WO2021115603A1

WO2021115603A1 - Flat magnetic valve for insert headsets

Info

Publication number: WO2021115603A1
Application number: PCT/EP2019/084926
Authority: WO
Inventors: Jyri PAKARINEN; Tommi Raussi; Petri Jarske
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2021-06-17

Abstract

A device (10) for selectively controlling in an earphone system the occlusion of an ear canal, using a valve member (14) comprising a half-disk shaped aperture (13), covered by a half-disk shaped lid (15) connected to a magnet bar (17A), and a solenoid (18) arranged near the aperture (13), wherein the magnet-lid combination is arranged to rotate around a pivot. Feeding an electric current into the solenoid (18), creates a magnetic field, pulling one of the magnetic poles and making the lid (15) to rotate either shutting or opening the valve member (14), wherein allowing a certain amount of friction between the lid (15) and the aperture (13) prevents the free rotation of the lid (15), thereby creating a bi-stable configuration that allows a venting valve with relatively large hole size to be implemented in a flat structure and operated with minimal power usage.

Description

FLAT MAGNETIC VALVE FOR INSERT HEADSETS

TECHNICAL FIELD

The disclosure generally relates to headphones, more particularly to devices and methods for controlled occlusion of an acoustic pathway arranged in ear-fitting headphones (such as earphones or insert-type headphones) between a portion of the ear canal and the external environment.

BACKGROUND

When listening to headphones, certain amount of sound isolation from the external environment is usually preferred for an enjoyable listening experience. One way to achieve this isolation is using insert-type headphones, i.e. headphones where a resilient, compressible tip of the headphone is pushed a little in the ear canal for acoustic sealing. Another benefit of insert-type headphones is that due to the sealing effect between the auditory canal and surrounding environment, low- frequency sounds are more pronounced, leading to a better bass response when listening to music.

Due to these benefits, insert-type headphones are very popular in the current consumer market. However, a drawback of this type of headphones is that the user’s own voice sound too “boomy” or “echo-like” due to the effect of occlusion. This occlusion effect is caused by bone-conducted sound vibrations reverberating off the object filling the ear canal. Another drawback is that with insert-type headphones, the ear canal sweats and sometimes gets itchy or irritated due to lack of ventilation.

Known methods for relieving the occlusion effect in headphones are implementing an electronically controlled physical valve in the headphone body or using active noise control in reducing the low frequencies in the ear canal. These methods are generally called de-occlusion techniques. While active noise control may relieve the occlusion effect to a certain extent, it does nothing to help the lack of ventilation and the resulting ear canal sweating. Thus, active noise control is an inferior solution compared to an actual valve for resolving the problems caused by insert- type headsets. Electronically-switchable physical valves can allow, to a certain extent, both ear canal venting and de-occlusion, and they can further enable the users to hear their surroundings. The main drawbacks of the existing physical valve solutions however are their large size or oblong shape. In particular, the existing solutions cannot easily be implemented as flat structures, which makes them rather unpractical for use in insert-type headphones.

SUMMARY

It is an object to provide an improved method and device for selectively controlling the occlusion of an ear canal which overcomes or at least reduces the problems mentioned above by enabling a flat structure that is suitable for insert-type headphones.

The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect, there is provided a device for selectively controlling occlusion of an ear canal comprising: a sealing member configured to fit into an ear canal or to cover the opening of an ear canal to acoustically separate at least one portion of the ear canal from the external environment; an acoustic pathway arranged to allow acoustic waves to propagate between said at least one portion of the ear canal and the external environment, said acoustic pathway at least partly defined by a wall portion having therein an aperture; and a flat, substantially rigid valve member configured to selectively open or close said aperture by a rotational or translational motion relative to said aperture.

The disclosed device allows a valve with relatively large hole size to be implemented in a flat structure, which is especially well-suited for use in insert-type headphones, where miniaturization and sufficient venting is of key importance. Existing electrically-controlled valve solutions do not offer the flat structure - large hole combination, making them less useful or even useless for insert-type headphones.

