A newly built office complex is designed with glass facades between the offices and the hallway. The glass facades include a glass door. Although the glass structures themselves have a sufficient sound reduction value, the sound insulation between office and hallway was measured at 19 dB, which was far below the sound insulation criteria for offices given in the regulations. It was therefore important to find out where any weaknesses were introduced in the overall structure.
The first results from the initial recordings proved disappointing. Although it was possible to hear clear differences by using the virtual microphone, which enables the user to listen to specific points in the image, the coloring of sources was only seen on a glass facade standing perpendicular to the wall of interest, as seen on the left side in the image below. Clearly this was a strong acoustic reflection and not the main source itself.
Norsonic have now released the new upgraded NorReview v6.1.37. The new version contains the following new features:
- Support for the Nor150 “ProfileB” and “Moving” reports.
- Nor150 version 1.2 markers are now visible in the NorReview displays.
- Added “Visible” property for various markers. Available from the Marker Management Bar.
- Added “Stepping Surface Mesh” setting for the 3D view.
- 3D graph rotation and view-distance settings are now saved in the NorReview projects.
- “Pause-samples” are now excluded in the “Running Leq” calculation.
- “Pause-markers” are now taken into account when doing marker-selected calculations in the Lden and TA Lärm modules.
- Added support for markers in txt-file import.
- Improved handling of the graph-image scaling when doing “Generate Word Document”.
- Support for Profile data in “MultiFile” templates enabling use of multichannel Nor850 measurements in NorReview.
- Improved handling of date&time columns when doing “Generate Excel Report”.
- Improved handling of DIN 45681 pure-tone calculations.
- In addition, there are several minor bug fixes.
A combined bar, bistro and concert venue in the city center has been renovated with a great emphasis on acoustic noise dampening. Nevertheless, the venue is still getting complaints from neighbours close by due to breakout noise from the location, especially during late night concerts. The establishment consists of a bar and bistro on the ground floor, with the concert venue on the floor above. The concert venue has several windows facing the outside street and neighbourhood buildings, and it was desirable to pin point any acoustic weaknesses in these windows. Also it was of interest to see if the wall itself needed additional measures, or if the main source contribution came from the windows alone.
4dNoise gladly introduces the next generation acoustic calibration system of Norsonic to Hong Kong with said calibration system designed to meet all the local requirements and international standards. It is a system that provides quick and accurate calibration of instruments for measuring sounds through three varying modes. Apart from the different modes, the system also comes equipped with test report generator which is fully configurable, not to mention it comes with incorporated self test functionalities.
Apart from the launch of the acoustic calibration system, there was a seminar that was held on November 2015 which has generated a lot of discussions and interests from many of its attendees. The attendees of the seminar came from various sectors, from the government, private laboratories and acoustic consultants from all over the country. Some of the topics that were discussed in the seminar tackled topics including the importance of calibration, the standards of calibrating sound level meters, maintenance of the system and more. The calibration system is important being that it is an off the shelf system that can possibly meet all the relevant requirements but only at costs that is but a fraction of those of 4dNoise’s competitors.
Basically, the next gen acoustic calibration system is an all-in-one system that is fully automated and is readily available for upgrade. This system also makes it possible for a person to build their very own acoustic calibration laboratory that conforms to the international standards such as DIN45657, IEC61672, IEC60651 and more. The acoustic calibration system also offers varying features such as test signals that comply with international standards on calibration and many others as well. As for the three different interface modes of the system, it can be manual, semi-automated or fully automated.
Additionally, when it comes to calibration of microphone’s frequency response, it uses acoustical or electrostatic method. Aside from all these, there are many other features that the system has to provide including the built-in self test functions and fully generated test report. Many of those who have been in the seminar have given positive reviews for the system. Some has even quoted that “The quiet chamber is very innovative,” and that “The sound isolating gadget is very handy and innovative.”This just shows how the new gen acoustic calibration system has provided great advantages when it comes to sound calibration. It can clearly change the way that the field of acoustics is today and lead it to a good future ahead of it.
To know more about the acoustic calibration system, please visit https://4dnoise.com/sound-noise-and-vibration-systems/nor1504a-calibration-system-for-sound-level-meters-microphones-and-sound-calibrators/. For inquiries, please email at demo@4dNoise.com.
A new product catalogue is now available for downloading on 4dnoise.com
A conference hotel in Norway is using modular walls to divide large halls into several smaller conference rooms. The rooms are divided by modular walls that provide several different opportunities for subdivision and multipurpose use of the large area spaces.
