Overview
ISO 20906:2009/Amd 1:2013 is an important amendment to the international standard for acoustics focused on the unattended monitoring of aircraft sound near airports. This amendment refines procedures surrounding the calibration, testing, and operational checks of sound monitoring equipment designed to measure aircraft noise in the airport vicinity. Produced by ISO/TC 43 Subcommittee SC 1 (Noise), this standard ensures more reliable, consistent, and accurate acoustic measurements, supporting noise management programs and regulatory compliance in airport environments.
Key Topics
Calibration of Sound Monitors
- Calibration methods must follow IEC 61672-3 standards or use sound calibrators under appropriate environmental conditions (atmospheric pressure and temperature).
- Sensitivity corrections should consider deviations from annual average environmental conditions to enhance measurement precision.
Periodic Testing
- System performance testing must be conducted at least annually, with a maximum interval of two years.
- Testing assures continued compliance with Class 1 specifications in IEC 61672-1.
- Accredited laboratories conforming to ISO/IEC 17025 should perform testing for reliability.
- Inspection of physical elements such as rain protection, microphone support, and bird deterrent devices is mandatory during periodic testing.
Acoustic Sensitivity Check
- Acoustic checks use a sinusoidal tone within 160 Hz to 1250 Hz at sound pressure levels between 90 dB and 125 dB.
- Use of IEC 60942 Class 1 sound calibrators is required, with verification performed yearly by accredited labs.
- Sensitivity deviations beyond 0.5 dB indicate faulty monitors requiring repair and recalibration.
Automatic Operation Check
- The standard mandates daily automatic system operation checks to identify functional faults.
- Checks can be activated onsite or remotely and must exclude measurement during active sound events.
- The system must store and report operation check results for at least 12 months.
- Operation alerts necessitate investigation and possible recalibration or repair.
Actions on Alerts
- Data collected since the last successful check are considered suspect if operation alerts are detected, pending technical evaluation.
- Sensitivity checks following alerts determine the next steps, whether recalibration or repair.
Applications
ISO 20906:2009/Amd 1:2013 is integral to airports and environmental monitoring agencies focusing on:
- Long-term, unattended sound monitoring of aircraft noise to inform community noise management strategies.
- Ensuring regulatory compliance with local and international noise control legislation.
- Providing reliable acoustic data for analyzing trends and impacts of aircraft operations on surrounding communities.
- Supporting automated systems for real-time noise event detection and equipment performance validation.
- Enhancing maintenance protocols for acoustic monitoring equipment to guarantee data integrity.
Related Standards
ISO 20906:2009/Amd 1:2013 references several complementary standards critical to acoustic measurement:
- IEC 61672-1, -2, and -3: Covering sound level meter performance specifications, pattern evaluation tests, and calibration procedures.
- IEC 60942: Defines performance requirements for sound calibrators used during acoustic checks.
- ISO/IEC 17025: Specifies general requirements for the competence of testing and calibration laboratories involved in acoustic system testing.
Implementing ISO 20906 and its amendments supports adherence to a globally recognized framework for consistent aircraft noise monitoring, thereby fostering improved environmental and community noise management around airports.