A material's appearance is not enough to specify its acoustic performance. Review the complete construction, including the facing, backing, depth and installation, and ask for the relevant tested data for the intended use.
The Principle Behind Material Selection
Sound energy is absorbed when it encounters a porous or compliant surface that dissipates the energy as heat rather than reflecting it back into the space. The efficiency of that absorption, expressed as an absorption coefficient, varies by material and by frequency.
Low frequencies are harder to absorb than high frequencies and require either mass, depth, or resonant structures to manage effectively. High frequencies are absorbed by relatively thin materials. Mid-range frequencies, which carry most of the intelligibility of speech, respond well to standard absorptive panels and soft furnishings.
A practical acoustic specification for a restaurant does not require deep technical intervention at every frequency range. It requires sufficient absorptive surface area to control the accumulation of mid and high frequency energy as the room fills, and enough low frequency management to prevent the bass from the sound system from becoming problematic.
Specify the whole build-up
A facing material is only part of an acoustic construction. Ask for the relevant tested assembly, mounting depth, cavity or backing and frequency-dependent data. Do not assume tightly woven linen and velvet perform alike, that every slat arrangement diffuses sound, or that all perforation patterns are interchangeable.
Source: FIS (2021), Ceilings and Acoustic Absorbers, hosted by Rockfon
Timber Slat Systems
Perforated and slatted timber panels have become a prevalent finish in contemporary hospitality interiors. When specified correctly, they can also perform as acoustic treatment. A slatted panel with an absorptive backing layer absorbs energy through the backing, reducing reflections from what would otherwise be a hard timber face. Whether it also scatters sound depends on the geometry, so diffusion should be confirmed for the specific design rather than assumed.
The acoustic performance of a slatted system is dependent on the slot width, the depth of the cavity behind it, and the specification of the backing material. A slatted panel specified purely for aesthetic reasons, without consideration of these parameters, may offer minimal acoustic benefit. The same panel specified with acoustic performance in mind delivers both.
This is the distinction between acoustic integration and acoustic retrofit. One is designed. The other is added.
Perforated Ceiling Systems
Selected work
Bisushima
Architectural audio consultancy. Pequod Acoustics custom specification. Architecture by Ben Adams Architects.
As featured in Architecture Magazine
The ceiling is the highest-leverage acoustic surface in a restaurant. Perforated metal or plasterboard ceiling panels, with absorptive mineral wool or acoustic fleece behind the perforation, provide broad frequency absorption from the dominant surface in the room.
These systems are available in a range of visual finishes and perforation patterns. Open area, hole size and the backing specification all affect how a panel performs, and two patterns that look similar are not guaranteed to measure the same, so ask for the tested data for the pattern and build-up you intend to use. It is also worth keeping porous absorption, which reduces reflections within a room, separate from sound insulation, which stops sound travelling between spaces; they are different jobs and are not interchangeable.
Coordination with lighting, HVAC and speaker positions is essential. A perforated ceiling panel with acoustic backing performs at its best when speaker positions are designed to work with the treated ceiling, not placed without reference to it.
Distinguish absorption from sound insulation
Reducing reflected energy in a room and reducing transmission through a building are different questions. Specify the appropriate construction for the diagnosed issue, with formal specialist input where needed. Coordinate fire, cleaning, maintenance and access requirements as well as the acoustic brief.
Source: FIS (2021), Ceilings and Acoustic Absorbers, hosted by Rockfon
