REFLEXIVE SOUND DIFFUSION SPEAKER, SPATIALIZED SOUND GENERATION METHOD AND ASSOCIATED HOME CINEMA INSTALLATION

Abstract

The invention relates to a reflective sound-diffusion enclosure (10) for diffusing sound waves in a space comprising at least one flat reflective surface, forming a reflection plane; the reflective sound-diffusion enclosure comprising a chassis (32) which includes a mounting surface for loudspeakers (36); an array of at least two adjacent loudspeakers (36) mounted on said mounting surface (34) of the chassis, the loudspeakers (36) being arranged at an angle of inclination (β); and a control system (42) configured to send a specific electrical signal to each loudspeaker (36) and to control the electrical signals in amplitude and phase according to a spatial filtering method. The enclosure (20) also includes a waveguide (38) with at least one acoustic wall (40) disposed in front of the loudspeakers (36). Figure 2 is shown for abbreviated purposes.

Description

Title of the invention: REFLECTION SOUND DIFFUSION SPEAKER, METHOD FOR GENERING SPATIALIZED SOUND AND ASSOCIATED HOME CINEMA INSTALLATION Scope of the invention

[0001] The invention relates to a speaker, and more particularly to a sound-reflecting speaker, that is to say, a speaker designed to project sound waves to a listening point using at least one reflection off a reflective surface, such as a ceiling or a wall. The invention also relates to a method for generating spatialized sound and a home theater system. Furthermore, the invention can also be applied to multichannel music playback systems.

[0002] The invention is particularly suitable for multichannel sound systems used, for example, in home cinema installations. Prior art

[0003] In the entertainment sector, sound systems combined with widescreen displays allow viewers to watch movies at home with a quality that approaches that of movie theaters. Movie soundtracks can now be obtained and played back with sounds that create a sense of immersion for the viewer, also known by the English term "surround sound." Dolby Atmos® technology, developed by Dolby Laboratories®, is undoubtedly the most recognized for cinematic reproduction in digital home theaters. In addition to the horizontal Dolby Atmos® 5.1 or 7.1 format, which provides a perception of sound to the sides and behind the viewer, it is also possible to achieve vertical spatialization with Dolby Atmos® 5.1.4 or 7.1.4 formats, using four speakers positioned at a height. This technology allows for faithful sound reproduction in a three-dimensional space.

[0004] However, while audio enthusiasts may install complex speaker setups in dedicated rooms, the majority of consumers watch movies in rooms that are also living spaces, such as a living room or bedroom, or in spaces where they are not free to integrate multiple speakers. They therefore look for compact or even centralized systems.

[0005] To meet this need, soundbars have gained popularity, offering better sound quality than most speakers integrated into flat screens, and which can incorporate technologies that even allow for the reproduction of virtual spatialized sound through special processing and specific speaker arrangements.

[0006] These technologies make it possible to simulate the positioning of a loudspeaker on a wall or ceiling, creating a "phantom loudspeaker." Thus, instead of receiving only sound waves coming directly from a loudspeaker directed towards the audience, the audience can also receive one or more sound waves obtained by reflection off a surface by means of a loudspeaker located away from that reflecting surface. The term "phantom loudspeakers" therefore refers to a sound wave perceived from a loudspeaker whose position is simulated by at least one reflection off a reflecting surface, typically a wall or ceiling.

[0007] As illustrated in Figure 1 of the prior art, a reflected sound speaker 100 is placed on the floor of a home theater. The room comprises a floor 12, a ceiling 14, and side walls (not shown). In this example, the speaker 100 diffuses sound that is reflected by the ceiling 14. More specifically, the speaker 100 comprises a chassis 16 on which is mounted a loudspeaker 18 configured to emit sound towards the ceiling and form a phantom speaker that is perceived by a listener from a listening position Pe.

[0008] In this case, the ceiling 14 behaves as a reflecting surface, generally flat. In order to create a phantom enclosure from the listening position Pe, the loudspeaker 18 is preferably positioned on a mounting surface with an angle of inclination α between the axis of revolution Ar of the loudspeakers and the reflecting surface. The mounting surface can be flat or inclined so that the angle of inclination α is conventionally measured with respect to the reflecting surface, more precisely with respect to a plane parallel Ppp to the ceiling 14 in the example of [Fig. 1].

