Noise is unwanted sound. It can cause hearing loss, disturb verbal communication or cause nuisance.
The most common sources are industrial noise and traffic. Vibrations can cause damage to assets,
radiate noise or cause discomfort to people.
Reducing the noise and vibration levels can be expensive, which makes the definition of
allowable noise levels economically important also. The allowable sound pressure on the site
For noise control on industrial sites two topics are central:
Nuisance to neighbors
- Prevention of hearing loss
- Speech intelligibility and communication interference
- General nuisance
From these laws and guidelines were developed.
Guidelines provided by the World Health Organization can be found at Guidelines for Community Noise
After the definition of the allowable levels an approach to obtain the
required levels in the most economical way is needed. For a grass roots plant
it is important to start the design process from an overall overview of
the sources and the limits that they need to comply with. For this it is important to
recognize the characteristics of different sources. For modifications to an existing
facility the same principles apply, but implementation is limited by more
The place where noise abatement engineers prefer to reduce the noise is where it starts:
at the source. If this does not lead to the desired result the noise can be abated
at the transmission path. The last place is the receiver. Noise control at the source: design or select low noise machines
Noise reduction at transmission path: silencers, mufflers, mounting on vibration pads, enclosures, ...
Personnel protection: Ear caps or plugs
In short this means:
During project execution noise control is one of many things that need to be addressed.
It cannot be seen independent from the safety and functionality of the plant, its lay-out, schedule
Front End Loading
During first phase of the front end loading the main interest is to decide if this is
a project that the company wants to invest in and, if this is the case, to which capacity and where
to build it. At the end of the Front End Loading the project should be defined, including
noise control. This implies that first of all one needs to be sure what the allowable noise levels are,
both from a legal and social point of view. Secondly, one needs to be sure that these can be met.
For this the noise sources are evaluated and unsilenced level prediction methods are used
varying from in-house correlations and experience data to vendor provided data. For dominant
noise sources it is strongly recommended to make use of the vendor's knowledge.
These values are used in computer programs that provide noise contour plots. The noise levels
at the site and noise immission at the neighbors can be evaluated and the allowable level per
source and/or required noise reduction can be judged.
The front end loading will usually be completed with a noise control management sheet,
which provides a maximum allowable noise level per source.
The noise control management data sheet is used as the input for equipment requisitions
and specifications. Vendor quotations and guarantees need to evaluated. The noise control
management sheet and associated calculations need to be updated with the selected equipment data.
This will include good and bad news. In practice a number of dominant noise sources such as
compressors or air coolers will receive most of the attention to obtain the goals.
One can specify and perform noise measurements at the workshop for individual items.
After completion of commissioning and start up of the plant the noise levels on site
and outside the fence can be verified. This can be demanded by the authorities.