A method of encoding signal segments which represent unvoiced plosives. The signal segments to be encoded are contained within a speech signal divided into m=1, . . . , N frames. Each frame is subdivided into l=1, . . . , L subframes. The speech signal has a gain g.sup.m (l) within each subframe. An energy measure e.sup.m (l) representative of the signal segments' energy content is defined. An energy threshold e.sub.th (l) representative of a sudden energy change characteristic of an unvoiced plosive is also defined. For each frame, the energy measure e.sup.m (l) and the energy threshold e.sub.th (l) are derived for each subframe within that frame. If e.sup.m (l).ltoreq.e.sub.th (l) for each subframe within a particular frame, then a plosive locator l.sub.pl =0 and a plosive index i.sub.pl =0 are assigned to that frame to indicate absence of a plosive within that frame. If e.sup.m (l)>e.sub.th (l) for any subframe within the frame, then that frame's plosive locator l.sub.pl is assigned a non-zero value, with the plosive locator's value indicating location of the plosive at a transition point immediately following that one of the subframes within the frame for which e.sup.m (l)-e.sub.th (l) is greatest; and, that frame's plosive index i.sub.pl is assigned a non-zero value representing presence of a plosive within that frame.