NVH Testing

Have you ever noticed the feeling when you step into a luxury car?

The door closed with a single, solid "click," without any echo. Starting the engine, the cabin was almost silent. Driving over rough roads, the car rattled a little then stopped, without any shaking. Turning on the air conditioning, the fan sounded like a whisper.

It's not just the feeling of luxury that users experience. Behind this experience lies a crucial technical area in the automotive industry: NVH (Noise, Vibration, Harshness) .

1. What is NVH?

NVH is an abbreviation for: 

• – Noise
• – Vibration
• – Harshness  (Distortion/Harness of Operation)

These are three physical and sensory factors that any vehicle produces during operation – and three factors that modern automakers must control down to the millisecond, to the decibel.

Noise

This encompasses all the sounds generated during vehicle operation: engine noise, wind noise through the windows, tire friction, brake noise, electric pump noise, warning sounds from the ADAS system, etc. Some noises are physically unavoidable – but all can be controlled with proper engineering.

Vibration

This is mechanical vibration transmitted through the vehicle's components to the driver and passengers. You feel the vibration through: the steering wheel, seats, floor, and accelerator/brake pedals. Low-frequency vibrations (5–50 Hz) cause muscle fatigue; high-frequency vibrations (above 100 Hz) cause an unpleasant humming sound.

Harshness

This is the most subjective factor – the feeling of "stiffness," "roughness," or "jerking" that passengers experience when the car goes over potholes, speed bumps, or uneven road surfaces. Harshness is the intersection between mechanics and psychology, and is often the most difficult criterion to measure – as it depends on each individual's perception.

2. Why is the Cultural Center So Important?

"Customers don't buy specifications - they buy the feeling."

This is an undeniable truth in the automotive industry. A car might have the most powerful engine, the biggest battery, the best screen – but if the seats vibrate, the doors creak, or the wind whistles at high speeds, users wo n't feel that the car is worth the money they spent.

JD Power's research indicates that NVH (Non-Vehicle Performance) is one of the top three criteria influencing customer satisfaction and future car purchase decisions. This means NVH isn't just a technical issue – it's a business issue .

3. Cultural Activities in the Electric Vehicle Era: New, More Demanding Challenges

Many people think electric vehicles (EVs) will have "fewer NVH problems" because they don't have noisy internal combustion engines. The reality is quite the opposite.

When the internal combustion engine falls silent, all other noises become louder.

Inside the EV, the driver suddenly heard more clearly than ever before:

• The sound of tires rubbing against the road.
• The sound of wind blowing through the rearview mirror.
• The buzzing sound of inverters and electric motors at certain frequency ranges.
• A faint clicking sound from the regenerative braking system.
• High-speed whining sound from the electric transmission gears.

This is why EV manufacturers – including VinFast – invest heavily in NVH testing right from the design stage. They don't wait until the car is on the road to discover problems. Because at that point, the repair costs are no longer just a few million dong – but millions of dollars in product recalls and brand damage.

4. How Does the NVH Experiment Work?

This is where science meets art – and where specialized testing equipment becomes indispensable.

4.1. Data Acquisition

Sensors are mounted at various points on the vehicle: an accelerometer measures vibration, a microphone measures sound, and a strain gauge measures stress. The data collection system records signals in real time with a sampling rate of up to tens of thousands of points per second.

4.2. Frequency Analysis

The raw data is processed through Fast Fourier Transform (FFT) analysis to determine the resonance frequency , the source of vibration, and the path of the vibration. Engineers can then "see" precisely which part is causing the problem using a graph.

4.3. Testing under standard conditions

• Anechoic Chamber: Completely eliminates external factors, measuring pure NVH from the vehicle.
• Road Simulator: Simulates various types of terrain (asphalt roads, gravel roads, potholes) in a lab environment.
• Shaker Table: Tests the durability of individual components under the impact of accumulated vibrations.

4.4. Subjective Evaluation

Engineers and test drivers sit in the car and rate their driving experience on a standardized scale (usually from 1 to 10). This subjective data is then compared with objective data to make improvement decisions.

5. International Standards in NVH Testing

Not everyone can measure NVH however they want. Tests must adhere to strict international standards to ensure consistency and comparability across manufacturers.

These are also the standards that VinFast and other Vietnamese automakers need to meet when exporting vehicles to the US, Europe, and other international markets.

6. Consequences of Neglecting Cultural Heritage

To understand the importance of cultural values, consider what happens when they are neglected:

• - Negative feedback from users is spreading on social media just because of a strange noise coming from a car.
• - Product recalls are costly when vibrations causing metal fatigue are detected in critical components.
• - Lost ratings from organizations such as Euro NCAP, JD Power, and Consumer Reports.
• - Loss of loyal customers - because of one unpleasant experience, people switch brands.

This isn't theory. This is a real-world lesson that many global automakers have paid for with hundreds of millions of dollars.

7. Cultural Centers Are Not an Expense - They Are an Investment

Proper NVH testing requires specialized equipment, standardized procedures, and a well-trained technical team. It might sound expensive at first. But compare:

• NVH testing costs during the R&D phase: several hundred thousand dollars
• The cost of recalling a batch of vehicles due to undetected manufacturing defects: tens of millions of dollars.
• The cost of losing brand reputation : priceless.

The world's leading automakers – Toyota, BMW, Tesla, and increasingly VinFast – understand this. They don't view NVH (National Vehicle Performance Assessment) as the final test in the production line. They integrate NVH right from the design stage , using simulation software (FEA, SEA) and real-world testing equipment to optimize the product before the first car rolls off the factory floor.

8. Conclusion

A good car needs to be more than just fast and safe. It needs to feel right —quiet when it needs to be quiet, responsive when it needs to be responsive, and never make its occupants feel insecure or uncomfortable.

NVH is the language a car uses to communicate with its driver.

And professional NVH testing—with the right equipment, the right process, and the right partners—is the only way to ensure that language is always clear, consistent, and perfect.

📩 Are you looking for NVH testing solutions for your automotive project? Contact GPower Vietnam for advice on suitable equipment and processes - from sensors to complete test chambers.