Industrial Noise Surveys: How to Assess Noise Across a Manufacturing Facility

Every effective industrial noise control project starts with the same thing: reliable measurements. Without a noise survey, decisions about hearing protection, machine enclosures, barriers, silencers or layout changes are based on guesswork — and guesswork in a noisy facility is expensive.

An industrial noise survey is a structured assessment of sound levels across a manufacturing facility. It shows where noise is highest, who is exposed, which machines are responsible and whether noise is leaving the site boundary. It turns a noisy plant into a set of clear priorities.

For manufacturing plants, process facilities, utilities, 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 why industrial noise surveys matter, the types of survey, the instruments used, how a survey is planned and carried out across a facility, and how results are turned into action.

Why Carry Out an Industrial Noise Survey?

• Protect workers — identify areas and tasks where exposure may be hazardous.

• Meet regulatory requirements — OSHA's 29 CFR 1910.95, for example, requires a monitoring program when exposure may equal or exceed an 8-hour average of 85 dBA.

• Identify dominant sources — the OSHA Technical Manual states that the first step in noise control is to identify the noise sources and their relative importance.

• Design noise control — provide data to size enclosures, barriers, louvers and silencers.

• Check site boundary noise — Saudi Arabia's Ministry of Environment, Water and Agriculture began implementing a national noise regulation in June 2021, with penalties including non-compliance with permissible levels and failure to provide monitoring data to the National Center for Environmental Compliance.

• Verify improvements — measure again after controls are installed.

The scale of the issue is significant: NIOSH estimates that 22 million U.S. workers are exposed to hazardous noise on the job each year (Themann et al., Seminars in Hearing, 2023).

Types of Industrial Noise Survey

Area Survey (Noise Mapping)

Sound levels are measured at locations across the facility — typically on a grid and at workstations, walkways and boundaries — to show where noise is highest. Results are often presented as a facility noise map.

Personal Exposure Survey

Measures the noise exposure of individual workers over their working day, usually with personal dosimeters, to compare against exposure limits.

Source Identification Survey

Focuses on individual machines and processes to rank their contribution and understand their frequency content.

Boundary and Environmental Survey

Measures noise at the site perimeter and nearby sensitive locations to assess environmental impact.

Verification Survey

Repeats measurements after noise control to confirm the reduction achieved.

Area Monitoring vs Personal Monitoring

OSHA's standard explains when each is appropriate. Area monitoring may be used where conditions allow, but where high worker mobility, significant variations in sound level or a significant impulse component make area monitoring generally inappropriate, the employer must use representative personal sampling — unless area sampling can be shown to give equivalent results.

• Area monitoring is useful for — stable, fixed workstations and mapping where noise is highest.

• Personal monitoring is useful for — mobile workers, variable processes and impulsive noise.

Instruments Used in Industrial Noise Surveys

Sound Level Meters

Sound level meters are specified in IEC 61672-1, which defines two performance classes. Class 1 has tighter tolerances across frequency than Class 2 — for example ±1.1 dB versus ±1.4 dB at the 1 kHz reference, according to Cirrus Research's summary of the 2002 edition. Class 2 is commonly accepted as a minimum for workplace noise, while Class 1 is expected for some environmental work. The OSHA Technical Manual notes that standard Type 1 and Type 2 meters are reliable in the far field, while near-field readings close to a machine can be unreliable.

Octave Band Analysers

Octave band analysers attach to or are built into Type 1 meters and split sound into frequency bands, identifying the most prevalent frequencies to guide control. The OSHA Technical Manual notes low-frequency noise is more difficult to control.

Personal Noise Dosimeters

Worn by workers to record exposure over a shift. OSHA requires measurements to integrate all continuous, intermittent and impulsive sound levels from 80 dB to 130 dB.

Sound Intensity Equipment

ISO 9614-1 describes determining the sound power of sources using sound intensity, applicable in situ for sources whose noise is stationary in time — useful for ranking sources and sizing enclosures.

Calibrators

OSHA requires instruments used for monitoring to be calibrated to ensure accurate results. Field calibration checks before and after measurements are standard good practice.

How to Plan an Industrial Noise Survey

Step 1: Define the Objectives

Is the survey for worker exposure, source identification, boundary compliance, design input or verification — or several of these?

Step 2: Carry Out a Work Analysis

ISO 9612, the international engineering method for occupational noise exposure, requires a work analysis that establishes the nominal working day, identifies tasks and significant noise events, supports the choice of measurement strategy and forms the basis of the measurement plan.

Step 3: Collect Facility Information

• Layout drawings and equipment lists

• Operating schedules, shifts and production modes

• Worker roles and movement patterns

• Location of sensitive receivers at and beyond the boundary

Step 4: Choose the Measurement Strategy

ISO 9612 describes three strategies:

• Task-based — the working day is split into tasks, each measured separately.

• Job-based — random samples are taken while workers perform particular jobs.

• Full-day — levels are recorded continuously over complete working days.

Step 5: Plan Measurement Positions

Select grid points, workstations, walkways, control rooms, refuges and boundary positions, and schedule measurements to cover each operating mode.

How to Carry Out the Survey Across the Facility

1. Calibrate instruments — before and after each session.

2. Record operating conditions — which machines are running, at what load and speed.

3. Measure area levels — at grid points and workstations to build the noise map.

4. Measure personal exposure — using the chosen ISO 9612 strategy.

5. Capture frequency data — octave bands at key sources and positions.

6. Isolate sources — probe near equipment, switch machines on and off, or use temporary covers, as described in the OSHA Technical Manual.

