1. Flutter Echoes
Flutter Echo from walls, floor and ceiling resulting in bad stereo image, metallic sound and ear fatigue.

2. Standing Waves
Standing Waves create resonate to a room ( especially at low frequencies ) making speakers, Mic and/or listening position placement difficult. Bass level changes and Speakers sounding so different in various position within a room.

3. Reverberation
Too long reverberation time blurring details of a sound.

4. Coincidence Modes
Imbalance between different frequencies ( some sound louder than the others ) due to coincidence dimension of a room.

These acoustic problems will definitely exist within your room that cannot be IGNORED. These are also problems that cannot be solved by any electronic device of any kind and prices !!

The only solution is to treat your room acoustically. This is A MUST for anyone who wants quality Sound.

MODES

MODES are the pathways between reflective surfaces which the sound waves travel back and forth and finally returning to it’s starting point. The frequencies of these sound waves is called Modal frequencies, and the Modal Frequencies of a room are determined by it’s size and geometry shape.

There are Axial, Tangential and Oblique Mode as shown at Fig. 1 below.

STANDING WAVE

Standing Waves is a kind of Mode. When sound wave return in phase to its starting point, the energy will build up, and resonate continuously between two reflective surfaces, STANDING WAVE occurs. All Low Frequencies standing waves are our No.1 enemy and they must be smoothed out by Acoustic Treatment.

Another drawback of these Resonant room modes is that the room response becomes position sensitive both for the sound source such as Speakers or Instrument etc. and the receiver such as Microphone or Listener etc. That's why we hear more bass at one point and less on others within a room. And placing Speakers at various position make them sound so different. An untreated room in fact is devaluating your investment on your recording equipments and /or sound system.

COINCIDENCE MODE

If a room with identical dimension Length, and Width, they yield the same set of Modal Frequencies, this doubling of frequencies is called Coincidence Mode.
Music or sound play in this room will have a very imbalance Frequencies respond, Frequencies coincided with the coincidence modal frequencies will sound much louder than others frequencies, and these must be corrected by means of Acoustical Treatment.

REFLECTIONS AND COMB FILTER

Reflections from Walls, Floor and Ceiling will seriously BLUR out the stereo images. If reflections reach the receiver ( Listener or Mic ) with less than 30ms of delay time, usually caused by reflective surfaces within 8 to 10 meters distance from the sound source. Comb filter distortion will be produced, resulting a metallic sound and ear fatigue. And improper reverberation time will ruin all recording.