About : Sound Meters

Normal	A Weighting	C Weighting
Frequency Hz	dB	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
40	-34.6	-2
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	-0.1
2000	1.2	-0.2
2500	1.3	-0.3
3150	1.2	-0.5
4000	1	-0.1
5000	0.5	-1.3
6300	-0.1	-2
8000	-1.1	-3
10000	-2.5	-4.4
12500	-4.3	-6.2
16000	-6.6	-8.5
20000	-9.3	-11.2

    

How Sound Meters Work

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 weightings normally found on sound survey
meters are “A” and “C”. The “A” weighting is used by most rlegulatory agencies as the standard filter through which all the frequencies that can make up sound are filtered. The “weighted” intensity of the sound is then expressed in decibels (dB) by the meter. For the frequency weightings for the “A” and “C” filters on Sper Scientific sound meters, see the chart to the left.

Sound Meters Are Used By:

Industrial Hygienists
Measuring noise exposure in the workplace in compliance with OSHA hearing conservation program. Safety alarm testing.

Sound Engineers
Measure acoustics in interior design, sound system installation, sound proofing.

Construction Engineers
Municipal code compliance.

Industrial Quality Control
Measuring sound levels of bearings, machinery and other
products.

Environmental Scientists
Noise pollution from traffic, airports, machinery, etc.

Physics Laboratories
Sound wave measurements.