When measuring the sound insulation between adjacent rooms through the modular walls, the resulting value was found to be too low, and noise from one conference room could possibly disturb listeners at adjacent rooms. The dividing modular walls cover large areas, and are as high as 7 meters from bottom to top, which makes intensity measurements with handheld sound level meters difficult. The room dividers could have several weak points, which were not easily identifiable. It was thought that identifying and fixing the weak points in the individual modular walls would help increase the overall sound insulation capabilities of the entire wall element.
Nor848A-0.4 measurements were performed, and the acoustic camera was able to locate several weak spots on the walls even though the range where differences could be discovered were for certain areas below 0.05 dB.
The virtual microphone of the Nor848A-0.4 was very helpful during live measurements whereby you can scan and listen to the desired spots in the image, and also filter the listening function to desired frequency range. This made it possible to scan along edges and hear differences in frequency from different points. A change in frequency may indicate a sound leakage. Also by using the spectrogram function to get a visual representation of the spectrum of frequencies as they varied with time, one could further indicate a leakage at various parts of the walls.
A large LNG gas facility (approximately 300m x 150m) producing 300 000 tons of LNG annually is situated in a terminal area with the nearest populated area at a distance of around 1 km. Within the gas production facility, a low frequency tonal noise at around 500 Hz is generated causing complaints from nearby neighbours. The tone imposes a more stringent noise requirement on the facility, forcing noise reducing actions being made on the source.
In addition to the tonal noise, the entire LNG gas facility is rich in noise emitting sources, including losing and loading of maritime vessels, which further complicates the source location of the single tonal noise source. Also the location of the facility at the coastal regions of the western part of Norway, ensures that windy conditions are frequent, with wind noise further impeding the quality of acoustic recordings.
Based on measurements with hand held sound level meters, the problem area was narrowed down to be a large pipe in the midst of the facility. However it could not be
determined if the emitted tonal noise was from the entire pipe itself, or if it originated at a specific part of the pipe. There was also uncertainty whether there existed multiple
sources within the pipe, for instance at both the base and top layer. In the worst case the noise insulation would have to be performed over the entire pipe length, which could have been a very expensive solution.
By positioning the center of the acoustic camera towards the pipe and adjusting the frequency to display only coloring within the 500 Hz 1/3-band, the noise source was located within seconds, and the source producing the tonal part from the pipe was detected. Measurements from different measurement positions also confirmed the source location.
By placing the virtual microphone on the localised source and using the spectrogram function, it was easy to verify the position of the source emitting a tone at 460 Hz.
Although the measurement location had quite windy conditions, the wind noise did not affect the measurement results at all. Wind noise can be viewed as spatially white, which means that wind noise sampled at different places in space, as is done with the Nor848A, is not correlated from position to position. When many different signals from many microphones are added in the beamforming algorithm, the wind noise will be added out of phase and attenuated proportional with the number of microphones being used.
With the acoustic camera it was possible to detect the tonal sound of the most crucial parts of the turbine. This meant that the facility could focus on and implement noise reduction actions in the right places.
After pin pointing the location of the noise source, further analysis could be made with measurements performed closer to the source of interest in order to further determine
the position and cause of the generated tonal noise.
The Nor1517A system measures the airflow resistance in porous materials according to ISO 9053/DIN EN 29053 (DIN52213).
- Quality control in production process.
- Testing in research and development.
- Fast and accurate measurement and readout of measurement results.
- Accepts test material of various form and size.
- Easy setup and use.
- Large dynamic range of measurement.
- Measures at 2 Hz.
- Standards: ISO 9053/DIN EN 29053 (replaces DIN 52213).
- Measurement range: 10 Pa s/m to 30 000 Pa s/m, up to 200 000 Pa s/m when correcting for non-linearities..
- Airflow resistance: 0,5 cm/s and 0,05 cm/s.
- The piston can be set for 2 different stroke lengths: 28 mm and 2,8 mm.
- Max. diameter of test pieces: 100 mm.
- Calibration disc
- Sample holder 1517A/03
- Sound level meter Nor140 with microphone,sealing device and 1/3 octave filters
Product Data Sheet
Featuring the largest colour touchscreen in a handheld meter on the market today, the Nor150 Sound and Vibration analyser provides the user friendliness of a smartphone. Further features include:
- built in web server,
- GPS and
- advanced voice and text notes
- a dual channel analyser
Download Nor150 product brochure