ES2264879B1 - PANEL FOR ACOUSTIC TREATMENT THROUGH FRAGMENTATION OF REVERBERED SOUND. - Google Patents

Abstract

The panel (10), formed by a set of tubular elements (1) of variable section, has two faces with different acoustic behavior: it allows the passage of the incident sound on the face shown in the figure or "open" and reflects most of of the incident sound on the opposite or "closed" face. Installed with its "closed" face facing an enclosure (11) and separated at a distance (E), a sound pulse that strikes its "open" face will pass through it and reach the enclosure reflecting towards its "closed" face, from where it will be reflected again towards the enclosure, reverberating for a certain time caught between the enclosure and the panel. In each incident on its "closed" face, only a small part of the reverberated pulse will pass through it, returning to the room the incident pulse transformed into a series of successive fragments of much lower and decreasing intensities, separated from each other at intervals of time proportional to the distance (E).

Description

Acoustic treatment panel by Reverberated sound fragmentation.

Object of the invention

The object of the present invention is the obtaining a device in the form of a panel or screen, which improve the perception of the sound produced inside a closed room, that is its acoustic characteristics, by means of fragmentation or diffusion of the sound reflected by the enclosures of said room, or reverberated.

Background of the invention

I will refer exclusively to the device known by the technique as "Schroeder diffuser" for being, within the huge variety of elements available for acoustic treatment, the only direct antecedent related to the invention.

The Manfred R. Schroeder diffuser is a device that presents on one of its faces, a series of slots or gaps of different depths. The sound that hits on said face of the diffuser, it is divided by the gaps in fragments that penetrate inside and reflect when they reach the background, so each hole returns to the room its fragment with a  phase delay proportional to its depth.

Figure 11 shows in section, some gaps of a Schroeder diffuser in its basic version (21), its maximum depth (G), and through rays and vectors, the path of a sound pulse with flat wave front (13) that affects perpendicularly on its surface, the incident fragments in each hole (22), the reflected fragments (23), and their arrears phase (H).

Taken together, these reflected fragments produce a more diffuse sound than that corresponding to a flat surface and consequently allow a better perception of the direct sound produced, both in listening rooms and in music recording

This diffuser is mainly used fixed to the enclosures and it is quite expensive to manufacture, especially in its more complex versions.

Description of the invention - Basic proposal

The panel for acoustic treatment by fragmentation of reverberated sound, is characterized by being formed by a set of tubular elements (1), which have each of them its variable cross section, so that the cross sectional area at one of its ends (A) is larger than the cross-sectional area of the opposite end (B).

Figure 1 shows an example of an element tubular, basic component that characterizes the formation of the panel, square cross section and flat faces (1).

Figure 2 shows some elements geometries of the tubular element (1): the area of the section transverse at its major end (A), the area of the section transverse at its lower end (B), its length (C) and the angle (?) formed by their opposite faces.

The tubular elements (1) are located parallel to each other so that they present the same side cross-sectional ends of greater area (A) forming a face of the panel, so that adjacent tubular elements are linked together, directly through the mutual contact of edges of said ends or indirectly through an element intermediate structural (3) without leaving open spaces, determining with its length (C) the depth of the panel, and forming with the edges of the cross-sectional ends of smaller area (B) the other opposite side of the panel.

Figure 3 shows a panel (3) formed by 12 tubular elements (1) and two intermediate structural elements (2), seen from the face formed by the ends of the elements Tubular cross-section of smaller area (B), or face "closed".

- Construction variant

This constructive variant is characterized because the tubular elements are fixed individually (1) or in a assembly or panel (3) inside a tubular mounting frame, so that there are no open spaces between the edges perimeters of the cross-sectional end of greater area of the tubular element or as a whole and the inner surface of the frame, forming a unit or building block, which used individually or installed next to each other to cover larger surfaces.

