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Direct field and reverberant field

The architectural acoustics is in charge of studying the phenomena aimed at an adequate and functional propagation of sound within a space, which can be from a concert hall to a music studio. recording. For this reason, architectural acoustics also deals with the problem of acoustic conditioning and absorption. Any room must have a series of acoustic qualities that allow what happens in it to be heard and understood perfectly. These acoustic qualities are, among others, the early reflection of sound, reverberation, the existence or not of echoes and resonances, sound coverage of sources, etc.

Direct field and reverberant field, what are they?

First of all, to define these two concepts it is necessary to know what the sound field is. This is defined as the sound pressure level at each point in a space. A sound field is composed of the direct field and the reverberant field. The direct field is the area in which the sound is perceived directly from the source without being reflected by any surface of the room. On the other hand, the reverberant field is the area in which the sound is perceived after suffering multiple reflections that overlap each other, giving rise to the sound being reflected and resonates in practically all points of the room. In this way, the annoying phenomenon of reverberation is produced. These two components have very different behaviors. The direct field decreases the further we move from the emitting source, and it does so at 6 decibels (dB) for each doubling of the distance. On the contrary, the reverberant field is constant in rooms and closed rooms. This is because the sound bounces off walls and objects, and all these reflections overlap each other, resulting in a distribution that is as uniform as it is annoying. Image result of direct field and field reverberant There are areas where it is only possible to have a direct field, such as in an open field. The reason is that sound can travel freely without reflections, and therefore the sound pressure level decreases rapidly with distance. In a room, direct field and reverberant field are combined, so that the first can be found close to the source but the reverberation appears at a certain distance from it. To achieve intelligibility of sound sources in a room, the direct field must prevail over the sound field. A clear example of the predominance of the reverberant field over the direct field are restaurants, in which it ends up being impossible to understand the people who are close to us when there are several people speaking at the same time.

Controlling the critical distance with acoustic panels

Finally, we can define the critical distance as the distance from which the reverberant sound field predominates over the direct field. This can be controlled by the acoustic conditioning of the rooms using suitable acoustic panels and modules. At ideatec, we have acoustic panels and diffusers made of wood, foam, polyester mineral fiber, and many other materials to achieve quality acoustic results. Discover our products and enjoy personalized treatment.