AMSTERDAM – Our latest book Sound Materials is released today. In this publication, the author Tyler Adams navigates the field of sound absorbing materials to present the definitive resource guide. His hopes are that this book will encourage conversations between designers and engineers and in a small way advocate for greater consideration of, and enthusiasm for, acoustics in the design of everyday objects and environments. Here, we caught up with him to find out more about the book.
How did this book come about? Can you describe your initial inspiration?
I work as an acoustical engineer and consult on a variety of projects, either solving existing noise problems or working with architects and other engineers in the creation of new spaces and environments where acoustical considerations are integrated into the design process. On many of these projects I've had to provide material recommendations to the design team and lend my expertise about those materials. There simply weren't enough reference sources to explain what these materials look like, how they function and what they are capable of – from a design perspective. I noticed that there are a variety of material catalogues for architects and designers – such as those published by Frame (Materiology for instance) – but to date there haven't been any such references dedicated to sound absorbing materials.
Was there specific moment in your consulting career where you recall pinpointing the need for such a book as this?
I think it was the lack of information available that posed a few challenges. There is some misinformation out there and people think certain materials absorb sound when they actually do not. Also, many designers think ceiling tiles and fabric-wrapped panels are the only show in town and sometimes feel aesthetically limited when they need to consider acoustics on their projects. I hope the new Sound Materials book demonstrates the wide variety of materials already available, but also encourages designers to think creatively about what is aesthetically possible when working with sound absorbing materials. I also envisioned this book as an opportunity to advocate on behalf of the field of acoustics and to encourage designers to engage with engineers and integrate acoustics into the earliest stages of their design process.
What was your approach to organising the content?
The book organises materials according to how the materials absorb sound. The two main categories would be porous materials and resonant materials. Porous materials, such as open-celled foam, provide sound absorption due to their interconnected pore structure. Resonant materials absorb sound in a slightly more complicated manner. A simple example is an empty bottle – when you blow across the top, you hear a tone at the resonant frequency. Air in the neck of the bottle will move back in forth like a spring and this can provide sound absorption. When you perforate a sheet of wood or metal with lots of little holes, each hole is essentially a tiny bottle neck that can be designed to absorb sound through resonance.
Porous material account for more than one third of the 100+ sound absorbing materials featured. Why are porous materials the most common?
Think of soft, squishy, fuzzy materials – carpet, drapes, clothing, furniture – they all absorb sound because they are porous. There just happen to be a large number of porous materials already in the world and sound absorption is just one, often unintended, attribute. Felt is one of the earliest materials that was employed for sound absorption in the early twentieth century, but has been used for clothing, textiles and industrial applications for many centuries. Open-celled foam is used in upholstery, clothing, bedding and packaging and also happens to be an effective sound absorber. Porous materials abound!
From an acoustical perspective, porous materials absorb sound pretty effectively across the range of audible frequencies, particularly in the range of human speech. And since many of these porous materials are commonly used for other applications, they tend to be cost-effective and readily available.
Is it possible to say which is the 'best' sound absorbing material of all time? Or if not, which is the most popular? And why?
For many decades glass and stone wool (fibreglass or mineral wool) have been the most common or popular absorptive materials. They are both relatively inexpensive and can be fabricated into rigid boards or flexible blankets. They are the basis of most ceiling tiles and fabric wrapped wall panels. Even in cases where you have a resonant material with a wood or metal material finish, there is usually a stone or glass wool backing material that is providing much of the absorptive performance. Stone and glass wool are fairly inexpensive and readily available and both are used for thermal insulation applications such as in attics or inside wall cavities.
What are the factors involved in deciding which type of sound absorbing material should be used in a certain environment?
Many of the functional factors relate to how well the materials resist moisture, dirt and debris or stand up to impacts and abrasion. In commercial kitchens, healthcare environments and some specialised industrial and manufacturing spaces, such as clean rooms, material finishes need to resist contamination and be cleanable. Sound absorbing materials are important in these spaces because they allow people to communicate. When you're under the knife in a surgery room, you want the nurse to be able to clearly understand what doctor is saying.
Materials used outdoors to reduce noise, such as highway sound walls or in mechanical equipment yards, have to withstand harsh weather conditions and resist deterioration from UV. Materials used inside of cars, which quiet the machinery and influence your impression of the quality of the vehicle, need to be very lightweight and flexible and form fitting.
How would you say preferences for materials amongst acoustic engineers, for instance, have changed over the years?
I'm not sure if preferences for materials have necessarily changed for engineers. Often preferences are driven by aesthetic, functional, or budgetary considerations from the end user or designer/architect. In many environments, the acoustical goals can be achieved with a wide variety of materials and this fact opens up a lot of possibilities for designers to collaborate with engineers to create environments that meet their aesthetic vision while achieving the desired acoustic outcomes, such as reduced noise, improved speech intelligibility or enhanced clarity from a sound system.
What is the 'next big thing' in sound absorbing materials? Where is the future of this field headed?
I think the future of the field will be driven by the collaboration between designers and engineers. The book highlights several materials and applications where this collaboration has been incredibly fruitful and I hope the book opens up a dialogue between disciplines and inspires new projects.
A number of emerging materials are presented in the book. I think aerogels and activated carbon present some big possibilities in the near future. They're both lightweight, highly absorptive and can be integrated into other materials to create composites. Aerogels are also effective thermal insulators and have been used in aerospace applications, such as insulating the Mars Rover. As the production costs have come down, aerogels are now being integrated into facade glazing to improve thermal performance. I hope we see some new sound absorption applications in the future.
How did you go about selecting the real-world projects that should be showcased?
I chose projects that demonstrated elegant solutions to acoustical problems but were also aesthetically dazzling. For me, these projects celebrate the greatness that happens when designers and acoustic engineers come together. In some cases, the sound absorbing materials themselves comprise the defining visual feature of the space and in others they are integrated in a manner where they disappear into the architecture unnoticed. I also tried to underscore the wide variety of environments where these materials occur – courtrooms, hospitals, schools, swimming pools, airport terminals, homes, concert halls, etc.
What is next on the horizon for you?
I've been developing a few new sound absorbing materials with a focus on materials that are both sustainable and low cost. Additionally, there are some materials I have been testing for sound absorption performance which are mostly building materials that are not presently used for absorption but due to their porous structure present some possibility for absorption applications.