Ключевые слова: abstract, academic, audience, background, blur, blurred, bokeh, business, businessman, center, class, classroom, computer, concept, conference, congress, convention, corporate, defocused, education, event, explaining, group, hall, knowledge, lecture, lecturer, meeting, participants, people, person, presentation, professional, public, question, room, seminar, sit, speaker, student, students, trainer, training, workshop,