Overview
ISO 13325:2019/Amd 1:2023 is an important international standard published by the International Organization for Standardization (ISO) that provides an amendment focused on the uncertainties involved in tyre-to-road sound emission measurements. This document updates the 2019 edition by incorporating detailed considerations of measurement uncertainties specifically related to the coast-by free-rolling methods used for assessing tyre noise emissions. The amendment aligns with the established principles found in the ISO/IEC Guide 98-3 (GUM:1995) for expressing measurement uncertainty.
This standard is critical for professionals engaged in tyre acoustics testing, vehicle noise certification, and environmental noise management, providing a robust framework to improve accuracy and confidence in tyre noise emission data.
Key Topics
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Measurement Uncertainty in Tyre Noise Testing
The amendment addresses various sources of uncertainty affecting the coast-by method, including:
- Variations in surface texture and test track conditions
- Vehicle design and operating conditions
- Environmental factors such as temperature, humidity, and atmospheric pressure
- Measurement system performance and equipment calibration
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Uncertainty Categories
The document groups uncertainties into three principal categories to clarify their influence on test results:
- Within a single test cycle: Minor ambient condition variations during a test day using the same test equipment and vehicle.
- Day-to-day variation: Fluctuations due to equipment changes, environmental factors, or vehicle differences over extended periods.
- Site-to-site variation: Differences arising from various test locations, equipment, vehicles, operators, and surface properties.
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Statistical Approach and Expert Judgment
Uncertainties are quantitatively estimated using available statistical data, tolerance analyses, and expert assessments. Users are guided to follow the ISO/IEC 98-3 framework for calculating and reporting uncertainty, including the use of expanded uncertainty for a 95% confidence level.
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Uncertainty Budget and Factors
The amendment provides a detailed uncertainty budget encompassing factors such as:
- Microclimate wind effects
- Background noise fluctuations
- Vehicle-specific influences like suspension and wheel geometry
- Measurement instrumentation precision (e.g., sound calibrators, microphones complying with IEC standards)
This comprehensive identification helps ensure consistent, traceable tyre noise assessments.
Applications
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Tyre Manufacturers and Testing Facilities
Ensures more reliable and reproducible tyre noise emission measurements to comply with regulatory requirements and support product development.
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Regulatory Bodies and Environmental Agencies
Supports the accurate evaluation of noise pollution from road transport, enabling better enforcement of noise limits and quieter road infrastructure designs.
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Automotive Industry Noise Certification
Assists vehicle manufacturers in meeting sound emission regulations by addressing test uncertainties linked specifically to the tyre-road interaction noise component.
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Research and Development
Provides a methodological foundation for enhancing tyre noise testing protocols, enabling researchers to quantify and reduce uncertainties systematically.
Related Standards
- ISO 13325:2019 - The base international standard detailing coast-by methods for measuring tyre noise emissions without the uncertainty amendment.
- ISO/IEC Guide 98-3 (GUM:1995) - The definitive guide for expressing and evaluating measurement uncertainty, referenced as the methodological basis in this amendment.
- IEC 61672-1 - Specification for class 1 sound level meters, relevant for measurement equipment qualification.
- IEC 60942 - Standard for acoustic calibrators used in noise measurement calibration processes.
This amendment reinforces the importance of harmonized test procedures and uncertainty quantification to achieve accurate, internationally comparable tyre noise emission measurements. It benefits all stakeholders involved in environmental noise control, vehicle certification, and tyre performance testing. For detailed implementation, users are encouraged to consult the full ISO 13325:2019/Amd 1:2023 document and accompanying normative references.
Open preview (PDF)Tyres — Coast-by methods for measurement of tyre-to-road sound emission — Amendment 1: Uncertainties
