Still topical- Microtech Gefell - Turnkey indoor and outdoor acoustic test benches for the automotive sector


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Still topical- Microtech Gefell - Turnkey indoor and outdoor acoustic test benches for the automotive sector

Exterior and interior noise measurements are of increasing importance for the vehicle development as well as in the production-side quality assurance and are decisive for the type approval or the product sound design.

In order to obtain a type approval for vehicles as a precondition for the sale in different markets, it is required, among other things, to carry out a type test, e.g. according to standard ISO 362-1:2015, to meet the acoustic requirements.

For this purpose, a special driving cycle is executed on a defined measuring section.

Microtech Gefell has long-time experience in planning and installing the necessary pass-by measuring sections.
A special acoustic measuring system, different control signals such as light barriers, speed measuring system, GPS (if any), climate data recording and road temperature measurement are integrated into the system.
They are implemented by means of installation-related planning as well as performance for fixed installations of pass-by test stands under field conditions.

Weatherproof microphones from MTG’s product range are used for permanently installed systems. Together with the used sound level measuring system, they form a sound level measuring chain which is used for checking the standard values and, simultaneously, for the frequency-related analysis of the driving noise.

Microtech Gefell -Turnkey intdoor solutions - Simulation test benches

In order to develop vehicles for the fulfilment of the driving noise standards, which vary widely all over the world, prior to the type test, test stands for simulated pass-by with fixed vehicle on a chassis dynamometer and microphones arranged in lateral rows are used. Using the microphone rows, a pass-by of the vehicle is simulated by software.

Microtech Gefell also has extensive experience in planning and installing such test stands and is able to integrate the components necessary in addition to the measuring system. The structural and building-related work, e.g. acoustic room setup and drive systems, is coordinated for the projects by Microtech Gefell, but it is not included in the company’s scope of work.

Furthermore, the Microtech Gefell team plans and installs the metrological components in any kind of acoustic and vibration test stands such as sound measuring rooms with chassis dynamometers, modal analysis and hydro pulse systems.

Calibration of microphones used on pass-by measuring sections or pass-by simulation test benches

At the same time, Microtech Gefell offers - with an own calibration laboratory for factory calibration and as DIN/ISO 17025 laboratory and DKD laboratory approved by the German Accreditation Body (DaKKS) - a calibration of the measuring microphones and sound pressure measuring stands used at pass-by measuring sections or pass-by simulation test stands.

The calibration of the weatherproof microphone units and the other sensors can be carried out by Microtech Gefell as well. In case of acoustic calibrations, highest accuracy is crucial here since the absolute permissible limits of the driving noise of vehicles are determined for the type approval as absolute sound level measurements.
It depends, among other things, on the microphone sensitivity determined as calibration values by the calibration laboratory and on the absolutely precisely determined sound pressure measuring standard in the form of a calibrator or pistonphone whether a vehicle series complies with the maximum permissible driving noise which can be found in the car registration document for each type and whether this vehicle series may be produced at all.

In view of the scandals regarding exhaust emission values at various manufacturers, which were reported in the press, the high responsibility of the performing calibration laboratory and its employees for the calibration and its traceability becomes clear.

Microtech Gefell -Microphones in weatherproof overall arrangements

As a traditional company with nearly 90 years of experience in microphone development and production, Microtech Gefell produces microphones in weatherproof overall arrangements, already mentioned, which are perfectly suitable for the high requirements regarding accuracy, climate resistance especially in case of pass-by measuring sections installed outdoors and long-term stability.

A high degree of protection against influences such as temperature and relative humidity is required for such models in order to be generally suitable for the high accuracy requirements imposed in the automotive sector.

This also applies under the complicated conditions of permanently installed systems in the open air in different climate zones of the world where there are more and more vehicle manufacturers today.
Especially in Asian countries, e.g., there is an enormous increase in vehicle manufacturers and vehicles produced whose conditions deviating from our climatic conditions also have to meet the accuracy requirements of the used acoustic measuring equipment by Microtech Gefell.

EMC safety of acoustic measuring systems

A complicated problem to be solved is, for example, the EMC safety of such acoustic measuring systems since the high interference-safety requirements of Germany or the European Union do not exist all over the world.

Possible interference signals of such unforeseen operating conditions at any location on the globe must not influence the highly accurate measurement result under any circumstances. Microtech Gefell is able to realise particularly interference-free transmission methods over long distances.

The symmetrical form of the measuring signal transmission known in the Studio Technology product area and the digital interfaces also coming from this market are very meaningfully used due to the synergy effect at Microtech Gefell.

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Georg-Neumann-Platz 1

07926 Gefell


+49 36649 882-0

+49 36649 882-11

Halle 1 Stand 1-502

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