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Latest Noise News

noisetools noise analysis software

Ideal PC Specifications for the NoiseTools Software

NoiseTools PC Specifications – Last updated July 2015

The NoiseTools software (supplied with the Optimus Sound Level Meter, doseBadge Noise Dosimeter, Trojan Noise Nuisance Recorder, CR:800C and CR:260A sound level meters) can be run on most modern PCs. To get the best from the software the PC should meet the minimum specifications below and where possible meet the recommended specifications. Read More »

What is Equivalent Continuous Sound Level (Leq)?

Noise 101: What is Equivalent Continuous Sound Level (Leq)?

For anyone that is measuring sound, you’ve probably come across the term Leq or Equivalent Continuous Sound Level. But what is it and how can it help us when measuring noise with a sound level meter?

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noise action week - tackling neighbourhood noise nuisance

Noise Action Week 2015: Tackling Neighbourhood Noise Nusiance

May 18th – May 23rd 2015 is Noise Action Week. As we’re dedicated to noise measurement, it’s certainly something we’re keen to promote. So, here’s an overview of what Noise Action Week is all about, how you can get involved and ways of dealing with neighbourhood noise nuisance.

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Recommended By Our Noise Experts


What are Octave and Third Octave Band Filters on a Sound Level Meter?

When more detailed information about a complex sound is needed, the frequency range of 20Hz to 20kHz can be split into sections or bands. This is done electronically within a sound level meter.

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a sound level meter to IEC 61672 standard

What’s the Difference Between a Class 1 and Class 2 Sound Level Meter?

We’ve covered the differences between Class and Type in sound level meter standards in a previous post but what the differences between a Class 1 and Class 2 sound level meter?

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What are A, C & Z Frequency Weightings?

On your sound level meter or noise meter you will often see references to Frequency Weightings such as ‘A’, ‘C’ or ‘Z’.

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Cirrus Product Updates


NoiseTools is now compatible with Windows 8.

A new version of the NoiseTools software is available that is compatible with the new Windows 8 operating system.
Version 1.4.4 of NoiseTools can be downloaded from the Cirrus website or updated from within NoiseTools itself.

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PTB Type Approval for the optimus sound level meters

We are delighted to announce that the optimus red and optimus green sound level meters have been Type Approved by the PTB in Germany!

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Tonal Noise Analysis with Optimus Green Sound Level Meters

Often the sound energy from a noise source will be spread over a wide band of frequencies. Sometimes a noise source will emit noise that is concentrated in a narrow part of the spectrum or contains a high proportion of energy at a single frequency (a “pure tone”).  This is referred to as tonal noise.

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