ISO 5128:2023

Overview

ISO 5128:2023 - Acoustics - Measurement of interior vehicle noise defines a modern, technology‑neutral engineering method to measure interior vehicle noise (sound pressure levels) for road vehicle categories M and N under typical driving conditions. The standard specifies conditions, instrumentation, test facilities and data‑processing rules required to obtain reproducible and comparable measurements of cabin sound during representative driving cycles. It excludes agricultural tractors and field machinery and does not target extreme‑event maximum levels that would cause instantaneous hearing damage.

Key topics and technical requirements

• Test equipment and calibration: requirements for acoustic instrumentation, vehicle speed and engine‑speed measurement devices, and meteorological sensors to ensure traceable results.
• Test facility and track: outdoor test site surface and meteorological condition specifications (temperature, wind, humidity) to limit environmental variability.
• Vehicle preparation: battery state, tyre condition, loading, seat adjustment, opening/window states and active sound systems are controlled for consistency.
• Microphone positions: prescribed single and multi‑position mounting locations related to seats, standing locations or sleeping berths to capture representative interior sound.
• Test cycles and operating modes: defined urban, suburban, rural and motorway cycles (and combinations) that reflect in‑use driving statistics (references include WLTP, WHVC, VECTO data).
• Measurement and data processing: procedures for readings in motion and at standstill, cycle‑based representative sound pressure levels, cycle combination rules, exposure normalization and calculation of final results.
• Uncertainty and reporting: guidance on measurement uncertainty, precision considerations and mandatory test report contents for reproducibility.

Applications and who uses it

ISO 5128:2023 is intended for:

• Vehicle manufacturers and acoustics engineers for product development, validation and NVH benchmarking.
• Independent test laboratories and proving grounds to perform standardized interior noise testing.
• Regulators and occupational health authorities assessing long‑term exposure, driver/workplace noise compliance and consumer safety.
• Fleet operators and procurement programs for monitoring, acceptance testing and consumer information/benchmarking initiatives.
  Practical uses include standardized comparisons, verification tests against specifications, regulatory assessments related to occupational noise exposure, and consignment monitoring to check consistency between units.

Related standards

• WLTP, WHVC and VECTO driving data (referenced for driving statistics)
• ISO/TC 43 (Acoustics) outputs and other acoustics measurement standards (for instrumentation and calibration practices)

ISO 5128:2023 provides a robust, repeatable framework for measuring and comparing interior vehicle noise with a focus on representative exposure and long‑term health, rather than short‑term peak events.