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Learn Sound Control

Why controlling sound is so important

Acoustic absorption plays a vital role in shaping how we hear and experience sound in any space—whether it's a recording studio, restaurant, office, or home. Without treatment, sound waves bounce off hard surfaces, creating long and unpleasant reverberation times. This can blur detail, mask the original sound source, and make communication or listening uncomfortable. Read More

When sound reflects unevenly around a room, certain frequencies become exaggerated while others are diminished—creating distortion, or what's commonly known as peaks and troughs. This effect can make music sound muddy, conversations hard to follow, and overall acoustics feel harsh or fatiguing.

By strategically placing acoustic panels within a space, excess reflections are absorbed, and the sound becomes clearer, more balanced, and easier on the ears.

High-performance materials like polyester fibre and rock wool offer excellent acoustic absorption at a low cost. While originally designed for use inside walls of industrial or high sound-pressure environments, these materials are also effective when used externally to reduce echo and improve acoustic clarity in everyday spaces.

How sound absorption actually works

To absorb sound efficiently without taking up unnecessary space, a material must be porous—packed with tiny air pockets. As a sound wave travels through this labyrinth of fibres or cells, it repeatedly transitions from air to solid and back again. Each transition creates friction, converting a small portion of the wave’s energy into heat (imperceptibly low). This gradual loss of energy is called dissipation. Read More


Why Porous Materials Excel

Fibrous batts (fibreglass, mineral rock wool, polyester) and open‑cell foams are ideal because their structure maximises these air‑to‑solid interfaces, making them highly effective broadband absorbers.


Thickness, Density and Gas-Flow Resistivity
  • Thickness determines how low in the frequency spectrum absorption remains effective. Thicker absorbers tackle lower frequencies.
  • Density (or gas‑flow resistivity) must balance thickness:
    • Thicker panels → lower density
    • Thinner panels → higher density
    If density is too high for a given thickness, the panel starts reflecting rather than absorbing.
The Power of an Air Gap

Leaving an air gap behind the absorber—ideally the same depth as the absorber itself—boosts low‑frequency performance. Why? Particle velocity peaks at roughly one‑quarter of a wavelength from a rigid surface (your wall). Placing porous material where air is moving fastest maximises friction and, therefore, absorption. Beyond a certain gap, benefits taper off (diminishing returns).


Tackling Deep Bass

Sub‑bass wavelengths are often too long for practical porous absorbers. Instead, resonant (membrane) absorbers—such as limp‑mass vinyl or diaphragmatic panels—target these frequencies by vibrating in sympathy with the wave and dissipating its energy.

By combining the right material, thickness, density, and placement, you create a controlled acoustic environment that keeps reflections in check and lets the original sound shine through.

Diffusion and absorption

While diffusion and absorption are technically opposites, they are often used together to achieve balanced acoustics. Absorption works by removing sound energy from a space, helping to create a quieter, more controlled environment. Diffusion, on the other hand, is designed to scatter sound energy rather than eliminate it—preserving a room’s liveliness while avoiding harsh echoes or focused reflections. Read More

Diffusive elements are typically made from timber or other hard materials and shaped according to precise mathematical formulas. These structures help create pleasant, natural-sounding reflections, which are especially useful in spaces like live rooms or recording studios where a rich, tonal ambience is desired. In contrast, absorption is preferred in critical listening environments such as mixing rooms, where the goal is to minimize the influence of the room on what is heard through the speakers.

While there are standard practices for using absorption and diffusion in different types of rooms, the final approach often depends on personal preference and the unique character of the space.

Treatment Vs Proofing

Sound treatment and soundproofing are often confused, but they serve very different purposes. Treatment focuses on improving the acoustic quality within a room—reducing echo and creating a more controlled listening environment. Soundproofing, on the other hand, is all about preventing sound from entering or leaving a space. It deals with sound isolation, not sound control. Read More

Soundproofing is a complex process and depends heavily on the specifics of a building’s structure. Porous materials like acoustic panels are excellent at absorbing sound within a room, but they’re poor insulators. Sound can still pass through them easily, so they’re not effective at stopping noise from travelling between rooms. What they can do is reduce reverberation, which in turn lowers the overall sound energy that might leak out.

Our panels are designed for absorption—not isolation. They help create better sound inside a room but won’t block noise from passing through walls or floors. True soundproofing requires heavy, dense materials like mass-loaded vinyl (MLV), bricks, concrete, or specialised construction techniques. It's most effective when integrated during the building phase and is generally difficult (and expensive) to add afterward.

While we don’t provide soundproofing products or installation, we do offer a consulting service to help guide you through the most effective strategies for your space.

Densities, gas flow and material types

There’s often confusion around the role of density in sound absorption, especially when comparing different insulation materials. Many people assume that higher density automatically means better acoustic performance—but in reality, the more relevant factor is usually gas flow resistivity. Read More

Understanding Density and Gas Flow Resistivity in Acoustic Materials

There’s often confusion around the role of density in sound absorption, especially when comparing different insulation materials. Many people assume that higher density automatically means better acoustic performance—but in reality, the more relevant factor is usually gas flow resistivity.

What Is Gas Flow Resistivity?

Gas flow resistivity (measured in Rayl/m² or Pa·s/m²) describes how much a material resists the flow of air through it. Since sound travels as air pressure waves, this measurement is closely tied to how much sound energy a material can absorb.

While density (in kg/m³) tells you how much material is packed into a certain volume, gas flow resistivity tells you how easily air—and therefore sound—can move through it. A material with the right level of resistance will allow sound to enter and gradually lose energy (by turning into heat), rather than reflecting off the surface or letting it pass through unchanged.

