Hollola’s Heinsuo school is one of the first schools in Finland to apply an open learning environment model. AINS Group designed the school’s acoustic solutions, thereby contributing to the creation of much-needed guidelines for acoustical design of open learning environments. The work was carried out as a life-cycle project. A central part of the acoustic solution was formed by a sound-masking system, which reduces noise distractions over large distances. This marks the first time that a sound-masking system has been introduced for a school environment.