Figure 4 shows an example of a variant constructive in which a tubular element (1) is fixed in the inside of a tubular perimeter mounting frame (4) of depth (D), cropped for better viewing, forming a unit or building block (5), seen from the side of the end of the tubular cross-sectional element of greater area (A) or his "open" face.

Figure 5 shows another example of a variant constructive in which two tubular elements (1) are fixed in the inside of a tubular perimeter mounting frame (6), forming a unit or building block (7), seen from the side of the end of the tubular cross-sectional element of smaller area (B) or his face "closed."

Figure 6 partially shows a panel (8) formed by a set of building blocks (7), seen from the end side of the tubular cross-sectional element of greater area (A) or its "open" face.

Figure 7 shows another example of a variant constructive, in which a panel (3), consisting of 12 elements tubular (1) and two intermediate structural elements (2), is fixed inside a tubular perimeter mounting frame (9) depth (D), partially trimmed for better visualization, forming a set (10), seen from the side of the end of the tubular cross-sectional element of greater area (A) or your face "open" and installed at a distance (E) of separation of an enclosure (11).

Operating mode

I will consider that the luminous analogy is fulfilled to establish the sound path, and that the panel is rigid, fixed, and unable to exchange mechanical energy with said sound, and to simplify the analysis, I will not indicate the emissions secondary that by diffraction are generated at the edges.

- The sound strikes the "open" face of the panel

When the sound strikes perpendicularly on the "open" face of the panel, the edges of each tubular element act by dividing all the incident sound into fragments that propagate through its
inside.

Figure 8 shows a section (12) of a panel with mounting frame and through rays and vectors, the path of a sound pulse with a flat wave front (13) that affects perpendicular to its "open" face on an element tubular interior, and the output sound pulse (14) that presents a certain dispersion or diffusion.

The rays that move away from each tubular element obliquely, they are composed with the corresponding symmetrical of the adjacent tubular element, resulting in the same propagation direction of the incident wavefront.

As can be seen, setting a value suitable for the angle (α) that the opposite faces form of the tubular element (1), all the incident sound passes through the panel and continues its propagation without changing direction.

- The sound strikes the "closed" face of the panel

When the sound affects perpendicularly on the "closed" side of the panel, the edges of the lower end size of each tubular element act by dividing the sound incident in two parts, a part that spreads inside, and another part that propagates outside said tubular element.

Figure 9 shows a section (12) of a panel with mounting frame and by means of rays and vectors, the path of a sound pulse with a flat wave front (13) that perpendicularly affects its "closed" face on an inner tubular element , and as it is divided into two parts, a part that propagates through its interior and that crosses the panel or led (15), and another part that propagates through its exterior and that changes direction or is reflected when it reaches the junction between adjacent tubular elements or with the mounting frame (16), and having a certain dispersion or
diffusion.

Naming I the intensity of the sound that it affects the closed face of the panel, and because both the conducted sound part as the reflected sound part is finally distributed on the same surface of the panel, the part conducted of said sound will be of intensity IC = I.B / A and the part reflected will be of intensity IR = I. (A-B) / A. By properly establishing B << A, a panel capable of  reflect most of the sound that hits your face "closed".

In summary, the proposed panel has different properties on the sound depending on whether it affects one or the other face; conducts the sound that hits your "open" face, and reflects most of the sound that hits your "closed" face, so that device behaves like a diode
acoustic.

An in-depth study of their behavior with different shapes and proportions of the tubular elements, will allow obtaining geometries with an optimized response for each acoustic need
specific.

Panel usage

These properties confer innovative and Interesting possibilities of sound control.

- Use as acoustic screen

By placing the panel between a disturbing sound source and an area to be protected, with its "closed" face facing the sound source, it is possible to obtain high attenuation values of said sound over the area to be protected, due to its high capacity
reflective

Your main advantage over a blind screen conventional, is that when facing his face "open" to the area to protect, keeps it free from reflections of other sounds from that address.

