Sound level meters measure sound pressure (waves) by taking sound in through a microphone and processing it with a filter. This filter gives a “weighting” to the frequencies which make up the sound. The “weighted” intensity of the sound is then expressed in decibels (dB) by the meter. The weightings normally found on sound meters are “A” and “C”. “A” weighting is the standard filter used by most regulatory agencies. See the chart below for the frequency weightings for the “A” and “C” filters on Sper Scientific sound meters.

Sound Meters Are Used By:

• Industrial Hygienists who measure noise exposure in the workplace in compliance with OSHA hearing conservation program.
• Safety alarm testing.
• Sound Engineers, for measuring acoustics in interior design, sound system installation, and sound proofing.
• Construction Engineers.
• Municipal code compliance officials.
• Industrial Quality Control for measuring sound levels of bearings, machinery and other products.
• Environmental Scientists, for measuring noise pollution from traffic, airports, machinery, etc.
• Physics Laboratories for testing sound wave measurements.

Normal Frequency Hz A Weighting dB C Weighting dB
10 -70.4 -14.3
12.5 -63.4 -11.2
16 -56.7 -8.5
20 -50.5 -6.2
25 -44.7 -4.4
31.5 -39.4 -3.0
40 -34.6 -2.0
50 -30.2 -1.3
63 -26.2 -0.8
80 -22.5 -0.5
100 -19.1 -0.3
125 -16.1 -0.2
160 -13.4 -0.1
200 -10.9 -0
250 -8.6 0
315 -6.6 0
400 -4.8 0
500 -3.2 0
630 -1.9 0
800 -0.8 0
1000 0 0
1250 +0.6 0
1600 +1.0 -0.1
2000 +1.2 -0.2
2500 +1.3 -0.3
3150 +1.2 -0.5
4000 +1.0 -0.8
5000 +0.5 -1.3
6300 -0.1 -2.0
8000 -1.1 -3.0
10000 -2.5 -4.4
12500 -4.3 -6.2
16000 -6.6 -8.5
20000 -9.3 -11.2