Two of the major types of acoustic interaction found among insects are synchrony and alternation. Males in groups form choruses and in some species males synchronize their signals. That is, their sounds tend to overlap for a significant portion of the time. Although there may be some slight phase differences among individuals, their relative phases are nearly zero. The other type of chorusing is where the males produce signals that alternate and are non-overlapping. For duets of males producing alternating signals, the relative phases of the signals are nearly 180^o.