Industrial Noise Mapping: Visualizing Sound Levels Across a Factory

Sound levels in a factory are rarely uniform. One end of the hall may sit comfortably below hazardous levels while another is dominated by compressors, presses or conveyors. Walk the floor with a sound level meter and the numbers change every few metres. A noise map turns those numbers into a picture.

Industrial noise mapping visualises sound levels across a facility, usually as coloured contour zones on a floor plan. It shows at a glance where noise is hazardous, where hearing protection is needed, which machines dominate and where noise control will make the biggest difference.

For manufacturing plants, process facilities, data centres and plant rooms in Saudi Arabia, AcouStick's engineering service begins with assessment and survey — measurement and diagnosis of noise and vibration — before designing and supplying KSA-manufactured noise control systems.

This guide explains what an industrial noise map is, how one is produced, how to read it, and how it supports hearing conservation and noise control.

What Is an Industrial Noise Map?

An industrial noise map is a floor plan of a facility overlaid with measured or interpolated sound levels, typically shown as colour-coded contours or zones.

A 2025 NIOSH paper in the Noise Control Engineering Journal (Yan, Hrica, Elmashae and Yantek) describes the NIOSH Noise Mapper application, which generates sound level contour maps of a workplace, graphically revealing which work areas are safe and which are hazardous to hearing.

Why Create a Noise Map?

• Identify hazardous areas — NIOSH notes maps show where noise levels are hazardous.

• Place signage and PPE — the same paper notes maps help determine locations for noise hazard signage and personal protective equipment.

• Support training — site-specific hazard training and helping workers locate noise-generating machinery.

• Prioritise noise control — show where enclosures, barriers and silencers will help most.

• Plan layouts — position new equipment and workstations away from high-noise zones.

• Track change — compare maps before and after noise control or process changes.

Noise Maps and Regulatory Context

Noise maps support, but do not replace, exposure assessment:

• OSHA 29 CFR 1910.95 — requires a monitoring program when exposure may equal or exceed an 8-hour average of 85 dBA, sets a 90 dBA permissible exposure limit and allows area monitoring only where high worker mobility, significant level variation or impulse noise do not make it inappropriate — otherwise representative personal sampling is required.

• ISO 9612 — the international engineering method for occupational exposure, with task-based, job-based and full-day strategies.

• EU Directive 2003/10/EC — action values of 80 and 85 dB(A) and a limit of 87 dB(A).

• Saudi site boundaries — the Ministry of Environment, Water and Agriculture began implementing a national noise regulation in June 2021.

Projects in the Kingdom should be assessed against the occupational health and safety requirements that apply locally.

How an Industrial Noise Map Is Produced

Step 1: Prepare the Floor Plan

Obtain an accurate plan showing machines, walls, walkways, workstations and control rooms.

Step 2: Define the Measurement Grid

In a 2016 study published in the Journal of Human, Environment and Health Promotion, Majidi and Rezai divided the floor into 2 m × 2 m squares following a NIOSH guideline and measured at the centre of each square, removing stations that fell on equipment — 158 stations in total.

Step 3: Choose and Calibrate the Instrument

Sound level meters are specified in IEC 61672-1, with Class 1 having tighter tolerances than Class 2 (Cirrus Research). The OSHA standard requires instruments to be calibrated. Majidi and Rezai used a calibrated meter on slow response, holding the microphone at least 1 m from reflective surfaces and 1.5 m from the floor.

Step 4: Record Operating Conditions

Note which machines are running, at what load, and during which shift — a noise map is only valid for the conditions measured.

Step 5: Measure Each Grid Point

Take A-weighted readings at each station; add octave-band measurements at key locations to link noise to sources.

Step 6: Interpolate and Plot

Software estimates levels between measured points. The NIOSH Noise Mapper interpolates using cubic spline and BlockLLS algorithms; Majidi and Rezai entered levels into GIS software (ArcMap) to plot contours, reporting GIS-based maps as more realistic than routine square-by-square maps.

Step 7: Colour-Code the Zones

Majidi and Rezai used three categories: green below 65 dBA, yellow 65 – 85 dBA and red above 85 dBA. Bands should be chosen to match the applicable action levels and limits.

Step 8: Review and Report

Identify hotspots, dominant sources, affected workstations and recommended actions.

How to Read a Noise Map

• Hotspots — red zones mark where levels are highest and protection or control is most needed.

• Gradients — tightly packed contours show where levels change quickly — often near a dominant source.

• Workstations in high zones — priorities for exposure assessment and control.

• Quiet zones — suitable for offices, rest areas or relocated workstations.

• Boundary zones — help assess noise reaching the site perimeter.

Remember: a noise map shows sound levels at locations. Personal exposure depends on how long each worker spends in each zone.

Interpreting Distance and Room Effects

• Distance — in a free field, doubling distance from a source reduces level by 6 dB (The Engineering ToolBox) — indoor halls do not always follow this because of reflections.

• Reverberation — indoors, reflections raise levels away from machines. Doubling absorption lowers the reverberant level by 3 dB, but not the direct sound close to machines (NRC Canada).

From Noise Map to Noise Control

The OSHA Technical Manual organises noise control into source, path and receiver:

• Source — balancing, speed control, damping (up to 30 dB on vibrating panels), vibration isolation, modification or substitution.

