Christophe Debonne & Dominiek Callewier ©2021
Let us compare good acoustics with good (going) food. What ultimately determines whether you are satisfied and have enjoyed the moment? This is not an easy question, as the answer is a combination of many elements, linked to the food (quality and freshness of the ingredients, originality of the recipe, correct cooking method and temperature, presentation and arrangement, etc.), the setting (nature and style of the building and space, furniture and garnishes, table arrangement, music, etc.) as well as to the other guests at the table and the conversations at the table. Defining good acoustics is at least as complex as determining what good food is. It is also a combination of technical elements, experiential aspects, dynamic in nature, in a changing occupancy of spaces and moreover with unclear objectives: sometimes we prefer silence to concentrate, at other times we want to hear each other well.
Numerous studies, measurement campaigns, observations, executions and evaluations in office environments have brought us to a global and conceptual insight into 'good' acoustics for office environments. This insight can be summarized in 5 (psycho) acoustic aspects (without order of importance) that have a great influence on the well-being of office users, the '5 commandments'.
Imagine for a moment that noise or bad acoustics would stink? Would you want to work in that stench day in day out?
Of course not! That is why the 5 commandments put forward a number of key elements that together ensure 'good acoustics'. These are decisive for the well-being of the users of these spaces and therefore also for their productivity:
1. Ensure good control of reverberation and speech intelligibility ;
2. Ensure good background noise control;
3. Provide sophisticated and considered sound insulation and privacy where necessary;
4. Ensure a well-considered layout of the workplaces, with special attention to acoustic sight lines and disturbance perimeter ;
5. Ensure the right ' look and feel ', adapted to the function of the various spaces.
Reverberation in a space is the result of too little acoustic absorption. The trend in modern, sleek architecture may be 'in'; this is often detrimental to reverberation.
In any case, the reverberation time should be limited to 0.8 sec in offices and conference rooms. This can be done by introducing sufficient absorbing materials into the space, in addition to the 'hard' materials such as glass and concrete.
Good intelligibility of the speaker must also be ensured.
Background noise (from ventilation, for example) should not be too high, but neither should it be too low. Too high levels are nerve-racking; too low levels promote 'disturbance' and loss of 'privacy'.
Masking noise should also be perceived as 'pleasant', and preferably not 'directive', meaning that one 'experiences' a pleasant background noise without consciously hearing it or being able to indicate where it is coming from.
A trend in acoustic office design advocates the 'open plan' office, where as little sound insulation as possible is needed. Few or no barriers are supposed to ensure better communication, more team spirit etc. The reality is that the productivity of office workers in an open office is easily up to 40% lower than employees who work in a more discreet environment. In the meantime, the 'open plan' concept has already been abandoned by many architects and management, precisely because of the disastrous consequences.
Considered sound insulation between operationally separated entities is a must where concentration and confidentiality are important.
A sound source, especially human speech, will be all the more disruptive if the person being disrupted 'sees' the source. The layout of office workplaces with multiple people is therefore extremely important to avoid these disruptive effects. On the other hand, some visual/auditory interaction is also desirable.
For larger workspaces, the concept of partitions between furniture can somewhat reconcile both elements (limiting sightlines but maintaining interaction).
In any case, a thorough layout study of office furnishings is necessary, especially when it comes to larger entities with larger numbers of users.
The furnishings of offices and meeting rooms (furniture, walls, floor, etc.) can be both soothing (and therefore conducive to concentration) and very 'clean'.
Often too 'clean', well being also 'mean'; the opposite of 'cosy'. Very clean is sometimes associated with 'professional', but then also quickly degenerates into 'cold'. A place where one will not want to stay longer than necessary.
The influence of look and feel on acoustic well-being should not be underestimated. For example, respondents in a sleek, clean environment will more likely pick up speech-intelligible signals compared to people in a 'warmer' environment.
The look and feel is also often the appearance of a corporate culture. It is important to make the right choices with the users, based not only on the insights of the interior architect, but also on those of the (acoustic) design engineer.