Flutter echo is an acoustic defect, also known as fluttering echo. It is the effect of multiple echoes, where a specific sequence of sounds is repeated several times. This occurs when sound waves bounce off flat surfaces and obstacles, most often in small rooms. The repeatedly bouncing sound waves resemble the fluttering wings of animals, hence the name of this phenomenon.
The scale of this phenomenon in small rooms arises from the fact that the acoustic wave has little space and can bounce off the walls multiple times before fading away. A curious example of observing flutter echo can be clapping your hands when you are in a narrow corridor.
Currently, flutter echo is easy to eliminate at the design stage of a concert hall or theater. Acoustic waves easily bounce off walls that are parallel to each other, so it is enough to tilt one of them by at least 5° to eliminate this acoustic defect. Additional support can come from sound-absorbing or sound-dampening materials.
