**2.3 Acoustics in architecture**

Architectural acoustic design starts from the acoustical engineering. The connection between the physics and their applications when Wallace Clement Sabine, father of the modern building acoustics, gets the attention of the sound in the different lecture halls in Harvard where he studied physics science. Absorption formula title—Sabine's Formula—honoring his hard studies and experiments to reach today science the Acoustical Design in Buildings. The acoustics of buildings face several obstacles: the modern design trends, the type of materials, the mechanical systems in the buildings, and the surrounding level of noise.

The modern trends in design open up the spaces, no matter the functions and the privacy required for specific zones. Accordingly, the masking noise between the interface and the user concentration disappears.

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**Figure 5.**

*Acoustics from Interior Designer Perspective DOI: http://dx.doi.org/10.5772/intechopen.84167*

pollution of our environment.

**2.4 Acoustics in interior design**

*2.4.1 Spaces for speech intelligibility*

acoustics performance (**Figure 5**).

tion and prevent a safe environment for the users.

contribute to the noise pattern of the buildings.

The building materials become economic in terms of structural properties in favor of space and cost saving. Such products create extra load on the noise produc-

Mechanical systems in the buildings are necessary with today's climate. The air-conditioning systems, the elevators, and the ventilation are all components that

The level of noise's pollution created by today's lifestyle that is transmitted to the building add additional problems and multiply to a disastrous extend the noise

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].

Speech clearness is vital in a specific type of functions. Without speech intelligibility, classes' success could fail. Teacher explanations, court sessions, and board meetings are functional, practical examples where speech is the key role of their success. Large institutions need clear discussions to make efficient decisions. In the court, when the speech is not clear, many judicial problems could take part from innocently. Such spaces need clear speech with no reflection nor echoes. In such functions, the number of absorber materials should increase in favor of the reflectors. The absorption material scheme when exceed, will produce a harmful background and thus will require more effort from the sources to enable the audience to hear. Therefore the introduction of some diffusers is necessary to balance the

*Examples of classroom, boardroom, and court room where the speech intelligibility needs many absorbers.*

These problems are the main concern of the architectural acousticians.

**Figure 4.** *The six-story ceremony hall in Ālī Qāpū palace in Isfahan, Iran.*
