Arena acoustics are tuned for the concert calendar

Sound treatment in modern venues is specified by the events that fill the other three hundred days, and matchday inherits the result.

Acoustic consultants working on a new arena are given a brief that lists sport somewhere in the middle. Above it sit the touring shows that will pay the debt, and touring shows need controlled reverberation, predictable decay times and a room that behaves the same way with a line array hanging in it. Those requirements point towards absorption. Matchday atmosphere points the opposite way, towards a live room that holds and reflects crowd noise back down onto the floor.

You cannot fully have both, so the room gets designed for the paying calendar and the sport is handed whatever falls out. Then, on the first big night, everyone remarks that the new place feels quieter than the old one, and it is blamed on the fans or on ticket prices or on the corporate seats, all of which contribute, but the panels in the roof deck are doing more work than any of them.

There are mitigations and they are largely broadcast tricks rather than architecture. More effect mics, closer to the crowd. A crowd bed mixed higher. In-house sound systems that add reinforcement during breaks, which is a thin substitute and which some competitions restrict because it drifts towards manufacturing an atmosphere rather than capturing one.

I think the honest move is to stop treating this as a mystery and put it in the specification. If a venue is going to host a professional team as an anchor tenant, the acoustic brief should carry a matchday requirement with a measurable target, negotiated by the tenant as part of the lease and paid for by whoever benefits. Retractable or deployable absorption exists. It is expensive and it is a fraction of the cost of the building.

The reason it rarely happens is that the anchor tenant is usually the weakest party in the room during design, contributing the least capital and the fewest event days.

So the club moves into a ground engineered for a different product, and spends a decade explaining to supporters that the new place just needs time to feel like home.