Overview
ISO 10847:1997 - "Acoustics - In‑situ determination of insertion loss of outdoor noise barriers of all types" defines procedures for measuring the insertion loss of outdoor noise barriers under real‑world conditions. The standard specifies in‑situ measurement planning, microphone and source/receiver positions, required instrumentation, meteorological monitoring, and reporting so that barrier performance can be quantified reliably for a given site and set of conditions. It is intended for routine performance checks, engineering evaluation and diagnostic studies, and accommodates both barriers to be installed and those already in place.
Key topics and requirements
- Definition of insertion loss: Difference in sound pressure level at a receiver position before and after barrier installation, with source, terrain and meteorological conditions held equivalent.
- Measurement methods:
- Direct method: Preferred when “before” measurements are possible (barrier removable or not yet installed). Same reference and receiver positions used for before/after.
- Indirect method: Used when the barrier already exists; “before” levels are estimated from measurements at an equivalent site.
- Instrumentation:
- Use Type 1 or Type 2 sound level meters (IEC 651), integrating/averaging meters for LAeq/LAE (IEC 804).
- Calibrators meeting IEC 942, octave/third‑octave filters meeting IEC 1260.
- Windscreens on microphones; at least two simultaneous measurement systems (reference + receiver).
- Meteorological sensors: anemometer (±10% uncertainty), thermometer (±1 °C), hygrometer (±2%).
- Environmental and meteorological controls:
- Document and maintain equivalence of terrain profile, ground surface, reflecting structures and meteorological conditions between before/after tests.
- No measurements when average wind speed exceeds 5 m/s; wind vector components from source to receiver must be comparable.
- Temperature between before/after within 10 °C; similar humidity and cloud‑cover class.
- Acoustic descriptors: Use A‑weighted equivalent continuous sound level (LAeq), sound exposure level (LAE), octave/one‑third‑octave band levels or Lmax. Background noise must be ≥10 dB below the measured source level.
- Reporting: Record method type, instrumentation, site layout, source and barrier details, meteorological data and uncertainty estimates.
Applications and users
- Who uses ISO 10847: acoustic consultants, environmental engineers, road/rail/highway authorities, barrier manufacturers, urban planners and regulatory agencies.
- Typical uses: verifying noise barrier performance after installation, comparing barrier designs at the same site, validating acoustic models, compliance checks and forensic noise studies.
Related standards
- IEC 651: Sound level meters
- IEC 804: Integrating averaging sound level meters
- IEC 942: Sound calibrators
- IEC 1260: Octave and fractional‑octave filters
Keywords: ISO 10847, insertion loss, outdoor noise barriers, in‑situ measurement, acoustics, LAeq, sound level meter, meteorological conditions.
