ISO 16254:2016

Overview - ISO 16254:2016 (Acoustics)

ISO 16254:2016 specifies an engineering method for measuring sound emitted by road vehicles of categories M and N at standstill and low-speed operation. Derived from ISO 362‑1, the standard reproduces sound levels from principal vehicle sources under conditions relevant to pedestrian safety, and includes procedures to evaluate external sound generation systems (ESGS) used to signal vehicle presence for vulnerable road users. The method emphasizes simplicity while ensuring reproducible, objective acoustic results in extensive open-space test environments (e.g., certification testing, manufacturing, official test stations).

Key topics and technical requirements

• Scope and purpose
  • Measurement of vehicle sound at standstill and low speeds to characterize detectability and information content for pedestrians.
  • Objective reporting of sound pressure level, frequency content, and changes with vehicle speed.
• Instrumentation
  • Acoustic and speed-measurement instrumentation requirements, calibration, and compliance (sound level meters, calibrators, filters).
• Acoustic environment
  • Test-site criteria favoring large open-field (free-field) conditions; guidance for hemi-anechoic/anechoic indoor testing and component testing.
• Meteorological & background-noise controls
  • Environmental condition monitoring and background-noise measurement/correction procedures to ensure valid results.
• Test procedures
  • Full-vehicle test steps covering microphone positions, vehicle conditions (test mass, tyres), operating modes, data compilation, standstill and low-speed (e.g., 10 km/h) results, and reporting.
• Frequency-shift and signal analysis
  • Methods for identifying tonal content and frequency shifts as a function of speed; FFT/one-third-octave analysis guidance.
• Uncertainty and reporting
  • Measurement uncertainty framework (GUM-aligned), required test-report content, and annexes with development background and flowcharts.

Applications and who uses it

• Vehicle manufacturers - design verification of acoustic profiles and external sound generation systems for compliance and pedestrian safety.
• Acoustic engineers and test laboratories - standardized test protocols for reproducible sound emission data.
• Regulatory agencies and certification bodies - objective measurement basis for certification and regulation of low-speed vehicle noise and ESGS performance.
• Component suppliers - performance testing of external sound generators as standalone components.
• Accessibility and safety advocates - reference for objectively assessing how vehicles convey approach/location/speed information to pedestrians.

Related standards (key references)

• ISO 362‑1 (accelerating vehicles engineering method)
• ISO 10844 (test track specification)
• ISO 26101 (free-field environments)
• IEC 60942, IEC 61260‑1, IEC 61672‑1 (electroacoustics)
• SAE J2889‑1 (minimum noise measurement)
• ISO/IEC Guide 98‑3 (GUM - uncertainty)

Keywords: ISO 16254:2016, acoustics, measurement of sound, road vehicles, category M and N, standstill, low speed, engineering method, external sound generation system, pedestrian safety, sound pressure level, frequency content.