Ключевые слова: adult, attention, attentive, backs, blur, busy, colorful, conference, congress, crowd, event, female, foreground, forum, group, hall, indoors, information, interested, knowledge, learn, lecture, lecturer, listeners, listening, male, many, meeting, men, participants, people, person, presentation, public, rear, room, row, seated, seminar, sit, speaker, training, view, watching, woman,