ACOUSTICAL ABSORBER FOR ABSORBING BASS OR SUB-BASS

SOUND

Technical field

[0001] The present disclosure relates to the field of acoustical absorption, in particular to an acoustical absorber for absorbing bass or sub-bass sound.

Background

[0002] Document CN203583696 discloses a variable sound absorber which comprises a plurality of rotatable regular triangular prism sound absorbing blocks which are arranged in parallel, wherein rotating centres are located on the same straight line; and three cylinders of each regular triangular prism sound absorbing block are three sound absorbing surfaces with different absorption rates.

[0003] Document CN203583696 does not disclose an efficient tunable acoustical absorber for absorbing bass or sub-bass sound.

[0004] These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.

General Description

[0005] It is disclosed an acoustical absorber for absorbing bass or sub-bass sound comprising:

a housing;

an exteriorly-facing air-tight diaphragm comprising a centre plate and a peripherical flexible elastic membrane, said housing and diaphragm defining an internal volume;

an internal acoustic absorber comprised in said internal volume; wherein the diaphragm is arranged for vibrating on external sound pressure to create air displacement in said internal volume.

[0006] In an embodiment, said diaphragm is arranged to be a spring-mass system, wherein the membrane is the spring of the spring-mass system and the centre plate is the mass of the spring-mass system.

[0007] In an embodiment, said internal acoustic absorber is a passive absorber or a Helmholtz cavity resonator, in particular the passive absorber being acoustic foam.

[0008] In an embodiment, said internal volume is divided into two sub-volumes divided by the internal acoustic absorber, the first sub-volume facing the diaphragm and the second sub-volume facing the housing away from the diaphragm.

[0009] In an embodiment, said internal volume is air-tight.

[0010] A bass absorber can be defined as an absorber effective at frequencies starting at 60-100hz. A sub-bass absorber can be defined as an absorber effective at frequencies starting at 20-60hz. Constructing accurately tuned diaphragm absorbers is difficult - it is normally possible to achieve a narrow frequency range of absorption (avoiding attenuation of adjacent non-modal frequencies), but it is difficult to obtain a device where such frequency is tunable as disclosed. Also, a lighter, more efficient bass or sub-bass absorber is disclosed, in particular by the use of an efficient and light weight diaphragm arrangement. Also, by allowing tuning by placing weights on said diaphragm or by changing the internal volume by way of adaptations tied to the triangular shape, the disclosed bass or sub-bass absorber is very practical and flexible to adapt to different frequencies.

[0011] In an embodiment, the mass of the diaphragm is variable such that the frequency absorption profile of the acoustical absorber is tunable by varying said mass.

[0012] In an embodiment, the diaphragm is arranged to receive frequency-tuning weight or weights for tuning the frequency absorption profile of the acoustical absorber. [0013] In an embodiment, the centre plate of the diaphragm is arranged to receive frequency-tuning weight or weights for tuning the frequency absorption profile of the acoustical absorber.

[0014] In an embodiment, the centre plate of the diaphragm comprises releasably attached frequency-tuning weight or weights for tuning the frequency absorption profile of the acoustical absorber

[0015] In an embodiment, the frequency-tuning weight or weights are releasably attached by permanent magnets, in particular the frequency-tuning weight or weights are permanent magnets.

[0016] In an embodiment, the internal volume is adjustable for tuning the frequency absorption profile of the acoustical absorber.

[0017] In an embodiment, the acoustical absorber is shaped as a prism, wherein one or more lateral faces of the prism comprise an exteriorly-facing air-tight diaphragm, and one or both of the prism top faces are longitudinally movable for varying the volume of said internal volume for tuning the frequency absorption profile of the acoustical absorber.

[0018] In an embodiment, said diaphragm comprises one or more additional centre plates placed in said membrane such that the plates are separated by a membrane region from each other and separated by a membrane region from the acoustic absorber housing.

[0019] An embodiment comprises a plurality of exteriorly-facing air-tight diaphragms, each comprising a centre plate and a peripherical flexible elastic membrane, the housing and the diaphragms defining said internal volume; wherein said plurality of diaphragms are arranged for vibrating on external sound pressure to create air displacement in said internal volume.

