• Campbell Associates

SOUND INTENSITY FOR SOUND TEST ENGINEERS

Why a sound intensity instrument is a must-have tool for any sound test engineer in a poor acoustic environments?


Carrying out a sound intensity measurement is perhaps not considered the easiest of sound measurements to undertake or get your head around for anyone unfamiliar with the technology. It’s could be previously considered a time-consuming measurement changing spacers mid-measurement and the theory somewhat complex to understand. I've spent some time with Erlend Fasting from Norsonic understanding just how the new Nor150 sound intensity instrument makes the process faster, easier and more understandable for acoustic consultants, and test engineers that carry out multi-fold tests frequently, to deliver their products on time, to their customers.


Norsonic has been working hard to simplify the measurement process of a sound intensity measurement. One key factor of the process is time, so a special focus has been made to reduce this, in turn, reducing cost by eliminating the requirement to change the spacer between the microphones. Aside from this matter, Norsonic recognises we need a better visual display of data, and data that can be understood quickly by the test engineer. In the next few paragraph's I will explain how Norsonic has overcome this fine line between convoluted or visually understandable in the new Nor150 Sound Intensity Instrument.

The Nor150 intensity meter from Norsonic ensures a reliable, simple and confident way to measure, far advancing any other current technology.


Why? Because the Nor150 utilises a new innovative probe, instrument hardware and calibration technology that minimises duplication of work and increases measurement capability. The instrument provides smart-phone technology that doesn’t rely on a computer to produce answers yet, gives answers like you were on your PC.


It’s an instrument that can enable the user to visualise their measurement, the surface, and put the measurement data into context, with frequency displays for both positive and negative intensity in real-time, with on-screen warnings and notifications as-well-as suggestive actions to ensure the user is measuring in-accordance to the standard and guideline.


New probe and calibration technology


The Nor150 utilises the Nor1290 probe with two opposing microphones spaced with either a 12 mm, 50 mm or 100 mm spacer, phase-matched by the instrument.


These spacers historically defined the possible frequency range measurable by the instrument, which is described as the dynamic capability between two microphones. The better dynamic capability we have, the further reliable and capable our measurement is with its selected spacer across the frequency range.

If we have a wider frequency range and improved dynamic capability available, we can measure more efficiently and importantly save time, rather than repeating measurements to collect absent or erroneous frequency data by using bigger spacers.

Outdated systems typically cannot achieve acceptable dynamic capability at low frequency when using smaller spacers, consequently, the operator must change the spacer to one larger, calibrate, and repeat the measurement to include this missing data.


With the Nor150, the Nor1290 probe and our new Nor1294 phase matching calibrator, we can achieve impressive dynamic capability across the frequency range.


This is done by placing the Nor1294 phase calibrator coupler between the two microphone probes, closing the pressure vent and utilising a known signal from in-built Nor150 signal generator. The system will then perform various signal checks over 30 seconds to correct the phase match between microphones, and ensure the dynamic capability meets and even exceeds the minimum standard requirements. You can see the typical Nor1290 probe performance in the graph below. The orange bars demonstrate the typical performance with the Nor1290 probe and 12 mm spacer against the standard requirements indicated in blue and green for the different sized spacers. This dynamic capability should ensure the user only needs to use the 12 mm spacer for the entire measurement!







The Nor150 is so advanced that it keeps a history of pressure, phase and residual calibrations for future reference. See the histogram on the left.






Keeping track of your measurement position?

The Nor150 is configured with various standards and measurement surface types the user can apply. These measurement templates can be configured so that the user can define the shape, size and surfaces into segments for the measurement. The meter visually displays a mesh drawing of the shape, with results displayed in each field, including the display of errors or missing data which are seen in the below image. The on-screen values can be switched between LwA, IAeq & LAeq by simply pressing the FUNCtion key.



The user step by step carries out the measurements in any order that works for them, carrying out a horizontal and vertical pass where required. Should the user make errors during the measurement, simple warnings are displayed as icons and notifications. The operator can tap on the warning using the touchscreen display and a solution from the guideline will be presented to the user, which makes this system the most intuitive and simple to use the device on the market today.



How can sound intensity benefit me?

Imagine having a test environment that wasn’t perfect, a noise source you couldn’t segregate from other sources, external noise sources you aren’t allowed to turn off. And even if you could, the cost would astronomical.

So, how can I overcome this?

The simple answer might be to leave everything where it is and use the sound intensity measurement method.

The measurement of sound intensity is helping manufacturers, consultants and operators all around the world. For instance, if the engineer should need to know the sound power level of the pump alone (within the factory environment), while the pump is fixed and operating between two other noise sources (motor and fluid) in its real-life simulation, how can an accurate sound power level result be achieved?

Using the Nor150 and probe kit, we can easily measure the output of the pump safely, by creating a defined measurement mesh around the pump installed, and specify the mesh and shape dimensions within the sound level meter and carry out the measurement according to the standard to give us the result of the pump only. We are then able to measure, visualise and quantify sound intensity radiating in positive and negative directions from the machinery and other sources to ensure an accurate and reliable result, according to the selected method and standard in the instrument.



How can sound intensity benefit me?

Imagine having a test environment that wasn’t perfect, a noise source you couldn’t segregate from other sources, external noise sources you aren’t allowed to turn off. And even if you could, the cost would astronomical.

So, how can I overcome this?

The simple answer might be to leave everything where it is and use the sound intensity measurement method.

The measurement of sound intensity is helping manufacturers, consultants and operators all around the world. For instance, if the engineer should need to know the sound power level of the pump alone (within the factory environment), while the pump is fixed and operating between two other noise sources (motor and fluid) in its real-life simulation, how can an accurate sound power level result be achieved?

Using the Nor150 and probe kit, we can easily measure the output of the pump safely, by creating a defined measurement mesh around the pump installed, and specify the mesh and shape dimensions within the sound level meter and carry out the measurement according to the standard to give us the result of the pump only. We are then able to measure, visualise and quantify sound intensity radiating in positive and negative directions from the machinery and other sources to ensure an accurate and reliable result, according to the selected method and standard in the instrument.




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