How U determine first and second reflection points

Or, each wall will have first reflection point from the speaker on the same side and the reflection of the speaker on the other side is considered second refection point?

seems like slight difference in definiton of first and second reflection point by Tvad and Fmpnd.

Eandylee - Correct, however there are actually more if you take the floor and ceiling into account, and don't discount them as they are quite significant. It's easy to put a rug on the floor - a bit more difficult on the ceiling.

Don't forget the reflection points from the rear wall. In a wide room, these can be more intrusive at the listening position than the reflections off the side walls.

As a rule of thumb, if the distance the sound travels from the speaker to the reflecting wall and on to the listener, is more than 5 ft. longer than the distance traveled directly from the speaker to the listener, the ear will be able to distinguish this reflected sound in time and not confuse it with the image. That is why it is important to get speakers away from side and rear walls if possible.

You can see that if a speaker is more than 2 1/2 ft. off any wall, this criteria is always met. Still, the clarity of the image will always benefit with some absorption in the room, and putting it at the reflection points is a good place to start. Experiment.

WOW!!! To show you how fast we all responded, I thought I was the FIRST to respond because there WERE NO responses when I typed mine!! Good luck with your system.