It’s a pretty typical question when someone is exploring the purchase of a sound level meter. What’s the difference between a type 1 and type 2 instrument? “About $1,500” is usually not the best way to answer that question.
While there is a difference in price,we are talking about the precision of the instrument, and more specifically, the microphone of the instrument. Generally speaking, and depending on the frequency of the noise signal, a Type 1 sound level meter will be accurate plus or minus-1 dB and a Type 2 sound level meter has an accuracy of plus or minus 2 dB.
In the United States, OSHA requires that a Type 2 instrument (or better) be used to monitor noise exposures for occupational hearing conservation programs. These will most likely work for most of your applications.
If you need a higher level of precision, an engineering grade Type 1 instrument may be a better fit. These meters are more sensitive to lower levels which is can be relevant for environmental noise surveys, building acoustic surveys, or for designing engineering controls. You may want to use a Type 1 instrument in legal situations when your data is being used as evidence. Here, a more accurate meter may be more convincing even when the regulations do not demand it.
There are Type 0 instruments available for laboratory applications.
Here’s a quick chart of variably levels with each type of instrument
|Freq range Hz||Type 0||Type 1||Type 2|
|31.5 to 2000||± 1||+1.5, -1||± 3|
|2000 to 4000||± 1.5||+2.5, -2||+3, -4|
|4000 to 5000||± 1.5||+3.5, -3||+4, -6|
|5000 to 6300||± 2||± 4||+5, -8|
|6300 to 8000||± 3||± 5.5||+8, -9|
|8000 to 10000||± 3.5||+7, -8||Not specified|
|10000 to 12500||± 4.5||+8, -11||Not specified|
Ultimately, your application and data required will guide you to the right instrument. If you need help finding the right instrument for your application the representatives at RAECO LIC will be happy to help.
Raeco LIC is the authorized representative of 3M Detection Solutions in the Midwest US.