If you think the answer to "What is acoustic treatment?" is window treatments, you'd be off-pitch. Rather, it's something you apply to a room to optimize it for sound.
For musicians, it's par for the course in recording studios, whether professional or home-based. But it has many other use cases beyond optimizing a room for music. There are ways of applying it to a variety of environments across industries.
You might think the answer is sound proofing, but it's much more than that. A more accurate definition is applying sound- or noise-reducing products to floors, walls, and ceilings to control sound and create a more pleasant environment.
That environment might include something as large as a gym or other indoor space such as a school pool, corporate auditorium, or a cafeteria, all of which tend to have hard surfaces that reflect sound. This can lead to acoustic problems that the average person would call noise. Smaller venues — such as bars, restaurants, places of worship, and classrooms — have their own sound characteristics that can also be managed by optimizing sound.
What a building or room is made of has a significant effect on how sound and noise behaves or travels within it. Different building materials have their own properties of acoustical absorption. Hard and flat surfaces — such as drywall, glass, metal decking, and concrete — reflect sound. An obvious example is a gymnasium, where the bouncing of dodgeballs reverberate loudly. While the students playing are not likely to care about the noise, understanding what acoustic treatment is can matter if that same gymnasium is used for other activities such as school assemblies and ceremonies.
Not only do the surfaces and the size of the room matter, but so do the shape of the space and the shapes within that space. Sound will travel and bounce off surfaces in a relatively empty space in comparison to a room full of different objects.
When setting up a space for better sound, the first thing that comes to mind is technology. Whatever the environment — be it an auditorium, worship space, or music studio — there's likely a lot of cabling, loudspeakers, and microphones involved. These must be complemented by acoustic treatment. Without it, your space will have an uneven frequency response.
However, the goal isn't necessarily to get rid of all reverberation and sound reflection — you're trying to control the behavior of sound to create a neutral sound balance, and thus a more enjoyable environment. This requires a combination of absorption and diffusion of the sound.
For absorption, many materials can be used — the most common being foam — to soak up sound energy at both high and low frequencies. An example of the latter would be bass, which can be "trapped" using a combination of hard, soft, thin, and thick materials and even air in the form of a gap between the wall and the materials designed to trap it.
The most obvious benefit of optimizing a space for sound is to keep others around the area happy. If you decide to convert a shed into a music rehearsal space, for example, they will appreciate your efforts.
But there are many other reasons for improving acoustics depending on the space, including the privacy of the occupants, improved speech clarity, higher quality interactions, and improved concentration and productivity levels for the occupants. It can also maintain and increase the health and well-being of occupants and prevent ear fatigue, which can manifest in many ways, including pressure on the eardrums, a dull ache in the ears, headaches, and even hearing loss.
Different spaces have different requirements, especially if they're used for multiple purposes. A home music studio or even a professional studio has clear requirements to handle the sound from the source to the microphone and manage how it reflects off the surfaces. An auditorium must account for a variety of performances, including spoken presentations, solo musicians, and even full-blown orchestras. A wide variety of public gathering should be accounted for. Today's places of worship can also be multipurpose, and not all churches are purpose-built edifices.
Proper acoustics ensure all speech and music elements can be heard clearly by everyone in the room, no matter how far they are from the front of the church.
A restaurant is an example of a space where acoustics are important and highlight a need for creative solutions for diffusion and absorption. Most restaurants aren't built with favorable acoustic conditions in mind thanks to the use of hard, non-porous materials that don't absorb the noise inside. Instead, the sounds generated by diners and even the kitchen tend to be amplified by the reflection of noise off the floor, walls, and ceiling.
That said, treatment is still possible and can be aesthetically pleasing by integrating and fitting panels into ceilings and walls as decor. Ideally, a restaurant should be designed with good acoustics in mind. Hearing the clangs of pots and pans doesn't lend itself to a comfortable dining experience.
Other spaces that could benefit from treatment to enhance the experience of customers include classrooms to allow students to concentrate and learn, spas and salons to further a state of relaxation, and waiting rooms for medical and accounting offices — where patient privacy can be maintained while creating a more soothing environment for people who may be anxious.