Sound Power Measurement Hemisphere kit
The GRAS hemisphere kits are optimized for easy sound power testing ensuring acoustically correct and repeatable mea surement data. The hemisphere kits are straightforward to assemble and it is simple to position the microphones and access the DUT.
The GRAS hemispheres are compliant with the ISO 3744, 3745 and 3746 (ANSI S12.54, S12.55, S12.56) standards and accommodate for 4, 10 and 20 positions. The hemisphere kits contain the mechanical structure, microphone sets and cables.
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Product Applications
Two hemisphere structures are available; a 1 m measurement radius and a 2 m measurement radius. Each structure is available in CCP Hemisphere Kit, LEMO Hemisphere Kit and LEMO lownoise Hemisphere Kit variants.
Typical applications and use
Depending on the size and the emitted acoustic level of the DUT, the hemispheres will allow sound power measurements on everything from small-sized personal electrics to office machines and IT products, household appliances, power tools, and smaller engines. The only restriction is, that the characteristic dimension of the DUT may be no more than half the measurement radius.
Design
The hemispheres, 1 m or 2 m radius, are available as preconfigured kits with 4, 10 or 20 microphone sets in 3 variations; CCP, LEMO and low-noise LEMO. The microphone sets can be connected directly to all professional measurement systems and are available for both CCP and 7-pin LEMO inputs. If your system platform supports intelligent transducers according to IEEE 1451.4 (TEDS), the system can be set up to identify the microphone properties and position in the array.
Calibration
All included microphone sets are delivered with individual calibration charts including sensitivity values and frequency responses. These sensitivity values can be used directly in your system setup.
For frequent measurement chain verification a reference sound source will be required. GRAS supplies 114 dB types for the standard microphone sets and a special 94 dB adapter for the low-noise sets. Depending on the use and your internal quality control requirements we recommend that the sets are re-calibrated at least every second year.
Datasheets