Phenomenon noise

What is noise?

A sound is characterized by its sound level (sound pressure) and by its tone pitch (frequency). Thereby sounds in a frequency range between 2000 und 5000 Hz at a similar sound pressure are sensed subjectively louder than sounds below or above this frequency range.

Pestering noise at the workplace

Willi Schneider, chairman of buero-forum, assisting chairman of the German office network

In the workplace, noise is the biggest disturbing factor. Every fourth employee is suffering from noise. As pestering noise, acoustic noises are characterized, which disturb the psycho-social or physical well-being and causes a feeling of discomfort by the person concerned. Therewith noise constricts the communication, influences the concentration and often makes sick. The term pestering noise cannot be defined objectively. Acoustic measurements and specified guidelines can only give an indication for the level of disturbance, as the human being reacts very subjectively to noise. If a noise is sensed or not sensed as a disturbance, is dependent on the sound level and further criteria. Significant is the kind of sound and more important the situation and attitude towards the sound source of the person concerned. Therefore it is unreasonable to meticulously measure data without having in mind the emotional level of the concerned person or employee. The individual valuation is finally determining if somebody is pestered by noise. When working intently in front of a screen, every noise, which is not caused by the working person itself, is classified as disturbing. As self-caused noises are considered only one’s speaking and the speaking of the discussion partner as well as the own keyboard noise and signal noises (e.g. the ringing of the one’s telephone). The disturbance level is extremely high if outside speech-related noises are involved, which can be understood – even partially – by the person concerned.     

Consequences of noise

Noise disturbs. Noise stresses. Noise disturbs the concentration. Not only, but also in the office. And with missing concentration the quality of work reduces. Performance will be minimized or becomes incorrect.
A performance loss of 20 - 30% is traced back to concentration leakage by experts of REFA and VDI. These assumptions are now confirmed by the scientists Dipl.-Psych., Dipl.-Ped. Ch. A Sust and Prof. Dr. Eng. Lazarus. In the case report FB 794 of the Federal Institute for Occupational Safety and Health (BAuA), scientists deal with the “Noise level and VDU-Work - The effects of mid-intensity noise on simulated office activities of differing complexity”.

The corresponding result is, that with an increasing complexity of tasks, the noises with a relatively high intensity and information transfer do clearly interfere the performance of the test person. A higher time requirement and an increasing error rate had been the results – but also the recreation necessity had risen. Overall it can be determined, that the revenue and expense calculation declines, as more time is required (due to the need for more frequent checking of progress, the more frequent necessity to begin tasks again, more laborious methods of working to ensure correctness) to achieve a result which is qualitatively sufficiently satisfactory. In the case of tasks of a higher complexity with a high amount of informational input and where subjected to high-intensity noise, subjects tend to leave the results of the tasks incomplete or to stop work on them altogether.

Criteria to the sound-technical evaluation of VDU-workstations:

Source: Investigation and reduction of noise at VDU-workstations in the office and in production, work task scientifical findings nr. 124 VDU-work – noise reduction in large capacity offices; Editor: Federal Institute for Occupational Safety and Health, Dortmund 2003

• Criterion 1: That of a single, identifiable sound source created proportional sound level should not exceed more than 4 dB compared to the sound level of any other sound source altogether. Otherwise the workstation has to be classified as “inconvenient” in terms of sound-technical evaluation.

• Criterion 2: Conversations out of other work areas and from the outside should not be hearable. That implies, that in small offices the proportional level of intruding noises from the outside should be at least 5 dB below the existing basic sound level, in large capacity offices at least 3 dB.

• Criterion 3: If the concerned person does not work, the combined sound level from all sources should be as low as possible. The result of this evaluation can be seen in the following table.

These three criteria are applicable to all VDU-workstations in offices. They apply to large capacity offices or single offices as well as to combined offices. If criteria 1 to 3 lead to a different evaluation, then the more inconvenient is applicable to evaluate the workstation.

Sound-technical evaluation of VDU-workstations:

For a better understanding, see some examples: The sound level in the open nature is around 30-40 dB. Normal speech at a distance of one meter is 55-60 dB. Loud speech at a distance of one meter is about 65-70 dB. Intense street noise at a distance of seven meters is 80-85 dB.

A permanent load of above 65 dB leads to disruptions of the autonomic nervous system, permanent loads of above 80 dB to hearing damages.

A permanent load of above 65 dB leads to disruptions of the autonomic nervous system, permanent loads of above 80 dB to hearing damages.