Sound Noise Ordinance and Light Level / Photometric Surveys for OSHA Compliance: Safety, Security and Productivity


Environmental noise is a form of acoustic pollution which has the potential to disrupt human communication, create annoyance, damage hearing and is regulated by the federal OSHA (Occupational Safety and Health Administration) Noise Standard 29 CFR 1910.95 along with other state agencies.  In some cases it can also interfere with sensitive equipment such as that used in the nanotechnology and semiconductor industry.

It is also regulated in residential areas by municipalities such as Fort Worth to provide comfort and peace to residents.

Sound Level Map
Sound Level Map

If you are receiving complaints from workers, or have been contacted by OSHA regarding a potential excessive noise issue, ScanTech can evaluate the environment for continuous (data-logging over time) and impulsive noise on the dB(A) and dB(C) scales to determine compliance. We can also fit workers with a continuous dosimeter to track sound pressure levels as they move into different work areas at different times of day. (meeting ANSI & IEC Type II standards)

8 Hour Dosimetry Extrusion Area with 90 dB OSHA Line
8 Hour Dosimetry of Extrusion Area with 90 dB OSHA Line

Our sound level meters are able to average noise at slow, (1 second per sample) fast (0.125 seconds per sample which corresponds to the response time of the human auditory system) or custom sampling rates as fast as 0.035 seconds which are used for impulsive (sudden, short) noise measurements. Impulse sounds are generally defined as acoustic events lasting less than 1 second with a repeat interval of greater than 1 second.

The data logging function also enables the measurement of reverberation which is the measurement of time it takes for the sound level to drop 60 dB or a factor of 1 million, and characterizes how “reflective” a room is to acoustic vibrations.

Sound Level Decay Graph
Sound Level Decay Graph


In general, interference with speech communication occurs when intrusive noise exceeds about 60 dB (Federal Interagency Committee On Noise 1992). Indoor speech interference can be expressed as a percentage of sentence intelligibility among two people speaking in relaxed conversation approximately 3 feet apart in a typical living room or bedroom (U.S. Environmental Protection Agency 1972).
The percentage of sentence intelligibility is a non-linear function of the (steady) indoor background A-weighted sound level. Such a curve-fit yields 100 percent sentence intelligibility for background levels below 57 dB and yields less than 10 percent intelligibility for background levels above 73 dB. The function is especially sensitive to changes in sound level between 65 dB and 75 dB.
As an example of the sensitivity, a 1 dB increase in background sound level from 70 dB to 71 dB yields a 14 percent decrease in sentence intelligibility. The sensitivity of speech interference to noise at 65 dB and above is consistent with the criterion of DNL 65 dB generally taken from the Schultz curve. This is consistent with the observation that speech interference is the primary cause of annoyance.
Typically, homes in the United States provide 15 dB of sound attenuation with windows open and 25 dB with windows closed and air conditioning operating.
Some guidelines on judging sleep interference. The EPA identified an indoor DNL (Day-Night Average Sound Level)  of 45 dB as necessary to protect against sleep interference (U.S. Environmental Protection Agency 1978). Assuming a very conservative structural noise insulation of 20 dB for typical dwelling units, this corresponds to an outdoor day-night average sound level of 65 dB to minimize sleep interference.
ScanTech Technical Consulting also has experience in doing “on-paper” studies for environmental impact and Environmental Survey Assessments (ESA) including the DNL influence of major roadways, railways, airports, etc. including the CEQR noise level standards of New York City.



Light levels are also regulated as a minimum amount of ambient light is required for task lighting, surgical, patient and hospital environments, street and residential illumination, parking lots, parking garages, emergency lighting, stairwells, exit signs, etc. Also, specific levels of lighting are measured in lux (metric per square meter) or candlepower (also known as foot candles which is a standard per square foot) are recommended for different types of tasks which vary from quality inspection to operating rooms.

Many cities such as Plano and McKinney have illumination / glare ordinances which limit the amount of light which can emanate from the borders and perimeters of a property. The amount allowed depends on how the neighborhood is zoned. (residential / light commercial, etc.) Parking lot lighting may cause excessive light to be transmitted through the windows of an adjacent bedroom window in which case light level testing is called for. In many cases the lighting testing data is compared to photometric maps prepared by a lighting engineer.

Other aspects to consider are the total illumination output of the light (measured in foot candles or lumens) and distribution across the emitting surface, color temperature of light, (measured in degrees Kelvin) diffusivity, distance from the light fixture to the surface(s) to be illuminated, the color, texture and composition of the surface(s) and type of lighting. (incandescent, fluorescent, halogen, LED, etc.)

ScanTech has light meters which are suitable for measuring virtually all forms of lighting with color and cosine correction built in for greater accuracy.

Datalogging light levels over long spans of time to see lighting level trends or shorter intervals to determine flicker rates are also available services.

Step Lighting Design
Step Lighting Design

There are also appropriate levels of lighting for ATM (Automated Teller Machines) and banking security compliance, ADA lighting requirement surveys and is often a part of the property exchange / due diligence / renovation process.

ATM Machine Light Requirements for Security
ATM Machine Lighting Requirements for Safety


Flicker rates can cause headaches and fatigue, impair productivity and be indicative of faulty lighting equipment which can propagate or indicate EMI (Electromagnetic Interference) from other sources present in your facility.

Percent Flicker and Flicker Index Different Light Sources
Percent Flicker and Flicker Index Different Light Sources


Excess radiated light at the wrong times of day (particularly the shorter wavelengths) can interfere with melatonin synthesis, circadian rhythms and create issues with insomnia, lack of restful REM sleep, unnecessary fatigue and a general lack of alertness. This is a genuine health hazard that broadly affects the quality of life from proper immune system function to increased risk of accidents.

Graph Showing Circadian Sensitivity vs. LED Light Wavelength
Graph Showing Circadian Sensitivity vs. LED Light Wavelength



ScanTech can even measure light levels that are normally invisible such as in the UV-A / UV – B (also known as UVA and UVB) spectrums which comprise wavelengths from 240 nm – 390 nm. This even includes part of the UVC / UV-C spectrum which is considered to be in the range of 100 nm – 280 nm and is often used for germicidal / sterilization processes.

While useful for many forensic and industrial / medical processes, these wavelengths can cause damage to human skin, (skin cancer / melanoma)  eyes from welding, paintings, artwork, historical museum pieces, fabrics and dyed products, rubber, polymers, etc.

If you require consultation for either health & safety, the preservation of materials (either modern or of historical significance such as artifacts) or need to gauge the exposures / effectiveness of an ultraviolet related application or impacted environment, then contact ScanTech.

ScanTech services and consults in the Dallas – Houston – Austin – Fort Worth and San Antonio metropolitan regions.

Lighting Calculator and Light Level Guide for Rooms

Indoor and Outdoor Lighting Levels in Lux and Candlepower (foot candles)

Ergonomic Computer Use Sitting and Standing Calculator

Sound & Noise Decibel Level Comparison Chart

OSHA Extended Shifts Decibel Limits

Hearing Test Website

TWA Sound Dose Calculator for OSHA NIOSCH ACGIH

REW Software – Room EQ 1/3 Octave

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