Resonant Fleece — Acoustic solutions in New Zealand wool

01 — The problem why rooms sound wrong

Modern interiors are built from every surface sound loves to bounce off.

Glass, polished concrete, exposed steel, hard timber. They photograph beautifully and they reflect almost everything that hits them. The result is a room where speech smears into itself, music loses its edges, and everybody quietly raises their voice.

λ/4

Bass needs metres, not millimetres

A porous absorber only works properly once it is about a quarter of a wavelength thick. At 100 Hz that is 860 mm of material. Nobody hangs that on a wall — so most panels simply give up on the low end.

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Absorption is not insulation

Soaking up reverberation inside a room and stopping sound passing through a wall are opposite problems with opposite physics. Sold together, delivered badly, they disappoint on both counts.

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The grey tile problem

The acoustic market's default answer is a flat rectangle of mineral fibre or PET felt. It works, it looks like ceiling tile, and it usually ends its life in landfill.

02 — Technology two physics, one panel

A textile that dissipates. A frame that resonates.

Sound absorption is not one phenomenon. Porous materials convert sound to heat through viscous friction as air is forced through their pores — a mechanism that scales with material depth, and therefore struggles at low frequencies. Resonant cavities do the opposite: they are compact, tuned, and devastating in a narrow band. Put them together and each covers the other's blind spot.

Layer one

Knitted strong-wool face

Stitch-level control lets a single piece carry varying porosity, pile height and thickness — a seamless sculptural surface that nonwoven felt cannot make. Acoustically it is a graded porous absorber: airflow resistivity tuned by knit density rather than by pressing a board.

σ ≈ 4 000 – 30 000 Pa·s/m² · set by stitch

Owns the mid and high frequencies — speech, sibilance, clatter — and the entire look of the object.

Layer two

3-D-printed resonant frame

The frame is not a skeleton — it is the bass. An array of printed necks and coiled cavities behind the textile, each cell a Helmholtz resonator with its own tuning, deliberately staggered so the array covers a band rather than a spike.

Because it is printed, the tuning is a parameter, not a product line.

f₀ = (c / 2π) · √( A / V·L_eff )

Owns the low frequencies a porous absorber would need a metre of depth to reach.

How it stacks up

One panel, read from the front.

Sound meets a soft, deep, three-dimensional wool surface: the highs never come back. What passes through arrives at an array of tuned cavities, half of them resonant cells, half open air — and the frequencies wool cannot touch are converted into air motion in a neck, then into heat.

The whole assembly is 40–200 mm deep, mounts on a standard rail, and comes apart into wool and polymer for recycling.

Incoming soundsource

Knitted wool facemid · high

Three-dimensional reliefscatter

Printed resonant cellslow

Air cavity + mountingtuning

Interactive · absorption model

Watch the bass appear.

This is the real calculation, not a drawing: a Delany–Bazley porous layer over an array of Maa perforate cells and air cavities, combined by transfer matrix. Move the sliders and the curve moves the way a measured panel would. Then switch the resonant frame off and watch the low end fall away.

Wool alone, flat to the wall Wool + air cavity Wool + resonant frame

Wool face thickness 30 mm

Frame + cavity depth 100 mm

Knit density Medium

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NRC — average α at 250, 500, 1k and 2k Hz

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α at 125 Hz — the bass the frame is there for

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total panel depth off the wall

Model: Delany–Bazley empirical fibrous layer, Maa micro-perforate necks, rigid-backed air cavities in parallel admittance, normal incidence. It is a design tool and an honest illustration of the mechanism — not a datasheet. Product figures will be published from ISO 10534-2 impedance-tube and ISO 354 reverberation-room measurement on real prototypes.

03 — Applications where it earns its place

Six settings, six different problems.

The same two mechanisms, weighted differently. An open-plan office needs speech intelligibility across a wide floor; a control room needs a flat decay at 80 Hz. The frame is what lets one product do both.

Offices & workplaces

Open plan turns every conversation into everybody's conversation. Wool ceiling rafts and wall reliefs cut reverberation and the low-mid rumble of an air-handling system in the same object.

Priority: speech clarity, 250 Hz – 4 kHz, plus HVAC rumble

ii.

Homes

Hard-floor, open-plan living is an echo chamber with a sofa in it. A sculptural wool piece reads as art on the wall and quietly takes the ring out of the room — and out of the video call in the corner of it.

Priority: warmth without deadness, objects people want to look at

iii.

Music venues

Small venues live or die on whether a kick drum stays a kick drum. Tuned frames target the room modes that turn low end into mud, while the wool face keeps the space lively rather than dead.

Priority: modal control, 60 – 200 Hz, durability, fire performance

iv.

Recording & broadcast studios

Control rooms need a short, even decay at every frequency — the hardest specification in the building. Per-cell tuning lets a treatment be designed against a measured room response rather than sold by the square metre.

