Home theater dimensions follow the same room ratio criteria as other room usages. https://www.merriam-webster.com/dictionary/home%20theater
There is nothing different for home theater dimensions as there are with mix, live two channels, whatever the source of energy you are placing within it. You must consider two types of energy in any critical listening environment. You must first and foremost consider low-frequency pressure issues. Along with these pressure issues, you must also lower reverberation (reflection) times. Pressure from lower frequencies blur and smart our audio. Reflections from the walls interfere with speech intelligibility which is the ability to hear as many words in a sentence as we can. The goal is 100% but is rarely achieved. If you have been in a room where you hear “bass boom” you understand low-frequency pressure. If you have been in a room where the reverb times are so high you can not hear or understand the person speaking next to you, you understand the power and distortion of reflections.
Home theater dimensions do need to address the low-frequency issues. This is due to today’s systems of producing full range energy from all the channels. There are also multiple channels of energy to deal with. The main focus for home theater dimensions must take into account all of that energy and the full range frequency response of each discrete channel. Home theater dimensions must allow for more volume in the room. Think of your room as a glass of water. The glass holds 16 ounces of fluid. With a home theater you are placing 24 maybe 32 ounces of “liquid” sound into the room. The liquid that spills out of our “glass” is distortion. Home theater dimensions must provide for the proper volume, so that the glass is large enough to support multiple subwoofers and multiple channels of full range energy.
Let’s look at a best case scenario when it comes to home theater dimensions. In order to really manage low-frequency energy, we need to have enough room volume or glass size to hold all of this multiple channel energy. A good home theater dimension width starting point is 23′ – 27′. A good length would be 31′ – 35′. A ceiling height of 13 – 15″ would work well with the other home theater dimensions described above. These home theater dimensions will produce a room volume that will still exhibit low frequency issues but the lower frequency issues will have less amplitude or strength and thus will respond well to treatment. A home theater dimension of 25′ w x 13′ h x 35′ long will produce a frequency response that can easily be managed with the proper rates and levels of absorption across each offending wall surface area. https://www.projectorscreen.com/projector-screen-calculators
In all rooms, we have pressure and reflection issues. To make matters worse, each wall surface area produces different problems when it comes to pressure and reflection issues. Each wall surface area must be measured for the frequency and amplitude of the issues that wall is producing. This is where people fail. They apply the same technology throughout the room when each wall surface area is producing both a different low-frequency pressure issue along with a different middle and high frequency reverberation time issue. This produces more issues than it solves. When you are dealing with pressure and reflection issues, you must quantify and qualify each wall issue by developing a strategy instead of just applying tactics that you think or feel will work. Acoustics is a branch of physics that requires extensive training in math and physics. This is why most fail. They fail at the mathematics required within physical science.
Before you begin any project type when it comes to room acoustics, whether it is trying to determine the proper home theater dimensions, designing a vocal room, or a live recording room, you must develop a strategy before you apply any treatment tactics. You must determine what the room usage is and what size to use for your specific usage. With a treatment strategy based upon the room issues, you can then assign the appropriate treatment types which will go a long way to saving money. Acoustical treatments require that you cover large amounts of surface area with treatment types that can be expensive. If you develop a strategy and then apply tactics, you will minimize expenses and mistakes.
At Acoustic Fields, we have a design service where we do all the “heavy lifting”. https://www.acousticfields.com/home-theater-acoustics-service/ We assist you with noise measurements. We assist you with all the absorption and diffusion requirements within the room to match the room usage. We will assist you with speaker placement and listening positions along with two program types. Once we have analyzed all the room data, we will prescribe the treatment types, amounts, and positions of the treatment. At that point, you will have two options. You can purchase the materials from us and build the products yourself. https://www.acousticfields.com/shopping/ You can also purchase the products directly from us. Each system has its pluses and minuses. You must first define the acoustical issues, apply the necessary treatment types, and then decide based upon budget and skillset, which treatment methodology you will use.