The perfect and most effective distance lies between 85 cm (33 in) and 1.5 m (5 ft) - depending on the listener's position. However, you can also obtain very good results at a distance of 70 cm (28 in). An easy way to home in on the right distance is to sit down in the listening seat and ask a friend to hold up a mirror and move it along the wall. As soon as you see the speaker in the mirror, you know where the acoustic reflection comes from. Now measure the distance between the speaker and mirror, and mirror and listening seat, then subtract the distance between the speaker and listening seat. You will see from the result whether you are above or below the critical distance of 1.7 m (5.6 ft).

If you are well below this value, you can try to dampen or diffuse critical room resonances in order to reduce their effects. In the case of dampening critical resonances, part of the energy is destroyed by friction. For instance, heavy fabrics can be hung a few centimetres from the wall which dampen the reflections. If you want to go a step further, you can even use special dampening material. In this case we recommend that you use the heavier material. We can assure you that an area of 1 m (3.3 ft) height and 0.5 m (1.6 ft) width put on the reflection point may produce astounding results. In the case of diffusing critical resonances, the sound should be reflected in different ways. A shelf with many books of different sizes can do the trick. However, you can also buy so-called diffusers, specially designed for the diffusion of sound waves.

Let us say another word about the general concept of spatial perception. If you enter a completely dark room, you will immediately know the approximate size of the room even though you cannot see to orient yourself. You therefore rely on spatial information and relate to small sounds. The knowledge we have obtained about the size of a room generally helps to prevent that we perceive sound from music reproduction as something coming "from behind" the back wall.