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Latest Noise News

visit cirrus at stand f18 at the health and safety event 2015

Counting Down to the Health & Safety Event 2015

Can you believe we’re just over a week away from the start of the Health & Safety Event 2015? Held at the NEC in Birmingham from March 24th – 26th, this promises to be an unmissable event for any Health & Safety Professional. Here’s a look at what Cirrus Research is bringing with our exclusive event preview.

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Fast, Slow and Impulse Time Weightings

What are Fast, Slow & Impulse Time Weightings?

LAS. LAF. LCS. LCF. These are common terms you probably see when taking a noise measurement with your sound level meter. The “F” and “S” indicate the different Time Weightings used for that measurement but what do they mean?

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what are the 4 different types of noise

What are the 4 Different Types of Noise?

Noise comes in all shapes, sizes and sounds. It’s part of our everyday lives but before you can accurately measure it, you need to know what the different types of noise are. Here’s my advice.

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Recommended By Our Noise Experts

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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

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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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