[0020] An embodiment comprises a plurality of exteriorly-facing air-tight diaphragms in a same face of the acoustical absorber. [0021] In an embodiment, the peripherical flexible elastic membrane is a continuous surface membrane and the centre plate is attached to one of the opposite faces of said continuous surface membrane.

[0022] In an embodiment, the peripherical flexible elastic membrane is a continuous surface membrane and the centre plate is divided into two sub-plates, each attached to one of the opposite faces of said continuous surface membrane, as in a sandwich.

[0023] In an embodiment, the peripherical flexible elastic membrane is a non- continuous surface membrane having an opening, wherein the centre plate is attached to cover said opening.

[0024] In an embodiment, the centre plate is made of a wood-based material, in particular MDF.

[0025] In an embodiment, the acoustical absorber is shaped as a prism and is configured to be mounted against a corner of an interior room with the diaphragm facing said room.

[0026] It is also disclosed an acoustical absorber assembly comprising a plurality of assembled together acoustical absorbers according to any of the disclosed embodiments.

[0027] In an embodiment, the assembly is shaped as a triangular prism where each of the prism lateral faces comprises an exteriorly-facing air-tight diaphragm.

[0028] In an embodiment, the acoustical absorber assembly is configured to be mounted against a corner of an interior room.

Brief Description of the Drawings

[0029] The following figures provide preferred embodiments for illustrating the description and should not be seen as limiting the scope of invention.

[0030] Figure 1: Schematic representation of an embodiment of the acoustical absorber comprising a housing and an exteriorly-facing air-tight diaphragm comprising a centre plate and a peripherical flexible elastic membrane, wherein an internal acoustic absorber is comprised in the internal volume of the acoustical absorber.

[0031] Figure 2: Schematic representation of an embodiment of the acoustical absorber comprising a housing and an exteriorly-facing air-tight diaphragm comprising a centre plate and a peripherical flexible elastic membrane, wherein an internal acoustic absorber is comprised in the internal volume of the acoustical absorber and said internal volume is divided into two sub-volumes which are divided by the internal acoustic absorber, creating a cavity facing the housing away from the diaphragm.

[00S2] Figure 3: Schematic representation of an embodiment of the acoustical absorber comprising a housing and two exteriorly-facing air-tight diaphragm, in opposite faces of the acoustical absorber, each comprising a centre plate and a peripherical flexible elastic membrane, wherein an internal acoustic absorber is comprised in the internal volume of the acoustical absorber and said internal volume is divided into two sub-volumes which are divided by the internal acoustic absorber, each of the two sub-volumes being delimited by each of the diaphragms.

[0033] Figure 4: Schematic representation of an embodiment of the acoustical absorber comprising a housing and two exteriorly-facing air-tight diaphragms, in opposite faces of the acoustical absorber, each comprising a centre plate and a peripherical flexible elastic membrane, wherein two internal acoustic absorbers are comprised in the internal volume of the acoustical absorber and said internal volume is thus divided into three sub-volumes, creating a cavity between the two internal acoustic absorbers.

[0034] Figure 5: Schematic representation of an embodiment of an assembly of two acoustical absorbers, each comprising a housing and an exteriorly-facing air-tight diaphragm comprising a centre plate and a peripherical flexible elastic membrane, wherein an internal acoustic absorber is comprised in the internal volume of the acoustical absorber, such that a back wall of the housing of the two acoustical absorbers is a common wall shared by both acoustical absorbers. [0035] Figure 6: Schematic representation of an embodiment of an assembly of two acoustical absorbers, each comprising a housing and an exteriorly-facing air-tight diaphragm comprising a centre plate and a peripherical flexible elastic membrane, wherein an internal acoustic absorber is comprised in the internal volume of each acoustical absorber and the internal volume is divided into two sub-volumes which are divided by the internal acoustic absorber, creating a cavity facing the housing away from the diaphragm, such that a back wall of the housing of the two acoustical absorbers is a common wall shared by both acoustical absorbers.

