Overview
ISO 6969:2004 - "Road vehicles - Sound signalling devices - Tests after mounting on vehicle" specifies how to test vehicle sound signalling devices (horns, electropneumatic and pneumatic alarms) after they are mounted on the vehicle. The standard defines measurement apparatus, test site and ambient conditions, microphone positioning, supply conditions (electrical and compressed air), measurement procedure and accepted sound-pressure-level limits (A-weighted). It refers to ISO 512 for technical specifications of signalling devices and to IEC 61672 for sound level meters.
Key topics and requirements
- Measurement equipment: Use a sound level meter complying with IEC 61672. Electrical meters class 0.5 for electrical measurements.
- Test site: Open area with at least a 50 m radius; central test area practically horizontal over 20 m and surfaced (concrete/asphalt); no long grass or loose soil.
- Ambient conditions: No wind > 5 m/s; ambient noise must be ≥10 dB lower than each sound component (not required for components <70 dB(A)). Temperature within instrument range.
- Microphone position: Axis horizontal and parallel to vehicle longitudinal plane, pointing forward. Place at (7 ± 0.1) m from the foremost vehicle point within a 0.5 m test circle; centre at 1.0 m above ground.
- Measurement settings: Fast time constant; A-weighted results referenced to 2×10−5 Pa; measure positions in the test circle to find maximum level.
- Supply conditions:
- AC-driven devices: test with engine at 50 %, 75 % and 100 % of manufacturer’s maximum speed (no other generator loads).
- DC devices: operate at test voltages (e.g., nominal 6 / 12 / 24 V → test 6.5 / 13 / 26 V) and measure terminal voltage during operation.
- Pneumatic devices: supply per manufacturer instructions.
- Test duration and cooling: Maximum continuous operation 30 s; allow at least 20 min cooling between tests.
- Sound-level limits: Measured under the prescribed conditions, maximum 112 dB(A). Minimum levels vary by vehicle class:
- Mopeds ≤30 km/h: 70 dB(A)
- Mopeds >30 km/h: 73 dB(A)
- Motorcycles ≤7 kW: 83 dB(A)
- Vehicles with ≥4 wheels and motorcycles >7 kW: 93 dB(A)
(Note: national legal requirements may differ.)
Applications and users
- Vehicle manufacturers and OEM horn/signal suppliers - to verify installed device performance and ensure conformity with ISO 512 and regulatory limits.
- Test laboratories and certification bodies - for type approval, in-service testing and quality assurance of installed sound signalling devices.
- Regulatory and compliance teams - to harmonize vehicle audible-signal testing with modal regulations and market approvals.
- Design and validation engineers - to assess installation effects on horn performance and acoustic safety.
Related standards
- ISO 512 - Road vehicles: Sound signalling devices - Technical specifications
- IEC 61672 - Electroacoustics: Sound level meters
- ECE R28, ECE R63, 93/30/EEC - relevant vehicle/audible-signal regulations and directives
Keywords: ISO 6969:2004, sound signalling devices, road vehicles, tests after mounting, microphone positioning, A-weighted dB, IEC 61672, ISO 512, vehicle horn testing.