This study focuses on temporal aspects of the music of Krzysztof Penderecki and deals with these on the level of textural activity. The analyses are based on a referential idea called a "discrete sound event," defined as an occurrence of a sound or collection of sounds which, as a unit, is distinct from the surrounding texture. These sound events are then used to appraise textural activity from layer fluctuation and composite density. The pieces selected for applying these techniques are the Threnody to the Victims of Hiroshima, from 1960, the Fluorescences, from 1961, and the 1965 Capriccio for oboe and strings.