Sound field mapping

What is sound field mapping?

Sound field mapping is a very efficient measurement method for the fast detection of acoustic problem areas. A sound field map usually displays the measured sound levels as a color gradient over a photo of the measured structure. This superimposed representation allows the acoustic weak points to be quickly identified. In the broadest sense, this representation is comparable to the contour lines on maps.

To create such maps, acoustic measurements have to be performed at a large number of spatially precisely defined positions. Subsequently, the interpolation between the measuring points is carried out using various mathematical methods. The following figure shows an exemplary sound field map above a PC workstation with 2 loudspeakers (for better clarification only above the right side). With this map you can quickly see that most of the noise is coming from the loudspeaker.

Schallfeldkartierung I Sound Field Mapping - HoloMetrix GmbH

What types are there?

In practice 3 different methods for sound field mapping have been established.

Sound field mapping using sound intensity measurement

If there is a stationary acoustic problem, the use of a sound field mapping by means of a sound intensity probe is suitable. The sound intensities are measured one after the other at the defined positions. A corresponding software then superimposes the measurement results graphically over an image, which allows the radiated sound power on this partial area to be determined. Furthermore, it is possible to quantify changes in the structure with a new measurement. The results can then be used to derive and evaluate various measures.

This method for sound field mapping has relatively low requirements on the measurement technique, since it only requires two channels and an SI probe. On the other hand, however, the effort required to carry it out is somewhat higher.

Our patented Augmented Reality Software virtually defines the exact measurement positions by means of AR-glasses. This considerably reduces the effort to perform such a sound field mapping.

If you are interested in this method, please send us a message. We will be glad to help you.

Acoustic near field holography

With some measurement objects it can happen that a large number of potential sound sources are present in a very confined space (e.g. in a combustion engine). To ensure a reliable localization of these sound sources, a very high spatial resolution is required. In practice a sound pressure microphone array is used for this purpose. These, mostly hand-held, arrays are moved several times at a distance of 10-15 cm above the surface of the measurement object. This small distance is necessary to ensure that they operate in the acoustic near field of the object.

The significant advantage of this method is that even closely spaced sound sources can be reliably separated and ordered. However, the demands on the measuring instruments are considerably higher than for sound field mapping using sound intensity measurement.

Far-field method using beamforming

The far-field methods also work with a microphone array. However, the sound sources are determined by the effect of the time of flight difference at great distance from the sound source. This is done using beamforming calculations (methods for determining the position of sources in wave fields).

In practice, the far-field method is performed with so-called acoustic cameras. Such systems are very well suited for the fast detection of acoustic weak points. However, additional measuring equipment is also required here. Furthermore, measures for improvement are difficult to quantify with a renewed comparative measurement.

If you are undecided which of these methods you should choose in your specific case, we will be happy to advise you. We will also map the sound field of your measurement object for you.

Our services include

  • Sound field mapping with sound intensity probe
  • Sound field mapping with sound pressure measurement
  • Localization of unwanted sound sources
  • Evaluation of acoustic measures on a structure
  • Easy interpretation of the results

Contact

HoloMetrix GmbH
Wixhäuser Str. 23
64390 Erzhausen
Germany

+49 6150 8507158

Frankfurt University of Applied Sciences Logo

FOUNDED OUT OF THE FRANKFURT UNIVERSITY OF APPLIED SCIENCES

© 2021  HoloMetrix GmbH – All rights reserved

Sound field mapping

What is sound field mapping?

Sound field mapping is a very efficient measurement method for the fast detection of acoustic problem areas. A sound field map usually displays the measured sound levels as a color gradient over a photo of the measured structure. This superimposed representation allows the acoustic weak points to be quickly identified. In the broadest sense, this representation is comparable to the contour lines on maps.

To create such maps, acoustic measurements have to be performed at a large number of spatially precisely defined positions. Subsequently, the interpolation between the measuring points is carried out using various mathematical methods. The following figure shows an exemplary sound field map above a PC workstation with 2 loudspeakers (for better clarification only above the right side). With this map you can quickly see that most of the noise is coming from the loudspeaker.

Schallfeldkartierung I Sound Field Mapping - HoloMetrix GmbH

What types are there?

In practice 3 different methods for sound field mapping have been established.

Sound field mapping using sound intensity measurement

If there is a stationary acoustic problem, the use of a sound field mapping by means of a sound intensity probe is suitable. The sound intensities are measured one after the other at the defined positions. A corresponding software then superimposes the measurement results graphically over an image, which allows the radiated sound power on this partial area to be determined. Furthermore, it is possible to quantify changes in the structure with a new measurement. The results can then be used to derive and evaluate various measures.

This method for sound field mapping has relatively low requirements on the measurement technique, since it only requires two channels and an SI probe. On the other hand, however, the effort required to carry it out is somewhat higher.

Our patented Augmented Reality Software virtually defines the exact measurement positions by means of AR-glasses. This considerably reduces the effort to perform such a sound field mapping.

If you are interested in this method, please send us a message. We will be glad to help you.