In one embodiment the thickness of said valve member measured in the direction of propagation of the acoustic waves is smaller than the smallest diameter of said aperture, allowing for an optimal valve thickness to diameter ratio in insert-type headphones.

In a possible implementation form of the first aspect said valve member comprises a lid having a shape substantially corresponding to the shape of said aperture; and an actuator configured to induce a rotational or translational motion of said lid relative to said aperture using an electric current, allowing fora small structure size in insert-type headphones.

In a further possible implementation form of the first aspect said actuator comprises a magnet bar comprising two opposite magnetic poles fixed to the lid; and a solenoid arranged near the aperture and configured to provide alternating magnetic fields and thereby attracting one of said two opposite magnetic poles, depending on the charge from said electric current, thus enabling fast and precise operation of the valve.

In a further possible implementation form of the first aspect said valve member is configured to be bi-stable by preventing free rotation of the lid relative to said aperture when no electric current is fed to the actuator, so that electric power is required only for changing the open/close state of the valve. Allowing a certain amount of friction between the lid and the chassis prevents the free rotation of the lid, so that current needs to flow in the coil only for changing the lid state (open/close) instead of sustaining a state, which offers power savings, especially important for wireless solutions.

In a further possible implementation form of the first aspect both said aperture and said lid are half-disk shaped, and wherein the lid comprises a solid material and is configured to rotate around a pivot axis between a closed state of the valve member where the lid completely covers the aperture and an open state of the valve member where there is no overlap between the lid and the aperture.

In a further possible implementation form of the first aspect said actuator comprises a straight magnet bar, comprising two opposite magnetic poles, fixed to the straight edge of the lid; and at least one solenoid arranged near an end of the straight end of the aperture and configured to provide alternating magnetic fields to attract one of said two opposite magnetic poles, depending on the charge from said electric current, and thereby rotate said lid around said pivot axis.

In a further possible implementation form of the first aspect both said aperture and said lid are disk-shaped, and wherein said lid comprises at least two mesh layers, each mesh layer comprising parallel slits, wherein the slits of the mesh layers are arranged correspondingly, so that relative motion between the mesh layers can result in closed state where the mesh layers completely block airflow through said aperture and in an open state where the mesh layers only partially block air flow through said aperture.

In a further possible implementation form of the first aspect the slits of said mesh layers are arranged to result in a fine mesh resolution that allows air flow but prevents passage of at least one of dust particles or liquids through said aperture in an open state.

In a further possible implementation form of the first aspect said actuator comprises a an L-shaped magnet bar, comprising two opposite magnetic poles at its two ends, fixed to a first mesh layer, with the corner of the L-shaped magnet bar arranged at the center of the disk-shaped first mesh layer; and a solenoid arranged near the aperture and configured to provide alternating magnetic fields to attract one of said two opposite magnetic poles, depending on the charge from said electric current, and thereby induce a relative rotational motion between said first mesh layer and a second mesh layer around a pivot axis so that in an open state the mesh layers form a grid with perpendicular slits and in a closed state the slits of the mesh layers are aligned to block airflow. In a further possible implementation form of the first aspect the slits of the mesh layers are arranged in a parallel fashion, and wherein said actuator is configured to induce a translational motion between said mesh layers so that in an open state the slits of the mesh layers are arranged to create pathways to allow air flow through and in a closed state the slits are offset to block air flow.

According to a second aspect, there is provided an earphone system for selectively controlling occlusion of an ear canal comprising: an acoustic driver configured to generate acoustic waves for delivery into the ear canal in response to an input audio signal; and a device according to any one of the possible implementation forms of the first aspect.

Combining an acoustic driver with a valve as described above enables implementing the device in headsets for selectively controlling occlusion of an ear canal.

According to a third aspect, there is provided a method for selectively controlling occlusion of an ear canal comprising: providing a device according to any one of the possible implementation forms of the first aspect; receiving a control signal based on a user interaction with the device; and changing the state of the valve member to open or close said aperture based on said control signal.

