What is slap echo?
Slap echo is echo that is so clear, it sounds exactly the same when reflected.
How would I know if I have a slap echo problem?
Clap your hands, if you hear the clap come back, in perfect reflection, multiple times, you have a slap echo.
What causes slap echo?
Its caused by surfaces that are specific distance apart, and completely parallel and hard. Take a squash court, it doesn't have slap echo, because the sound is reflected and immediately distorted, because of the size of the room.
Can slap echo be solved?
Yes, simply with acoustic treatment on one of the offending surface. Both of the parallel surfaces do not need to be addressed.
Where is slap echo most common?
It is very common in larger rooms, such as auditoriums and gymnasiums and worship centers. In these rooms, you may not notice slap echo, until you actually make a large sound such as a handclap, or someone hits a drum. I know of a situation where the drummer in a band was seated, playing with his back to the wall, and he had trouble staying in time, because the sound reflections were so perfect.