Saturday 15st May 2021

Noise measurement: overkill for the illegal exhaust system!

Reading time approx. 8 Minutes

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Unfortunately in tuning it is often nothing special that an exhaust system without expert opinion or EC marking is installed on the vehicle. In order to be able to register an exhaust system, you need proof of the correct one Exhaust gas treatment and Noise behavior. This works with a corresponding certificate or the EC label. The driving noise is decisive for the noise behavior. This is in vehicle registration in field U.3. It is regulated according to ECE R51. The stationary noise is responsible for the associated comparison variable.

Procedure of the stationary noise measurement

Stand noise measurement Tuning police noise measurement: Overkill for the illegal exhaust system!

  1. the environmental parameters must match
  2. Measurement allowed can not be near Walls take place (they change the sound)
  3. Ambient noise must be as possible low breast
  4. Underground must fixed and Dry breast
  5. It almost has to calm breast
  6. Standing noise measurement with a measuring device in one distance by 1 meters to the exhaust port and at the angle of 45 °
  7. Then accelerate until Rated speed is reached
  8. Rated speed hold briefly, then quickly accelerate take away
  9. maximal measured value is that Standing noise

Process of driving noise measurement according to ECE R51

  1. Measurement is only allowed on one certified or approved Test track be performed
  2. Measurement allowed can not be take place near walls (they change the sound)
  3. Ambient noise must if possible low breast
  4. Underground must fixed and Dry breast
  5. It almost has to calm breast
  6. Measurement section has a length of 20 meters
  7. After 10 meters, the 90 ° angle to the measuring section at a distance of 7,5 meters at a height of one meter Measuring head positioned
  8. Then with 50 km/h Approach the starting point of the measuring section in third gear
  9. From this position accelerate fully und am 20 meter point immediately remove the gas
  10. Measurement always 2 x in both directions of travel carry out
  11. Average of all measurements is that Total reading
  12. The basis for the noise measurements is Section 49 of the StVZO

Noise measurement by the police - Procedure!

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  • Near field measurement Police check after EC directive 70/157 EEC
  • Measure / log ambient noise (if the value is less than 10dB (A) below the later measured value, the measurement is invalid)
  • calibrated Measuring instrument must be used
  • Measurement on free smooth surface (no walls or other sound reflectors nearby)
  • Measuring device in Height of the exhaust mouth (at least 20 cm above the ground) with a Distance of 50 cm and at the angle of 45 ° ± 10 ° to the opening of the exhaust (Angle of 45 ° = if the exhaust points to 6 o'clock, the device must be centered between 4 and 5 o'clock - Motorrad)
  • number of revolutions constant hold, then suddenly gas take away
  • at least 3 measurements carry out
  • the arithmetic Average has always been measurement result (the three individual measurements must not deviate from one another by more than 2 dB (A))
  • Police often use (no guarantee) one Measurement tolerance of 5 dB (A) - measurement result less 5 dB (A)
  • at rated speed <5000 RPM will with 3/4 rated speed measured
  • at rated speed > 5000 rpm will with 1/2 rated speed measured.

We think you should be embarrassed about that absolutely correct execution respect, think highly of. If there is a discrepancy, it should be done immediately Protest are inserted and the measurement is questioned. Certainly it can't hurt the officials on that either Costs to draw attention to one faulty Messung arise. For example the cost of the Certificate from TÜV, for the Taxi home or, if necessary, the cost of that tow away of the vehicle to the location of the report.

Sports buttons, sound generators, speaker systems

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Many connect one high performance with a loud sound of the Exhaust System. The manufacturers who have been conveying this association for many years are also responsible for this - not least of course for marketing reasons. To get a good sound is therefore not even illegal tuning of the vehicle. Instead, they are in many models Sports buttons, sound generators or even whole Speaker systems installed. And that as standard and until a certain approval date even absolutely legal. But how is that actually possible?

Prescribed limit values

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The existing limits (in decibels) are not the same for every vehicle. If a car comparatively difficult and highly motorized is, it may accordingly be louder than a vehicle which easier is and about not that much power disposes. The permitted value therefore depends on how things are with the Ratio of power and mass looks like. The limit values ​​can be for a Mid-range cars to the 72 decibels with a sports car it can be 75 decibels be. Whether a vehicle can actually comply with the prescribed limit values ​​will be discussed before the Zulassung of the vehicle checked. The corresponding procedure is called "Type test for noise emissions in vehicles". The test takes place outdoors instead of what the big automakers extra Test tracks have erected. For the actual execution of the test, examiners are appointed by TÜV or even the DEKRA invited. Journalists are denied entry - mostly from "Capacity reasons".

