Noise

WHITE PAPER: Open collaborative spaces are great - sometimes. However, studies show that office workers spend up to a quarter of their day affected by audible interruptions and distractions.

Blair McKolskey and Greg Tate examine ways to mitigate productivity-affecting disturbances.

The importance of collaboration

Research shows that collaboration is the most viable way to harvest the knowledge resident in our best companies. Increasingly this is taking place via less formal interactions.

Unplanned interactions amongst colleagues remain the ripe ground upon which teams can increasingly advance the company’s goals. Knowledge that is openly discussed in these unplanned interactions moves in a diffusion-style transfer from those who have it to those who want it – even if they don’t yet know that they do.

Is noise harmful?

How many times per day do we overhear another conversation at work? Our ability to intercept a conversation and contribute enhances the productivity of teams by enabling results that would otherwise require formal process (research, meetings etc.). But consider this – this process of knowledge sharing may be valuable, but ironically it could also be harmful. Research shows that focused work remains more than 50% of our daily work life. So although the audibility of this knowledge transfer may be welcome to some, to others involved in focused work it will be more likely to be distracting.

According to a Basex study, office workers spend a quarter of their day consumed by interruptions and distractions – which wastes both time and money (Wallis, Steptoe, & Cole, 2006). This study reported that the ongoing splintering and diverting of worker attention was responsible for the loss of up to 2.1 hours of worker productivity per day. The hours lost included not only interruptions and distractions but also the time associated with recovering from distraction and getting back on task.

How does noise affect us?

Hearing is one of the most acute senses. The human ears are incredibly sensitive in the audible frequency range (20Hz to 20kHz). We are able to hear an incredibly broad range of sound. Our tolerance of noise differs from person to person and sensitivity can increase depending upon our mood, for example we may be less able to cope with loud noise when we are stressed.

In the office environment, sound can affect people in different ways. Studies have shown that exposure to noise can adversely affect our ability to concentrate and can also contribute to a build up of stress and frustration, reducing our overall tolerance levels. Greater than half of all office workers report being disturbed by conversations and other noise distractions in the workplace, yet some people are more irritated by such interruptions than others.

Introverts vs extroverts

Introverts differ in their perception of noise compared to extroverts, rating themselves as more “noise sensitive” and performing more poorly than other more extroverted subjects when tested in the presence of noise. While extroverts often enjoy working in the presence of music, introverts may tend to prefer quieter conditions. However both introverts and extroverts performed poorly under test conditions when affected adversely by noise. Most often people are more irritated and distracted by less necessary sounds, such as casual chit chat, than they are by routine and unavoidable sounds, such as tapping on keyboards.

Managing speech noise in the workplace

Speech is considered by most of those surveyed to be the most annoying and distracting type of office noise. This is also one of the most difficult types of noise to eliminate; it is human nature to seek to communicate, and open plan office environments are becoming more predominant. Therefore it is important to combat the negative effects that this can have in the workplace. How do we do this?

Strategies for managing noise

Different types of businesses require different workplace design strategies. Table 1, outlines a way to segment the way cognitive work is performed. In this example, for a legal firm the large proportion of work will be done in a focused manner with private/confidential collaborations. Contrast this with creative firms who thrive in open, energised collaborative spaces and perform a mix of focus/non-focus work. Each of these companies requires a different strategy to balance the work process with the acoustic requirements of the space. Here are some strategies that can be considered:

1. Create Zones

Activity-based working is now a well accepted design strategy providing destination spaces for those who need to focus as well as energized and activated spaces for collaboration. Acoustic strategies can provide passive sound absorption for both types of spaces so that one type of work is not negatively affected by the noise generated by the other.

2. Get Masking

Background noise is able to provide masking properties to assist in speech privacy. In the ASB North Wharf building in Auckland’s CBD, for example, the background noise created from babble (multi-talkers) in the large atrium feeds into the adjacent neighbourhoods and provides noise masking. This strategy is generally only effective with a large number of occupants (500 or more). Malcolm Dunn, from Marshall Day Acoustics, relates this acoustic hum to being equivalent to that of an airport’s natural hum. The advantage of natural masking is that higher levels of masking noise 48dB(A) can be achieved using this method. By comparison, electronic masking has a lower threshold, with 36dB(A) being the level where people become annoyed. A massive 12 dB(A) difference is extremely significant in improving speech privacy between occupants in large spaces.

3. Get Above It

Careful consideration of sound-absorbing products in the ceiling plane can provide acoustic dampening for a space. In these types of environments, an absorptive ceiling with a Noise Reduction Coefficient (NRC) of 0.9 is highly recommended. If there is no absorption in the ceiling plane, soft furnishings can provide additional absorption as well as diffusing the sound. In smaller, open-plan environments, designers should give careful consideration to vertical acoustic wall panels to reduce lateral sound reflections. This is important in both medium to large meeting rooms to eliminate flutter echoes. Flutter echoes are sound waves bouncing back and forth between walls - especially if the walls are parallel and have no absorption, for example plaster walls.

4. The Psychology of Space

Screens have played an interesting role in the evolution of acoustic requirements. Beyond dispute, the most effective acoustic strategy is to have occupants adjust their own behaviour. Where screens prevent occupants seeing another co worker, the sound levels tend to rise. When all residents have immediate eye contact, the awareness of others working nearby will cause voice levels to modulate at a lower level due to human response and body language. In these cases, the height of the screens is a very important parameter.

5. Furniture as Architecture

There is an increasing use of furniture instead of walls to create acoustic pods that provide a destination solution for focused work. These destination pieces of furniture provide several benefits. The acoustic benefits of filtering out external speech-frequency noise enhances the ability to focus. Importantly, the mere fact of being situated in one of these areas sends a signal to co workers that you intend to focus and to consider carefully before interrupting this particular style of work.

6. Emerging Technology

Nanofibre technology is a revolutionary method of providing acoustical damping in composite materials. Nanofibrous membranes within composite materials lower the first absorption resonance of noise which provides additional sound absorption. It is now possible to purchase office furniture that incorporates this technology and offers options for both collaborative and focus situations.

Active noise control (ANC), also known as noise cancellation, or active noise reduction (ANR), is a method for reducing unwanted sound by the addition of a second sound which is specifically designed to cancel the first. Modern active noise control is generally achieved by creating a signal that will effectively reduce the volume of the perceivable noise. Noise cancelling headphones that use active noise control are an example of this. Electronics in the ear piece create a noise-cancelling wave that is 180° out of phase with the ambient noise. This wave acts like a noise eraser.

Infusion and not confusion

Whatever the size of the company, the need for open collaboration is growing in importance. The infusion of specialist knowledge throughout the team will maximise the productivity of a firm. Larger companies will benefit greatly due to the greater role of specialisation that naturally occurs in a big organisation. However, small and medium size companies will also gain increased productivity from open-plan and activity-based working. In both cases, well considered acoustic strategies are vital in ensuring the infusion process does not become a confusion process.

Words: Blair McKolskey, Greg Tait
A version of this article was first published in Interior Magazine.

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