[0009] A crosstalk problem exists between the origin of the sound source and the phantom speaker, for example in thin soundbars. For the purposes of this invention, crosstalk corresponds to the ratio between the reflected background amplitude Sr at the listener's position and the background amplitude Sd at the same position originating directly from the speaker, as illustrated in [Fig. 1]. Indeed, from the same loudspeaker, the propagation time of sound waves received by reflection is greater than the propagation time of sound waves transmitted directly. The presence of the directly transmitted sound waves Sd then disrupts the listening quality of the phantom speakers and limits the spatialization of the sound. Furthermore, if the directivity of the source is insufficient, the sound pressure emitted towards Sd and Sr is similar.In this case, the difference in distance traveled between the two waves is not significant enough, so the background sound attenuation SR is not sufficient to make the latter negligible compared to the sound wave Sd.

[0010] To limit crosstalk, it is therefore necessary to reduce the direct transmission of sound from loudspeakers intended to generate Sr sounds by reflection.

[0011] To address this crosstalk problem, several distinct techniques exist.

[0012] As illustrated in Figure 1 of the prior art, document FR 3105692 proposes combining the reflective sound-diffusion loudspeaker 18 with a waveguide in order to control the directivity and limit the amplitude of the directly transmitted sound wave Sd. However, this solution is limited in effectiveness to certain frequency ranges, particularly low and mid frequencies, due to compactness constraints.

[0013] Furthermore, for a loudspeaker to be directional, its radiating surface must be large relative to the wavelength. A waveguide increases this radiating surface, but even at low frequencies, it is particularly difficult to implement a waveguide in a compact enclosure. Moreover, a waveguide typically exhibits variations in directivity, and a waveguide with constant directivity would be difficult to integrate into a compact enclosure due to its height, which is typically greater than 25 cm.

[0014] Another completely different solution proposes to use several loudspeakers and to control them in amplitude and phase according to a spatial filtering method to improve the directivity of the sound beam coming from the loudspeakers.

[0015] The frequency range in which the directivity control operates depends on the size of the array and the distance between the loudspeakers. To control directivity at low frequencies, it is necessary to use a large number of loudspeakers or large loudspeakers to increase the total length of the array. This solution is therefore not compatible with a compact system. These systems are also limited at high frequencies because the distance between the loudspeakers must remain small compared to the wavelength. Thus, when the frequency becomes high, secondary sound beams, or side lobes, appear, which may be directed towards the listener, reducing the level of crosstalk.

[0016] Another solution proposes creating interfering waves with the directly transmitted sound waves Sd in order to cancel or reduce them. For example, document WO 2020 / 102183 describes a loudspeaker system for reproducing a height sound image. To limit crosstalk, the system also includes a loudspeaker arranged at floor level. This loudspeaker is configured to emit a cancellation sound wave, in opposite phase to that of the reflecting loudspeaker, so as to suppress the directly transmitted sound wave Sd, i.e., without reflection, from the reflecting loudspeaker.

[0017] This solution is not very effective because of the excessive distance between the sources, and complex because it requires knowledge of the environment in order to obtain effective digital filtering and limit crosstalk.

[0018] Similarly, in document WO 2020 / 181288, a soundbar includes ceiling-facing spatial speakers and front speakers that emit sound directly towards a listener. Some of the front speakers are used to create a wave that suppresses the direct component of the wave emitted by the spatial speakers. The spatial speakers are phase-controlled to improve the directivity of the resulting sound signal and limit the formation of a direct sound wave towards the listener.

[0019] This solution once again proposes a complex filtering technique, and uses additional loudspeakers to limit crosstalk of the signal located at the ceiling.

[0020] Whatever solution is used and in view of the low effectiveness of known solutions, it should be noted that, in order to limit crosstalk, commercial speakers use an inclination of the loudspeakers with an angle of inclination α between 70 and 90° with respect to the reflection surface.

[0021] However, this limited angle of inclination means that the reflective sound diffuser must be placed less than two meters from the audience for the sound waves reflected off a ceiling or wall to be perceived correctly. Therefore, there is a need to extend the reflective sound diffusion distance, for example, to accommodate rooms where the listening position Pe is more than two meters from the reflective sound diffuser.

