Overview
ISO/TS 13471-1:2017 - "Acoustics - Temperature influence on tyre/road noise measurement - Part 1: Correction for temperature when testing with the CPX method" specifies procedures to quantify and correct the influence of temperature on tyre/road noise measurements made with the close‑proximity (CPX) method. The document normalizes CPX measurement results to a reference air temperature of 20 °C and covers the influence of air, road and tyre temperatures on CPX levels (LCPX). It supports similar methods such as on‑board sound intensity (OBSI).
Key topics and technical requirements
- Scope and purpose: Normalize CPX results obtained over a wide temperature range (practical measurement range noted around 5 °C to 35 °C) to a common reference temperature to improve comparability.
- Temperature measurements: Guidance on instrumentation and measurement locations for air temperature, road surface temperature (optional) and tyre/tyre‑tread temperature (optional).
- Correction procedure: Definition of a temperature correction term (CT,t) and temperature coefficient (γt) used to adjust CPX broadband and spectral levels to the 20 °C reference.
- Semi‑generic approach: Corrections are provided distinguishing the two ISO reference tyres and major road pavement categories; tailored corrections for specific tyre/road combinations are recommended where possible.
- Spectral correction: Procedures for frequency‑band corrections in addition to overall A‑weighted levels.
- Uncertainty assessment: Measurement uncertainty evaluation following ISO/IEC Guide 98‑3 (GUM), addressing sources such as temperature coefficient variability, road category, and sensor accuracy.
- Reporting: Requirements for documenting temperatures, corrections applied, and uncertainty estimates in the test report.
- Informative annexes: Discrete temperature coefficients, road surface descriptions, and guidance on choosing normalization temperature.
Applications and users
ISO/TS 13471-1:2017 is used by:
- Acoustic test laboratories performing CPX or OBSI testing
- Tyre and vehicle manufacturers for product development and validation
- Road authorities and pavement engineers assessing surface noise
- Researchers studying tyre/road noise mechanisms
Practical uses include normalizing before/after pavement treatments, comparing tyre or surface performance across seasons, and reducing temperature‑related variability in noise datasets.
Related standards
- ISO 11819‑2 - CPX (close‑proximity) method for tyre/road noise
- ISO/TS 11819‑3 - Reference tyres for CPX
- ISO/IEC Guide 98‑3 (GUM) - Uncertainty of measurement
Keywords: ISO/TS 13471-1:2017, CPX method, tyre/road noise, temperature correction, tyre temperature, road surface temperature, ISO 11819-2, OBSI, CPX level, temperature coefficient.