Why Is Your Workplace Still So Noisy?
Noise monitoring identifies where exposure occurs; engineering analysis explains why. By working systematically from source to transmission path and worker, employers can reduce exposure rather than continually compensating with hearing protection.
In Brief
- Above the upper exposure action value of 85 dB(A), employers must establish and implement a programme of technical and organisational measures to reduce exposure.
- Personal dosimetry identifies exposed workers and tasks. Source and frequency measurements then help select an effective engineering control.
- A control is complete only when its acoustic performance, safe operation and continued use have been verified under representative conditions.
Hearing protection is visible, easy to issue and relatively quick to replace. Engineering noise control can appear less certain because it requires investigation of machinery, processes and transmission paths. Yet the Control of Noise at Work Regulations 2005 place prevention and reduction ahead of reliance on personal protection.
The most useful question is not “Which ear defender should we buy?” It is “What creates the exposure, and what change will remove energy before it reaches the worker?”
At Sysco Environmental, we connect personal exposure data with task observation and source diagnosis. This prevents effort being directed at the loudest-looking machine when another source or short-duration activity actually drives the daily dose.
Start with the Exposure That Needs Controlling
The lower daily or weekly exposure action value is 80 dB(A), and the upper value is 85 dB(A). The exposure limit value is 87 dB(A), taking hearing protection into account. Peak sound-pressure values also apply.
The assessment should identify workers at risk, daily or weekly exposure, peak noise, sources and the measures needed. A fixed sound-level survey alone may miss mobile work, intermittent operations and the time workers spend in each location.
Personal dosimetry can show when dose accumulates. Pair the time history with a task log, production data or worker interview. A short high-noise intervention may be more important than a continuously audible but remote source.
Once the priority exposure is established, measure around the relevant process using a suitable sound-level meter. Where frequency content matters, octave-band information can help distinguish aerodynamic noise, impacts, vibration and tonal machinery components and can support enclosure or silencer design.
Diagnose Source, Path and Receiver
Noise control can act at three points:
- Source: reduce the acoustic energy generated by impact, turbulence, vibration, combustion or electrical and mechanical forces.
- Path: interrupt transmission through air or structures using distance, isolation, absorption, barriers or enclosures.
- Receiver: reduce the number of people exposed, their duration or residual sound reaching the ear.
Source control is normally the most robust because it protects everyone and is less dependent on behaviour. Path controls can be highly effective when correctly designed. Receiver controls, including hearing protection, remain important but should not become the default while practicable technical measures are overlooked.
Use a Structured Investigation
Observe the process throughout its operating cycle. Note material impact, speeds, pressures, loading, wear, guards, doors and operator interventions. Ask workers when the sound changes and whether maintenance or product variation affects it.
Where it is safe and operationally possible, controlled on-off comparisons can isolate components. Only competent people should operate or isolate machinery, and safeguarding must not be defeated for acoustic testing.
Useful diagnostic methods include:
- near-source sound-level comparisons;
- octave-band analysis;
- vibration measurements;
- temporary damping or shielding trials;
- comparison of loaded and unloaded operation;
- maintenance-condition checks; and
- review of manufacturers' emission data.
Smartphone applications may help demonstrate a concept but should not replace suitable calibrated instrumentation where measurements support legal or technical decisions.
Reduce Impact and Mechanical Noise
Impact noise arises when components, tools or materials strike. Reduce drop height, speed or force; cushion contact surfaces; use resilient linings; or replace impact transfer with controlled movement. A change in material handling can reduce noise while also limiting damage and dust.
Mechanical noise can indicate wear, imbalance, misalignment or poor lubrication. Bearings, gears, belts and cutting tools should be maintained to their intended condition. Maintenance can reduce exposure and prevent energy loss or premature failure.
Machine panels and guards may radiate sound when excited by vibration. Stiffening, damping or isolation can reduce radiation, but modifications must preserve guarding, fire resistance, cleaning and access requirements. Added mass or damping material should be suitable for temperature, contamination and hygiene conditions.