[0022] The technical problem of the invention is therefore to obtain a solution for generating one or more phantom speakers covering a wide range of frequencies, usable for compact systems, with limited crosstalk and offering better flexibility in positioning the listener. Description of the invention

[0023] The invention proposes to address this technical problem by using the cooperation of a waveguide and an array of at least two juxtaposed loudspeakers which can be controlled according to a spatial filtering method to generate a beam of sound waves, also called "beam-forming" in the Anglo-Saxon literature.

[0024] With these elements, the loudspeakers are mounted on the chassis with a high angle of inclination, between 30° and 70° between the axis of revolution of the loudspeakers and the reflecting surface, that is to say with a different angle from the angle seen on commercial products.

[0025] A major problem encountered when projecting a beam of reflected sound waves is that it must be neither too wide, to limit crosstalk, nor too directional, to avoid limiting the listener's positioning. The invention required extensive research to evaluate the factors that could improve or limit the directivity of a reflected sound wave beam over a wide frequency range.

[0026] It is possible to obtain a beam of sound waves with improved directivity by using a spatial filtering method with a loudspeaker array or a waveguide. Contrary to expectations, it has been observed that combining a waveguide and a spatial filtering method increases their respective performance and goes beyond simply combining these two technologies.

[0027] Indeed, even at low frequencies, a waveguide with small dimensions is often insufficient to achieve good directivity. The presence of a waveguide combined with a spatial filtering technique makes it possible to improve the directivity of a sound wave beam at low frequencies.

[0028] It has been found that by operating with a determined angle of inclination, the generation of a reflected beam of sound waves is still limited by the presence of high-frequency secondary lobes emitted in the direction of the listening position.

[0029] The addition of a single waveguide has the surprising effect of blocking the propagation of high-frequency side lobes, greatly limiting crosstalk for the beam of sound waves reflected further forward relative to the listening position.

[0030] Against all expectations, the invention then makes it possible to meet the criteria of Dolby Atmos® 5.1.4 or 7.1.4 formats by going beyond the angles usually observed, that is to say with an angle of inclination between the axis of revolution of the loudspeakers and the reflection surface, between 30° and 70°, while providing a compact speaker.

[0031] To this end, according to a first aspect, the invention relates to a sound diffusion enclosure by reflection intended to diffuse sound waves in a space comprising at least one flat reflection surface, forming a plane of reflection for said sound waves; the sound diffusion enclosure by reflection comprising a chassis which includes a mounting surface for sound diffusion speakers by reflection; an array of at least two speakers juxtaposed and mounted on said mounting surface of the chassis, each speaker comprising an axis of revolution and is arranged with said axis of revolution forming an angle of inclination with respect to the plane of reflection; and a control system configured to send a specific electrical signal to each speaker and to control the electrical signals in amplitude and phase according to a spatial filtering method.

[0032] The reflective sound diffusion enclosure is remarkable in that the enclosure further comprises a waveguide mounted on the chassis; the waveguide comprising at least one acoustic wall placed in front of the loudspeakers; and in that the angle of inclination of the loudspeakers is between 30° and 70°.

[0033] With the large angle of inclination of the loudspeakers, the invention offers a solution usable for a large number of rooms, in particular rooms in which the listening position is located more than two meters from the speaker.

[0034] Furthermore, the cooperation of the waveguide and the spatial filtering method makes it possible to limit crosstalk, even with a small footprint

[0035] Indeed, the loudspeaker array can be made with small loudspeakers to fit into a soundbar-type enclosure. The limited directivity of the beam obtained by the small loudspeakers at low frequencies is compensated for by the waveguide. The combination of waveguide and spatial filtering increases the directivity of the enclosure at low frequencies. At high frequencies, the waveguide acts as an acoustic barrier, limiting the direct propagation of secondary beams towards the listener. In one embodiment, the signal sent to the loudspeakers comprises a first component generated using a spatial filtering method to obtain a first beam of sound waves, and a second component generated using a spatial filtering method to obtain a second beam of sound waves, with a different directivity than the first beam of sound waves.

[0036] Thus, the reflective sound diffusion enclosure can emit two distinct beams from the loudspeakers.

[0037] One beam can generate a phantom speaker above and in front of the listener, while another beam can generate a phantom speaker above and further behind the listener to reproduce the effects of a Dolby Atmos® 5.1.4 or 7.1.4 format

[0038] Advantageously, the control system includes a filter for generating a different signal for at least one of the loudspeakers. The filter may be an analog electronic filter, a passive filter, or a digital filter.

