Have you ever walked past a pneumatic hammer on road and winced because the sound was too loud? Being exposed to loud noises for a small period of time is not harmful, but imagine having to suffer it a longer period of time. If you work in such an environment then the first thing that you need to do is measure that noise in order to reduce it.
Measuring noise accuracy used to be a tricky and tough job but now there are digital sound meters Making precise measurements of noise used to be quite a tricky and tough job but now with the help of digital sound meters it can be measured in no time. Let’s have a closer look at it.
HTC SL-1352 Sound Level Meter
Sound level Meters– A sound level meter measures the sound in a unit of Decibels(dB). The dB scale is logarithmic i.e. 2dB is 10 times 1dB on a linear scale.
50 dB is the sound of a loud conversation. 85 dB causes hearing damages after 8 hours and 100 dB causes hearing damage after 15 minutes.
The microphone on the top end of instrument records the sound and the stick ensures that the sound wave is not distorted by the reflections. The recorded sound is amplified and filtered before giving a reading on the display.
If your device has an integrating sound level meter, then it can record the sound levels over a period of time and then give the average value. For even longer periods, there are data logging meters which can be connected to a computer and draw charts and graphs for prolonged periods of time(even weeks).
The accuracy of the instrument determines the price and the purpose of the instrument. Meters with (±) 0.4 dB accuracy is used for lab reference, (±)0.7 dB for precision works, (±)1.0 dB for the general purpose and (±)1.5 dB for noise surveys.
The microphones are also of various kinds. Random Incidence microphones are used when there is a high level of reflections(should be held around 70 degrees for accurate measurement), Free field microphones for open space which is free from reflections(0 Degree) and Pressure microphones for closed cavities.
Highly accurate SLMs have a type 1 rating. These cost more than 10,000. SLMs with a type 2 rating are also accurate and can be used for most of the applications.
Factors to consider before buying an SLM- (All these factors vary according to the purpose)
- Measurement Range: For most of the application a range around 30-130 dB is sufficient.
- Resolution(the lowest input the device can take)- A resolution of 0.1 dB is a must.
- Display- Around 20 mm screen length and 3 1/2 digits display is appropriate for most of the applications.
To measure using an SLM-
- SLM should be held at an arm’s length and tip it towards the sound source.
- At installation sites, SLM should be positioned away from walls, floors or other boundaries.