Room Accoustics

Acoustical considerations for your home th eater

The average person does not put much thought into acoustics and their effect on sound.  Acoustics are simply the characteristics of a room that determine the quality of your sound.  Have you ever listened to a speaker at a store and then when you listen to it at home it sounded different.  The acoustics of the room probably played a significant role.  Think about a time when you heard speakers outside in the open.  The lack of reflections created sound that was more then likely dull and lacking bass.  Then think about a time inside an old cathedral or a room with a hard finish walls and hardwood floors.  The sound reflects much more and echoes in these environments.

The goal is to absorb and diffuse the sound where appropriate in order to achieve the highest sound quality.

There are some simple rules to consider when designing a home theater room in order to increase sound quality.  In order to avoid standing waves, which can distort the mid range and bass frequencies, especially in the corners of rooms and near the walls:

• Avoid rooms that are cubes (such as 8' x 8' x 8')
• Avoid rooms where 2 of the 3 dimensions are the same (such as 8' x 8' x 12')
• Avoid rooms where the dimensions are multiples (such as 8' x 16' x 24')
• Keep seating areas away from corners and walls.
• An example of an ideal room ratio is 1 x 1.5 x 2.2, which could translate to 8' x 12' x 17.5'

Excessive reflections from parallel hard surfaces will cause unpleasant echoes.  When you go to a movie theater you will notice that the sides are covered with sound absorbing material or with drapes in order to minimize unwanted reflections.  When planning your home theater, you can control reflection by placing sound absorbtion materials on the wall between the speakers and your seating area.  However be careful to not overdo sound absorbtion or your room will sound dead.

Another aproach is to add sound diffusion which can be as simple as having a bookshelf in the back of the room to scatter the sound rather then absorbing the sound.

There are companies that sell sound absorbtion materials, acoustical ceiling tiles and sound diffusion products, and they can make a tremendous impact on the sound of your home theater, but don't underestimate the benefits of properly placed regular household items such as drapes, carpeting and bookshelves.

Sound Control

Another important thing to consider when planning a home theater is how to keep sound from the theater in the room so you are not distracting the rest of the home as well as how to keep the sound from outside the room from distracting your family during the movie.  At a minimum a layer of insulation should be used to help isolate the sound, but for those planning a dedicated home theater, additional accoustical sound barriers should be considered.  Doors into the room should be of solid construction and should be sealed to prevent sound from transmitting into or from the room.

Sound control is even more important if you are in an apartment or a duplex where you share a wall with your neighbor.  If you don't want to become enemies with your neighbor, you definately need to consider ways to isolate your sound.