Resonics Director & Acoustic Specialist Matt Bullen was recently interviewed at an Q&A session for Audio Visual magazine. You can learn more about his views on the subject of audio visual room acoustics below:

1 – Why is it important to have good acoustics in spaces using AV equipment?

It’s obvious to say that audio quality is a critical part of any AV installation. A simple truth is that if the room acoustics are poor then the audio quality, especially for those listening in remotely, will be poor. There is literally nothing that can be done to the equipment itself to mitigate the issues caused by sub-standard room acoustics. Many office meeting rooms have ‘spider phones’; where meetings are purely audio calls – these rooms are often worse than video conference calls because you don’t have the visual prompts to assist if the sound quality is poor.

Most of us have experienced a video or audio meeting where the speech intelligibility is so poor that much of the conversation is missed, leaving the participants frustrated or sometimes the meeting just has to be stopped altogether. This only increases the feeling that face-to-face meetings are always much better. This has a lot to do with a high reverberation time in the space, caused by excessive hard surfaces; this uncomfortable room ‘echo’ just makes it impossible to have an effective meeting. Despite the improved understanding of the benefits of room acoustics we have seen in the last 10 years, one of our main areas of business is still ‘fixing’ poor acoustics in commercial meeting rooms. We are often asked to help in brand new, beautiful looking office fit-outs where the room acoustics have been ignored and the audio part of the audio/visual installation is just not fit for purpose.

Businesses invest considerable sums in AV equipment installations. From a financial perspective, the case for the importance of good room acoustics in AV rooms could not be put better than as follows: –

The average cost of a typical size audio visual installation in the UK can range from £10,000 to £20,000 per room”. Full teleconferencing installations such as TelePresence can cost £100,000 to £200,000. Many businesses will invest these sums and blame the equipment for unsatisfactory audio quality, when in reality it is almost always the room acoustics that is causing the problem” – Matt Williams, Carillion Communications.

We are often contacted by AV companies who are asking for our help in determining where the problem lies with the AV installation. In my view, every AV specialist should caveat their proposals by saying that the room acoustics should be considered as part of the AV installation. The acoustic treatment itself should cost a fraction of the cost of the AV install – so given its importance it really should be a ‘no-brainer’ for the client.

But it’s not all about financials. Still the most common complaint in the office working environment is about noise / acoustic comfort – and this extends to those spaces where teleconferencing is utilised. Spaces where acoustics have been considered properly are comfortable and inviting and studies have shown time and again good room acoustics is a positive factor in employee well-being. Acoustics clearly impacts productivity and absenteeism and we are seeing this intuition grow in the same way we understand that good lighting, climate, or the general office environment is fully understood. Please see here some information on how noise can impact the employee.

So, we can summarise the question of AV room acoustics importance by simply saying that it allows the equipment to work properly, it creates a comfortable, less stressful space for employees with all the benefits you might expect. We haven’t touched on the fact that if AV rooms work properly, this will reduce travel and reduce impact on the environment. The current global crises is showing us daily the range of acoustic quality we get when listening to broadcasts based in homes and working from home ourselves.

2 – What are the main considerations for acoustic design in terms of conference/meeting rooms?

In most cases we are primarily concerned with controlling VC room reverberation time (RT), (RT can be described as the severity of ‘echo’). To do this we need to assess the existing reverberation time (RT) of the room or space, which we can use as a starting point. We generally do this in two main ways. 1. Carrying out on-site RT60 testing using measuring equipment, or 2. Simple but effective desktop modelling, off-site. Using room data such as the size/volume of the room and the existing surface finishes of the space.

This information gives us the starting point to begin assessing how much acoustic treatment we need to design into the space.

VC meeting rooms have well understood reverberation time targets that we need to meet. Many of the audio visual equipment manufacturers (such as Polycom & Cisco) include recommended room RT times in their system guidelines. We then design our treatments to allow us to guarantee we achieve those acoustic targets.

Our goal is to ensure that the meeting participants have an optimised audio experience when using teleconferencing equipment, but we also want our solutions to look cool; so we work closely with our clients to achieve this, designing the acoustic treatments to walls and ceilings using a wide range of tested acoustic products, often customised. Acoustic surfaces are visible, so there is always a great opportunity to use the treatment as an architectural finish. It’s actually quite common for clients to choose acoustic products for their aesthetic value alone.

3 – What acoustic treatments, physical techniques and materials are available for meeting room spaces? What is the cost?

When we started specialising entirely on interior acoustics back in 2009, there were very few acoustic product manufacturers. Now there are many competing product manufacturers from all over the world. Some examples of manufacturers are as follows: – Saint Gobain Ecophon (Fibreglass / painted surface), Autex (PET – recycled plastic bottle), BAUX (cement / woodwool), Abstracta (fabric / wool / PET). Site built stretched fabric systems for walls and ceilings are a particular favourite of ours. Each manufacturer produces a range of products for walls and ceilings including baffles, rafts, wall panels and even acoustic lighting. Costs vary greatly and depend on the complexity of the installation and type of product used. Most installations will cost the client (on average) between £100m2 – £150m2. Architectural trends are always changing and we are seeing that budgets are increasing for the acoustic elements of schemes, particularly prestigious projects where customised, aesthetics focused, acoustical surfaces are becoming more popular. Acoustic treatments need not look like they have been installed to improve the sound environment. Office meeting rooms shouldn’t look like home studios but instead should be integrated seamlessly into the design.

4 – What are the most common mistakes or pitfalls when planning/designing and implementing acoustic treatments

One big and surprisingly common mistake we come across is where clients have used sound absorption acoustic products to treat sound proofing /or sound isolation issues (i.e. sound is leaking from one room to another). The issue of sound transfer between office rooms/spaces can be a critical issue to resolve for many businesses. Speech privacy is important; if intelligible speech can be heard between rooms, confidentiality is compromised which can and does bring a host of potential problems for employers and individuals.

Although sound absorption panelling within rooms can slightly reduce the transfer of sound to other areas (by absorbing the sound within the room); you need a lot of panels and it really isn’t an effective sound proofing solutions. Some companies offer sound absorption panelling as the solution for poor room sound attenuation, this is wrong and should be avoided. Often, the issue is weak points in the partitioning system itself, or for example sound often leaks through the ceiling, into the void and transfers to other areas. If this problem cannot be resolved with remedial works such as building barriers above ceiling voids, the best solution is to install a sound masking system (a demonstration video also shown below) :


Other mistakes we come across is clients who have installed products that are simply not suitable for the space – especially in terms of the class of absorbency. We often have to remove panelling that has been installed and replace with products that are effective. We also often find that the room acoustics have not been properly calculated in the first place. This tends to lead to putting a few panels on the walls, perhaps feeling a slight, but disappointing acoustic improvement. Often clients carry out these works and never really know how good the acoustics could and should have been and in the process making the room ugly! We have found that some clients have installed too much absorption to a space, making it ‘too dry’ or deadened; this is unusual but in all instances we have seen frightening sums of money wasted on acoustic treatments that are ineffectual.

For any further questions in regards to any of the above and if you are still feeling uncertain about audio visual room acoustics then please feel free to get in touch with any of our experienced and fully-trained acoustic specialists at any time.