Are the tests realistic at all?

To find out, testers have to be interviewed who independent from the manufacturers. For example that Frauenhofer Institute for Building Physics in Stuttgart. Here the acousticians simulate a noise test on the Indoor roll test stand. During this test, the vehicle is accelerated so that it is exactly halfway across a 20-meter route 50 kilometers per hour has on the speedometer. When this point is reached, find out more faster. However, this is usually the case no more than 80 km / h reached. Which gear and at which speed is driven the vorgeschrieb and depends on the model. All count within the 20 meter long route measured values. Ultimately, the is chosen highest valuethat was achieved.

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This procedure is called "Accelerated drive by“And only takes a few seconds. Now, of course, the question arises whether these few seconds realistic values for the real noise behavior later on on the road. Another test is carried out to check this. Here the test driver gives Full throttle and drives all courses out. The results you get now exceed the maximum allowed 72 decibels clear. According to the institute that was involved in developing the process, that is true absolutely okay. Because after all, be it not meaning and purpose the test to get peak values, but it would just be about a standardized procedure to search with the vehicles accordingly compared can be. This is how most of the traffic takes place in the city, which is why when checking on moderate accelerations is set. That way you should realistic Values ​​for city traffic can be determined.

Although this procedure has been used for many years, it is by no means perfect. The EU is now also of this opinion, which has therefore expanded the test procedure accordingly. So are speeds upper- or below 50 km / h driven and also so-called Constant travel. These trips are then rated differently and ultimately result in a "urban sound level". However, the value that is determined here also corresponds to not reality - so the opinion of some environmental associations and the acousticians of the Federal Environment Agency.

Vehicles sometimes 500 times as loud

That technology exists that controls the volume of vehicles intentionally increasedis no longer a secret. That is why experts are calling for the Federal Environment Agency to ban the relevant technology. To show that the matter is serious, the office took measurements itself. These were three cars and three motorcycles that were tested on an outdoor test track. During this test it was found that some of the vehicles 100 or even 30 minutes are louder than under the conditions prevailing during the type test. Vehicles that are extended accordingly are approximate 30 minutes louder than the same model in the process of Type test. Based on these determined values, the Federal Environment Agency, which is responsible for noise reduction in road traffic, demands a ban.

With the appropriate weighting the official procedure drops the Constant speed most weight what for highly motorized (sports) cars is a clear advantage. And these advantages are the reasons why loud cars yet comply with the limit values and the sale of Sound amplifiers and Flap exhaust systems continues to take place. After all, the technique is perfect legallyas long as the limit values ​​are not exceeded .

Extremely loud and at the same time legal vehicles

Many wonder what a Sports buttonas it is often built into sports cars. According to Hans-Martin Gerhard, who is also a specialist in traffic noise at Porsche, such a button serves "to emotionalise the driver". If you press the button, the relatively solid and purring sound is transformed into a deep bubbling. Every time the ignition key is turned and the engine is restarted, the vehicles are initially set to normal mode again. If you want more, just press the Sound button. The use of the key is (Luckily) perfectly legal.

Who sets the limit values?

The use of the button may be within the legal framework, but whether the use is actually “socially compatible” is the other question. There was even a special column in the Table für die permitted decibel values the cars laid out. One speaks here of "Cars with fewer than four seats and a low R point". The R point is the hip point of the car above the road. With this type of sports car, 75 instead of 72 decibels are allowed - the law plays into the hands of modern technology. However, in the future it is also conceivable to choose a different approach, for which it is corresponding standards needs. The automakers are also in the process of adopting such standards not completely uninvolved, since these are also in the Working group on noise protection of the UNECE, the Economic Commission for Europe and the United Nations. It was only recently adopted stricter limits. There are even plans to make these even stricter in the future (in the middle class from 2022: 70 decibels, from 2026: 68 decibels). With these values, the noise level, officially measured, corresponds to that of an electric car.

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Keywords on the topic: Acoustic noise measurement, noise measurement, stationary noise measurement, driving noise measurement, near field measurement, sound measurement, dBA measurement!

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