The “Interval between sounds” property specifies the amount of time that passes between the start of one sound and the start of the next. This is because the intended purpose of scatterer sound modules is to support ambience where many small, discrete sounds are starting and ending independently.
If your sound files are of a consistent length, you should be able to achieve the effect you want simply by adding the length of the sounds to the value of the Interval between Sounds" property. If they’re of varying lengths… Well, there’s a number of possible ways to go about it, but without knowing the details of what you’re trying to achieve it’s hard to know what to recommend.