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Noise and Vibration Analysis for Improved Product Quality

Jun 21, 2023

Modern industrial businesses must continue to improve product quality in order to remain competitive. Regardless of your industry or what you manufacture, consider implementing smarter vibration measurement strategies. Noise, vibration and harshness, also known as NVH, have strong correlations with product quality, both from a manufacturing perspective and from that of the end user. Learn how to better control vibration with better measurement methods and analysis.

Noise and Vibration Analysis for Improved Product Quality

Noise and Vibration Measurement Analysis for Improved Product Quality

The Dangers of Excessive NVH

Noise and vibration are undesirable characteristics in any industrial application. Excessive vibration in manufacturing will result in wider margins of error and less reliable components. With wider-than-ideal tolerances in production, fit on the assembly line will likely become a problem, which will only exacerbate vibrations in the finished product. Even in situations where additional vibration does not pose a significant mechanical threat to the integrity of the product, it can result in harshness that reduces the user’s perception of quality.

Therefore, reducing vibration improves product quality across the board. To reduce vibration, you will need to take accurate measurements at various stages of your manufacturing and assembly processes. By collecting and analyzing data related to noise and vibration, you can identify your most glaring needs and take steps to mitigate excess vibration and noise.

Noise, Vibration, and Harshness Measurement Methods

There are several ways to measure noise and vibration accurately. Although noise and vibration are often discussed in tandem, we recommend using specialized measurement devices for each. Vibrations can occur at frequencies beyond the range of human hearing, requiring more accurate testing methods. Accelerometers and laser scanners are ideal for measuring vibrations.

Meanwhile, what we consider noise is limited to humans’ hearing range. It’s not enough to only measure noise in raw decibels, as human hearing has different levels of sensitivity at different frequencies. A high-pitched cooling fan, for example, is much more likely to be noticed by a user than a larger, low-pitched fan producing the same decibel output. Finally, harshness is best measured by individual testers, as it’s a subjective component.


Accelerometers are an excellent tool for measuring vibrations at multiple steps in the manufacturing process. Due to their small size and robustness, they can be placed on almost any surface, even in extreme operating conditions. You can even retrofit them onto older manufacturing equipment to spot excess vibration that could lead to defects in your finished products. After assembly, accelerometers can be installed in various places to get a holistic vibration reading during testing.

Piezoelectric quartz accelerometers have long been the standard due to their wide measurement range of up to 100g and the convenience of not requiring external power. However, quartz is also fragile, and few applications actually need the wide range offered by piezoelectrics. Alternatively, consider micro-electrical-mechanical systems (MEMS), which consist of a tiny silicon chip that can feed digital signals directly to a receiver.

Laser Scanning Vibrometry

For the most precise measurements, laser scanning vibrometry is the gold standard. If you are looking to produce components with the tightest tolerances possible, use light to measure vibration. Laser scanning detects a Doppler shift whenever vibration occurs, and laser systems can detect vibrations that produce movement measured in nanometers.

Laser scanning also produces more accurate measurements since it does not introduce any additional load onto the parts being tested. This makes laser scanning ideal for small component manufacturing, where the added weight of a piezoelectric or MEMS accelerometer could have a major impact on the system’s stability. Furthermore, laser scanning is non-destructive, which is useful for testing expensive prototypes for the aerospace and automotive manufacturing industries.


Regarding noise, the technology involved is much simpler. Since noise measurement is based on human perception, you can generally use a standard sound level meter to evaluate noise. More advanced meters include useful features for data analysis, such as saving data to an SD card and outputting both WAV and TXT files.

Measuring Harshness

Harshness is a subjective measurement based on the user’s perception of noise and vibration. Therefore, it’s best to measure overall harshness with a finished product and human testers. Although acoustic engineers know which frequencies and loudness levels are likely to be bothersome, it’s difficult to evaluate harshness one component at a time.

This is an especially important step to take for product quality in the aerospace and automotive fields. Passenger areas need to maintain a comfortable noise level. Harshness testing with live participants can help you identify troublesome noise sources that may have been overlooked during production.

Using NVH Data to Improve Products

Once you’ve chosen the ​right measurement instruments for your ​applications, the next step is to collect test data for future analysis. This data ​can help you improve both your production processes and the quality of your final products, depending on how you apply the insights derived from the data.

Improving Production Quality

Improving production quality will improve the quality of the final assembled product. The best way to increase the reliability of your products ​is to minimize vibration in manufacturing. Data gathered from accelerometers or MEMS on your fabrication machines can identify excessive vibration. ​Over time, you will be able to predict when a machine is likely to fall out of spec and require maintenance.

This approach optimizes your time and your machines’ performance. Rather than maintain all your equipment periodically, you can simply focus on the machines that are producing too much vibration and keep them within tighter tolerances.

Improving the End-User Experience

Noise and harshness have a direct impact on the end user’s perception of your final product. You may find that engine noise, for example, propagates too much in the passenger cabin of a vehicle. Additional dampening materials or improved engine mounting could ​mitigate the problem. Solutions to noise and harshness will likely require additional engineering, but your final product will stand out for its quality.

Implementing all of these measurement methods and analyzing the data they provide can be a challenge. Contact SAAB RDS to learn more about how we can help your business improve product quality through a digital transformation.