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Exhaust Noise Control of Motor Vehicles

Posted on 07 Jun 2013 in Noise Patrol | 0 comments

Strolling down the road, a couple is talking while listening to chirping of the birds and wind playing with the trees. All of a sudden he says: “Did you hear that?” and he steps on the road to look around. She is then confused and asks: “What is it?” “It was something that sounded like a great car”, he replies and still a bit startled joins her back on the pavement.

As the conversation between the couple illustrates, a sound of a car is of high importance and the quality of it determines whether it provokes a positive reaction or not. But there is a very important distinction between a quality sound and too much sound. When there is too much sound, it is called noise. The term “too much sound” is not defined as a general rule, but it depends on the annoyance it causes with the person perceiving the sound. And that is how we come to a crucial part of this article. Cars have to sound great to be desired and wanted – hence the offer of aftermarket exhausts is very appealing. But sounding good is not enough. The annoyance sound is causing is expressed in dissatisfaction and stress in people’s lives when they are exposed to it regularly. That is why a special standard and directive have been adopted in Europe, but legislation is accepted elsewhere in the world as well. The key purpose is to limit and control the noise produced by vehicle’s exhaust.

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The interesting fact is that the need for control of vehicle exhaust noise has not decreased despite the improvements in manufacturing processes of motor vehicles and better driving economy. A lot of car manufacturers have made a big progress on the quality of perceived engine sound. That does however not necessarily mean less noise. The need for measurements is also demanded by society which insists on living comfort.

In short, the legislation requires a stationary measurement with microphone placed in a specific distance and angle from the car with measurements performed at RPM that is specific for each car.

To comply to such demands, we have designed a system consisting of state-of-the-art measurement instrument with vast legacy of sound and vibration components from manufacturer Bruel & Kjaer. That means no measuring range worries, easy and quick calibration facility and compliance with relevant standards with type approval. It is all managed and controlled from a Smart device running an app to control, observe and overview the measurement process. It is meant for field or stationary use with more than 8 hours of autonomous operation.

Measurements of vehicle exhaust noise are usually made in the field where time and place are limited. To help authorities perform measurements accurately is not enough and a mean of presenting a measurement report proved to be a must. So to comply with all the regulations and also to make the task easier, the Smart device has the ability to overview measurement in a clear, easy to understand manner and then also wirelessly print through the embedded printer. We wanted the user to have full control with all the relevant information presented to ensure full control and confidence in results.

Versatile design means the system can be used in Technical or police inspections. On the other hand, it is not limited to that either. It can also be used and adapted to measuring race vehicles/bikes making sure they comply to the prescribed limits.

Engine noise can be enjoyed … If it is not too loud.

More about the Noise Patrol.

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