Acoustics, applied to architecture, is, in principle, knowledge of the facts.
Throughout the history of mankind, the knowledge of the laws of nature and of physics has made it possible to create the Greek theater, the Roman arenas, the great and magnificent European theaters of the eighteenth and nineteenth centuries, and and many others great exemples, all perfectly functioning untill contemporary days, without necessarily requiring the use of electroacoustics, even because there was no electricity in those times, as well as the coatings that are taxed as acoustic nowadays because there was also no industry in the way we have today. I say taxed as acoustic because everything in nature has acoustic properties, being the placement “acoustic materials” a redundancy.
Nothing against electricity and / or the materials industry (taxed as acoustic), since they mean necessary advances in technologies. However, especially with regard to materials, special care must be taken in their applications, since they have often been adopted in random ways, aiming exclusively at the plastic aspect and forgotten the technical aspect.
Considering that in architectural acoustics of an enclosure the basic premise is to listen well, we call attention to three measures also basic in the architectonic acoustic study of the same:
- Acoustic conditioning via internal geometry:
The good internal geometry of an enclosure is responsible for no less than 80% of its good internal audibility, such as the examples cited above: the Greek theater, the Roman arenas, the eighteenth and nineteenth century theaters, etc., always focusing on the function to which the enclosure is intended. See examples below:
- Acoustic conditioning via coatings, etc.:
The complementation (the other 20%) or possible correction of deviations for good internal audibility is due to the balanced adoption of the various internal coatings of the enclosure, its furniture and fundamentally based on the fluctuation of its occupancy rate (the same environment can be crowded or semi-occupied, and because the human body is also an “acoustic material”, interferes with the regulation of the room’s reverberation time). And this reverberation time is directly connected to the volume and the specific destination of the enclosure, being mathematically represented by the equation: Tr = (0.161 x V) / ΣSi x αi, where V is the internal volume of the enclosure, Si is the area of a certain internal surface of the enclosure and αi is the acoustic absorption coefficient of the same surface considered. In addition, all this considering the low frequencies, the averages and the highs. See examples below:
- Sound insulation:
Acoustically isolating an enclosure is given, basically, due to the necessary increase of the masses of the component materials of its enclosure and the thicknesses of the surfaces of that enclosure (the thicker the surface composed of the same material, the greater its acoustic insulation at low frequencies).
The acoustic insulation of an enclosure has two basic functions:
- Block harmful external noise that impairs good internal audibility of an enclosure;
- To block internal noise with respect to ensuring public quiet or good internal audibility of contiguous enclosures.