[0039] It is thus possible to limit the diffusion of high frequencies for the loudspeaker furthest from the acoustic wall of the waveguide.

[0040] Preferably, the control system applies to at least one loudspeaker, a low-pass type filter with a cutoff frequency between 5 kHz and 20 kHz, preferably 10 kHz.

[0041] In some embodiments, the control system applies to at least one loudspeaker a digital filter calculated using the method known as “Pressure Matching”. This method uses measurements or simulations of the acoustic pressure generated by each loudspeaker at predefined points in space in order to create filters that produce a beam to predefined properties, notably by canceling the acoustic pressure in a given direction. This helps to limit the level of crosstalk.

[0042] In some embodiments, the loudspeakers are arranged with a distance of less than 8 cm between the edges of two adjacent loudspeakers. This distance makes it possible to obtain a particularly effective beam emission angle through spatial filtering.

[0043] Preferably, the acoustic wall of the waveguide has a height of at least 4 cm. The waveguide then very effectively limits the emission of sound waves, particularly at low frequencies.

[0044] In embodiments, the loudspeakers are inclined along a plane of inclination, and the waveguide includes an acoustic wall forming an angle between 50° and 100° with the plane of inclination of the loudspeakers.

[0045] Advantageously, the waveguide has an elliptical or rounded profile with respect to the loudspeakers. An elliptical or rounded profile helps to limit wave diffraction and improve the performance of the waveguide.

[0046] According to a second aspect, the invention relates to a method for generating spatialized sound comprising the steps of: providing a home cinema installation comprising at least one sound diffusion speaker by reflection according to the first aspect; sending to each speaker of the speaker a first signal component, according to a spatial filtering method to generate a first wide beam of sound waves; sending to each speaker of the speaker a second signal component, according to a spatial filtering method to generate a second directional beam of sound waves.

[0047] According to a third aspect, the invention relates to a home cinema installation comprising at least one sound diffusion speaker by reflection according to the first aspect. Brief description of the drawings

[0048] The invention will be well understood and other aspects and advantages will become clear upon reading the following description, given by way of example with reference to the accompanying figure plates on which:

[0049] [Fig-1] is a schematic cross-sectional view of a diffusion enclosure of its reflection of the state of the art implemented in a home cinema installation;

[0050] [Fig.2] is a schematic perspective view of a sound diffusion enclosure by reflection, according to an embodiment of the invention, implemented in a home cinema installation;

[0051] [Fig.3] is a schematic cross-sectional view of a loudspeaker and a waveguide of the reflective sound diffusion enclosure along the cross-sectional plane Pc of [Fig.2];

[0052] [Fig. 4] is a schematic cross-sectional view of a reflective sound diffusion enclosure, according to another embodiment of the invention, implemented in a home cinema installation; and

[0053] [Fig.5] is an explanatory diagram of the signal generated by the sound diffusion system by reflection of the [Fig.4]. Detailed description of the invention

[0054] An embodiment of a sound-diffusion enclosure 20 by reflection is illustrated in Figures 2 and 3. The enclosure 20 can be integrated into a listening room 22 or a home movie-viewing room, for example, in a room dedicated to home cinema, or even in a living room. The enclosure 20 is designed to diffuse sound waves in a space comprising at least one substantially flat reflective surface, forming a reflection plane 24 for said sound waves. The reflective surface can be formed on a wall, a deflector, or any other object capable of reflecting a sound wave.

[0055] The listening room 22 comprises a ceiling, which here forms the reflection plane 24, a floor 28, and side walls. Typically, a listening room includes four side walls, and the height from the ceiling to the floor is approximately 2.5 m. Of course, the invention can be adapted for a room with a different ceiling height and more or fewer side walls.

[0056] The sound diffusion enclosure 20 by reflection is arranged on the floor 28 at the level of a front wall 30 and faces a listening position Pe at the level of which a listener, not shown, can be installed.

[0057] It is possible to provide several listening positions confined within a listening area, and the listening area can be more or less wide depending on the desired configuration. The distance between the speaker 20 and the listening point Pe can, for example, be between 2 and 4 m.

[0058] The enclosure 20 has a chassis 32 which includes a mounting surface 34 for reflective sound-diffusion loudspeakers 36. The mounting surface 34 is preferably a flat surface but may include curves or angles to conform to the aesthetic appearance of the enclosure.

