ZEMCH 2015 - International Conference Proceedings | Page 855

where the employee workspaces are not separated by definitive structural features such as walls . Compared to traditional cellular offices , open plan offices provide opportunities to adapt to various configurations within the given space thereby allowing the means to accommodate more people in the area ( Schlittmeier & Liebl 2015 ). In a study comparing occupants in open plan offices and cellular offices , common sources of dissatisfaction in the former was air quality and thermal comfort ( Pejtersen et al . 2006 ). Mucous membrane symptoms , headaches and fatigue were 2-3 times more prevalent in occupants of open plan offices , with almost 8 times more occupants having concentration difficulties . Post occupancy surveys are an important means of understanding the problems faced by occupants of indoor environments ( C . Huizenga et . al 2006 ). Such information is a vital tool in optimising the existing buildings to achieve better occupant comfort and satisfaction . Secondly , it can provide information for future design and construction of buildings and indoor environments . Since occupant satisfaction has a positive relation to their perceived productivity ( Leaman et al . 2007 ), optimising the indoor environment would have economic benefits for the employers .
Occupants expressed satisfaction of noise levels at an approximate level of 45dB ( Huang et al . 2012 ). Performance of cognitive tasks is reduced at the normal sound levels of 51dB ( LAeq ) prevalent in offices while there was significantly less distraction at lower levels of 39 dB ( LAeq ). Although the ideal scenario for acoustic efficiency would be to create individual rooms for each employee , limited space makes this economically and functionally impractical . In such situations , efficient planning and development of the acoustic quality of spaces should be considered so as to create a more acoustically viable environment ( Jensen & Arens 2005 ). Spatial organisation is an effective means of reducing background sound within the work environment ( Jahncke et al . 2013 ; Schlittmeier and Liebl 2015 ; Jensen & Arens 2005 ). Designating separate zones for employees with concentration intensive tasks can ensure less distraction due to ambient speech . Employees with speech intensive jobs ( such as sales personnel ) could be spatially segregated from employees who require greater silence and concentration in their tasks . This could enable greater efficiency and job satisfaction . Another spatial tactic would be to designate quiet zones or ‘ think tanks ’ to conduct concentrated work and communication rooms to conduct phone calls . Encouraging an office culture of acoustic etiquette , or having a timeframe for silence during the day , are some measures that can be adopted by the employers to achieve an acoustic friendly environment for all ( Schlittmeier and Liebl 2015 ).
Although optimised spatial arrangement and office culture are initial measures in improving workplace acoustics , it cannot in itself block ambient speech and noise . Thus , it is imperative to employ methods that will reduce the disturbance caused by ambient noise . To achieve this , the sound signal from the emitter would have to be modified such that it has minimal impact on the cognitive function as well as the subjective understanding of the recipients . Laboratory and field findings demonstrate that is possible to create a STI below 0.5 ( LAeq ), which is an approximate threshold level beyond which task performance gets affected by sound disturbance , within a 2.5 – 5 m radius of the workstation ( Jahncke et al . 2013 ). Using sound absorbent interior finishes ( flooring , wall coverings , ceiling panels , soft furnishing , etc .) will help absorb the sound energy . Partition screens can be covered on both sides to moderately create a sound barrier between workstations . Although these measures reduce the distraction impact of background speech on the listener , often the speech is still distantly intelligible . By using sound masking techniques , the ambient speech can be superimposed with a ‘ masking ’ sound signal so as to considerably reduce the disturbance effect of the background speech ( Schlittmeier and Liebl 2015 ; Huang et al . 2012 ; Jahncke et al . 2013 ; Jensen & Arens 2005 ). Proposed masking levels for open plan offices are in the range of 40 and 45dB ( LAeq ).
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