Arrival gap

The time between the arrival of the direct signal and reflections. See also initial time-delay gap.
Source: Master Handbook of Acoustics

In acoustics, the term "arrival gap" refers to a phenomenon where there is a silent interval between two successive sound waves that arrive at a listener's position. This interval is caused by the difference in the arrival time of the two waves due to the difference in the distance traveled by each wave. The arrival gap can have an impact on the perception of sound and is an important factor to consider in the design of sound systems and the control of noise in various environments.