Reducing the undesired or harmful effects of sound is a goal for every sound engineer.
One of the most popular techniques consists in blocking the sound transmission path using passive acoustic material treatments.
Passive acoustic barriers are made of heavy and/or dense material in combination with porous, open-celled absorptive materials that stop the sound energy passing through the structure.
The LMS Test.Lab product family includes several solutions to determine acoustic properties of materials or even complete components like doors, panels or mufflers.
The impedance tube is a common instrument for material absorption tests. LMS provides a complete and easy-to-use solution for the entire process including phase calibration. Results include normal incident sound absorption, reflection factor, acoustic impedance & admittance ratio. An extended version of the impedance tube can also be used for sound transmission loss testing on components like mufflers. In this case, a 4-microphone matrix method is used. The same set-up can also help determine the sound transmission loss of material samples.
Room methods require a larger investment in infrastructure but offer several advantages compared to the impedance tube test, such as larger sample testing, a non-homogenious object characterization, or a more realistic random incident sound field. The LMS Acoustics solutions are used for absorption & sound transmission loss testing according to international & in-house standards.
For in-situ transparency testing on components like a car hood, a cockpit dashboard or a firewall, LMS Test.Lab Sound Intensity or LMS Test.Lab Holography applications are a perfect fit. These quantitative engineering methods provide maximum understanding of weak acoustic spot location.
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