- Use as a sound fragment panel reverberated or diffuser panel

Placing the panel with its face "closed" faced with a closing of a room or enclosure, and separated from this one at a distance equal to or greater than the length of the element tubular, has a great capacity for sound fragmentation reverberated or diffusion, see Figure 7.

The sound that hits the face "open" panel, will be able to go through it and continue its displacement to the enclosure, where it will be reflected by going towards the "closed" face, from where it will be reflected again towards the enclosure, so that sound will remain reverberating for some time caught between the enclosure and the "closed" side of the panel.

In each incident on said face "closed", as seen, only a small part of the sound reverberated will be able to pass through it, so each element tubular panel returns to the room the incident sound transformed into a series of successive fragments, of intensities much smaller than the incident sound, and decreasing, separated from each other at time intervals proportional to the distance (E) of separation between the panel and the enclosure.

Installing the panel slightly obliquely  with respect to the closing of the room, the distances of this one to each tubular element will be different and therefore also the value of phase delays generated by each tubular element in Each fragment of his series.

Figure 10 shows a section (17) of a panel with mounting frame, installed at a distance (E) of a enclosure (11) slightly obliquely, and by rays and vectors, the approximate path of a sound pulse in front of flat wave (13) that perpendicularly affects the open face of the panel, the same sound pulse after crossing the panel (18) or conducted, the same sound pulse once reflected by the enclosure (19), and the protruding fragments (20), with their phase difference (F).

Because the panel generates so much over the sound conducted as on the reflected sound a certain diffusion, the outgoing fragments also have a diffusion increasing, becoming a sound of much less intensity that the incident sound, flowing for a very long time prolonged, presenting diffusion characteristics without precedents

Improvement on the current state of the art

The acoustic behavior of the set panel-enclosure can be compared with that of a Schroeder diffuser of equal dimensions in which each hole or slit corresponds to a tubular element of the panel and in which its maximum depth is equal to the maximum distance between panel and enclosure.

The Schroeder diffuser returns for each hole or slit, a single fragment of the same intensity as the sound of input, instead the panel / enclosure assembly returns for each tubular element, a series of successive fragments of intensity much lower than the input sound and decreasing value, up to exhaust the reverberant sound between the panel and enclosure, so which generates a lot of fragments of much smaller intensity.

The Schroeder diffuser is capable of generating on each fragment, a phase delay of maximum value proportional to its depth, instead the whole panel / enclosure generates phase delays proportional to the distance that separates it from the enclosure, both for the first fragment of the series as between each successive fragment, so that its ability to generate phase delays is much greater.

Advantages of the proposed panel

- Used next to a room enclosure in the indicated way, it has a fragmentation capacity and generate phase delays far superior to those of a diffuser Schroeder of equal area.

- It has a much lower depth (C) that the depth (G) of a Schroeder diffuser, which makes it lighter and manageable.

- Does not necessarily require an installation fixed and its use by a foot or support confers mobility and consequently great versatility and adaptability to user needs

- Modifying its distance and angle with respect the delays of phase produced and obtain the optimum acoustic effect.

- All tubular panel elements proposed may be the same, unlike the gaps in the Schroeder diffuser in which everyone presents different depth, which allows a more serial manufacturing process Simple and lower cost.

Brief description of the drawings

- Figure 1 shows an example (1) of element tubular.

- Figure 2 shows some elements geometric of the tubular element (1).

- Figure 3 shows the "closed" face of a panel (3).

- Figure 4 shows the "open" face of a building block (5) of a tubular element (1) with frame (4).

- Figure 5 shows the "closed" face of a building block (7) of two tubular elements (1) with frame (6).

- Figure 6 shows the "open" face of a part of a panel (8) formed by a set of blocks of construction (7).

- Figure 7 shows the "open" face of a constructive variant (10) of the panel (3) with tubular frame (9),  installed in front of an enclosure (11).

- Figure 8 shows the path of a pulse sound (13), which affects the "open" face of a panel (12).

