LT6748B - Acoustic diffuser - Google Patents

Abstract

Acoustic diffuser is device, that redistribute the acoustic energy of intense reflections by spatial and temporal dispersion. The invention is used to increase diffusion and reduce reverberation in the premises. Acoustic diffuser consists of perforated wooden planks filled with cylindrical wood bangle elements. Charcoal is a material used for the production of triangular acoustic diffusers with a high coefficient of reflection, which is an effective material for diffuser production. Charcoal is an ecologically clean and natural material. The acoustic diffuser increases the diffusion of sound while improving the acoustics of the room. The invention could be installed into auditorium spaces, concert halls, recording rooms, museums.

Description

FIELD OF THE INVENTION

An acoustic diffuser is used to create a diffuse sound field.

BACKGROUND OF THE INVENTION

The device, which is used for sound diffusion, allows you to control the sound level indoors. Diffusers of different designs are known: curved, curvilinear, asymmetrical, honeycomb, curved surface, Schröder diffusers, which are calculated for the corresponding square residue diffuser consistency (QRD). All diffusers are made of solid material. Acoustic diffusers are placed in the upper corners of the premises, at the intersection of wall and ceiling surfaces, in front of the sound source.

Acoustic diffusers reflect and distribute sound throughout the volume of the room. In this way, a diffuse sound field is formed.

Diffusers can be one-dimensional and two-dimensional. The one-dimensional diffuser will disperse the sound horizontally. A two-dimensional or 2D-diffuser will dissipate sound in a hemispherical form, both horizontally and vertically.

To solve the world's acoustic problems, an original sound-scattering design called the Schröder diffuser is used. The advantage of a scrubber diffuser with other types of diffusers is that a high degree of sound energy dissipation can be achieved with it.

Research is being conducted around the world to develop ecologically clean and cost-effective sound reflection solutions to environmental pollution. Materials such as wood and its products can be used as low-cost and environmentally safe acoustic solutions. In acoustics, there is a problem with the choice of material from which the diffuser will be made, because the reflection coefficient of the material must be high enough. This means that plain foam, pumice, gypsum are unsuitable because they absorb sound energy. Materials with a sufficiently high reflectance are suitable for the manufacture of diffusers.

Patent US20120018247A1 wedge-shaped, acoustic diffuser dissipates and reflects sound. The latter diffuser is made up of cells of different depths that scatter sound. The invention has recesses that allow to disperse the sound of different frequencies - from low to high frequencies. The depth of the recesses can be selected using calculations. A diffuser is essentially a device with varying cell depths.

The disadvantage of the acoustic design is that materials with insufficient reflection coefficient are used in the manufacture of the diffuser. The disadvantage is that rectangular planes do not scatter sound as effectively as planes of other shapes.

SUMMARY OF THE INVENTION

The object of the invention is to increase diffusion and reduce sound reverberation in a room. The scope of diffusers is limited to creating a diffuse sound field and improving "spatial" sound.

The acoustic diffuser is triangular in shape and consists of perforated planes with perforation of cylindrical elements. The triangular acoustic diffuser dissipates sound waves and reflects on its uneven surfaces. The developed diffuser consists of recesses of different depths. Depth variables will provide smoothness for sound propagation.

The structure consists of wooden perforated planes, the holes of which are filled with cylindrical elements made of wood biochar. The triangular planes distribute the reflected sound well in different positions with respect to the source and increase the diffusion level of the sound field in the room. The materials from which this construction is made are environmentally friendly.

Acoustic diffuser can be used to solve the following tasks: sound propagation in the room, improving language perception in auditoriums, concert halls, echo cancellation.

When a sound wave meets an obstacle, a reflection of the sound wave occurs. Reflection efficiency is characterized by the reflection coefficient. Investigations of the sound reflection coefficient of wood biochar cylindrical elements in comparison with wood have been performed.

The analysis of the research results showed that the value of the reflection coefficient of wood biochar is 0.98. The value obtained corresponds to a very high reflectance and the possibility of applying this material to the production of diffusers. According to research, a cylindrical wood biochar element has a higher sound reflection coefficient than a wood surface.

The sound reflection coefficient of the wood surface varies in the range 0.65-0.9, this value is lower than the carbon reflection coefficient of the wood. This advantage of wood biochar allows it to be used as a material for sound reflection, while cylindrical wood biochar elements reduce absorption.

The acoustic diffuser, consisting of perforated planes filled with cylindrical elements of wood biochar, replaces the existing acoustics of space due to the scattering of the reflected acoustic energy in various directions, both horizontally and vertically. Additional scattering occurs as sound energy enters the triangular parts of the diffuser. A triangular acoustic diffuser will dissipate standing waves that accumulate in two parallel walls of the room.

Schröder diffusers, whose design is based on number theory, are an excellent tool for creating a diffuse sound field in rooms for different purposes. In fact, the Schröder diffuser is a diffraction grating that dissipates the sound energy falling on it over a wide frequency range, even at high angles of incidence.

Calculation of the scrubber diffuser. The scrubber diffuser consists of a series of cells of different depths but of the same width formed in a wooden housing of the diffuser.

The design of the diffuser is based on the quadratic subtraction from number theory, applying the calculation of mathematical sequence, which is determined by the ratio:

s _n = n modulus (N) of module ² , where s _n is the sequence of values of the relative depth of the diffuser cells, n is a negative integer {0, 1, 2, 3 ...}, deciding the corresponding cell number,

N - primary number {2, 3, 5, 7, 11, 13, 17 ...}. (A simple number is a number other than 0 and 1 that divides only itself and the unit).

The correspondence of the number of cells to the power is known as the square operation. The operator module application divides the number by the module and saves only the remainder.

