VSAC+Pass-By System and Related Products

MSAC / VSAC

Pass-by noise (external vehicle noise) refers to the noise generated when a vehicle is in motion. Our company offers various methods for measuring pass-by noise both indoors and outdoors.

Indoor Vehicle Pass-By Noise Measurement System

※VSAC=Vehicle Semi-Anechoic Chambers
Pass-by testing can be conducted indoors.

Since 2019, indoor pass-by testing has been approved for certification testing (R51.03 Am4) production conformity. It is much easier to measure external noise using a chassis dynamometer installed in a spacious indoor semi-anechoic chamber. The controlled environment protects against wind and rain, ensuring high reproducibility and allowing measurements to be conducted year-round, 24hours a day.

Similar to external noise measurement, the vehicle is driven while fixed on the dynamometer, with a microphone array placed on both sides of the vehicle to measure the emitted sound. The microphone signals are processed alongside vehicle speed, providing results that can be directly compared to outdoor results, including Doppler corrections. This standard offers a method for correcting tire noise using outdoor measurement data from ISO test tracks.

Pass-by SPC (Sound Path Analysis)

Pass-by SPC investigates the impact of noise sources such as tires, engines/motors, and exhaust systems on overall pass-by noise.

Source Path Contribution (SPC) is a technique used to evaluate the contribution of suspected sound or vibration sources through various acoustic and vibration paths to any given receiving location. By focusing on the dominant sources, engineering efforts can be concentrated on the areas that have the greatest impact. While the SPC method is commonly used in the analysis of cabin noise, which involves both acoustic and vibrational sources, BK Connect Pass-by SPC is specifically designed for acoustic analysis using measurements from indoor pass-by setups.

Volume Velocity Sound Source Measurement

The Volume Velocity Sound Source Measurement software ( part of BK Connect ) is designed for measuring acoustic transfer functions.

Volume Velocity Sound Sources (VVS) typically measure acoustic transfer functions (ATF) related to source contribution analysis. HBK’s volume velocity sound source uses a specialized dual-microphone probe to directly measure volume velocity in real time with high accuracy. The volume velocity sound source measurement software is designed to work in conjunction with the VVS, enabling fast and efficient high-precision ATF measurements guided by a pre-loaded test plan to ensure accurate results.

Outdoor Vehicle Pass-By Noise Measurement System

Pass-by noise testing outdoors in compliance with ISO standards is possible.

Applicable Standards

• Accelerated pass-by noise testing for M category (light vehicles) and N category (trucks) in accordance with the requirements of ISO 362:1998 and ISO 362-1:2012, and for L category vehicles (motorcycles) in accordance with ISO 362-2:2012.
• Compliance with external noise requirements based on ISO 3325 (tires) and ISO 5130 (exhaust noise)
• Conformity to regulations following ISO testing procedures, such as UN/ECE R51.03 (noise emission for M and N category vehicles), UN/ECE R41.04 (noise for L category vehicles, motorcycles), and UN/ECE R117 (tire noise)

Vehicle Noise Testing : Applications

Compliance with R165 Reverse Warning Sound Measurement Regulations

Close Proximity Exhaust Noise and Horn Noise Testing

VSAC+Sound Level Meter 2245

Wireless Control via 2245 Model Mobile Application

The Sound Level Meter 2245 allows for remote operation from a distance away from a specific receiving point. By controlling it wirelessly via Wi-Fi, without needing to connect a microphone in the semi-anechoic chamber to the outside with cables, the influence of ambient noise from human activities inside the room is eliminated.