[0059] According to the invention, the enclosure 20 comprises an array of at least two loudspeakers 36 placed side by side and mounted on the mounting surface 34 of the chassis 32. As illustrated in [Fig. 3], each loudspeaker 36 comprises an axis of revolution Ar and is arranged with the axis of revolution Ar forming an angle of inclination [3] with respect to the reflection plane 24. For simplicity, the angle of inclination is shown with respect to a plane parallel Ppp to the reflection plane 24. Preferably, the angle of inclination [3] is fixed. Adding a system for varying the angle of inclination [3] manually or Electronically increasing the complexity of the enclosure is not necessary for its operation. Preferably, the loudspeakers 36 are arranged on the same plane. The angle of inclination [3] can be measured with respect to the plane of the loudspeaker in the case of a substantially flat loudspeaker, or with respect to a plane perpendicular to a line generating the loudspeaker cone in the case of a conical loudspeaker.

[0060] According to the invention, the tilt angle [3 of the loudspeakers is between 30° and 70°; preferably, the tilt angle [3 is between 30° and 69°, the tilt angle [3 is between 45° and 69°. Preferably the tilt angle [3 is 55°.

[0061] A control system 42 installed in the enclosure is configured to send a specific electrical signal to each loudspeaker 36 and to control the electrical signals in amplitude and phase according to a spatial filtering method.

[0062] Within the scope of the invention, a spatial filtering method is a signal processing method for forming a beam from an audio signal. It is implemented by combining an array of at least two loudspeakers individually controlled in phase and amplitude such that, in certain directions, the loudspeaker signals interfere constructively, while in other directions the signals interfere destructively. Several spatial filtering methods can be used within the scope of the invention, depending on the implementation requirements.

[0063] Speaker 20 preferably corresponds to a compact speaker that can be installed on a piece of furniture such as a hi-fi cabinet or a living room TV stand. For example, speaker 20 is a soundbar that can be placed under a screen. Thus, speaker 20 has small dimensions, for example with a height of less than 25 cm and a depth of less than 40 cm.

[0064] The mounting surface 34 can be arranged on an upper face of the enclosure, as illustrated in the embodiment of [Fig.2].

[0065] In other embodiments, the mounting surface can be arranged on another face of the enclosure, for example to use a wall as a reflecting surface.

[0066] The enclosure 20 comprises an array of at least two speakers 36 juxtaposed and mounted on the mounting surface 34.

[0067] Preferably, the loudspeakers 36 are structurally identical, but they may have different shapes or be made of different materials without changing the invention. In some embodiments, the loudspeaker diaphragms are advantageously substantially oval in shape, also known as "Race Track" diaphragms, in order to reduce the distance between the centers of each loudspeaker. For example, the loudspeakers may include at least one midrange or full-range loudspeaker and at least one tweeter.

[0068] The loudspeakers of the enclosure 20 are preferably aligned along the same axis, or along orthogonal axes, but other loudspeaker configurations allowing the implementation of a spatial filtering method are conceivable.

[0069] The enclosure 20 further comprises a waveguide 38 mounted on the chassis 32; the waveguide 38 comprising at least one acoustic wall 40 disposed in front of the loudspeakers 36. The waveguide 38 may comprise several acoustic walls. For example, the waveguide may have a conical or pyramidal shape.

[0070] The acoustic wall 40 is positioned in front of the loudspeakers 36 in the direction of the listening position Pe. The acoustic wall 40 can then limit the transmission of sound waves along a direct line between the loudspeakers 36 and the listening position Pe.

[0071] The characteristics of the acoustic wall 40 are then appreciated in a cross-section plane Pc which includes a direct line, represented by Sd on the [Fig.2], between one of the loudspeakers and the listening position Pe.

[0072] In the plane Pc, the acoustic wall 40 may include a linear profile opposite the loudspeakers 36, as illustrated in [Fig. 3]. Alternatively, the acoustic wall may have a profile including angles, or a convex profile, for example elliptical or rounded, opposite the loudspeakers.

[0073] As illustrated in [Fig. 3], the acoustic wall 40 of the waveguide has a height h of at least 2 cm, preferably at least 4 cm, and preferably between 4 cm and 20 cm. In the example of Figures 2 and 3, the height h coincides with the vertical, and the cross-sectional plane is that of Figures 2 and 3. The height h depends on the size, number, and spacing between the loudspeakers in the plane Pc.