Controlling the valve member using a control signal enables opening and closing the valve to certain extents in response to user inputs, even in combination with taking into account other inputs.

According to a fourth aspect, there is provided a method for selectively controlling occlusion of an ear canal comprising: providing an earphone system according to the second aspect; detecting whether the acoustic driver is generating acoustic waves for delivery into the ear canal; and changing the state of the valve member to open said aperture if the acoustic driver is not generating acoustic waves or to close said aperture if the acoustic driver is generating acoustic waves.

Only opening the valve member if the acoustic driver is not generating acoustic waves ensures that sound isolation remains optimal when sound is played back to the user, while also enabling that the user hears the external environment when there is no sound playback.

In a possible implementation form of the third or the fourth aspect the method further comprises: providing at least one additional sensor configured to detect at least one of an own voice of a user of the device or a noise level of the external environment and generate a sensor signal indicating the presence of said own voice or said noise level respectively; changing the state of the valve member based on said sensor signal to only open said aperture if said noise level is below a predefined threshold or if said own voice is detected, and to close said aperture if said noise level is above a predefined threshold.

Further taking into account own voice of a user of the device or a noise level of the external environment for controlling the valve enables more accurate response to the situation where the device is used, such as engaging in a phone conversation, or commuting in a very loud city environment.

These and other aspects will be apparent from and the embodiment(s) described below. BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 shows a cross-sectional view of an ear canal and a device arranged therein in accordance with one embodiment of the first aspect, including an enlarged view of the device itself showing approximate proportions;

Fig. 2 shows an isometric view of a valve member in accordance with an embodiment of the first aspect, wherein

Figs. 3A and 3B show isometric views of the above valve member in open and in closed state;

Fig. 4 shows an exploded isometric view of a valve member in accordance with another embodiment of the first aspect, wherein

Figs. 5A and 5B show isometric views of the above valve member in open and in closed state;

Fig. 6 shows a front view of a valve member in accordance with another embodiment of the first aspect in open and closed state;

Fig. 7 shows cross-sectional view of a system in accordance with an embodiment of the second aspect;

Fig. 8 shows a flow diagram of a method in accordance with an embodiment of the third aspect; and

Fig. 9 shows a flow diagram of a method in accordance with an embodiment of the fourth aspect.

DETAILED DESCRIPTION

Fig. 1 illustrates an ear canal 1 and a device 10 arranged therein according to the present disclosure. On the left side of the figure a schematic drawing of an outer ear is shown towards an external environment 2, the outer ear leading to an ear canal 1 showing a device 10 comprising a sealing member 11 that is configured to fit into the ear canal 1 to acoustically separate an inner portion of the ear canal 1 A from the external environment 2. The sealing member 11 is preferably compressible, made of a flexible and resilient material that is also anatomically suitable for long-term wear, such as silicone. In the illustrated embodiment the device 10 is an insert-type device, however in other embodiments the device can be arranged as an earphone or an over-ear headphone only covering the opening of an ear canal 1 towards the outer ear. The figure further shows an acoustic pathway 3 arranged within the device to allow acoustic waves 4 to propagate between said inner portion of the ear canal 1 A and the external environment 2.

The figure further includes an enlarged view of the device 10 with said acoustic pathway 3 arranged therein, at least partly defined by a wall portion 12 having therein an aperture 13. The device further comprises a flat, substantially rigid valve member 14 configured to selectively open or close said aperture 13 by a rotational or translational motion relative to said aperture 13. In an embodiment, the thickness T of said valve member 14 measured in the direction of propagation of the acoustic waves 4 is smaller than the smallest diameter D of said aperture 13 T < D. In an exemplary embodiment, the thickness of said valve member 14 is T=0.25mm, and the smallest diameter of said aperture 13 is D = 2mm.

Figure 2 shows an isometric view of an embodiment of a valve member 14 comprising a lid 15 and an actuator 16 configured to induce a rotational or translational motion of said lid 15 relative to said aperture 13 using an electric current. In this embodiment the lid 15 is arranged in a shape substantially corresponding to the shape of said aperture 13, however other configurations can also be used, as long as the lid is suitable to fully overlap said aperture 13.

