In brief
The Noise Regulation requires noise to be eliminated or reduced at source first; hearing protection does not replace these measures. The cheap and quick steps are maintenance, fixing air leaks and vibration isolation; machine enclosures and acoustic cabins are more expensive but effective; absorbent panels only reduce reflected sound. Organising working time reduces exposure, but on its own it is often not enough.
Why do noise reduction methods come before hearing protection?
In a noisy hall, the first measure that comes to mind is earplugs, but the order in the legislation is the opposite. Art. 5 of Law No. 6331 requires risks to be combated at source and collective protective measures to be given priority over personal protection. Art. 8/1 of the Noise Regulation applies the same principle to noise: taking into account technical progress and the possibility of control at source, the risk is eliminated at source or reduced to a minimum.
Art. 8/2 of the regulation lists the noise reduction methods one by one:
- Choosing working methods that produce less noise,
- Choosing equipment suited to the work that produces the least possible noise,
- Designing and laying out workplaces and work areas appropriately,
- Training employees in the correct use of equipment,
- Technically reducing airborne noise with screens, enclosures and sound-absorbing panels, and structure-borne noise with isolation and damping,
- Applying suitable maintenance programmes for the workplace, systems and equipment,
- Organising work so as to limit the duration and level of exposure and provide adequate rest breaks.
If exposure exceeds 85 dB(A), these measures are written into an action plan and implemented (Art. 8/3). For details of the thresholds, see our article on the 80, 85 and 87 dB limits. This article explains which measures should go into that action plan, and in what order.
First, get to know the source
An effective plan starts not with the finding that "the hall is noisy" but with the question of which machine produces sound by which route. Make three distinctions:
- Airborne and structure-borne sound. Fan, air jet and gear noise radiates directly into the air. Machine vibration, however, passes into the floor, platforms and ducts, and is radiated again from there as sound. The remedies for the two are different.
- Direct and reflected sound. Most of the sound reaching someone working right next to a machine comes directly. Someone in a far corner of the hall also receives sound reflected from the walls and ceiling.
- Continuous and impulsive sound. Impulsive sources such as shuttles, presses or falling parts raise the peak value even if the average level seems reasonable.
The average value in the measurement report is not enough to make these distinctions; source-by-source measurement and a noise map are needed. We explain the method in our article on workplace noise measurement. We plan measurements with authorised laboratories and enter the results in the risk assessment.
Reducing machine noise: what to do at source
In work to reduce machine noise, the lowest-cost steps are usually the most neglected:
- Maintenance. Worn bearings and gears, loose covers and sheet metal, and unbalanced fans increase noise over time. Adding a "noise and vibration check" line to the maintenance card catches the problem before it grows.
- Compressed air. Leaking connections and air pressure set higher than necessary are a significant noise source in weaving halls. Fixing leaks and setting pressure to need reduces both noise and energy consumption. Silencers are fitted to pneumatic exhaust outlets.
- Reducing impact. Shortening the height from which parts fall, and lining the inside of metal chutes and bins with impact-damping material, reduces impact noise.
- Fans and extractors. Excessive speed, turbulence at duct inlets and imbalance are checked.
Vibration isolation
Placing suitable elastic mounts under machine feet reduces the transmission of vibration to the floor and adjoining structures. This is particularly effective for machines working on upper floors or light platforms. Isolators are selected according to the manufacturer's instructions; a wrongly chosen soft mount can cause the machine to rock and compromise its secure fixing. Using flexible connectors in duct and pipe connections also stops vibration travelling along the line.
Enclosures and acoustic cabins: expensive but effective
When reduction at source is not enough, sound is cut off by putting a barrier between the source and the employee.
A machine enclosure is a housing that surrounds the machine completely, lined inside with sound-absorbing material. Its effect depends on how well it is sealed: even small openings left for cable and material passages markedly reduce the gain. When designing an enclosure, maintenance access, heat build-up and ventilation, the material feed route and how the machine's energy will be isolated for work inside the enclosure are considered together.
An acoustic cabin does the opposite: it protects the employee rather than the machine. If most of the operator's work consists of monitoring and control, a glazed control cabin overlooking the hall moves a large part of the exposure time to a quiet environment. Art. 8/4 of the Noise Regulation requires noise in rest areas to be suitable for their purpose too; moving the break area out of the hall is a cheap and lasting measure.
Absorbent panels: when do they work?
Covering walls and ceilings with sound-absorbing panels reduces reflected sound in the hall. So it makes a difference for those working far from the source and in halls with highly reflective surfaces, mainly concrete and sheet metal.
