GOVERNMENT REGULATIONS The Occupational Safety and Health Administration ( OSHA ) is part of the U . S . Department of Labor . This organization has studied and prescribed maximum sound pressure levels in the workplace , in relation to the number of hours per day the worker is exposed . These guidelines help audio engineers guard against permanent hearing loss .
The following chart shows the OSHA daily permissible noise level exposure guidelines .
THE LOUDNESS OF EVERYDAY LIFE It ’ s helpful to compare real-life sounds we hear in our everyday lives . Some can damage our hearing , even with minimal exposure . Guard your ears carefully . They ’ re the only ears you ’ ll get .
price from about $ 40 to $ 300 . Most of these instruments offer A- and C-weighting , along with slow ( average / RMS ) and fast ( peak ) attack times .
C-weighting is optimized for full-bandwidth sources at levels exceeding 85 dB . A-weighting filters out the high and low frequencies and is optimized for lower volumes . The A-weighted scale more closely reflects perceived volume , whereas the C-weighted scale measures amount of energy ( amplitude ).
Any piece of gear that quantifies amplitude must specify whether it ’ s sensitive to a full or limited bandwidth . Weighting is the qualifier for sound pressure level measurements .
SOFTWARE Software that analyzes sound pressure levels and frequency content is a very important tool for sound operators . Smaart version 8 — a popular sound analysis program from Rational Acoustics — not only measures realtime SPL and frequency content but it can also documents those measurements on a time line . In addition , software like Smaart can analyze acoustical environments and guide you through the proper setup for any sound system in any room . So , you might ask why you would need documentation and why not just use the decibel meter on your smartphone ?
A- , B- , AND C-WEIGHTING There are a few devices available to help you quantify specifically how loud , in dB SPL , you have your system set . The simplest and least expensive way to assess dB SPL is with a handheld decibel meter . These are available at most home electronics stores and , depending on features and manufacturer , typically range in
• C-weighting closely approximates fullbandwidth sensitivity . This is the scale that most accurately represents amplitude .
• A-weighting closely approximates loudness , attenuating the lower frequencies to resemble the response of the human ear ( which is most sensitive to frequencies between 1000 and 4000 Hz ).
• B-weighting includes more of the mid frequencies in its sensitivity than A-weighting . It ’ s usually used in conjunction with A- and C-weighting in analysis of acoustical anomalies .
Smaart from Rational Acoustics is a comprehensive acoustical and sound analysis software package .
THE PROBLEM WITH CELLPHONE APPS A decibel meter on any smartphone is at the mercy of the built-in mic , the way the case fits