The calculated control of sound in an enclosed space can be considered as a broad definition of room acoustics. The room can be considered as a system, and the design of the system would be room acoustics. The acoustic ‘sound’ of the 'system' will depend on the design of the system inputs and this would depend on the purpose of the space – is it a concert hall, a meeting room, an apartment?
Based on the required acoustic sound an Acoustic consultant will use various engineering methods to design the system. There are several elements that need to be carefully considered in a room’ design. Some of these include identifying room modes and controlling them by adjusting the basic shape and the resulting volume, identifying various sound reflection patterns inside the confined space and ensuring these are mitigated to remove negative sounds like flutter echoes and other tonal anomalies (modal responses) or reflections, calculating the reverberation time and adjusting this by adding or removing absorbing materials or including diffusion elements. Reverberation also causes additional noise and other factors that make communication and hearing all the words in some spaces difficult. Harder surfaces such as glass and brick have lower absorption properties and reflect sound. Softer surfaces such as fabrics and carpet etc. have higher absorption properties and absorb sound. Further studies in specialist areas, such as schools and performance spaces would also include evaluating the Clarity and Speech Transmission Index (among many other criteria) and controlling those by the use of carefully placed reflection and/or absorption which could also be aided in the electrical field by “Electro-Acoustic” design of audio systems.
Room acoustics is often analysed and evaluated using predictive computer-generated acoustic models and measurement systems. The 'Auralization' aspect of design software may be used to help acousticians and their clients understand the acoustic performance of the space prior to construction by listening to a room model through high quality headphones. Anechoic acoustic rooms fitted with speaker arrays are also used for this task.