Anechoic chamber for acoustic measurements
VDE
2018-05-03 page 347 0

Acoustics and noise emission - testing and certification at the VDE Institute

How loud is loud? At what point are noises that emanate from electrical products that we use daily hazardous to your health? Which legal requirements must be followed with a view to the volume of electric appliances and machines? The experts from the VDE laboratory for acoustics, noise emission and vibration measurements are very well-versed in their profession. In addition, there is very precise measurement technology and a modern testing environment.

Contact

Tobias Daum
Links

We offer tests with ultra-modern measurement technology

Thanks to various standards, regulations and directives, consumers and the environment will be protected from harmful noise emissions. At the same time, the manufacturer must ensure that appliances and machines follow the appropriate provisions and guidelines. The VDE Institute has long been testing compliance with normative and statutory provisions for acoustics and noise emissions for its customers. Acoustic tests are performed in a semi-anechoic room of accuracy class 1 (also known as an anechoic chamber) using the latest measurement technology. This ensures that the accuracy requirements of product standards, which mostly require just an accuracy class of 2, are consistently met and even significantly surpassed. Thanks to the option of processing the measurement data in real time, tests can quickly be completed and test results can be disclosed in a timely manner. A corresponding VDE certificate provides the right to label with a VDE mark, which signals quality and safety, serves as a competitive advantage, and makes it easy to enter international markets.internationale Märkte.

Our service offering

Our service offering includes many different tests in acoustics, noise emission and vibration. Type tests certify conformity with the 2000/14/EC Outdoor Directive or with other directives and product standards that require measurements of the sound power or sound intensity. In addition, there are EU energy label type tests for household appliances and appliances for commercial use.

All of our tests can not only be performed on the end product but also as early as during product development. In addition to the ones listed below, there is also an entire set of additional services related to acoustics, noise emission and vibration tests. These include measurements according to customer specifications as well as on-site tests.

An overview of our service offering

  • Investigating noises with a narrowband analysis
  • Locating the source of noise on appliances and machines
  • Measurements according to customer specifications
  • Psychoacoustic comparison test to assess sound quality
  • Reproducible measurements by preventing interferences in a measurement room according to DIN EN ISO 3745 (semi-anechoic chamber of accuracy class 1)
  • Testing mobile audio equipment and headphones using a head and torso simulator according to EN 50332
  • Tests during development
  • Type tests for the EU Directive 2000/14/EC (“Outdoor Directive”)
  • Type tests as part of the EU energy label and ECO Design Directive.
  • Type tests for all directives and product standards that require the sound power to be determined or the level of noise emission on the user’s ear to be measured
  • Vibration tests for hand-held tools

Our measurement and testing equipment

Microphone for acoustic measurement
VDE

The interior dimensions of our anechoic chamber measuring 12 m (length) x 10 m (width) x 6 m (height) allow for the enveloping surface measurement process to be carried out with a 4 m microphone radius, among other things.  Among other things, the “Outdoor Directive” requires this measurement distance for electric garden appliances and forestry machines that are used in the outdoors. Since the interior sound level of our anechoic chamber is below 7 dB(A), precise measurements can also be carried out with very quiet test subjects. Measurements can be performed with up to 20 microphones.

The acoustic characteristics of the anechoic chamber were verified by an acceptance test performed by the Physikalisch Technischen Bundesanstalt in Braunschweig (Physical Technical Federal Institute or PTB). Using the latest software offers many different evaluation and display options. The measuring appliances meet the highest Class 1 accuracy requirements according to IEC 61672-1:2002. All measuring appliances are fully traceably calibrated by a DIN EN ISO/IEC 17025-certified laboratory.

In accordance with the requirements in product standards, a variable reverberant wall with a size of up to 4.2 m x 5.6 m can be constructed to measure appliances in front of the wall.

Our measuring appliances allow for the following:

  • Noise spectrum analyses
  • Structure-borne sound measurements
  • Sound pressure level measurements
  • Sound intensity measurements

Further details about our test equipment

Headphones

Excessive volume from headphones regularly causes significant hearing damage. EN 50332 defines a measurement process with which threshold values are defined with a maximum sound level for headphones in conjunction with portable audio appliances. Some countries require compliance with these threshold values. As such, compliance with EN 50332 is of great importance for many manufacturers. For this process, a head and torso simulator is used, which is state-of-the-art and meets the latest requirements. Measurements are performed in a fully-automated manner via software.

Locating the sound source

Locating the sound source with an intensity probe is of particular interest for product developers. This measuring method is a dual-microphone technique with which the sound intensity or sound power of emitting surfaces can be calculated. It is used to detect the sound source, among other things. A sound mapping can be created with the help of a raster scan of the tested surface. A color is assigned to every single measurement point according to the intensity. This process is used in development to visualize weak points in systems during noise emission.

Narrowband analysis

An additional measurement method that is used in the VDE laboratory is the narrowband analysis. In this analysis with the FFT method (Fast Fourier Transform), high frequency resolutions (a resolution of up to 1 Hz) of the tested appliance are created. Discrete excitation frequencies, harmonious and sidebands can be identified and depicted during testing. This process is also useful for manufacturers in the development phase for locating interfering frequencies and eliminating them ahead of time by changing the design.

Sound quality and psychoacoustics

The type and quality of the noise, and not just the sound level, constitute the sound quality of a product, from household appliances to tools and automobiles. A customer can decide on whether they find a product attractive or abhorrent. The right “sound” can increase sales. Furthermore, the sound quality can help a appliance stand out from the masses. When testing psychoacoustic parameters, pure physical parameters such as sound level, frequency, bandwidth, duration or modulation depth are depicted at aurally-compatible parameters. At the same time, several physical sizes that can be assessed independently from other perceptions affect a psychoacoustic factor. Loudness, definition, roughness, tonality, impulsiveness or vibration strength are among the perception parameters that are used in psychoacoustics as a foundation for a hearing-related sound analysis and evaluation. The VDE Institute offers comparison tests where appliances from different manufacturers are compared and evaluated with the psychoacoustic parameters.

Utility installations

We can also cover our customers’ special testing requirements with variable power and voltage supplies. Variable power supply up to 75 kW (from DC to 5000 Hz) of continuous output.

  • Air-conditioned testing Environment
  • An exhaust gas extraction system allows for testing on appliances with a combustion engine
  • Connectors for water, wastewater and compressed air
  • Variable power supply with any superimposed voltage waveforms or voltage curves

You may also be interested in this