Acoustics

AVAS/NVH: Testing and Development for Optimum Vehicle Acoustics

Cars with excellent acoustics have been subjected to an intensive battery of tests. Vibrations that can be felt and heard in and around the car are investigated, unwanted noise is analyzed and suppressed and an internal and external acoustic design is developed. In our acoustic center, we can perform all the necessary acoustic tests for cars with combustion engines, hybrid drives and electric powertrains. These tests cover everything from material samples, subcomponents and individual assemblies through to complete vehicles.

Our specialist team provides the entire bandwidth of NVH (noise, vibration and harshness) test services, including areas such as acoustic comfort and aeroacoustics and the development and testing of Acoustic Vehicle Alerting Systems (AVAS) and e-sound. With the goal of achieving a vehicle that is completely free of unwanted noise, we become involved during the product development stage and use a combination of virtual simulations and physical testing methods to achieve the best possible solutions. Our standards-based, certified processes guarantee our customers the highest quality results.
 

NVH testing: rapid cause analysis and solution development

We have been carrying out NVH tests for over 20 years and these are now available at three sites: Munich, Ingolstadt and Sassenburg near Wolfsburg. Our team, which is made up of experts in acoustics, physics and psychoacoustics, has access to ultra-modern test facilities. The team members have extensive experience, excellent analytical skills and comprehensive operational knowledge, all of which are crucial for identifying the causes of problems and developing appropriate solutions quickly and reliably.

Optimizing acoustics: a permanent focus on possible consequences

Suppressing unwanted noise is not the be-all and end-all of acoustic testing. Any measure that is taken, such as adding an absorber, using a new material or changing the structure or combination of materials, generally has an impact on the properties of the component. To ensure that we both improve the acoustics and retain all the functions of the component, we make use of Bertrandt’s extensive product engineering expertise, in particular in areas such as product design and engineering design. One of the fields we specialize in is aeroacoustics, which involves blocking out unwanted wind noise, for example the humming sound that is caused when a window is opened.

 

Hybrid vehicles: acoustic testing and improvement in all operating modes

In the case of hybrids, all the operating modes must be taken into consideration. We carry out the tests and trials in the labs in our test centers. On a chassis dynamometer for acoustic testing located in an acoustic room, we simulate the different modes of the powertrain. The resulting excitations are evaluated and the phenomena are described and coordinated with the absorbers in the interior. When a new range of models is being developed, these acoustic testing and optimization measures begin early in the process. As well as providing support for vehicles that are in production, we also become involved in the concept and pre-development phases.

 

Electric mobility: AVAS and e-sound

In quiet electric vehicles, the noises in the interior, such as the click of the glove box shutting or the whirring of a window opening, are much more noticeable. We also work closely on acoustic comfort issues of this kind, together with the relatively new fields of testing and development relating to AVAS and e-sound design for the exterior and interior of BEVs.

In this area, we focus in particular on pass-by noise, in other words the external perception of the vehicle, and the question of how recognizable sounds can be influenced, for example by changing the structure of the body or using actuators. We are already running customer projects in these areas.

 

Important features in brief

  • Vehicle acoustics
  • Aeroacoustics
  • Psychoacoustics
  • Building acoustics
  • Room acoustics
  • Electroacoustics
  • Technical acoustics
  • Physical acoustics
  • Traffic noise
  • ISO 3744, 3745, 3746
  • ISO 10844
  • DIN 45681, 45631
  • ISO 226
  • ISO 532
  • Echo chamber, anechoic chamber, semi-anechoic chamber
  • Acoustic cabinet
  • Alpha Cabin
  • Window test rig, roof test rig
  • Chassis dynamometer for acoustic testing, all-wheel drive dynamometer, standard dynamometer
  • Siemens LMS Testlab
  • Müller BBM PAK
  • HeadAcoustics Artemis
  • Microphone
  • Intensity probe
  • Acceleration sensor

Our analyses cover airborne noise, structure-borne noise, fluid-borne noise, sound pressure (level), sound velocity, sound acceleration (level), sound intensity (level) and sound power (level):

  • Frequency analysis
  • Order analysis
  • Operational transfer path analysis (OTPA and TPA)
  • Experimental modal analysis (EMA)
  • Operational vibration analysis
  • Determining the insulation and insertion loss
  • Determining the reverberation time, sound power, sound pressure and sound pressure level
  • Lack of unwanted noise, occurrence of unwanted noise (squeak and rattle in the interior)

Your Contact

Sven Neumann

Vice President Operations – Testing Solutions