Commercial
Experiencing Acoustics
Often overlooked, acoustics play an incredible role in your experience of a space, and the memories you’ll have of it. So, let's geek out and discuss what exactly you need to consider when designing for acoustics, how it all works, and why it matters.
April 7, 2015
On a recent Friday night out and about with friends on Capitol Hill, I had the pleasure of checking out one of the newer restaurants as well as a theater for performance arts. While that doesn’t sound like an earth-shattering or atypical weekend evening for me, I was struck by the sheer difference of these two spaces.
On this particular night out and the spaces I visited, I was taken by how much of a role acoustics can play into your experience of a space as well as the memories you’ll have of that space. Being someone who enjoys food and always searching for great new places and experiences, our restaurant left me very impressed with the food and the ambiance of the space. Sounds like a winning combination right? Yes... but the other memory I have of that space is how loud it was. Not just the typical chatter or white noise you can get at restaurants, but rather, we had to talk so loud we started losing our voices. While I didn't notice how loud it was while in the space, as I was walking towards the theater I realized that my throat hurt and really noticed how quiet it was outside. Quiet outside isn't something you generally say on a bustling Friday night on the Hill, just to give some more context to the noise level.
On the opposite side of the spectrum was the sound quality of the theater. While everyone is generally quiet while the performance is going on, an actor could be whispering or mumbling and you could hear every single word they were saying. Certainly, you can make the argument that these spaces are so different and designed for different purposes but at the end of the day, acoustics are sometimes forgotten in a project and it becomes an afterthought. Onto the nerdy side of acoustics!
From a very broad definition, one could describe Architectural acoustics as the designing of spaces, structures, and systems to meet hearing needs. There are also “wanted” sounds, such as hearing everything in the theater, and “unwanted” sounds sometimes referred to as noise; examples of these are HVAC equipment to excessive noise levels of people talking. Everyone has a different level of discomfort but a basic guide is below.
Above: How much is too much?
In the case of the restaurant, there were hard surfaces everywhere. Concrete floor, stainless steel countertops, tiled walls, metal doors and an almost perfect rectilinear space. All of these elements were leading to sound bouncing around and hitting the hard surfaces, reflecting and amplifying back at us. Ultimately this could have been resolved in several different ways, but thinking about adding some layer of absorbent material to the ceiling, window treatments, or even the type of furniture to help attenuate the noise could have all gone into making the space better. With regard to the theater space, acoustics are generally one of the major items that we design to in order to ensure everyone has a pleasant experience. In that particular space, you could see acoustic tile on the ceiling, walls, set design, furniture that could help absorb sounds - even the floor plan of the space was different.
Top Left: Diagram of how sound bounces around in a room with hard surfaces and how it can be helped with absorbing materials. Right: Diagram of how sound reacts to different surfaces. Bottom Left: Example of how spaces are designed to direct sound.
When you think about trying to attenuate the sound of the space you also need to be aware of the different types of sound. There are two different classifications of sound; STC and IIC. STC stands for the sound transmission class which is a rating that is given to specific construction assemblies to reduce airborne sounds, such as voices, stereo systems, TV, and people talking. IIC stands for impact isolation class. This is a rating given to assemblies for structure-borne noises, such as equipment vibrations, people walking, dropping objects on the floor, just to name a few. A general rule of thumb: the higher the number, the better it’ll be in noise reduction. In both cases, a rating of 50 or above will meet minimum requirements for the International Building Code.
Top: Example of a situation where having a higher STC rating would be helpful. Bottom Left: Diagram of how structure-borne noises impact throughout the building. Bottom Right: Example of floor assemblies with their STC and IIC ratings.
So the next time you are out and about enjoying dinner, watching a performance - or just even at home - stop and think about the acoustics of the room and what items are either helping or hurting the sound. If you really want to be adventurous you can do like my professor in graduate school did and start clapping or making bizarre sounds in a space. During school, I always wondered what he was doing, let alone being embarrassed from time to time but it is a great way of exploring your space.
Fun Fact:
The quietest room in the world is an anechoic chamber at Orfield Laboratories in Minneapolis, MN; and the quietest natural space is in Olympic Peninsula, WA. Check out more in this video.
