ISO 13475-1:1999 PDF

Overview

ISO 13475-1:1999 - "Acoustics - Stationary audible warning devices used outdoors - Part 1: Field measurements for determination of sound emission quantities" defines field test methods to determine the sound emission of stationary outdoor warning devices (sirens and sound signalling devices). The standard specifies test site conditions, instrumentation, microphone placement, measurement procedures and reporting so that reliable, reproducible sound pressure and immission-relevant sound power values can be obtained for outdoor warning systems. It does not cover spoken messages or recommend specific warning signals.

Key topics and technical requirements

• Measurement methods: Two field methods are described
  • Flat-plate method - microphone mounted on a metal plate on the ground; measured level is reduced by 6 dB to account for the controlled reflection.
  • Horizontal method - microphone mounted at the same elevation as the device (preferred centre height 10 m); measurements account for direct and reflected paths.
• Reference distances and geometry: Preferred microphone distance is 30 m (maximum 50 m). Microphone positions and small sphere scans are defined for repeatability.
• Test site & mounting: Ground between source and microphone must be flat to within –1.0 m; no major reflecting objects within twice the measurement distance; mount device at manufacturer’s recommended height (10 m recommended).
• Instrumentation & calibration: Use class 1 or 2 sound level meters and octave filters per IEC 60651 / IEC 60804 / IEC 61260. Microphone diameter ≤ 13 mm for flat‑plate tests. Calibrators per IEC 60942; calibration traceable to national standards (calibrator interval ~12 months, other equipment ~24 months).
• Ambient conditions & exclusions: Record temperature, humidity, barometric pressure, wind (preferably