Acoustics — Laboratory measurement procedures for ducted silencers and air-terminal units — Insertion loss, flow noise and total pressure loss (ISO 7235:2003)

A considerable amount of research has been undertaken in labs in Cardington in the U.K., as well as at the University of Lund in Sweden covering fire, acoustics, differential movement, construction costs and disproportionate collapse.

The compliance of the sound calibration device with the requirements of IEC 60942:1988 shall be verified once a year and the compliance of the instrumentation system with the requirements of IEC 60651:1979/A1:1993, second edition, shall be verified at least every two years by a laboratory which is authorised to perform calibrations traceable to the appropriate standards.

The global network will include 321 stations and 16 laboratories using four different detection technologies: first, seismological monitoring to measure shock waves in the earth's surface; second, hydroacoustic monitoring to measure shock waves in water; third, infrasound monitoring to measure low frequency pressure fluctuations in the atmosphere; and, finally, radionuclide monitoring to measure the presence of certain radioactive fission products in the atmosphere, which will make it possible to determine whether they are the result of a nuclear explosion.

When an integrating averaging sonometer conforming to IEC standard 804 (which is well suited for measurement of the equivalent continuous sound pressure level of impulse noise) complies at least with the specifications of type 1 and has recently been fully calibrated in a laboratory, and the microphone is properly located (see 3.2 above), the results make it possible, with certain exceptions to determine whether a given exposure has been exceeded (see 4) even in complex situations; that method is thus generally applicable, and is well suited for reference purposes.