About Noise Services

Noise disturbances are a large part of the services we offer. From domestic complaints to large-scale acoustic planning.

The word NOISE refers to unwanted and unpleasant sound. Exposure to noise can be more damaging than you may realise. The obvious result being deafness (temporary or permanent), but other symptoms include stress and reduced concentration which can lead to accidents.

At MAS Environmental we offer our services to everybody having problems with noise, using the latest technology and expertise.

A typical example would be a Commercial site (for example a factory, a nightclub) disturbing a residential neighbourhood. Here we might be approached by either the local council or the residents themselves. Using noise monitoring equipment we would measure the levels of the disturbance and illustrate them using many techniques. Below is an example of a Noise Monitoring Data Graph. This sort of graph could be used in reports or in court to help illustrate how extreme the disturbance is.

If we found there to be a significant disturbance we might approach the company alerting them to the problem. We then could help the company and the council decide how to reduce these levels. Finding the source(s), measuring and calculating the levels, planning possible changes and providing acoustic dampening.

We have designed and implemented many successful noise-reducing solutions to a large variety of problems.

The science of sound

Sound is measured in decibels (dB). Decibels are units on a logarithmic scale. This means for a noise level to increase by 1 dB, the intensity of the noise must increase by 10 times. It is measured on a logarithmic scale as it makes the measuring simpler and more similar to the way the ear perceives sound.

The physical effect that a noise might have on an ear varies greatly depending on many factors. The sound level (dB) is the obvious factor. However also the frequency of the sound is also important, and the time the ear is exposed to the sound.

Frequency is an important factor to the effect on the ear. The ear is more sensitive to higher frequency sounds, therefore a low frequency sound will appear to be quieter than a high frequency sound measured at equal dB levels. Because of this a calculation called A-weighting is applied to noise readings.

If you look at the example graph from before, you will see it uses a scale of dB(A), and contains data for LAmax, LAeq and LA90 levels.

A-weighting on a noise meter measures the noise proportional to how the ear would perceive the sound, with more priority to the higher frequencies. This weighting is labelled as dB(A).

The LAmax shows the highest noise level reached in each minute.

The LAeq shows the calculated average noise level over each minute (each hour for Period LAeq).

The LA90 shows an accurate approximation to the background noise level, i.e. the sound level you'd expect if the noise disturbance wasn't present.

As you can see in this graph below, A-weighting reduces the lower (and some of the higher) frequencies in the noise readings, as they would be perceived quieter by the ear.

Here are some typical dB levels of noise:

Noise Source	Typical dB(A)
Urban Background (late night)	40-50
General Office or Supermarket	60
Car at 25mph (7.5m)	70
Heavy Goods Vehicle passing pavement	90
Pneumatic Drill (5m)	100
Loud Disco (1m from speakers)	120

Did you know...?

? A change of 3 dB is noticeable to most people ?

? An increase of 10dB is twice as loud ?

? Double the distance from the noise source reduces the noise by 6dB ?

? Adding two equal sounds causes a 3 dB increase ?

The "rule of thumb" is that the MAXIMUM daily exposure to these noise levels in a average 5 working day week...

• 90 dB for 8 hours
• 93 dB for 4 hours
• 96 dB for 2 hours
• 98 dB for 1 hour
• 102 dB for 30 mins

If these are exceeded in a working environment then action MUST be taken by the employer to reduce the noise or the time exposed to the noise. Failure to do so puts the employee's health at great risk.

We produce posters which illustrate the Noise Regulations exposure times, click here for an example. The Noise Regs Thermometer shows the action levels on the left (in dB) which correspond to the length of time at which action must be taken on the right. Therefore, if you are working in a factory environment of 98dB for more than 24 mins, ear protection and training must be provided by law.

Any exposure to noise will have an effect on hearing. Extremely loud noises can cause instant damage, but regular exposure to low level noise will also be harmful. At work, this falls under Health & Safety.

Training

We offer training for anyone who deals with noise issues. We have a range of successful courses for Noise Professionals and Environmental Health Officers. Details of all the courses can be found in Training.