**2.4 Acoustics in interior design**

Interior design, as specialization, dates to 1890. Elsie De Wolf developed the Colony Club in the US, and from then, it becomes a profession. The architect—the worker' supervisor in Latin—was in charge of all the building details, including the interior. Well, the interior design is the profession that cares, protects, and sustains the human life in a healthy, green, and safe environment. The interior acoustical intermediate that is appropriate to the function, reaching the audience in proper level to success the communication, without disturbing or even harming the users hearing, is a prosperous acoustical design. The classification of the interior spaces could lead to a better understanding of the role of the acoustical design to succeed in the functionality of the space. The interior acoustical design differs from the spaces where speech intelligibility is necessary to the spaces where quietness is vital, to spaces where the music needs enhancements, to spaces of private communications, and to spaces where public announcements take places. Each of these categories will require a specific combination of materiality schemes that balance between the physical properties and their quantities to provide an adequate acoustical environment [6].
