If the early reflections occur within about 50 – 80 milliseconds (ms) and are reasonably similar to the direct sound, they are not heard as separate from the direct sound. For rapidly varying sound, such as speech, the limit is around 50 ms while for slowly varying music, the limit is closer to 80 ms.
The source is perceived to be in the direction from which the direct sound arrives provided that (1) successive sounds arrive within about 35 milliseconds, (2) the successive sounds have spectra and time envelopes reasonably similar to the first sound, and (3) the successive sounds are not too much louder than the first. This is referred to as the precedence effect.