[0036] Figure 7: Schematic representation of an embodiment of the acoustical absorber comprising a housing and an exteriorly-facing air-tight diaphragm comprising a centre plate and a peripherical flexible elastic membrane.

[0037] Figure 8: Schematic representation of an embodiment of the acoustical absorber comprising a housing and an exteriorly-facing air-tight diaphragm comprising two centre plates and a peripherical flexible elastic membrane.

[0038] Figure 9: Schematic representation of an embodiment of the acoustical absorber comprising a housing and two exteriorly-facing air-tight diaphragms each comprising a centre plate and a peripherical flexible elastic membrane.

[0039] Figure 10(a): Schematic representation of an embodiment of the acoustical absorber comprising a housing and an exteriorly-facing air-tight diaphragm comprising a centre plate and a peripherical flexible elastic membrane, wherein the diaphragm is placed offset relative to a face of the acoustical absorber where the diaphragm is located.

[0040] Figure 10(b): Schematic representation of an embodiment of the acoustical absorber comprising a housing and an exteriorly-facing air-tight diaphragm comprising two centre plates and a peripherical flexible elastic membrane, wherein the diaphragm is placed offset relative to a face of the acoustical absorber where the diaphragm is located.

[0041] Figure 10(c): Schematic representation of an embodiment of the acoustical absorber comprising a housing and two exteriorly-facing air-tight diaphragms each comprising a centre plate and a peripherical flexible elastic membrane, wherein the diaphragms are placed offset relative to a face of the acoustical absorber where the diaphragm is located.

[0042] Figure 11: Schematic representation of an embodiment of the acoustical absorber comprising a housing and an exteriorly-facing air-tight diaphragm comprising a centre plate and a peripherical flexible elastic membrane, wherein a movable wall allows to vary the internal volume of the acoustical absorber for tuning the frequency absorption profile.

[004S] Figure 12(a): Schematic representation of an embodiment of the acoustical absorber comprising a housing and an exteriorly-facing air-tight diaphragm comprising two centre plates and a peripherical flexible elastic membrane, wherein a movable wall allows to vary the internal volume of the acoustical absorber for tuning the frequency absorption profile.

[0044] Figure 12(b): Schematic representation of an embodiment of the acoustical absorber comprising a housing and two exteriorly-facing air-tight diaphragms each comprising a centre plate and a peripherical flexible elastic membrane, wherein a movable wall allows to vary the internal volume of the acoustical absorber for tuning the frequency absorption profile.

[0045] Figure 13 and 14: Schematic representation of an embodiment of the acoustical absorber comprising a housing and an exteriorly-facing air-tight diaphragm comprising a centre plate and a peripherical flexible elastic membrane, wherein the centre plate of the diaphragm comprises frequency-tuning weight or weights for tuning the frequency absorption profile of the acoustical absorber.

[0046] Figure 15: Schematic representation of an embodiment of the acoustical absorber comprising a movable wall for varying the volume of said internal volume for tuning the frequency absorption profile of the acoustical absorber.

[0047] Figure 16: Results obtained with different frequency-tuning weights. Detailed Description

[0048] Figure 1 illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and an exteriorly-facing air-tight diaphragm 2 comprising a centre plate and a peripherical flexible elastic membrane 3, wherein an internal acoustic absorber 5 is comprised in the internal volume of the acoustical absorber.

[0049] Figure 2 illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and an exteriorly-facing air-tight diaphragm 2 comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein an internal acoustic absorber 5 is comprised in the internal volume of the acoustical absorber and said internal volume is divided into two sub-volumes which are divided by the internal acoustic absorber 5, creating a cavity facing the housing 6 away from the diaphragm 2.

[0050] Figure 3 illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and two exteriorly-facing air-tight diaphragm 2, in opposite faces of the acoustical absorber, each comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein an internal acoustic absorber 5 is comprised in the internal volume of the acoustical absorber and said internal volume is divided into two sub-volumes which are divided by the internal acoustic absorber 5, each of the two sub-volumes being delimited by each of the diaphragms.