• Path — acoustic enclosures, barriers, silencers, louvers, lagging and absorption in the hall.

• Receiver — quiet control rooms and refuges, booths, layout changes and work organisation, with hearing protection as the final layer.

After controls are installed, a repeat map shows the improvement and updates hearing protection zones. OSHA also requires repeat monitoring after changes in production, process, equipment or controls that increase exposure.

Noise Mapping in Saudi Facilities

Saudi industrial and utility facilities often operate around the clock, with large cooling and ventilation systems running alongside production. Noise maps should reflect the main operating modes — including peak production and high cooling loads — and, where neighbours are nearby, extend to boundary positions relevant to the national noise regulation.

Common Noise Mapping Mistakes

Mistake 1: Grid Too Coarse

Hotspots can be missed between widely spaced points.

Mistake 2: Mapping Only One Operating Condition

Maps change with production, shifts and equipment.

Mistake 3: Treating the Map as Exposure Data

Personal exposure also depends on time spent in each zone.

Mistake 4: Measuring Too Close to Reflective Surfaces

Majidi and Rezai kept the microphone at least 1 m from reflective surfaces.

Mistake 5: Uncalibrated Instruments

Results cannot be relied on.

Mistake 6: No Follow-Up Map

Improvements remain unverified.

Noise Mapping Checklist

• Is an accurate floor plan available?

• Is the grid spacing suitable for the space?

• Are instruments of a suitable class and calibrated?

• Are operating conditions recorded?

• Are colour bands matched to applicable limits?

• Have hotspots and dominant sources been identified?

• Is personal exposure assessed separately where needed?

• Will the map be repeated after changes?

How AcouStick Supports Noise Mapping and Control

AcouStick's engineering workflow begins with assessment and survey, followed by acoustic modelling and design, specifications, shop drawings, submittals and site support. Noise map results lead directly to KSA-manufactured solutions:

• Enclosures and booths — for dominant machines and operator refuges

• Louvers and attenuators — for ventilation openings and ducts

• Barriers, mass loaded vinyl and damping — for walls, guards and panels

• Structural isolation — isolators and mounts

• Absorption — baffles, wool panels and perforated metal panels

Frequently Asked Questions

1. What is an industrial noise map?

A floor plan overlaid with colour-coded sound levels showing where noise is high and low across a facility.

2. How is a noise map made?

Sound levels are measured on a grid with a calibrated meter, then interpolated by software into contours or zones.

3. What grid size should be used?

It depends on the space; one published study used 2 m × 2 m squares following a NIOSH guideline.

4. Is a noise map the same as an exposure assessment?

No. Maps show levels at locations; exposure depends on time spent in each area and may require personal monitoring.

5. How are noise maps used?

To identify hazardous areas, place signage and PPE, train workers, prioritise noise control and plan layouts.

6. How often should a noise map be updated?

Whenever production, equipment, layout or controls change, and after noise control is installed.

Final Takeaway

An industrial noise map turns scattered measurements into a clear picture of where noise is — and where action is needed. Built on a sensible grid, calibrated instruments and recorded operating conditions, it guides hearing protection, noise control and layout decisions across the factory.

Need a noise map for your Saudi facility? Contact AcouStick to plan an assessment and the noise control that follows.

If you need to see where noise is highest in your facility, AcouStick can help plan the noise survey and map, and the controls that follow.

Email: info@acoustick.co | Call: +966 51 130 809 | Web: www.acoustick.co

REFERENCES

• Yan, L., Hrica, J., Elmashae, Y., & Yantek, D. "Test method for evaluating the NIOSH Noise Mapper application in a hemi-anechoic chamber." Noise Control Engineering Journal, Vol. 73, No. 2, 2025 (CDC Stacks).

• U.S. Occupational Safety and Health Administration. 29 CFR 1910.95, "Occupational noise exposure": osha.gov/laws-regs/regulations/standardnumber/1910/1910.95

• International Organization for Standardization. ISO 9612:2009, "Acoustics — Determination of occupational noise exposure — Engineering method" (preview edition, iTeh Standards).

• European Agency for Safety and Health at Work (EU-OSHA). Directive 2003/10/EC — noise (minimum health and safety requirements regarding exposure of workers to noise): osha.europa.eu/en/legislation/directives/82

• Saudi Gazette. "Environment ministry begins implementation of noise regulation across Saudi Arabia." 2 June 2021: saudigazette.com.sa/article/607325

• Majidi, F., & Rezai, N. "Study of Noise Map and its Features in an Indoor Work Environment through GIS-Based Software." Journal of Human, Environment and Health Promotion, Vol. 1, No. 3, 2016, pp. 138–142.

• Cirrus Research plc. "What's the Difference Between a Class 1 and Class 2 Sound Level Meter?" (on IEC 61672-1 performance classes), Cirrus Research Blog: cirrusresearch.com

• The Engineering ToolBox. "Sound Propagation — the Inverse Square Law": engineeringtoolbox.com/inverse-square-law-d_890.html

• Warnock, A.C.C. "Reverberant Noise Control in Rooms Using Sound Absorbing Materials." Building Research Note, National Research Council Canada, June 1980: nrc-publications.canada.ca

• U.S. Occupational Safety and Health Administration. OSHA Technical Manual, Section III, Chapter 5: "Noise": osha.gov/otm/section-3-health-hazards/chapter-5