Harmonising Workspaces: How Quality Acoustic Design Pays Dividends

So you’d like to create a ‘well’ space but not sure where to start with acoustics? This blog should demystify the terminology and guide to towards optimising your space, technology and the time of your staff.

Since the office is here to stay, let’s look at the problems we’re facing…

For over a decade, office noise levels have been named repeatedly as factor driving down personal productivity. Only 36% of employees were ‘satisfied’ with their office noise levels in 2022 according to Leesman Index.

With the increase of hybrid working, virtual meetings are on the rise which means even more office noise. Without knowing there are systems out there to help with this, it can be challenging to know how to overcome the issue of noise because workplace noise is predominantly verbal communication.

The World Green Building Council estimates that productivity can decrease by as much as 66% in open-plan offices with high noise levels.

Facilitating communication with remote staff has never been more important so let’s drill into the acoustic factors affecting the success of that plan that you can easily do something about...

 

Reverberation

Reverberation Time (RT) refers to how long it takes for a sound to decay by 60dB after the sound source (someone talking) stops. In simple terms, is your meeting room echoey or can you hear people talking from across the office? If it is, it means your RT is higher than what is considered comfortable for communication.

Some manufacturers of audiovisual equipment note the RT time that their products have been tested at which gives you an idea of what to aim for - typically 500milliseconds or, 0.5 seconds. A person speaking is a sound source and the intelligibility of their speech is determined my the RT.

It’s easier to understand speech if you’re in the meeting room with the talker but for those at the far end, it can be very stressful and disengaging if the microphone is picking up direct speech and additional reflections from smooth surfaces like glass or plasterboard walls. The use of the space, its dimensions and the interior surfaces will affect how much acoustic treatment you will need and where is best to install it.

Intelligibility of speech is measurable using the Speech Transmission Index (STI). Here, we can say that the STI is poor because you struggle to understand what the talker is saying.

Acoustic absorption panels will help to reduce the RT which will make a big difference to how the room ‘feels’ to staff. To help understand what we mean by that - Imagine standing in a cave vs your living room. Even with your eyes closed you can tell the difference as you hear how sound behaves in those two environments.

Knowing how much panelling to use and where to put it is something the professionals will help you with but remember, not all panels are created equal. Ever wondered why some products are £15 and some are hundreds? There is a classification system from A to ‘unclassified’ in terms of how much they absorb – i.e. how effective they are at absorbing sound. The classification of a product is determined with strict testing in accordance with BS EN ISO 354, an international standard which tests the absorption coefficient across 18 frequencies (Finishes and Interiors Sector, Specifiers Guide, 2021). You should also consider sustainability when selecting products, these days that doesn’t mean compromising on looks.    

Panelling is best used closest to the noise source, at it’s first reflection which is usually an adjacent wall from the sound source. Be careful not to ‘overcorrect’ a noise issue; too much absorption will feel unnatural and lifeless.

A balance should be struck.

 

Sound Masking

What about if you’re sitting in an open plan office? Because office design favours layouts which make the most of natural light and views of the outside, there are no physical barriers to block sound from travelling across the space.

Modern offices sometimes suffer from being too quiet so if your staff make calls from their desks in a open plan space, how can you mitigate the risk of them distributing others whilst also being able to focus on their work?

Here is where ambient noise levels come into play. Ideally, you want to avoid a library-esque vibe by encouraging communication between staff. Seeing staff wearing headphones for concentration on their in-the-office-day is heartbreaking.

Sound masking systems can be used to artificially raise the ambient noise levels using network of loudspeakers in the ceiling. The system plays an unobtrusive sound similar to airflow. Essentially, you’re playing a gentle background sound that will cover or mask other sounds which are quieter. For example, conversations become less intelligible over distances which is great for increasing speech privacy.

Paradoxically, sound masking can enhance collaboration by providing a level of speech privacy. It allows for more open-plan office designs without sacrificing the need for privacy during confidential discussions.

We can see that speech privacy is a key indicator of staff satisfaction. One of the reasons we find speech privacy to be such a hot topic is because we are drawn to conversation. When a conversation is intelligible (where the words are comprehensible), we find it almost impossible to ignore – even if we don’t want to listen.