[0051] Figure 4 illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and two exteriorly-facing air-tight diaphragms, in opposite faces of the acoustical absorber, each comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein two internal acoustic absorbers 5 are comprised in the internal volume of the acoustical absorber and said internal volume is thus divided into three sub-volumes, creating a cavity between the two internal acoustic absorbers 5. [0052] Figure 5 illustrates a schematic representation of an embodiment of an assembly of two acoustical absorbers, each comprising a housing 6 and an exteriorly- facing air-tight diaphragm 2 comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein an internal acoustic absorber 5 is comprised in the internal volume of the acoustical absorber, such that a back wall of the housing 6 of the two acoustical absorbers is a common wall 8 shared by both acoustical absorbers.

[0053] Figure 6 illustrates a schematic representation of an embodiment of an assembly of two acoustical absorbers, each comprising a housing 6 and an exteriorly- facing air-tight diaphragm 2 comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein an internal acoustic absorber 5 is comprised in the internal volume of each acoustical absorber and the internal volume is divided into two sub-volumes which are divided by the internal acoustic absorber 5, creating a cavity facing the housing away from the diaphragm 2, such that a back wall of the housing 6 of the two acoustical absorbers is a common wall 8 shared by both acoustical absorbers.

[0054] Figure 7 illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and an exteriorly-facing air-tight diaphragm 2 comprising a centre plate 4 and a peripherical flexible elastic membrane

3.

[0055] Figure 8 illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and an exteriorly-facing air-tight diaphragm 2 comprising two centre plates 4 and a peripherical flexible elastic membrane 3.

[0056] Figure 9 illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and two exteriorly-facing air-tight diaphragms 2a, 2b each comprising a centre plate 4a, 4b and a peripherical flexible elastic membrane 3a, 3b.

[0057] Figure 10(a) illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and an exteriorly-facing air-tight diaphragm 2 comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein the diaphragm 2 is placed offset 9 relative to a face of the acoustical absorber where the diaphragm 2 is located.

[0058] Figure 10(b) illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and an exteriorly-facing air-tight diaphragm 2 comprising two centre plates 4 and a peripherical flexible elastic membrane 3, wherein the diaphragm 2 is placed offset 9 relative to a face of the acoustical absorber where the diaphragm 2 is located.

[0059] Figure 10(c) illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and two exteriorly-facing air-tight diaphragms 2 each comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein the diaphragm 2 is placed offset 9 relative to a face of the acoustical absorber where the diaphragm 2 is located.

[0060] Figure 11 illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and an exteriorly-facing air-tight diaphragm 2 comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein a movable wall 10 allows to vary the internal volume of the acoustical absorber for tuning the frequency absorption profile.

[0061] Figure 12(a) illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and an exteriorly-facing air-tight diaphragm 2 comprising two centre plates 4 and a peripherical flexible elastic membrane 3, wherein a movable wall 10 allows to vary the internal volume of the acoustical absorber for tuning the frequency absorption profile.

[0062] Figure 12(b) illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a housing 6 and two exteriorly-facing air-tight diaphragms 2 each comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein a movable wall 10 allows to vary the internal volume of the acoustical absorber for tuning the frequency absorption profile. [0063] Figures 13 and 14 illustrate a schematic representation of two embodiments of the acoustical absorber 1 comprising a housing 6 and an exteriorly-facing air-tight diaphragm 2 comprising a centre plate 4 and a peripherical flexible elastic membrane 3, wherein the centre plate 4 of the diaphragm 2 comprises frequency-tuning weight or weights 11 for tuning the frequency absorption profile of the acoustical absorber.

[0064] Figure 15 illustrates a schematic representation of an embodiment of the acoustical absorber 1 comprising a movable wall 10 for varying the volume of said internal volume for tuning the frequency absorption profile of the acoustical absorber.

[0065] The term "comprising" whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof.

[0066] The above described embodiments are combinable. The following claims further set out particular embodiments of the disclosure.