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ARCHITECTURAL ACOUSTICS                                                                  with its respective properties, the absorption coefficients.
                                                                                         Based on reasonable standards generally accepted by everyone, this notion
The sound we hear in a room is a combination of the direct sound propagated              and organized comprehension on how the absorption helps the hearing
by the sources and all the direct and indirect reflections from the surfaces (floor,     perceptibility, these teachings started to be strongly applied in room´s acoustic
walls and ceiling), as well as the limit rate of the room itself (length, width,         projects. The international standards were created with the collaboration and
height). It is by handling the indirect reflections on the surfaces that it is possible  the involvement of standards normalization institutions; ISO, ASTM, etc.
to affect and alter considerably the acoustic features of the room and the
consequent way we hear and perceive sound. Hence one of the central topics               The architectural acoustics experts study the behavior of sound in closed
in the interiors acoustics.                                                              enclosures or semi-open, as well as the sound transmission between
                                                                                         buildings. The sound absorption and diffusion is a crucial part when studying
The acoustics of buildings was an undeveloped aspect until relatively recent             the behavior of sound in closed rooms to ensure a good intelligibility of speech
times. In the primordial approaches to this subject the roman architect Marcus           and music.
Pollio, that lived during the 1st century AC, made some guesses and some                 The sound insulation in buildings in general, as well as in urban projects, is
pertinent observations regarding the reverberation and interference that could           important to minimize the propagation of undesired sounds between rooms
be carried by us. However, the scientific aspects of the subject were only later         and adjacent buildings. In this way the negative acoustic effects are minimized,
developed by the American physicist Joseph Henry in 1856 and more                        like the noise contamination and misrepresentation of frequencies by several
thoroughly by the American physicist Wallace Sabine in 1900. The following               factors.
years, after this historical landmark that was the Foundation of the architectural
acoustics by Sabine, were spent studying how the absorption affects the
At that time a library was then created with absorbent materials, characterized

COMMON SOUND PROBLEMS IN ROOMS                                                           dead points, on which some frequencies are therefore cancelled as we do not         CONCEPTS AND BUSINESS PHILOSOPHY
                                                                                         feel them or hear them. All these acoustic phenomena called interferences
The acoustics of a room is satisfactorily adequate when there is a correct               simultaneously impair hearing and the sound capture by microphones.
balance between absorption and sound reflection. That balance is determined
by the physical space (dimensions of the room) and by the materials used on              When we talk about a “good room sound” we are probably talking about the
the coating. However, the acoustic phenomena like problematic echoes and                 acoustics as the acoustic science had been discussed about for hundreds of
excessive reflections can frequently occur even in a room with an adequate               years. Until then, a good acoustics were achieved by experimentation, by
reverberation time. When you have for instance a ceiling or a wall with a                experience or simply by accident. Currently, we know a lot about the
concave shape, it will be highly reflective. In such cases, the sound is                 parameters that influence the sound in a room. Talking about the control room
concentrated in a certain point where anomalies are felt and where the sound             of a studio, we know that basically, this room should work as neutral as
has an increased feature, distorted and bad. In the same way, a narrow corridor,         possible, a room with the right dimensions and proportions that has the
connected to a room between parallel reflective walls, can work as a trap, an            recommended materials so it can be balanced in all its sound spectrum, but
absorbent chamber generally beneficial for the lower frequencies.                        this is not always the case: Here is a list with important parameters to have into
Although the level of absorption of a room is being controlled, other acoustic           consideration for good acoustics: Appropriate Reverberation time, Modal
imperfections can emerge and cause uncomfortable reflections and repeated                Consistency, without floating echoes, good sound distribution, appropriate
echoes, it is then imperative to pay some attention to the elimination of the            sound pressure level, low level of background noise achieved by insulation.
interferences. The interferences emerge from the differences on the distances
from the direct sound and the reflected sound, which produce the so called

