Making room for safer sounding workplaces

Across all types of workplaces and sectors, people are exposed to high levels of noise. Excessive levels can affect people’s ability to do their job well, cause serious health problems, or lead to danger if warning signals cannot be heard.

Photograph: Unsplash

Balancing aesthetics and functionality is a challenge in room acoustics. Modern architecture is often based upon new and innovative technologies, featuring large open rooms with many sound-reflecting materials and minimalistic décor such as exposed concrete and glass facades.

This can result in generally higher sound levels and poses a great challenge to achieving pleasant acoustics suitable for the intended use of the room, as well as issues for clear speech transmission.

Early review of room acoustics when designing spaces and planning work processes is important. Many problems, and hence costly solutions, can be avoided by designing a beneficial floor plan which considers the zoning of different work processes. This can help to minimise costs by needing less acoustic treatment and being able to choose the most effective solutions in the planning and building stages, instead of fixing them after completion.

Key risks

There are two main concerns in spaces where the room acoustics are poor. The first is safety. In areas where there is an emergency announcement system, or places where protecting people depends on them understanding announcements (such as industrial sites, health facilities, airports, public buildings, ships etc.), there are typically strict requirements that need to be met for their effective operation. Places like educational facilities, courtrooms and political spaces also pose important requirements for speech intelligibility.

The other concern is acoustic comfort. While not directly life-threatening, it can have a serious impact on health and performance. In places like restaurants, schools and offices, bad acoustics can lead to discomfort, causing loss of revenue or reduced cognitive performance and health issues. This can lead to poor work performance among employees and students alike.

Sectors particularly affected

There are high-profile projects everybody thinks about when talking about acoustics, like concert halls and auditoriums, to enrich the sound. However, everyday rooms, like schools, healthcare facilities, restaurants, airports and offices, are just as important. These sites often suffer from poor acoustics because this gets overlooked in the planning stage.

There is a vast array of acoustic considerations in the ever more flexible work environments of today (desk sharing, remote work, etc.). In the education sector, there are challenges with changing modern teaching concepts – for example, less focus on a lecture-based lesson. This means that making sure that rooms are well designed for clear speech transmission from the lecturer to the students is vital.

Noise regulations, guidelines and standards

Room acoustics regulations and guidelines are dependent both on country-specific and international legislation and standards, while the ISO 3382 series defines the relevant metrics and how they are measured. While numerous standards are well established, new ones are being developed for specific places like music practice rooms and teaching spaces.

Assessing the impact of noise in a room

Acoustic consultants (building, environmental, or acoustic), engineers and interior architects can use specialist simulation software in the design process to optimise the room layout. This helps ensure that excessive noise is reduced, and good acoustic conditions are achieved, supporting workers’ wellbeing and productivity.

Using input data, the software produces a noise map of the area, such as a production plant, and produces a colour-coded, visual display of how it will propagate and at what volumes. This helps to isolate and address problem areas. Different options can be trialled and costed on the computer, rather than having to expensively retrofit mitigation measures. In addition, future noise levels can be predicted, and pre-emptive steps taken to control it.

Graphic: SoundPLAN

One project we supported was a noise assessment for a new control room for a power company that was to be built in a former transformer station. The original architecture was to be preserved, while the complete inner structure was rebuilt. This resulted in a very uncommon floor plan with an unusually high ceiling and a gallery. It took several iterations to come to a functioning acoustic concept that worked with the architects’ requirements while allowing a sufficient environment for highly concentrated working. Modelling of floor plans and sectional cuts during the planning phase as well as using colour maps for documenting noise helped to illustrate results.

Auralisation

The option to use auralisation to communicate results to laypeople is also helpful. This enables you to hear what the noise generated by a source in a room will sound like before it is constructed. This tool helps to communicate the effects of acoustic treatments directly to clients, independent of their background in acoustics.

For example, one of our room acoustic projects was demonstrating a scenario for a customer that produces acoustic absorbers and offers consulting to businesses to improve their acoustics. To display the effectiveness of their solutions to laypeople, who can sometimes struggle to see the benefits of measures taken, they asked us to auralise a benchmark office before and after treatment with their products. By supplying audio files representing the results, we helped the customer to showcase their added value to their customers in an easy-to-experience manner.

Software to analyse and document workplace noise

Specialist software is also available that enables occupational health and safety experts to easily map, assess and document noise levels, to ensure that they are compliant and protecting their workforce. With the programme-supported calculation of noise exposure at the workplace, risk assessment becomes an easy task.

Based on measurement data, coloured noise maps can be generated to visualise the distribution of the noise levels over the area using fast interpolation algorithms. This saves manual numerical analysis. Meaningful tables and graphic outputs are created at the push of a button, which allows you to present and document your results professionally and clearly.

Look for software that can calculate any floor plans. Many programmes are only capable of calculating standard, rectangular rooms. The software should enable you to manage multiple mapping areas and numerous measurement files, with the ability to combine data as needed. For example, you may wish to analyse different floors or different days of the week. With the help of formulas, you can link the measurements to perform advanced analysis, such as calculating mean values or differences.

Metrics for predicting and measuring room acoustics

Although during recent decades reverberation time has been the predominant metric, in recent years the STI (Speech Transmission Index) has gained momentum as a method for prediction and measurement of speech transmission quality.

Like many other room acoustics software solutions, we work with a derivative of ray tracing. While some solutions neglect diffraction altogether or rely on the detour method, our approach incorporates uncertainty-based diffraction. This means the rules that govern the sound field simulations are always the same, irrespective of where we are in an environment, what point we are at in the simulation, and what the sound particles have done previously. This yields more realistic and consistent results especially in the lower frequencies, while still being limited by being an energetic high-frequency approximation.

Furthermore, the geometry of the room and the objects within it are fully incorporated. This helps avoid various problems with results that have been seen in the past. Users can tackle issues in a larger context – for example, calculating noise radiation to the outside from a well-defined source distribution inside, such as in an industrial noise planning scenario.

Graphic: SoundPLAN

Room acoustic trends

There are moves to a more human perception approach, as well as actively using sound to improve and shape human wellbeing – for example, through immersive soundscapes. Another trend is modern absorber variants like metamaterials, which are engineered to have special/desired acoustic, or mechanical properties. Moreover, the need to acoustically treat rooms in places like educational facilities and restaurants is gaining awareness, and these projects are becoming more common.

Like all other realms of our life, the acoustic market is becoming more aware of the need for sustainability. There are moves towards using more natural and environmentally friendly products to optimise rooms for acoustic performance.

There are developments too on the interface between room acoustics and electroacoustics – how sounds are amplified and transmitted through sound sources – for example, loudspeakers. There will be improvements regarding the inclusion of more physical effects into noise prediction models – for example, taking phase into account or using hybrid methods.

Also, AI will change the way we work and design within the field of room acoustics in ways that are not yet fully imaginable. And as BIM (Building Information Modelling) becomes more common, that will bring more changes. 

Dr Thomas Judd is a software developer and Stefan Welgard is an assessor of room acoustics at SoundPLAN.