -7, Quantities and units — Part 7: Acoustics 1 ) ISO 266, Acoustics — Preferred frequencies IEC 60942, Electroacoustics — Sound calibrators IEC 61 1 83, Random-incidence and diffuse-field calibration of sound level meters
3 Terms and definitions
For the purposes of this International Standard, in addition to the terms and definitions given in ISO 31 -7, the following definitions apply. Definitions of other relevant quantities are given in IEC 61 672-1 .3.1 aircraft any machine that can derive support in the atmosphere from reactions of the air other than the reactions of the air against the earth’s surface 3.2 beats periodic variations in amplitude that result from the superposition of two simple harmonic quantities of different frequencies and NOTE Beats involve the periodic increase and decrease of amplitude at the beat frequency . 3.3 crew station location intended to be occupied or used only by aircraft crew during flight operations 3.4 crew sleeping quarters enclosed compartment for crew rest or sleep NOTE Crew sleeping quarters are also known as crew rest quarters, crew rest modules, or crew rest areas. 3.5 passenger compartment any area intended to be occupied by passengers during flight 3.6 synchrophaser device to control the rotational speed and phase of propellers on multi-engine aircraft 3.7 steady flight conditions under which aircraft parameters that significantly affect interior sound pressure levels are controlled so as to yield reproducible results
4 Instruments
4.1 General A complete sound measurement system is composed of a microphone system, data recording and data analysis devices, a sound pressure level display device, and a sound calibrator to establish the overall acoustical sensitivity of the system. A measurement system may include multi-channel instruments and shall conform at least to the applicable class 2 performance specifications of IEC 61 672-1 . A measurement system, including a microphone system according to 4.2, that utilizes an integrating-averaging sound level meter or a conventional sound level meter with exponential time weighting shall conform at least to the applicable class 2 specifications of IEC 61 672-1 . One- third-octave-band time-averaged sound pressure levels shall be determined with spectrum analysers that conform at least to the class 2 specifications of IEC 61 260.