Priority: flat, short RT60 across the band, first-reflection control

Hi-fi loudspeakers

Inside a cabinet, wool has been the fill of choice for decades — and coarse crossbred fibre is well suited to it. We are developing knitted, form-fitted internal damping and printed rear-wave traps for cabinet builders, plus wool-faced baffle surrounds that stop edge diffraction at the source.

Priority: internal standing waves, rear-wave absorption, diffraction

vi.

Architectural feature work

Atria, lobbies and stairwells where the brief is a statement object that also has to hit an acoustic target. Knit and print are both digitally driven, so bespoke geometry costs design time rather than tooling.

Priority: form, scale and specification — one-off geometry, repeatable physics

04 — The material why this fibre, this country

New Zealand grows a fibre the world stopped valuing.

Crossbred — "strong" — wool is coarse, around 35 µm, and for years has often cost more to shear off a sheep than it earns at auction. It is renewable, biodegradable, naturally flame-resistant, and it manages moisture and heat as well as it manages sound. We think it has been waiting for the right structure.

What the research supports

Coarse-wool felt has reached a noise reduction coefficient of roughly 0.4 in published impedance-tube work — comparable with commercial ceiling tiles. Crossbred waste-wool fabrics span roughly 0.26 to 0.64 depending on how they are built. Thickness and pile height are the levers that matter.

In other words: the fibre clears the bar. The interesting question is what you build with it.

The honest caveat

The literature is consistent that finer fibres absorb sound better, while coarser fibres insulate heat better. New Zealand strong wool sits firmly on the coarse side. On fibre diameter alone it is not the ideal absorber.

That is precisely why the structure exists. Geometry, pile, thickness and the printed cavity do the work the fibre diameter does not — and the same coarseness that costs us absorption buys a genuine thermal story alongside it.

Circular, and not retrospectively

A domestic waste stream as the primary input
Wool face separable from frame for repair or recycling
Biodegradable fibre; no bound mineral or glass dust
Made close to where the fibre is grown

Where we sit

New Zealand wool acoustic panels already exist and some are made by serious companies. Almost all of them are flat and felt-like: a wool face doing porous absorption, and nothing underneath it addressing the bass.

Our position is the structure — three-dimensional knitted form over a tuned, printed resonant frame. That combination is, as far as we can find, unoccupied.

05 — How we work measurement in, measurement out

Specified against your room, not a catalogue.

Measure

Impulse response and RT60 by octave band in the actual space, plus the geometry that produced it.

Model

Transfer-matrix modelling of the panel stack against your measured curve, targeting the bands that are actually wrong.

Make

Knit the wool face; print the frame with its cell tuning baked into the geometry. Both digitally driven, both bespoke.

Mount

Standard rail fixing, 40–200 mm off the wall or suspended as rafts. The mounting depth is part of the tuning.

Verify

Re-measure. Publish the before and after. If the room did not change, neither did we do our job.

06 — Size your room a first-pass estimate

How much treatment does your space actually need?

A Sabine estimate — the same equation acousticians start from. It assumes an untreated hard-surfaced room and a 1200 × 600 mm panel. Treat it as an opening conversation, not a quote.

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Resonant Fleece panels, first estimate

Reverberation now

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Target

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Wool surface

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Panel size

1.2 × 0.6

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07 — Evidence read the working

We would rather show you the physics than assert it.

Resonant Fleece is a research-stage venture and we say so plainly. The mechanisms below are textbook; the combination is what we are building and testing. Everything we claim traces back to published work or to a measurement we will publish.

The physics of sound absorption

Our full technical reference: porous dissipation, Helmholtz and membrane resonance, the quarter-wave rule, diffusion, metamaterials and transmission loss — with the equations and two interactive calculators.

Open the technical reference →

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Concept & research brief

The venture thesis behind Resonant Fleece: the three building blocks, the value propositions, the market, the competitive landscape, and the sixteen peer-reviewed sources the design rests on.

Open the concept brief →

Key sources include Delany & Bazley (1970) on fibrous absorbers; Maa on micro-perforated panels; Cox & D'Antonio, Acoustic Absorbers and Diffusers; Allard & Atalla, Propagation of Sound in Porous Media; and published work on the sound absorption and thermal insulation of pure and crossbred sheep waste wool, knitted spacer and crochet fabrics, and 3-D-printed acoustic metamaterials. All are indexed in the concept brief.

08 — Get in touch architects, acousticians, growers, builders

Tell us about the room.

Email

lee.mauger@gmail.com

Where we are

Aotearoa New Zealand — working with growers, knitters and acousticians across the motu.

Where we're up to

Research and prototyping. We are looking for pilot rooms, wool partners and manufacturers who want to measure something rather than be told about it.

Bring us a measurement

An RT60 by octave band, or even a phone recording of a hand clap, tells us more than a floor plan. Attach whatever you have.

The physics of quiet, spun from New Zealand wool.