Density vs. Resistivity

Materials like glass wool and rock wool can have the same density but behave differently acoustically due to variations in fibre type, thickness, and structure. That’s where gas flow resistivity becomes a more reliable predictor of sound absorption performance.

Here’s the basic principle:

  • Too low resistivity: Sound passes through the material with little energy loss → not much absorption
  • Too high resistivity: Sound reflects off the surface before entering → again, not much absorption
  • Ideal resistivity: Just enough resistance to slow the wave and convert energy into heat → optimal absorption

Frequency Matters

What makes this more complex is that the “ideal” resistivity depends on the frequency of the sound.

  • High frequencies (e.g. 10,000 Hz) have fast, small air particle movements. They’re easier to absorb and don’t require much resistance.
  • Low frequencies (e.g. 100 Hz) have slow, large waves that penetrate deeper and require more resistive material to be absorbed.

Light, porous materials are great for high-frequency absorption. Increasing density (and resistivity) will help capture more low frequencies. But if you go too far, higher frequencies can start bouncing off instead of being absorbed.

What About Polyester?

Polyester insulation performs differently to glass wool or rock wool, not because it's less effective, but because of how it's structured. Polyester fibres are typically thicker, smoother, and more uniformly arranged. This results in:

  • A less chaotic air path (lower tortuosity), meaning air—and sound—can move through it more smoothly
  • A softer, less irritant material that’s easier and safer to handle
  • A more stable structure that maintains shape over time

Because of this smoother airflow, gas flow resistivity values don’t translate directly between polyester and other fibre types. Polyester may have lower resistivity on paper, but when properly designed and layered, it still performs very well acoustically—especially when tuned for the right frequency ranges and installed at appropriate depths or with air gaps.

In fact, polyester’s balance of performance, safety, and durability makes it a popular choice for many professional and home audio environments. It’s less prone to shedding fibres, doesn’t irritate the skin, and offers long-lasting acoustic performance when used thoughtfully.

The Takeaway

When selecting acoustic materials, it’s important to understand both density and gas flow resistivity—and how these interact with the type of material you're working with. The key to effective absorption is matching the material’s properties to the frequencies you want to treat.

While traditional metrics like resistivity are useful, they’re not the whole story. Material structure, fibre geometry, and product design all play a crucial role. Polyester, for example, offers excellent real-world performance when applied with these factors in mind—and it brings added benefits in terms of safety, sustainability, and ease of use.

Absorption coefficients, Noise Reduction Coefficients (NRC) and R-values

Absorption coefficients, Noise Reduction Coefficients (NRC), and R-values are common ratings you’ll see when comparing sound-absorbing materials, each describing different aspects of their performance. Read More

Absorption Coefficients

Absorption coefficients are used to measure how much sound energy is absorbed by a material at specific frequencies. They range from 0 (no absorption) to 1 (total absorption), and are typically shown across octave bands like 250 Hz, 500 Hz, 1000 Hz, etc. This helps you understand how well a material performs across the frequency spectrum, which is important for tailoring treatment to different acoustic needs like voice clarity, music balance, or low-end control.

Noise Reduction Coefficient (NRC)

The NRC is a simplified, single-number rating that averages a material’s absorption across the most important midrange frequencies (250 Hz to 2000 Hz). It’s a quick and useful way to compare overall acoustic performance between products. While not as detailed as a full absorption chart, NRC is helpful when you need a general sense of how much sound a material will absorb in common listening or working environments.

R-Values and Acoustics

R-values are often mistaken for sound ratings, but they actually measure thermal resistance—how well a material insulates against heat. They're relevant for keeping buildings warm or cool but don’t provide any insight into a material’s acoustic performance. If you're choosing materials for sound absorption, it’s important not to rely on R-values, as they don’t correlate with how sound behaves in the space.

Polyester vs other insulation absorbers

We use polyester insulation in all of our products for several key reasons. One of the most important is its safety — polyester is 100% allergy free, containing no breathable fibres and posing no health risks. This makes it a much safer choice for indoor environments compared to some other insulation materials, which may shed fibres or require protective handling. Read More

Durability and Sustainability

Polyester is extremely durable and built to last a lifetime without degrading, sagging or breaking down over time. It’s also environmentally conscious — made from recycled plastic bottles — helping reduce waste and lower environmental impact. Its lightweight nature makes it easier to work with and install.

Modern Performance and Versatility

As one of the most recent innovations in the insulation industry, polyester is now widely used in modern acoustic treatment due to its flexibility. It can be coloured, shaped, and moulded into any size or form without the need for additional coverings, making it ideal for creating clean, functional, and visually appealing acoustic products.

The Foam Fallacy

Foam is one of the most widely used materials for treating rooms, primarily because it’s cheap to manufacture, lightweight, and easy to ship. This has made it a go-to product for large-scale companies looking to market a quick-fix solution. Unfortunately, its popularity is more about convenience and cost than acoustic performance. Read More

The Reality Behind the Hype

Despite being heavily marketed as ‘studio-grade’ or ‘soundproofing’ foam, most foam panels are ineffective for meaningful acoustic treatment. These products primarily absorb high frequencies only, leaving the mid and low-frequency ranges untouched — the very frequencies that are most critical in music production, mixing, and listening environments.

Why Foam Falls Short

Foam lacks the density and structure needed to absorb lower frequencies, which are responsible for much of the muddiness and resonance in untreated rooms. Without addressing those frequencies, the sound in your space remains unbalanced. In short, foam might slightly reduce echo or flutter in the top end, but it gives a false sense of improvement and does little for overall clarity or control.

A Better Alternative

For serious sound treatment, denser materials like polyester or high-performance insulation are far more effective. They provide broad-spectrum absorption across lows, mids, and highs — giving your room the clarity and balance needed for professional audio work or high-quality listening.