How to measure vehicle noise

October 3, 2024 | Testing

When you drive a new car, you expect it to be quiet and comfortable. And achieving that level of refinement doesn’t happen by accident.

Before a vehicle ever hits the market, it undergoes extensive noise, vibration, and harshness (NVH) testing. These tests ensure that every car is comfortable, safe, and enjoyable to drive.

But measuring these factors isn’t something you can do in your average garage – it requires specialised facilities and advanced technology.

Here’s a closer look at how the various tests vehicle manufacturers conduct, why they matter, and the role we play at IAC Acoustics Australia.

1. Sound pressure level testing

Sound pressure level testing is the starting point for measuring vehicle noise. This test evaluates how loud a car is, both inside and out. Engineers use microphones and sound level meters to capture and analyse noise from the engine, tires, wind, and other sources. The goal is to pinpoint noise hotspots so they can be minimised.

At IAC Acoustics Australia, we provide Vehicle Semi-Anechoic Chambers (VSACs), which are designed to absorb sound reflections and meet international standards, allowing for precise noise measurements during various vehicle operations.

2. Vibration analysis

Vibration isn’t just annoying — it can impact how a vehicle handles and how comfortable it feels. Vibration analysis looks at how the car’s various components — like the engine, transmission, and suspension—affect the overall ride quality. Engineers simulate driving conditions using shake and rattle Facilities, equipped with hydraulic rigs that detect problematic vibrations to help refine vehicle design.

IAC Acoustics provides a turnkey service, including the necessary rigs and acoustic treatments, ensuring accurate testing without interference from external noises.

3. Acoustic material testing

The materials used inside a vehicle, from carpets to door panels, play a major role in managing noise. Acoustic material testing examines how different materials absorb or reflect sound. We provide the necessary equipment and environment to test a variety of materials, helping manufacturers choose the best options to minimise cabin noise.

4. Powertrain noise testing

The powertrain — including the engine, transmission, and drivetrain — is one of the biggest contributors to vehicle noise. Powertrain noise testing focuses on isolating sounds produced by these components.

We provide powertrain anechoic chambers, specially designed to test various transmission types in a high-absorbency environment, helping manufacturers optimise NVH performance.

5. Pass-by testing

Put simply, ‘pass-by testing’ measures the noise a vehicle makes as it drives past, simulating how it sounds to people nearby. This test is important for understanding and controlling the noise impact of vehicles on pedestrians and urban environments.

At IAC Acoustics, we provide specially designed chambers that recreate outdoor conditions indoors. These use advanced hemi-anechoic setups to capture precise external noise data, helping manufacturers reduce vehicle noise and meet international standards.