7. Measure the boundary — at the perimeter and nearby receivers.

8. Note impulsive events — OSHA limits impulse noise to a 140 dB peak.

9. Record everything — positions, times, conditions, instruments and calibration.

Interpreting the Results

Noise Map

Shows high-noise zones and helps define hearing protection areas and priorities.

Exposure Results

Compared with the applicable limits. International references include OSHA's permissible exposure limit of 90 dBA and action level of 85 dBA, NIOSH's recommended 85 dBA with a 3 dB exchange rate, and the EU Directive 2003/10/EC action values of 80 and 85 dB(A) with an 87 dB(A) limit. Saudi projects should be assessed against the occupational health and safety requirements that apply locally.

Source Ranking

Identifies which machines dominate at each workstation and at the boundary, so the loudest contributor is treated first.

Frequency Content

Links noise to its mechanism and points to the right control.

Distance and Room Effects

• Distance — in a free field, doubling distance from a source reduces level by 6 dB (The Engineering ToolBox).

• Reverberation — indoors, doubling absorption lowers the reverberant level by 3 dB, but not the direct sound near a machine (NRC Canada).

Turning Survey Results Into Action

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

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

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

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

OSHA also requires feasible administrative or engineering controls when exposures exceed its limits, with hearing protection used where those controls fail to reduce levels sufficiently.

Reporting, Notification and Repeat Surveys

• Report — objectives, methods, instruments, calibration, conditions, results, noise map, source ranking and recommendations.

• Notify — OSHA requires employees exposed at or above an 8-hour average of 85 dBA to be notified of results.

• Keep records — OSHA requires exposure measurement records to be retained for two years.

• Repeat — OSHA requires monitoring to be repeated after changes in production, process, equipment or controls that increase exposure or make hearing protection inadequate.

Industrial Noise Surveys in Saudi Arabia

Saudi facilities often operate continuously, with substantial cooling and ventilation plant running alongside production equipment. Surveys should cover day and night operating modes, seasonal changes in cooling loads where relevant, and boundary positions near residential or sensitive areas covered by the national noise regulation.

Common Survey Mistakes

Mistake 1: Measuring Only Overall Levels

Without frequency data and source isolation, the dominant source remains unknown.

Mistake 2: Measuring Too Close to Machines

Near-field readings can be unreliable.

Mistake 3: Missing Operating Modes

Start-up, blow-off, cleaning and peak production can change results.

Mistake 4: Using Area Monitoring for Mobile Workers

OSHA requires representative personal sampling where area monitoring is inappropriate.

Mistake 5: Skipping Calibration

Uncalibrated results cannot be relied on.

Mistake 6: No Follow-Up Survey

Without verification, the effect of noise control is unknown.

Noise Survey Checklist

• Are survey objectives defined?

• Has a work analysis been completed?

• Are instruments of a suitable class and calibrated?

• Is the measurement strategy appropriate for the workers and processes?

• Are grid, workstation and boundary positions planned?

• Are operating conditions recorded?

• Is frequency data captured for key sources?

• Are results reported, communicated and retained?

• Is a verification survey planned?

How AcouStick Supports Industrial Noise Surveys

AcouStick's engineering workflow begins with assessment and survey, then moves into acoustic modelling and design, specification, shop drawings and submittals, and site support with installation guidance and commissioning. Survey results feed directly into the selection of KSA-manufactured systems:

• Enclosures and booths — for compressors, generators, pumps and operator refuges

• Louvers and attenuators — for ventilation and plant openings

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

• Structural isolation — mounts and isolators for vibrating equipment

• Absorption — baffles, wool panels and perforated metal panels for large halls

Frequently Asked Questions

1. What is an industrial noise survey?

A structured assessment of sound levels across a facility to identify high-noise areas, worker exposure, dominant sources and boundary noise.

2. What equipment is used?

IEC 61672 Class 1 or Class 2 sound level meters, octave band analysers, personal dosimeters, sound intensity equipment and calibrators.

3. What is the difference between area and personal monitoring?

Area monitoring measures levels at locations; personal monitoring measures what individual workers are exposed to over their day.

4. How often should a noise survey be repeated?

Whenever production, processes, equipment or controls change in ways that could increase exposure, and after noise control is installed.

5. What happens after a noise survey?

Results are used to prioritise source, path and receiver controls, notify employees, and plan verification.

6. Does a noise survey cover boundary noise?

It can and should, where neighbours or sensitive receivers are nearby.

Final Takeaway

An industrial noise survey turns a noisy facility into clear, measurable priorities. With the right objectives, instruments, strategy and positions — and with sources isolated and ranked — survey results lead directly to effective, well-targeted noise control.

Need a noise assessment for your Saudi facility? Contact AcouStick to plan a survey and an engineered noise control strategy.

If your facility needs a clear picture of where noise comes from and who is exposed, AcouStick can help plan the survey and the noise control that follows.

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

REFERENCES

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

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

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

• Themann, C.L., Masterson, E.A., Peterson, J.S., & Murphy, W.J. "Preventing Occupational Hearing Loss: 50 Years of Research and Recommendations from the National Institute for Occupational Safety and Health." Seminars in Hearing, 44(4), 2023: pmc.ncbi.nlm.nih.gov/articles/PMC10562059

• 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

• International Organization for Standardization. ISO 9614-1:1993, "Acoustics — Determination of sound power levels of noise sources using sound intensity — Part 1: Measurement at discrete points": iso.org/standard/17427.html

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

• Kardous, C., et al. "Understanding Noise Exposure Limits: Occupational vs. General Environmental Noise." NIOSH Science Blog, CDC, 8 February 2016: cdc.gov/niosh/bulletin/2016/noise.html

• 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

• 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