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AcousTech performs 3 on-site visits in Darwin for acoustic testing accuracy


Acoustic Testing for Royal Australian Navy’s Offshore Patrol Boats




Kaefer Integrated Services Pty Ltd Australia (Contractor)



Flexshield's acoustic engineer takes a trip to Darwin
Testing the attenuators that control the noise for the main engine.

Initial project requirements:

AcousTech was contacted by KAEFER Integrated Services Pty Ltd Australia to assist on a project for the Royal Australian Navy’s offshore patrol boats.

Having operated in Australia for over 50 years, KAEFER Integrated Services safely delivers project and maintenance contracts in every state and territory. Today it is the leading provider of industrial services, with over 1,500 personnel delivering their disciplines in construction and maintenance.

KAEFER Integrated Services engaged AcousTech to assist with a project in the Northern Territory that involved a team from around the country and Germany. The team worked together to perform factory acceptance tests for four noise attenuators for the Australian Defence Force. Along with acoustic testing, the team made recommendations to improve the quality of the test set up during their three on-site visits.

The RAN’s offshore patrol boats feature noise attenuators located at the exhaust of the main and emergency engines, to reduce the amount of noise the patrol boats emit.

AcousTech’s Senior Acoustic Engineer travelled from Queensland to Darwin three times during the project.

Project challenges:

The testing process

The objective of the test at the factory was to determine the Insertion Loss (noise reduction when the attenuator is in place) before installation on the navy’s offshore patrol boats.

A loudspeaker unit was constructed to excite the testing rig and to measure the noise at the other end of the “exhaust”.

Each test is performed twice: once with the attenuator and once without it. When testing is complete and all the noise measurements are post-processed,  the Insertion Loss results are known. This allows recommendations on where to adjust the attenuators, the testing process, and more.

To achieve accurate results the environment used to complete the testing must be soundproofed; otherwise, the results will be inaccurate.

Flexshield solution:

Trip 1: Ancillary testing

On their first trip to Darwin, the team tested the ancillary attenuators (the smaller noise control solutions) for the emergency engines.

Trip 2: Primary engine testing

The second Darwin trip involved testing the attenuators which controlled the noise for the patrol boats’ main engines. During this testing, the results received were inaccurate due to the testing rig.

The team made recommendations for improvements to the testing rig to achieve the correct results, necessitating a third trip to the Northern Territory for AcousTech.

Trip 3: Final testing

The third trip to Darwin was to complete final testing with the new test rig. The main engines were tested as per the original process, which achieved more accurate results thanks to the improvements made to the test rig.

In different circumstances, AcousTech may test the space or piece of machinery, or complete modelling to determine which types of products must be installed to reduce noise emissions.

For more information about noise control solutions for the defence industry, contact Flexshield on 1300 799 969.