Both — but through different mechanisms. The Irrelevant Speech Effect drains cognitive energy through the automatic processing of background speech in working memory — a mechanism that operates below the level of conscious distraction and cannot be overcome through willpower or experience. The orienting response drains attentional energy through the reflexive redirection of attention toward sudden acoustic events. Both mechanisms are physiological, not volitional, and both are eliminated by acoustic enclosure (DS,A = 29.4 dB, ISO 23351-1). The “distraction” experience of open-plan noise is the conscious perception of these two underlying physiological processes, not the processes themselves.