[0074] As illustrated in [Fig.3], the distance d between the edge of the two juxtaposed loudspeakers 36 is preferably less than 10 cm, preferably less than 8 cm, preferably the loudspeakers are contiguous.

[0075] In the plane Pc, the acoustic wall 40 of the waveguide 38 forms an angle 0 with the tilt plane of the loudspeakers 36. The angle 0 depends on the height and profile of the acoustic wall.

[0076] Preferably, angle 0 is fixed. As with the tilt angle [3], adding a system for varying angle 0 manually or electronically would increase the complexity of the enclosure and is not necessary for its operation. Angle 0 is preferably between 45° and 110°, preferably between 70° and 100°.

[0077] In another embodiment not shown, the speaker is configured to diffuse sound by reflection off a vertical reflective surface, such as a side wall of a room. In this embodiment, the angle of inclination of the loudspeakers is also between 30° and 70°; preferably, the angle of inclination is between 30° and 55°. Preferably, the angle of inclination of the loudspeakers is 45°.

[0078] In order to simplify the explanation of the generation of sound wave beams by the control system 42, [Fig.4] illustrates an array of two loudspeakers 36. Of course, it is possible to use a system with an array of more than two loudspeakers.

[0079] The control system 42 can be configured to apply a phase delay (Ati to At4) or an amplitude delay in a specific, i.e. independent, manner to the signals sent to the loudspeakers 36.

[0080] Within the framework of the invention, signal filtering can be applied with passive filters or with their equivalent in digital filter, for example with a digital signal processor, infinite impulse response filters, or finite impulse response filters.

[0081] As illustrated in figures 4 and 5; the control system 42 can also be configured so that the speaker 20 emits two different beams of sound waves towards the listening position Pe.

[0082] For this purpose, the signal sent to the loudspeakers includes a first component Ui(t) generated according to a spatial filtering method so as to obtain a first beam of sound waves Fl, and a second component U2(t) generated according to a spatial filtering method so as to obtain a second beam of sound waves F2, with a different directivity from the first beam of sound waves.

[0083] As illustrated in [Fig. 4], the first beam Fl can then reach the listening position Pe after a reflection off the ceiling 26, so as to create a phantom speaker further forward of the listening position Pe. The second beam F2 can reach the listening position Pe after one or two reflections, for example off the ceiling 26 and a rear wall 44, so as to create a phantom speaker further backward of the listening position Pe.

[0084] The control system 42 may include a filter to generate a different signal for at least one of the loudspeakers.

[0085] For example, as illustrated in [Fig. 5], a low-pass filter (LPF) can be applied to the signal sent to the loudspeaker furthest from the acoustic wall of the waveguide. The filter's cutoff frequency can be, for example, between 5 kHz and 20 kHz, preferably at 10 kHz.

[0086] In a preferred embodiment illustrated in [Fig. 5], it is possible to add a "High Shelf" type FHS filter that amplifies or attenuates frequencies above the cutoff frequency by a specified amount to the loudspeaker closest to the acoustic wall of the waveguide, in order to increase its energy and maintain the total energy in the high frequency range.

[0087] The control system 42 may also include series filtering with, for example, a capacitor connected to the terminals of the loudspeaker 36. For example, the capacitor capacitance has a value between IpF and 20pF, preferably between 2pF and 12pF, preferably with a value of 6.8pF.

[0088] In this example, lowering the level of loudspeaker 36 reduces the effect of spatial filtering and consequently restores a directivity close to that of a single directional loudspeaker at very high frequencies. Thus, the directivity is wider, resulting in a larger and more homogeneous listening area, i.e., with fewer secondary lobes.

[0089] In another embodiment not shown, the orientation of the beams is obtained by modifying the relative phase of the loudspeakers using, for example, one or more all-pass filters.

[0090] In another embodiment not shown, it is possible to use a digital filter calculated using the method known as “Pressure Matching”. This method uses measurements or simulations of the acoustic pressure generated by each loudspeaker at predefined points in space in order to create filters that produce a beam with predefined properties, notably by canceling the acoustic pressure in a given direction. This makes it possible to limit the level of crosstalk.

