Architectural acoustics is the science that studies the behaviour of sound within a building. The design of a conference room, a hall, a theatre, etc., requires the analysis of all parameters related to sound and its propagation in the air.
In this first lesson we will address the first key concept related to the topic of acoustics: the sound wave.
The sound wave
In physics, the sound is defined as an oscillation (movement in space) done by the particles (atoms and molecules) in a given medium. This simple oscillatory motion propagates mechanically, originating a sound wave (or acoustic wave). The sound source can be any device, appliance, etc., that causes pressure variations, and the portion of space concerned by these variations is called sound field.
The propagation of sound occurs spherically, i.e. in all directions, and the speed of propagation depends on the nature of the elastic medium on which it diffuses.
In the acoustic design of a room you must take into account certain factors related to the sound wave such as magnitude, intensity, speed of propagation, and wavelength. When a sound wave comes into contact with the surface of an object, it can be reflected totally, partially, or not be reflected at all; it depends on the wavelength.
In the following illustrations, we see that if the size of the object placed in front of the sound source is greater than three times the wavelength, there will be total reflection; if the object is of equal size, there will be 50% reflection and 50% diffraction; if the object instead is smaller than 1/3 of the wavelength, there will be no reflection.
In the next lesson, we will study the concept of acoustic reverberation time and how it is measured during phonometric analyses.