First Reflection Point Calculator
Calculate mirror reflection points on side walls and ceiling clouds to eliminate comb filtering.
Room lengthm
Room widthm
Listener from frontm
Speaker from frontm
Speaker from leftm
Room heightm
Side wall reflection
1.26 m
from front wall along side wall
Ceiling cloud center
1.45 m
from front wall (plan marker C)
Recommended panel
4 in / 10 cm
porous absorber with air gap
Side-wall reflection point at 1.26 m from the front wall — that's where your first panel goes.
Preview only — open the 3D builder for full placement, treatment, and analysis.
What are first reflection points?
First reflection points are wall coordinates where speaker sound bounces directly to your ears within 15 ms. Placing absorber panels here prevents phase distortion and sharpens stereo imaging.
The acoustic mirror test
- Sit in your mixing chair facing forward.
- Have a friend hold a mirror against the left wall at ear height.
- Slide the mirror forward until you see the speaker tweeter in the mirror. Mark that spot on the wall.
- Hang a 2" or 4" thick acoustic panel centered over that mark.
Frequently asked questions
- What are first reflection points in acoustics?
- First reflection points are specific locations on room boundary surfaces where sound from loudspeakers reflects directly into the listener ears within 20 milliseconds, causing comb filtering and smeared stereo imaging.
- How do you find first reflection points with the mirror test?
- Sit in your primary mixing chair while a helper slides a handheld mirror along the side wall at ear height. When you see the reflection of the speaker tweeter in the mirror, mark that spot on the wall.