Sequential example of quadratic subtraction theory:

N = 5: 0 1 44 10

N = 7: 0 1 42 24 10

N = 11: 0 1 495 33 594 10

N = 13: 01 493 12 10 10 123 9410

N = 17: 0 1 49 1682 1513 13 1528 16941 0

The cell depth d _{n in the} diffuser design depends on its design frequency f ₀ :

dn = S _n x C / (f _o x 2 XN), d _n - cell depth with sequence number n, f ₀ - design frequency of the diffuser, Hz c - speed of sound in air, m / s

N is a simple number (diffuser row) corresponding to the number of cells.

The cells W must be small compared to the diffuser wave value W = (0.137 * c) / f _o . The operating range of the diffuser depends on the linear sizes of the diffuser cells. The lower limit of the operating range of the diffuser f _{) ow} depends on the size of the deepest cell. The upper operating limit fhigh of the diffuser depends on the value of the cell width W.

Diffuser calculation example. Diffuser calculation for a design frequency of 550 Hz (where scattering is most efficient). These values correspond to most of the midrange frequencies that significantly affect sound recovery.

Calculations have shown that the operating range of the diffuser is from 412.5 to 2007.3 Hz. The calculated width of the cell is 9 cm, and the size of the diffuser, which consists of seven elements with a width of 63 cm. The sound energy dissipation diagram of the diffuser is in the shape of a half cylinder. When the diffuser is square, the front must be analogous to the width in order to orient it in space. A height of 120 cm is sufficient for the calculated diffuser.

DESCRIPTION OF THE DRAWINGS

The figures show a triangular acoustic diffuser made of perforated planes, the holes of which are filled with cylindrical wood biochar elements.

Fig. 1. Acoustic diffuser made of perforated planes with holes filled with cylindrical wood biochar elements

Fig. 2. Acoustic diffuser, top view

Fig. 3. Acoustic diffuser, view of perforated planes

Fig. 4. Acoustic diffuser, view of the plane from the lower surface of the diffuser

Fig. 5. Acoustic diffuser, Section view

Fig. 6. Cylindrical wood biochar element

Fig. 7. Perforation filled with cylindrical wood biochar elements

Fig. 8. Frequency dependence of the sound reflection coefficient of wood biochar

Fig. 9. Frequency dependence of the sound reflection coefficient of a wooden surface

Table 1. Results of cell depth calculation

DETAILED DESCRIPTION OF THE INVENTION

The diffuser consists of a front plane (1), a side plate (2), a lower plane (3), inclined triangular planes (4), a lower inclined plane (5), cells (6), cylindrical wood biochar elements (7), a lower planes (8), perforated side separators (9) of internal elements, perforations (10).

Operating principle

The acoustic diffuser dissipates sound from 100 Hz - depending on the depth and number of cells. The acoustic diffuser is usually installed in front of the sound source, on the walls and ceiling, and sometimes in the center of the front wall. The sound wave is uniformly reflected back into space by applying a certain fixed sequence of front inclined planes (5), (4) (scattering occurs in a semi-circular shape), as well as reducing its energy during reflection on the road and prolonging the return time of the sound to the listener. The inclined triangular planes form a set of angles with the lower inclined plane (5), as well as the upper plates (1). Such a structure is connected to the lower part of the acoustic diffuser (8). The inclined planes (4), (5) are approximately the same length. The specified inclined planes are of different heights, the magnitudes of which are determined by a given sequence of numbers. The planes inclined (4) at an angle between 0 and 90 degrees, the indicated inclined planes are separated from the sides by separators (9). Figures 1 and 5 show how the sound wave moves from the sound source and enters the surface of the triangular planes (4,5) inclined in the diffuser, after which the sound wave is reflected from the uneven surfaces of the diffuser. The indicated planes of adjacent planes (4), (5) and separators (9) form a set of irregularly shaped cells (6). The said dividers (9) are approximately the same length as the inclined planes (4), (5). The specified structure of inclined planes and partitions may be joined on one or two sides by an additional material which is approximately the same shape (1), (3) as the partitions (9). The specified structure may be joined on one or more sides by a part of a triangular material (2). The spaces between the front plane (1), the side plates (2), and the lower plane (3) are called cells (6). The depths of the cells can be varied by the addition of inclined triangular planes (4), the reflective cell surfaces being joined at the lower edge, joined at different distances from the upper side of the front corner. Cell depth (6) provides the ability to spread over a wider frequency range. The propagation of sound inside the cells (6) is accompanied by multiple reflections of local waves, thanks to which the paths of the wave are of different lengths, with different delays in the moment of exit. Such actions distribute the energy evenly while maintaining its overall intensity. The increase in the number of cells in the Schröder diffuser results in a more even distribution of energy at the design frequency. The operating frequency range of the diffuser depends on the depths of the cells and the variations of their intervals. The lower these parameters, the higher the scattering at frequencies. On the inclined planes there are perforations (10) which are filled with cylindrical wood biochar elements (7) which increase the intensity of the energy reflected by the diffuser.

Claims (3)

DEFINITION OF THE INVENTION 1. Acoustic diffuser consisting of recessed cells of different depths, made of wooden wedge-shaped planes, characterized in that the recesses in the form of cells (6) are made of wooden sloping triangular planes with perforations (10, 4, 5), the holes of which are filled with cylindrical shapes. wood biochar elements (7). 2. Acoustic diffuser according to claim 1, characterized in that the perforation of the inclined wooden planes is 75%. 3. Acoustic diffuser according to claim 1, characterized in that the diameter of the cylindrical biochar elements of the wood is 20-40 mm.