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What Is...
A Sound Level Meter
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A Sound Level Calibrator
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What is a Sound Level Calibrator?

A sound level or acoustic calibrator is a small hand-held device that emits a "whistle" of very accurate tone and level. Some calibrators operate at more than one level and even more than one frequency. The most common calibrators operate at 94 dB at 1 kHz.

How to Use a Sound Level Calibrator

You should use a sound level calibrator to ensure that your sound level meter is working accurately just before making a measurement. Many regulations recommend or demand that you use a calibrator before and after making measurements and it is especially important when your measurements are being used for hearing protection reasons or for any legal purposes.

The calibrator should be fitted firmly onto the microphone and switched on. If a 94 dB calibrator is being used then the meters offered on this web site should read 93.7 dB (this is explained in the user manual). The reason for the level read being 0.3 dB lower than the calibrator level is due to the way a microphone works in free space compared to when inside the calibrator's cavity.

If the level is not correct then some sound level meters can be adjusted manually while others will do it automatically for you at the push of a button.

Are Sound Level Meters not Accurate?

Yes, sound level meters that meet the international standards are very precise and very accurate. However, the fluctuations in pressure that the microphone measures are so small that the microphone itself has to be very sensitive. The following can change the sensitivity of a microphone without you noticing any difference on the meter's display:

  • Large changes in temperature
  • Large changes in air pressure
  • Ageing of the microphone membrane
  • Dropping or knocking of the microphone

There are many things that can cause the measured levels to change, and these are just dealing with the microphone itself. After that we have the amplifiers, filters, etc., all of which are very sensitive.

The reason you use a calibrator is really to check that none of these things are going to cause your measurements to be inaccurate.

Can Meters Have Internal Calibrators?

It is essential that the microphone capsule is included in the calibration process. This is the most sensitive part of the whole instrument and the most likely to be damaged. The calibrator offered with our meters is an acoustic calibrator, not just and electronic test. This checks the whole measurement chain of the instrument, from microphone membrane to display.

 
Featured Products

Noise at Work
Very easy to use,
designed for
occupational noise
measurement.

Real-Time Filters
Real-time analyzer
with 1/3 octave band
filters.

 

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