- Figure 9 shows the path of a pulse sound (13), which affects the "closed" side of a panel (12).

- Figure 10 shows the path of a pulse sound (13), which affects the "open" face of a panel (16), installed in front of an enclosure (11).

- Figure 11 shows the path of a pulse sound (13), which affects a Schroeder diffuser (20).

Embodiment of the invention - Basic proposal

See Figures 1, 2 and 3.

The panel for acoustic treatment by fragmentation of the reverberated sound (3), can be constructed from the Following way:

The tubular elements (1) are made by folding and pasting a die cut piece of micro cardboard 1.7 mm thick channel, whose shape corresponds to the development of the tubular element, plus an additional tab of glued. The suggested dimensions for the tubular element are A = 60x60 mm, B = 17x17 mm, C = 95 mm.

Said tubular elements (1) join together. and to the intermediate structural elements (2) that can also be made in micro channel cardboard, by gluing forming small equal prefabricated panels, consisting of a few tubular elements, for example 4 elements (2x2), of 9 elements (3x3), etc.

These small panels are used in turn to form larger panels, using structural elements additional in 4 mm plywood, which generate each other openings in the form of open lockers of the same size as said panels, where these are introduced and fixed by pasted by their perimeter edge.

The described panel being a static device that to fulfill its function you must only present a structure sufficiently rigid to the passage of sound, it is possible to use in its manufacturing a great diversity of materials and finishes, with the only functional limitation of not generating resonances and have sufficient rigidity and mechanical strength for use and handling.

The tubular elements accordingly, They can also be manufactured in injected plastic, which is an option industrial more appropriate and allows an optimal design of its shape.

- Construction variant

See Figure 7.

As a constructive variant, the panel (3) can be installed inside a wooden mounting frame (9) 8 to 10 mm thick plywood, for example with a depth (D) equal to or slightly greater than (C).

The "closed" side of the panel can be covered with a cloth or other termination material open to the passage of sound, the "open" face can be seen.

See Figures 4, 5 and 6.

The building blocks (5), consisting of a tubular element (1) and a tubular frame (6), or (8), consisting of two tubular elements (1) and a tubular frame (7) can be constructed in one piece brick mode, in clay, ceramics or other similar materials, using its manufacturing technology
particular.

For the tubular block element (5) We suggest the following dimensions A = 150x150 mm, B = 40x40 mm, C = 240 mm, generating blocks of the same size, that is 150x150x240 mm For block (8), which contains two tubular elements, the Suggested dimensions are 300x150x240 mm.

To form the panel (8), the blocks are joined each other by mortar using the usual technology of construction of partitions, covering the necessary surface.

As in the case of panel (2), panel (7) must  be built separately from the enclosure and at a distance enough.

The present constructive variant has been considered to be used in urban acoustic treatment or industrial.

Claims (2)

1. Panel for acoustic treatment by means of fragmentation of the reverberated sound, which is characterized by being formed by a set of tubular elements (1) that each have their variable cross-section, so that the cross-sectional area in one of their ends (A) are greater than the cross-sectional area of the opposite end (B), and that they are located parallel to each other such that the cross-sectional ends of greater area (A) have on the same side forming a face of the panel, so that adjacent tubular elements are joined together, directly through the mutual contact of the edges of said ends or indirectly through an intermediate structural element (3) without leaving open spaces, determining with its length (C) the depth of the panel, and with the edges of the cross-sectional ends of smaller area (B) the other opposite side of the panel, and that is installed with their faces separated from the enclosures of the room or enclosure to be treated. 2. Panel for acoustic treatment by means of fragmentation of the reverberated sound according to Claim 1, characterized in that the tubular elements are fixed individually (1) or in an assembly or panel (3) inside a tubular mounting frame, so that there are no open spaces between the perimeter edges of the cross-sectional end of greater area of the tubular element or its assembly and the inner surface of the frame, forming a building unit or block, which are used individually or installed next to each other to cover larger surfaces.