01/06/2026

Acoustics in older, multi-purposed buildings

One of the sections in HELA Certification focuses on acoustics. What does the venue sound like? This is a more complex question than it may seem! Sound like for whom? For the audience? And who is the audience? This question dominates a lot of what we do and is one of the reasons the Complete training starts with audience expectations. Those expectations are based on a wide range of factors, but genre is one of the primary considerations.

Musical genre can adapt across a wide range of acoustic conditions. Short reverberation times favour amplified music or where individual acoustic performances need to be discernible, such as in string quartets, etc. Longer reverberation times help to gel symphonic sounds, particularly benefitting large orchestral works. The very long reverberation times of cathedrals and larger halls favour the more legato sounds of choral and organ music, where the beats are deliberately slow to make use of the multiple long reflections.

So, what happens when you change the use of a building, remove many of the structures that contributed to it having a functional reverberation time for day-to-day use, and then repurpose it as a multi-functional space?

This is an increasingly frequent proposition as older buildings are being converted form no longer needed single-use spaces to more community-focused multi-purpose use.

One such space is located near to the HELA Initiative office at @Derby Market Hall, a large Grade II-listed Hall, opened in 1866, one of the UK’s first purpose-built undercover markets. Designed by engineer Rowland Mason Ordish—whose work on the iron roof famously mirrors London's @St Pancras Station—it recently underwent a massive £35.1 million restoration to modernise its stalls, exterior, and historic vaulted iron roof. Looking at the documentation of the conversion, it was interesting to review the architect and acoustic consultants’ recommendations. The students, most of whom had recently completed HELA Certification were bemused that none of the recommendations had been implemented. Making measurements in the space, the 5.5 second reverberation at 1 kilohertz amazed the young listeners.

Speaking to people who work in the building, tales of hearing fatigue could be picked out from general comments that reflected the negative experience of working in a harsh acoustic environment.

So why were we there? As part of their @University of Derby degree course the students provide technical support for a wide range of events. The next event, for which this was an exploratory site visit, would be a ‘Night at the Musicals’ evening of West End hits. Alongside this would be a day of bands and other musical events in the centre of the market hall.

Somewhat despondent the students regrouped back at Uni to discuss strategies. The starting point was not the space, but the audience. What would they expect? To hear the words, to sing along to familiar tunes, was the general opinion. The size and nature of the audience were felt to be important. How many and where? Did we need to cover a wide audience area? The hall could probably contain about 5,000 people, but we were expecting considerably less, probably no more than 300 at any one time.

Thinking about the dynamics of a free event, people are willing to move closer if they want to hear. At a ticketed event, they expect a good experience from their seat. The decision was made therefore to only cover a fraction of the room. This would minimise the energy being used in the room, and would in theory, help with keeping background reverberation as low as possible.

Treating the area above and behind the stage was considered a must, along with anything that could help immediately around the stage area. Heavy drapes provided a roof and background. This made the onstage experience for the performers considerably easier; they were no longer fighting the room. For those close, the sound reinforcement system was angled steeply down, covering a comparatively small, carpeted area, but one that could easily accommodate the expected audience.

The event went well, the reverberation time close to the stage was improved, clarity was comparatively good. For those further away, such as at the stalls at the back of the market, you were still very much aware of a musical event happening in the space, but sound pressure levels were low enough to not to distract from the important affairs of retail trade.

As we move into an age of increased multi-use, it pays to take a holistic overview of events. What are you trying to achieve, not for the space, but for the audience? For the students, it was the realisation that a report representing only a fraction of an overall budget will be ignored, even though it would have had a tangible positive impact for all the venue’s users! Let’s hope they will be the generation that values acoustics in our day-to-day life!

< News