Avoiding Early Reflections
The speed of sound is approximately one foot (30 cm) per millisecond. Therefore, to preserve the natural soundstage on your recordings, there should be no reflected sounds arriving at the listening position with a path length less than ten feet (3 meters) longer than the direct path from speaker to listener (see Figure 8.1). This means that if the speaker or listener is placed closer than about 5 feet to a wall or other surface, that surface should be covered with sonically absorbent material.
Direct Sound
Reflected Sound
Figure 8.1 - The reflected sound must travel further than the direct sound, and therefore reaches the listener at a later time.
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