Issue 21, November 2006

Maintaining acoustic comfort in the office is more than just reducing loud office noises. The acoustic environment in the office comprises all the sounds that occur throughout the day. Some of these sounds are welcome and essential in some form, such as a telephone ring. However, when sounds annoy and distract your office occupants, they are perceived as noise and will hinder your office productivity.

It is often the case in office buildings that noise from the conversations of others is a major irritant for workers, especially in open-plan offices. A large survey of North American offices found that 54% of office workers were often bothered by noise: ringing phones and conversations were most disruptive.  Generally it is the information content, predictability, necessity, and controllability that determine the noise annoyance.

To achieve occupant acoustic satisfaction in your office it requires speech privacy and comfortable sound levels. For acceptable speech privacy your people need to be unable to understand conversations overheard from other areas/cubicles. This is a function of the ratio of sound energy from speech and other ambient sounds. If your office is quiet with little background noise, overheard speech can be perfectly intelligible and therefore more annoying because of its information content, unpredictability, and uncontrollability.

A moderate level of ambient sound will cover intermittent noise such as speech sounds, and thereby, reduce annoyance. Balanced sound levels provide privacy and prevent annoyance.

The best way to control and therefore minimise unwanted noise sources is via office design .  The acoustic properties of the office can significantly reduce sound travel by blocking sound transmission and by absorbing reflected sound.

It is important to note that only sound levels can be measured, noise is a subjective parameter.  Noise perceptions and its effect on occupants are best assessed via occupant satisfaction surveys.

Cetec regularly conducts Occupant Satisfaction Surveys to assess occupant perceptions of a workplace.  These survey can be conducted to assess all elements of Indoor Environment Quality, including Acoustic Comfort.  Typically we conduct surveys following a change in office conditions, either planned or unplanned such as a refit, relocation or incident investigation.  Before and after surveys are highly recommended to objectively measure the effects of the design change/s that aim to improve your office, whether this be for acoustics or any other IEQ component.

If you would like more information about the Speech Intelligentibility Index and the methods of assessing and predicting speech privacy, such as the relevant Australian Standards, Cetec can help you.

To read other related articles
Office Noise
 

Sundstrom E, Town JP, Rice RW, Osborn DP and Brill M (1994). Office noise, satisfaction, and performance. Environment and Behavior, 26(2), pp 195-222.

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