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Like a harmonious choir, the successful remediation of Taranaki Cathedral is dependent on all parts being in tune.

One of those is the building’s renowned acoustics. With Taranaki Cathedral Church of St Mary to host a wide range of arts, music and drama events once earthquake-strengthened, as well as regular church services, weddings and funerals, it is important that the acoustics are not adversely impacted by proposed modifications.

Working on this are acousticians Daniel Protheroe and Arthur Postles, of Marshall Day Acoustics. They have been at Taranaki Cathedral capturing and analysing the sound quality of the cathedral, and will then model the possible impact proposed building changes will have on the acoustics.

“Part of the proposed remediation and upgrade work is to make some changes to interior furnishings, such as removing the wooden pews and replacing them with chairs, changing the floor coverings and putting sound-proof glass in the chapel,” Cathedral remediation and design manager Jenny Goddard says.

“We want to know what impact, if any, this will have on the acoustics of the building and how best to mitigate any impact, such as whether we need to include more soft furnishings.”

Daniel and Arthur use their disco ball-shaped omnidirectional speaker to generate noise from two spots at the chancel and measure the received sound via a specialised microphone at 12 seats throughout the cathedral – front, back, and either side.

“We’re measuring what the sound is doing at those exact seats,” Daniel says. “There are a number of elements we’re capturing – the reverberance, the natural amplification, the spatial impression, which is the sense of being surrounded by music, and the clarity of sound, which can be different for both speech and music.

“This gives us a benchmark of what the space sounds like currently.”

The measurement system, called IRIS, was designed and developed by Daniel himself.

Once the benchmark measurements have been uploaded, each of the possible changes to be made to the interior, such as the replacement of pews, will be introduced into the computer modelling.

The software uses calculations for how sound travels and interacts with the environment to give them an understanding of how it will react in the modified interior.

“If there is any detrimental impact that needs to be addressed, Daniel and Arthur will be then able to give us advice on mitigation solutions,” Jenny says.

Marshall Day acousticians Arthur Postles, left, and Daniel Protheroe with the tools of their trade at Taranaki Cathedral Church of St Mary.