Control Compressed-Air and Aerodynamic Noise
Compressed air produces high-velocity turbulent noise and is often used at greater pressure or flow than the task requires. Eliminate unnecessary blowing, repair leaks and specify efficient low-noise nozzles. Where air is used for ejection or cleaning, consider a mechanical or enclosed alternative.
Fit suitable silencers to exhausts and pneumatic equipment, ensuring that back pressure does not impair safe function. Compressed air should not be used for cleaning clothing or skin.
Fans and duct systems generate aerodynamic and mechanical noise. Poor inlet conditions, sharp changes in direction, turbulence, imbalance and operation away from the efficient duty point can increase sound. Improvements may include better duct geometry, isolation, maintenance, lower speed, suitable silencers or a correctly selected fan.
Design Enclosures, Barriers and Acoustic Treatment Properly
Place sound-absorbing material inside an enclosure where appropriate to reduce reverberation. Select material that is safe for fire, contamination, cleaning and physical conditions. Acoustic foam is not automatically suitable for an industrial process.
Barriers work best when close to the source or receiver and when they interrupt the direct line of sight. They are less effective in highly reverberant rooms unless room absorption is also addressed. Screens should not obstruct emergency routes, visibility, LEV or safe material handling.
Acoustic treatment of walls and ceilings reduces reflected sound but does not normally control direct exposure close to a machine. Use it where reverberation materially increases the background or affects many workstations.
Isolate Structure-Borne Vibration
Check for rigid bridges such as pipework, guards or services bypassing the isolator. Changes should be reviewed by competent mechanical or structural specialists where they affect load, alignment or safety-critical systems.
Integrate Noise Control with Procurement and Change
Buying quieter equipment is usually easier than modifying noisy equipment later. Tender documents should state working conditions and require meaningful emission data, proposed controls and acceptance testing.
Compare machinery for the intended duty rather than relying on a headline decibel value measured under different conditions. Consider installation, room acoustics, materials processed and operator position.
Management of change should review noise when throughput, speed, tooling, guards, extraction or layout changes. A production improvement that reduces cycle time may increase impact rate or place more workers near the source.
Prototype, Verify and Maintain
Where uncertainty remains, a temporary trial can test the principle before full investment. Set an expected reduction and measure before and after under comparable operating conditions. Also obtain worker feedback about usability and unintended effects.
Commission the complete installation
Record the operating conditions, measurement locations and baseline so later deterioration can be recognised. Where a control depends on an interlock or operating discipline, verify that failure produces a safe response and does not encourage bypassing.
Verification should confirm:
- change in source level and personal exposure;
- performance across operating modes;
- absence of overheating, fume accumulation or access problems;
- compatibility with guarding and maintenance;
- effect on communication and alarms; and
- whether workers keep the control in its effective position.
Include acoustic controls in preventive maintenance. Seals deteriorate, panels are removed, silencers clog and isolation mounts fail. A control that worked at commissioning may gradually lose performance without an obvious breakdown.
Set simple indicators for routine inspection: enclosure gaps, damaged seals, abnormal vibration, air leaks, missing absorption, open bypasses and changes in sound character. Workers often notice deterioration first, so provide an easy reporting route and ensure maintenance feedback reaches the noise-risk owner.
After significant repair or modification, repeat the relevant acoustic and exposure checks. A replacement motor, fan or guard may meet the mechanical specification while changing the noise profile.
Retain Organisational Controls and Suitable Protection
Engineering measures may not remove all exposure. Restrict access, schedule work and provide refuges or remote operation where these measures reduce residual risk. Hearing-protection zones should match the assessed conditions.
Select hearing protection to reduce risk without overprotection. It must remain compatible with other PPE and essential communication. Health surveillance is required where workers remain at risk and should inform review of the complete control programme.
Sysco Environmental can identify exposure priorities, map sources and verify whether proposed controls reduce personal dose. The outcome should be a ranked improvement plan rather than a collection of disconnected readings.
Lasting noise reduction comes from understanding how energy is generated and transmitted, then designing that pathway out of the job.