Our instrumentation is maintained to NATA laboratory standards providing a flexible and confident "in-field" approach to any problem. Complete portability enables complicated field measurements minimising analysis delays and avoiding expensive laboratory time. This also allows us to provide laboratory quality measurements anywhere in Australia, or in the World.

Sound Pressure measurements are used for general noise measurements, or to identify easily discernible noise sources. Sound Intensity measurements clearly identify individual noise sources within noisy environments and enables the measurement of sound power levels for regulatory purposes. The measurement techniques are particularly useful for measuring individual machines under actual operating conditions without disrupting production schedules. Traditional measurements are limited to the frequency ranges of 100 Hz to 5 KHz, missing the critically important lower and upper frequencies regions.

We operate Real Time Sound Pressure and Sound Intensity measurement analysers with measurement frequency ranges from 0.4 Hz to 22 KHz in 1/1 octaves, 1/3 octaves, 1/12 octaves or 1/24 octaves as well as narrow band frequency analysis measurement analysers. Auto-correlation and cross-correlation modes are available to assess multiple interaction problems.

Advanced laboratory acoustic measurement equipment is utilised in the field to identify problems where they occur. The large dynamic range of our instruments ensure single-pass analysis eliminating costly multiple recordings. We are one of the few consultants in Australia possessing these advanced instrumentation systems.

To give you some idea of the power of these instruments, using one instrument, a real time sound pressure analyser, an experienced engineer and a senior professional officer in one day are able to measure more information, and more accurately, in the same time as four experienced engineers each equipped with individual sound level meters. (For more information)

The accuracy of the noise measurement systems that we use is the time freeze frame time capturing techniques utilised within the real time sound pressure analysers which are greatly superior to the measurements obtained using the serial form of measuring techniques that are used in sound level meters.

The simple reason for the superiority and greatly improved accuracy is that noises are continuously varying quantities. Using the serial form of measurement requires a great deal of field measurement experience to determine if the various measured results truly correspond to the actual noise being generated. Our freeze frame capturing techniques eliminate these unfortunate problems.

Using our proven techniques of measurement, we are able to capture sufficient data within reasonably short measurement periods. Using sound level meters the overall final measurement costs are significantly higher, and are less accurate than the measurement costs using real time sound pressure analysers.

Camets can provide all your acoustical and vibration measurement needs, including:

• up to one-twentyfourth octave noise & vibration measurements,
• narrow band noise & vibration measurements,
• sound intensity measurements,
• hearing conservation measurements,
• in-field sound intensity and sound pressure building element testing,
• sound power testing,
• long term unattended noise, weather & vibration moinitoring,
• measurements to Australian and International Standards,
• PLUS MANY MORE MEASUREMENT TYPES.

Put us to the test and ask for some free advice. For further information about Camets Acoustics please contact us

Comparison of Measurement Techniques

All noise is measured over a finite length of time and each measurement technique involves various time penalties. These time penalties are not immediately obvious to management. For this reason we have provided an actual example. Using different measurement techniques which clearly demonstrates the various time penalties involved.

The practical example below illustrates the time differences and cost penalties involved in the measurement of a Sound Power Spectrum for large stationary industrial equipment such as installed diesel generators, or steam turbines.

The sound power spectrum of a machine is essential as it gives a determination of its sound emissions free from the influence of where it was, is, or is likely to be located in the future. The sound power level is assessed by measuring the sound pressure levels over a imaginary surface completely surrounding the machine. These results, in conjunction with the area of the enclosing envelope surrounding the machine, are used to calculate sound power level.

EXAMPLE

In our example, we have assumed that we have one large machine installed in a large plant room. The size of the machine is five metres long by two metres wide by two metres high. The room enclosing the machine is fifteen metres long, by fifteen metres wide, by eight metres high.

The plant room is also frequently occupied and has been extensively acoustically treated. The machine is in continuous operation.

The sound measurements required, are carried out over an imaginary surface somewhere between surface of the machine, and a distance from the machine before the reverberant build-up starts to exceed the sound that is being emitted directly from the machine itself.

Room constraints and reverberant build-up limits the sound power measurement to within three metres from the centre line of the machine in this instance.

At the three metre distance from the machine it is not a simple matter of treating the source of noise as a single point source, but as a series of point sources scattered over the machine surface. Sound radiates from every panel of the machine in varying quantities and directions.

The measurement of the Sound Power Spectrum requires a series a measurements, using a grid over an imaginary conformal surface surrounding the machine itself.

Using a conformal surface one metre from the machine, there will be a number of measurement locations necessary.

If we measure over the one-third octave frequency range from 25Hertz to 20Kilohertz, this means there will need to be 94 individual measurement locations on the grid. Providing none of the locations requires more than one measurement, then there will be 2,820 individual one-third octave measurements undertaken.

To provide quality assurance, a second grid is required using a second conformal surface, one metre further out from the first conformal surface. An additional 158 measurement locations are necessary. This increases the overall total to 252 measurement points, and a total of 7,560 individual one third octave measurements are carried out.

The following tables compare the cost of the three alternative measurement techniques. A Precision Sound Level Meter (SLM), is compared with a Real Time Sound Pressure Analyser (RTSPA), and a Real Time Sound Intensity Analyser (RTSIA) when measuring a single large machine. The comparisons of systems and relative costs are set out below:

If the measurements require a halt to production, and we assume the field measurements can be completed within one hour using the Real Time Sound Intensity Analyser (RTSIA) the following hidden costs can be expected: