Office ‘pod’ acoustics – a consistent approach

Agile working

With the move to agile working, offices are increasingly required to accommodate a wide range of activities in the same space. This may include areas for focussed individual work, collaborative group work and use of video conferencing. To meet users’ adaptive needs over time, flexibility and a move away from fixed partition/meeting rooms is sought by many. This presents a unique acoustic challenge.

Pod design

Part of the solution is the provision of ‘pods’. These exist in a variety of forms, from small one person ‘off-the-shelf’ phone booths, to configurable meeting rooms. Each pod design offers different acoustic benefits. Some are designed to provide speech privacy, some to reduce distraction, and others to provide a quiet haven for focus. To help select the right product for each purpose, it is important to understand the level of acoustic performance achieved.

Lack of consistency

The problem currently faced in the industry is a lack of consistency in how these are tested, and how the performance is defined. This is reflected by a wide variation in test methods and acoustic parameters adopted by different manufacturers (eg, D_S,A, D_nT,w, D_p,w, D_w, R_w etc…). Whilst one pod may be tested to achieve a sound insulation performance of 40 dB, it could be poorer than one claiming a performance of only 30 dB but using a different parameter. This is confusing for acousticians, let alone anyone else and means we are comparing apples with pears. The lack of consistency along with unsubstantiated marketing claims (eg, terms such as ‘sound-proof’) make it difficult to answer straightforward questions such as, “will my conversation be private to someone outside the pod?”

A solution

To address this, Sandy Brown has teamed up with the Finishes and Interiors Sector, Cundall and The University of Salford to come up with a solution. The process started with several visits to showrooms and workshops to help determine the root of the issue and find the most beneficial solution for all. This was done with representatives from across the industry, from pod manufacturers, to acousticians, to furniture consultants. Through these visits, different requirements were identified, though all involved agreed the need for a consistent approach across the industry.

The standard

The most suitable standard, and one already commonly used, is ISO 23351-1:2020 Acoustics — Measurement of speech level reduction of furniture ensembles and enclosures — Part 1: Laboratory method. This is a laboratory test to show how much of a conversation inside a pod will be audible outside. Unfortunately, due to test method constraints, this only allows smaller one or two person pods to be tested. This is a primary reason why testing using this standard hasn’t been more widely adopted.

Verification scheme proposals

To address this, a verified assessment scheme is proposed to rate pods in accordance with ISO 23351, rather than testing. This scheme will be based on a desktop assessment, calculated using existing and experimental test data, and a review of the proposed pod constructions. An additional benefit of a desktop assessment, not achievable from lab testing, is output data about a pod’s directionality (ie, where any weak spots are in the construction). This is useful to the acoustician and helps to ensure that pods are installed most effectively in the context of a specific layout.

The aim of the scheme is to allow all pods, regardless of size or construction, to be either tested or assessed in accordance with the same parameter (D_S,A). This will create a level playing field allowing a direct comparison between the performance of pods, whether tested in a lab, or assessed through the verified scheme.

Now in the final stages of development, verification testing is being undertaken to ensure that the results of the assessment are robust. Once complete, the scheme will launch and be open to all pod manufacturers wishing to get their systems assessed. Hopefully, in the near future, we will be comparing apples with apples when it comes to office pod acoustics.

By Ben Southgate
BEng, MIOA