ROOM DESIGN                                                                              acoustic project for the interior rooms as part of the whole project.
                                                                                         In most cases this procedure does not have the best results, as the Architects
The Acoustic Design of a room should take into consideration the fact that               do not have the same kind of sensibility or understanding on musical acoustics
human hearing is complex, whether for physiological characteristics of the ear           as the Acoustics Musicians or Engineers with formation and higher sensitivity.
as for psychological characteristics. For example, sounds that are familiar to us        For the generalist planners, using diffuser elements can be a risk when not
are not interpreted in the same way, they look unreal. This is due to the part of        applied in a proper shape or proportion. They then choose more standardized
our brain that focuses and interprets the audition, which minimizes the attention        solutions using uniquely absorbents, not taking the risk of using diffuser
to these types of sounds. On the other hand, those sounds that we consider               elements, which require much more elaborate understanding and projects.
common and familiar are easily and quickly interpreted.                                  By doing so, you can give less importance to what the reflection by diffusion
Having this notion, it is easily understandable that sound can be radically              can help as for the balance of the reverberation times and the consequent good
altered in an enclosed space. For example, in a gym conditioned by the hard              environment intelligibility. It is therefore absolutely imperative to consider the
materials of the walls, ceilings and stands, the sound causes sound waves and            application of the diffusing elements in the acoustics projection in music
several beats, increasing the reverberation and totally misrepresenting the              rooms.
sound of the sound sources.
The Sound produced in a room is modified by reverberations due to the                    Over the last years, in more recent projects, it has been revealed a higher
number of reflections from the surfaces and to all existing elements in that             sensitivity to the use of diffusers and JOCAVI®, with its precious range of
room, as well as the furniture and the audience. For this reason a professional          products, has immensely contributed to that reality. The use of diffusers
audio room should have a normal reverberation level and intelligibility to ensure        represents a very conscientious work for the planner, as it cannot introduce
the sound´s natural playback for the events that take place there. To obtain the         excessive reverberation on any frequency, nor echo certain frequencies in an
best acoustic qualities, the rooms are designed in a way in order to ensure              odd way, nor produce undesirable interference effects or distortion. It is
balance between the absorption and the diffusion, with a minimum                         therefore an attractive task that excites the experts.
discrepancy of the time values versus frequency. The control of the low and              There are some available methods that make it possible to modulate the
mid-low frequencies is therefore essential, through the absorbent elements.              acoustic field associated to a sound source regarding a certain position or area
The enough reflection by diffusion is equally important to ensure a good natural         within a room. A geometrical modulation method very well known is the Ray
quality of the sound.                                                                    Tracing.
                                                                                         This computation technique is much more demanding than a simple
The most easy and common way of treating spaces for music is, without any                mathematical calculation. It requires a processing unit and makes the
doubt, to exclusively apply absorbent materials. This method is used uniquely            calculation slower. The method allows the planner to choose, adjust and
for reducing the reverberation time by the method of absorption. However, it is          distribute the acoustic handling materials and the surface´s coating according
not the most correct way of doing it because when you absorb too much you                to the control of reflections, the diffusion and absorption properties versus the
can see immediately a weakening of the high frequencies which will unbalance             frequency range, to achieve the desired acoustics for the sound source and
the reverberation times versus frequency. The effect will then seem like a dead          audience.
environment with the audible high frequencies in much lower levels, cancelling
the natural harmonics and diminishing the audition of the instrument´s timbre.           We are always improving.
In many cases, the room projects are designed by the generalist architecture             Welcome to JOCAVI® world, a wide range of Acoustic Solutions.
sector that is in charge, besides the conception of the building, also for the
                                                                                         Yours faithfully,
                                                                                         João Carlos Vieira
The passion for Musical Acoustics has guided my life since I was a child. The            Founder and CEO
taste for this matter with the tenacity to create and develop has been giving the
market, under Jocavi´s name, numerous high quality acoustic solutions.
For over twenty years I have had the pleasure to make this journey that makes
me feel accomplished and honored, with a work dedicated to those around me,
my friends and coworkers. JOCAVI® has now more than 100 different acoustic
products on the market, catalogued, organized and available for the most
complex and demanding applications, as well as for the most practical and
simple on the world of environmental acoustics.

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