Distance also has an effect: in a free field, when the distance from a point source doubles, the level of direct sound drops by about 6 dB. Moving workstations that do not need to be there, such as a packing or quality table, away from noisy machines is therefore a cheap layout measure.
Organising working time: a worked example
Daily exposure (LEX,8h) is calculated on the equal energy principle: if the time spent at the same level is halved, exposure drops by about 3 dB. This is why rotation works, but its limits need to be understood. The following example is for a weaving hall; the hall is taken as 91 dB(A) and the preparation department as 78 dB(A):
| Scenario | Daily split | LEX,8h |
|---|---|---|
| Current situation | 8 hours in the hall | 91.0 dB(A) |
| Rotation only | 4 hours hall, 4 hours preparation | 88.2 dB(A) |
| Reduction at source only | Hall reduced to 87 dB(A), 8 hours in the hall | 87.0 dB(A) |
| Both together | Hall 87 dB(A), 4 hours hall, 4 hours preparation | 84.5 dB(A) |
The table shows that rotation alone did not bring the employee below 85 dB(A); the 4 dB reduction achieved at source was not enough on its own either. When both were applied together, exposure fell below the upper action value. Rotation also has a cost: it can increase the number of people exposed to noise. So rotation is added alongside reduction at source, not instead of it.
Ranking by cost and effect
In textile businesses in Bursa and the surrounding provinces, especially in the OIZs (organised industrial zones) in Nilüfer and the TOSAB Bursa Textile Dyehouses Specialised OIZ in Badırga, weaving, twisting and compressor areas are the sources that come up most often. The ranking below is a general framework that can be used when building an action plan in such a business; the actual gain is verified by measurement on each machine.
| Measure | Relative cost | Who benefits? | Point to watch |
|---|---|---|---|
| Maintenance, loose parts, air leaks | Low | Everyone in the hall | Loses its effect if not tied to maintenance records |
| Pneumatic silencers, pressure setting | Low | Everyone in the hall | Should be set together with production parameters |
| Vibration isolation | Low–medium | Adjoining areas, floors above and below | Machine stability must not be compromised |
| Moving break areas and tables | Low | Those needlessly exposed to noise | Layout plan should be updated |
| Control or monitoring cabin | Medium | Operator | The work must genuinely be monitorable from the cabin |
| Machine enclosure | Medium–high | At and around the machine | Sealing, heat, maintenance access |
| Absorbent wall and ceiling panels | Medium–high | Those far from the source | Changes exposure at the machine very little |
| Rotation and time limits | Low | Employees on rotation | Number of people exposed may increase |
Hearing protection is used together with the measures in this table. The 87 dB(A) limit value may not be exceeded under any circumstances, including the effect of hearing protection. For the general order of measures see our article on the hierarchy of controls, and for other risks in the weaving hall our article on OHS in weaving businesses. Sector-specific planning is on our textiles page, and area-specific information on our Nilüfer OSGB page.
Choosing quiet equipment: decibels gained at purchase
The cheapest decibel is the one gained at the purchasing stage. Art. 7 of the Noise Regulation requires the risk assessment to take into account the noise emission information given by the manufacturer and whether alternative equipment producing less noise is available. To choose quiet equipment, add the following to the purchase specification:
- Noise emission values declared in the user manual, and the test conditions under which they were measured,
- A requirement to compare bids under the same measurement conditions,
- That an on-site measurement will be made after installation and that the result is one of the acceptance criteria,
- That accessories such as vibration mounts, silencers and enclosures are included in the bid.
After a new machine is commissioned, the measurement is repeated and the risk assessment is updated. Hearing monitoring for employees exposed to noise is planned by the workplace physician as part of health surveillance.
Frequently Asked Questions
We have handed out hearing protection; are further measures mandatory?
Yes. The Noise Regulation requires noise to be reduced at source first, and if 85 dB(A) is exceeded it requires an action plan containing technical and organisational measures. Hearing protection complements these measures.
Absorbent panels or a machine enclosure?
If high exposure is at the machine, an enclosure or reduction at source takes priority. If the problem is reflected sound across the hall and employees are far from the source, absorbent panels help. The decision is made on the basis of source-by-source measurement.
Does rotation solve the noise problem?
On its own it usually does not. When time is halved, exposure drops by about 3 dB; in a hall above 90 dB(A), this is usually not enough to bring the employee below the upper action value. Rotation is planned together with reduction at source.
Should the measurement be repeated after the measures?
Yes. The real effect of a measure can only be seen by measuring again. The result is entered in the risk assessment and the action plan; if the target has not been reached, the next measure is brought in.
A risk assessment that identifies and scores hazards on site, links each measure to an owner and a date, and has a clear renewal schedule.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.