[0091] A method for generating spatialized sound may include the following steps: - providing a home cinema installation comprising at least one speaker 20 for sound diffusion by reflection according to the invention; - send to each speaker 36 of the enclosure a first signal component Ui(t), according to a spatial filtering method to generate a first wide beam of sound waves Fl; - send to each speaker 36 of the enclosure a second signal component U2 (t), according to a spatial filtering method to generate a second directional sound wave beam F2.

[0092] In embodiments, the method may further include a step of applying a filter to the first signal component Ui(t) or to the second signal component U2(t), or to the sum of the components Ui(t) + U2(t) of a loudspeaker. For example, the filter may be a low-pass filter or an all-pass filter.

[0093] By this method, it is then possible to generate phantom speakers allowing to reproduce sound effects of a Dolby Atmos® 5.1.4 or 7.1.4 format.

[0094] It should be noted that, although the process of generating spatialized sound has been described in a certain order, it is possible to use another ordering of the steps.

[0095] In conclusion, the invention makes it possible to obtain a speaker 20 usable for compact systems, with limited crosstalk and offering better flexibility in positioning the listener.

Claims

Demands

1. A reflective sound-diffusion enclosure (20) for diffusing sound waves in a space comprising at least one flat reflective surface, forming a plane of reflection for said sound waves; the reflective sound-diffusion enclosure comprising: - a chassis (32) which includes a mounting surface for reflective sound-diffusion loudspeakers (36); - an array of at least two loudspeakers (36) juxtaposed and mounted on said mounting surface (34) of the chassis, each loudspeaker (36) comprising an axis of revolution (Ar) and is arranged with said axis of revolution (Ar) forming an angle of inclination (|3) with respect to the plane of reflection (24); and - a control system (42) configured to send a specific electrical signal to each loudspeaker (36) and to control the electrical signals in amplitude and phase according to a spatial filtering method;characterized in that the enclosure (20) further comprises a waveguide (38) mounted on the chassis (32); the waveguide (38) comprising at least one acoustic wall (40) disposed in front of the loudspeakers (36); and in that the angle of inclination of the loudspeakers (36) is between 30° and 70°.

2. Sound diffusion enclosure by reflection according to claim 1, wherein the signal sent to the loudspeakers (36) comprises a first component Ui(t) generated according to a spatial filtering method so as to obtain a first beam of sound waves (Fl), and a second component U2(t) generated according to a spatial filtering method so as to obtain a second beam of sound waves (F2), with a different directivity from the first beam of sound waves (Fl).

3. Sound diffusion enclosure by reflection according to claim 2, wherein the control system includes at least one filter for generating a different signal for at least one of the loudspeakers 36.

4. A reflective sound diffusion enclosure according to claim 3, wherein the control system applies to at least one loudspeaker (36), a low-pass type filter with a cutoff frequency between 5 kHz and 20 kHz, preferably 10 kHz.

5. Sound diffusion enclosure by reflection according to any one of the preceding claims, wherein the control system applies to at least one loudspeaker (36), a digital filter calculated from the method, known in English as “Pressure Matching”.

6. Sound diffusion enclosure by reflection according to any one of the preceding claims, wherein the loudspeakers (36) are arranged with a distance d of less than 8 cm between the edge of two juxtaposed loudspeakers (36).

7. Sound diffusion enclosure by reflection according to any one of the preceding claims, wherein the acoustic wall (40) of the waveguide (38) has a height h of at least 4 cm.

8. Sound diffusion enclosure by reflection according to any one of the preceding claims, the loudspeakers (36) being inclined along a plane of inclination, in which the waveguide (38) comprises an acoustic wall forming an angle 0 between 50° and 100° with the plane of inclination of the loudspeakers (36).

9. Sound diffusion enclosure by reflection according to any one of the preceding claims, wherein the waveguide (38) has an elliptical or rounded profile with respect to the loudspeakers (36).

10. A method for generating spatialized sound comprising the steps of: - providing a home cinema installation comprising at least one speaker (20) for sound diffusion by reflection according to any one of the preceding claims; - sending to each speaker (36) of the speaker a first signal component Ui(t), according to a spatial filtering method to generate a first wide beam of sound waves (Fl); - sending to each speaker (36) of the speaker a second signal component U2(t), according to a spatial filtering method to generate a second directional beam of sound waves (F2).

11. Home cinema installation comprising at least one reflecting sound speaker (20) according to any one of claims 1 to 9.

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