Fixing speech intelligibility in a reverberant cathedral at Saint Sophia’s

Located in Bayswater, West London, Saint Sophia’s Greek Orthodox Cathedral - also known as the Cathedral of Divine Wisdom - is a 19th-century Byzantine Revival church built to serve London’s growing Greek community. Its marble interior and domed architecture create a visually striking space, but one that presents significant acoustic challenges.

The challenge

Anyone who’s worked in a highly reverberant space - especially in churches where both speech and singing need to carry - knows how quickly clarity can fall apart.

At Saint Sophia’s Cathedral, the combination of hard marble surfaces and scale meant sound reflections were overwhelming. The existing system struggled to deliver intelligible speech, with regular complaints from congregants who couldn’t clearly hear services.

For API Sound & Visual, the challenge was clear: deliver consistent, intelligible coverage across the space - without compromising the building’s architecture.

The solution

API Sound & Visual worked with the CUK team to design a system that would perform predictably in a difficult acoustic environment. Using EASE Focus modelling, they mapped coverage and dispersion to understand how to control reflections and ensure even intelligibility throughout the space.

This allowed them to:

• Validate loudspeaker positioning before installation
• Design an effective delay strategy
• Reduce risk on-site
• Give the integrator confidence in the final result

The equipment

A Renkus-Heinz UBX Series system was specified to deliver highly directional audio where it was needed, while minimising reflections.

• Beam-steered loudspeakers provided controlled vertical coverage
• Delay speakers reinforced intelligibility further down the space
• A carefully designed coverage strategy ensured even performance front to back

Compact Powersoft amplification was used to support the system, enabling flexible tuning while keeping the installation tidy and easy to manage.

The system was carefully installed using existing fixing points to preserve the building and minimise visual impact.

The impact

The improvement was immediate.

Where speech had previously been unclear and inconsistent, the new system now delivers clear, intelligible audio across the entire cathedral, with worshippers able to hear and engage fully with services throughout the space.

The success of the project has also given the integrator confidence to specify the same solution on future installations.

What this means for integrators

Projects like this come with risk - acoustically challenging environments, client expectations, and limited margin for error. With the right design support and modelling upfront, that risk becomes manageable.

This is where the CUK team adds value:

• System design support before you commit
• Predictable outcomes in difficult spaces
• Backup when projects get complex

Great results start with the right partners and the right tools.👉 Browse more CUK Group installations and applications