Acoustic near field holography

With some measurement objects it can happen that a large number of potential sound sources are present in a very confined space (e.g. in a combustion engine). To ensure a reliable localization of these sound sources, a very high spatial resolution is required. In practice a sound pressure microphone array is used for this purpose. These, mostly hand-held, arrays are moved several times at a distance of 10-15 cm above the surface of the measurement object. This small distance is necessary to ensure that they operate in the acoustic near field of the object.

The significant advantage of this method is that even closely spaced sound sources can be reliably separated and ordered. However, the demands on the measuring instruments are considerably higher than for sound field mapping using sound intensity measurement.

Far-field method using beamforming

The far-field methods also work with a microphone array. However, the sound sources are determined by the effect of the time of flight difference at great distance from the sound source. This is done using beamforming calculations (methods for determining the position of sources in wave fields).

In practice, the far-field method is performed with so-called acoustic cameras. Such systems are very well suited for the fast detection of acoustic weak points. However, additional measuring equipment is also required here. Furthermore, measures for improvement are difficult to quantify with a renewed comparative measurement.

If you are undecided which of these methods you should choose in your specific case, we will be happy to advise you. We will also map the sound field of your measurement object for you.

Our services include

  • Sound field mapping with sound intensity probe
  • Sound field mapping with sound pressure measurement
  • Localization of unwanted sound sources
  • Evaluation of acoustic measures on a structure
  • Easy interpretation of the results

Contact

HoloMetrix GmbH
Wixhäuser Str. 23
64390 Erzhausen
Germany

+49 6150 8507158

Frankfurt University of Applied Sciences Logo

FOUNDED OUT OF THE FRANKFURT
UNIVERSITY OF APPLIED SCIENCES

© 2021  HoloMetrix GmbH – All rights reserved

Sound field mapping

What is sound field mapping?

Sound field mapping is a very efficient measurement method for the fast detection of acoustic problem areas. A sound field map usually displays the measured sound levels as a color gradient over a photo of the measured structure. This superimposed representation allows the acoustic weak points to be quickly identified. In the broadest sense, this representation is comparable to the contour lines on maps.

To create such maps, acoustic measurements have to be performed at a large number of spatially precisely defined positions. Subsequently, the interpolation between the measuring points is carried out using various mathematical methods. The following figure shows an exemplary sound field map above a PC workstation with 2 loudspeakers (for better clarification only above the right side). With this map you can quickly see that most of the noise is coming from the loudspeaker.

Schallfeldkartierung I Sound Field Mapping - HoloMetrix GmbH

What types are there?

In practice 3 different methods for sound field mapping have been established.

Sound field mapping using sound intensity measurement

If there is a stationary acoustic problem, the use of a sound field mapping by means of a sound intensity probe is suitable. The sound intensities are measured one after the other at the defined positions. A corresponding software then superimposes the measurement results graphically over an image, which allows the radiated sound power on this partial area to be determined. Furthermore, it is possible to quantify changes in the structure with a new measurement. The results can then be used to derive and evaluate various measures.

This method for sound field mapping has relatively low requirements on the measurement technique, since it only requires two channels and an SI probe. On the other hand, however, the effort required to carry it out is somewhat higher.

Our patented Augmented Reality Software virtually defines the exact measurement positions by means of AR-glasses. This considerably reduces the effort to perform such a sound field mapping.

If you are interested in this method, please send us a message. We will be glad to help you.

Acoustic near field holography

With some measurement objects it can happen that a large number of potential sound sources are present in a very confined space (e.g. in a combustion engine). To ensure a reliable localization of these sound sources, a very high spatial resolution is required. In practice a sound pressure microphone array is used for this purpose. These, mostly hand-held, arrays are moved several times at a distance of 10-15 cm above the surface of the measurement object. This small distance is necessary to ensure that they operate in the acoustic near field of the object.

The significant advantage of this method is that even closely spaced sound sources can be reliably separated and ordered. However, the demands on the measuring instruments are considerably higher than for sound field mapping using sound intensity measurement.

Far-field method using beamforming

The far-field methods also work with a microphone array. However, the sound sources are determined by the effect of the time of flight difference at great distance from the sound source. This is done using beamforming calculations (methods for determining the position of sources in wave fields).

In practice, the far-field method is performed with so-called acoustic cameras. Such systems are very well suited for the fast detection of acoustic weak points. However, additional measuring equipment is also required here. Furthermore, measures for improvement are difficult to quantify with a renewed comparative measurement.

If you are undecided which of these methods you should choose in your specific case, we will be happy to advise you. We will also map the sound field of your measurement object for you.

Our services include

  • Sound field mapping with sound intensity probe
  • Sound field mapping with sound pressure measurement
  • Localization of unwanted sound sources
  • Evaluation of acoustic measures on a structure
  • Easy interpretation of the results

Contact

HoloMetrix GmbH
Wixhäuser Str. 23
64390 Erzhausen
Germany

+49 6150 8507158

Frankfurt University of Applied Sciences Logo

FOUNDED OUT OF THE FRANKFURT UNIVERSITY OF APPLIED SCIENCES

© 2021  HoloMetrix GmbH
– All rights reserved