The evolution of architectural acoustics

Humans have been curious about acoustics since prehistoric times—well before we had a depth of scientific understanding. Back then, unexplained phenomena like the movement of sound within spaces, like caves, valleys, and mountain ranges were observed and documented in paintings on cave walls. Now, thousands of years in the future, our interest remains—and, thanks to brilliant minds throughout history, we now know why sound behaves the way it does.

The significance of Sabine’s reverberation time equation

 

For a long time, acoustic design in architecture was largely focused on amplifying sound naturally, as performers didn’t have access to microphones or PA systems. However, things began to change in the late 1800s, as people noticed the impact of reverberation on speech intelligibility.

 

A lecture hall constructed as part of Harvard University’s Fogg Art Museum in 1895 was rendered unusable due to significant reverberation, so the University contracted a young physics lecturer by the name of Wallace Sabine to come up with a solution. Working through the night when the campus was at its quietest, Sabine spent hours conducting experiments in the lecture hall to determine a mathematical relationship between the hall’s size, shape, and materials (including various soft furnishings), and the reverberation time. The impact of the soft furnishings and their surface area was of particular interest to Sabine. After rearranging a selection of cushions in the room and recording the reverberation time, Sabine deduced that the surface area of the cushions was linearly related.

 

The resulting equation, known as the Sabine Formula, is still used today to find a room’s reverberation time—earning Sabine the title ‘Father of Acoustics’, and propelling the field of architectural acoustics into a new era.

 

Following Sabine’s work at the Harvard University lecture hall, he went on to develop one of the world’s first acoustic materials, the Rumford Tile—an acoustic tile designed to blend into the stone materials common in church buildings at the time. However, as cities grew and noise became a significant issue for inhabitants, the search for new acoustic materials that were accessible and easy to mass-produce continued.

New technology and the impact of environmental noise on wellbeing

 

Our present day understanding of architectural acoustics has been influenced by a number of technological advancements post Sabine’s work at Harvard. Due to the technological developments of World War II, materials such as fibreglass and foam entered the mainstream. Lightweight and affordable, these materials were quickly adopted to create acoustic panels that could be retrofitted into commercial, residential, and educational spaces.

 

The Oscilloscope, an electronic tool that graphically displays the waveform of frequencies, emerged in the mid 1900s, making it significantly easier for acousticians to study sound and reflections within a space. Radio and film technology was also improving, and with the rise of recording studios and sound stages came an increasing need for high-performance acoustic material.

 

In 1970, the book ‘The Effects of Noise on Man’ by Kryter was published, evaluating the effects of environmental noise on wellbeing. Following the publication of this book, numerous studies emerged examining the effects of noise on children’s development and education, noting a significant link between environmental noise and stress. In 1995, the World Health Organisation published the first community noise guidelines, and studies have continued to further our understanding of the impact of noise in a variety of environments, including the workplace.

Acoustics in the workplace: from factory floors to the open-plan office

 

Workplace noise levels have been an important consideration since the early 1900s, however, recommendations and limits were almost entirely focused on machinery and construction noise. Office noise is a recent field of study, with most information on noise-related wellbeing emerging post 2010.

 

With our increasing understanding of the negative impacts of environmental noise on health and wellbeing, acoustic treatment has become a significant focus for architects designing education and office buildings. Alongside studies on noise and wellbeing, researchers have also been investigating the health impacts of aesthetics and material composition. As a result, trends such as biophilic design and low-VOC materials have emerged. Similarly, sustainability has pushed manufacturers to seek out recyclable, carbon neutral, and organic materials with the goal of reducing construction waste.

 

Taking a holistic approach to wellbeing in buildings means many acoustic materials are now being designed to cater to a number of issues, including noise reduction, indoor air quality, aesthetics, and sustainability. Though this is still a relatively new aspect of architectural acoustics, it is fast becoming the norm, with manufacturers pushing the envelope globally.

 

Today, acoustics are considered a fundamental part of every build—opening up a whole new world of innovation. Manufacturers and design professionals are increasingly collaborating to create acoustic solutions that not only enhance the space sonically, but also contribute to the beauty, health, and sustainability of the building.

 

At Autex Acoustics®, we’re passionate about the transformative power of interior acoustics, and the possibilities for groundbreaking design through collaboration. Get in touch to discuss your next project—we would love to hear from you.