ISO 362-2:2009

Overview

ISO 362-2:2009 - Measurement of noise emitted by accelerating road vehicles - Engineering method - Part 2: L category - specifies an engineering procedure to measure noise from road vehicles in category L3, L4 and L5 (primarily motorcycles and three‑wheelers) under typical urban traffic conditions. The method reproduces noise from principal sources during normal driving (commonly on roads with 50 km/h and 70 km/h limits) and is intended for reproducible, simple testing suitable for type approval, production checks and official testing stations. Vehicles in categories L1/L2, M/N and L6/L7 are excluded (see ISO 9645 and ISO 362-1).

Key topics and technical requirements

• Vehicle coverage: L3 (two‑wheel motorcycles), L4 and L5 (three‑wheel vehicles). L1/L2 and M/N excluded.
• Acceleration specification: Uses a performance‑based acceleration defined by a power‑to‑mass ratio (PMR). PMR is calculated from rated engine power and test mass (PMR = (P / m_test) × 1000), with different procedures depending on PMR thresholds (e.g., PMR > 25).
• Operating modes: Two primary phases - a wide‑open‑throttle acceleration and a constant‑speed phase - chosen to simulate urban in‑use operation while maximizing repeatability and reproducibility.
• Instrumentation: Acoustic instrumentation (sound level meters compliant with IEC 61672‑1), sound calibrators (IEC 60942), engine/vehicle speed measurement and meteorological sensors.
• Test environment: Requires an extensive open test area meeting acoustical site criteria (see ISO 10844) to control reflections and background noise.
• Test conditions: Defines microphone positions, vehicle conditioning (kerb mass, test mass, driver mass), operating conditions and readout/reporting procedures.
• Uncertainty and reporting: Measurement uncertainty framework aligned with ISO/IEC Guide 98‑3 (GUM). Annexes provide flowcharts, background, and indoor-test guidance.

Applications and who uses it

ISO 362-2:2009 is used by:

• Vehicle manufacturers (motorcycle and three‑wheeler designers) for product development and type approval noise testing.
• Test laboratories and certification bodies performing type approval, production checks and spot verifications.
• Regulators and policymakers establishing noise limits or assessing compliance of urban traffic noise sources.
• Acoustical engineers and R&D teams working on noise control, exhaust systems, powertrain NVH and real‑world noise performance.

Practical benefits include standardized, reproducible measurements that reflect urban in‑use behavior, helping reduce community noise impact and ensuring consistent regulatory compliance.

Related standards

• ISO 362-1 (M and N categories)
• ISO 9645 (L1 and L2 mopeds)
• ISO 10844 (test track specification)
• ISO 4106 (engine power test code)
• IEC 61672-1 (sound level meters)
• IEC 60942 (sound calibrators)
• ISO/IEC Guide 98-3 (GUM - measurement uncertainty)

Keywords: ISO 362-2:2009, vehicle noise measurement, L category, motorcycle noise testing, type approval, PMR, urban traffic noise.