Four disciplines, which overlap on nearly every commission. Most projects need two of them and the interesting ones need all four.
Room acoustics
How a space sounds from the inside: reverberation, early reflections, clarity, envelopment, and the balance between a performer and the room they are working in. We model at concept stage from volume and surface schedule, refine through ray tracing and, where the geometry justifies it, wave-based methods at low frequency, and we verify by measurement on completion.
Shape first, materials second. A room’s volume, its proportions and its section decide most of its behaviour before a single finish is chosen, and those are free to change on a drawing and enormously expensive to change afterwards. Where we are appointed early, the majority of our recommendations cost nothing. Where we are appointed late, they are all materials, and materials are what you buy when the geometry is already fixed.
Typical deliverables: a concept acoustic report with the volume and target justified, a surface schedule with computed reverberation by octave band, review of the architect’s drawings at each stage, a defect-free specification for the seating, and a commissioning measurement against the design targets.
Noise control
Plant, traffic, railways, neighbours, and the rehearsal room on the other side of the wall. We survey on site over a full week rather than a representative afternoon, because the specification is decided by the worst hour and the worst hour is rarely the one you happen to visit in.
Work includes environmental noise surveys and planning-condition assessments, plant noise breakout calculations and attenuator specification, building services noise limits to NR or RC, facade sound insulation design, and party-wall and floor constructions with their junction detailing — which is where the laboratory figures are lost in practice, and where the site attendance is worth more than the calculation.
Structure-borne vibration
A railway under a concert hall is a structural problem before it is an acoustic one, and it cannot be treated after the fact: there is no absorber for a floor that is itself radiating. Isolation has to be designed with the structural engineer at concept stage, because it changes the load path.
We measure existing ground-borne vibration in the free field and in the structure, model the transmission to the finished room, specify bearings by natural frequency and static deflection, and — importantly — attend site during the fit-out. Most isolation failures are not design failures. They are a conduit, a batten or a fire-stop bridging the break, installed by somebody who had not been told the gap was structural.
Electroacoustics
Where the room cannot do it alone: speech reinforcement in a reverberant church, distributed systems in a station concourse, a line array in a room whose reverberation was decided in 1420 and is not negotiable.
We design the system to finish the room’s argument rather than to shout over it. That means throwing energy at the audience and not at the vault, using delay to keep the perceived source at the speaker rather than at the loudspeaker, and setting the whole thing well below the level at which it becomes noticeable. A room that needs its loudspeakers to be intelligible has failed. A room that has them and rarely uses them has a margin. We tune in the finished space, with an audience where we can arrange it.