COMMON ACOUSTIC PROBLEMS IN ROOMS
COMMON ACOUSTIC PROBLEMS IN ROOMS
What is one of the most common acoustical problems in many rooms? “Flutter echo”. What is flutter echo? First let’s start off by giving those of you who don’t have a background in acoustics the definition of an “echo”, an “echo” is sound being reflected off of a surface and returning to you ears. Like what you experience when shout hello in a canyon. A flutter echo is equally spaced in time repetitive and successive sound reflections. This to varying degrees can make speech difficult to understand or in some cases totally unintelligible in rooms. It can also effect your perception of music’s tonal qualities by adding a negative pitch or timbre coloration. This problem can be greatly amplified by speakers and their placement in the room. What are the main causes of this Problem? Those perfectly designed parallel walls and the ceiling and the floor of a room being parallel. So when you design your room, keep this in mind.
For those of you whose room has already been built, there are some measures I can suggest that can greatly reduce or eliminate this problem completely. The first is the use of sound absorption materials on one or more walls and or on the ceiling. There are many high-end products on the market designed to help you address this problem, if you have a big enough budget. For those who don’t have a big budget, you can use egg cartons, office ceiling & wall tiles. The general idea is to keep the sound waves from reflecting back at you in an equally time spaced repetitive rate. The second suggestion would be the use of sound diffusers unlike absorption materials diffusers redirect and or scatter sound waves, thus prevent the sound waves from being able to reflect back at you in a uniformed rate. Again, if you have the budget there are lots of high-end products to meet your needs. If your budget is tight, you can also make your own diffusers. Wood make a great diffuser so does Masonite. The idea is to make sure the surface is curved, angled or slotted. Strategically placed book shelving will also work well as room diffuser.
Another common acoustical anomaly - that of “standing waves.”
Here we are describing a type of low frequency reflection, caused by dimensional relationships within the room. Low frequency standing waves can be predicted mathematically when the dimensions of the room are known. Standing waves build up in the listening environment and conspire to sabotage the low-end performance of stereo systems and can greatly affect the recording qualities of a studio’s “live room”. A low frequency standing wave is likely to “bloat” the character of the bass, causing severe peaks at points throughout the range. The only cost-effective method available on the open market for the treatment of standing waves is the use of ASC Tube Traps (AKA bass traps). These units, placed in the corners (The point of maximum pressure) can dramatically improve the quality of low frequency sound in a space plagued by standing waves.
For those with do-it-yourself abilities, good news, in next week’s blog, I will give you step-by-step instructions on low cost ways to make your own room bass trap.