In the embodiment illustrated in Figs. 2 to 3, the actuator 16 comprises a (permanent) magnet bar 17 comprising two opposite magnetic poles (S showing South pole marked as light gray, N showing North pole marked as dark gray) fixed to the lid 15 and a solenoid 18 arranged near the aperture 13 and configured to provide alternating magnetic fields and thereby attracting one of said two opposite magnetic poles, depending on the charge from said electric current.

The solenoid is a type of electromagnet arranged to generate a controlled magnetic field through a coil wound into a tightly packed helix. In an embodiment, the solenoid comprises a coil whose length is substantially greater than its diameter. The coil can be arranged to produce a uniform magnetic field in a volume of space when an electric current is passed through it.

In the embodiment illustrated in Figs. 2 to 3, both said aperture 13 and said lid 15 are half-disk shaped, and the lid 15 comprises a solid material and is configured to rotate around a pivot axis (illustrated with dashed line) between a closed state of the valve member 14 where the lid 15 completely covers the aperture 13 and an open state of the valve member 14 where there is no overlap between the lid 15 and the aperture 13.

Figs. 3A and 3B (b) show isometric views of the above valve member 14 in open (Fig. 3A) and in closed state (Fig. 3B). To open or close the valve, a current is fed into the solenoid 18, making it attract the south pole of the magnet 17A and keeping the aperture 13 open to function as a venting hole, as shown in Fig. 3A. When an opposing current is fed into the solenoid 18, as shown in Fig. 3B, it begins to repel the south pole and attract the north pole of the magnet 17A, making the lid 15 rotate around the pivot (indicated with the dashed line) and closing the aperture 13.

In an embodiment, the valve member 14 is configured to be bi-stable by preventing free rotation of the lid 15 relative to said aperture 13 when no electric current is fed to the actuator 16. Allowing a certain amount of friction between the lid 15 and the rest of the device prevents the free rotation of the lid 15, so that current only needs to flow in the solenoid 18 for changing the lid 15 state (open/close) instead of sustaining a state, which offers power savings, especially important for wireless headphone solutions.

Figures 4 to 5 illustrate an alternative implementation of the valve member 14, wherein instead of a solid lid 15, two mesh layers 19A and 19B are used. When the mesh layers 19A and 19B are perpendicular to each other, the structure forms a grid (Fig. 5A) which allows air to pass but may prevent dust or even liquids, depending on the mesh resolution. When the mesh layers 19A and 19B coincide (Fig. 5B), also air flow is blocked.

In the embodiment illustrated in Figs. 4 to 5, the actuator 16 comprises an L- shaped magnet bar 17B, comprising two opposite magnetic poles at its two ends, fixed to a first mesh layer 19A, with the corner of the L-shaped magnet bar 17B arranged at the center of the disk-shaped first mesh layer 19A; and a solenoid 18 (similar as described above) arranged near the aperture 13 and configured to provide alternating magnetic fields to attract one of said two opposite magnetic poles, depending on the charge from said electric current, and thereby induce a relative rotational motion between said first mesh layer 19A and a second mesh layer 19B around a pivot axis (indicated with the dashed line) so that in an open state (Fig. 5A) the mesh layers 19A,19B form a grid with perpendicular slits and in a closed state (Fig. 5B) the slits of the mesh layers 19A,19B are aligned.

In a further alternative implementation of the valve member 14 shown in Fig. 6, based on the implementation described above with respect to Figs. 4 to 5, the slits of the mesh layers 19A,19B are arranged in a parallel fashion, and said actuator 16 is configured to induce a translational motion between said mesh layers 19A, 19B so that in an open state the slits of the mesh layers 19A, 19B are arranged to create pathways to allow air flow through and in a closed state the slits are offset to block air flow. In this embodiment the actuator 16 can be implemented in the form of a solenoid - magnet configuration as described above, or as a small-size electric motor, but further electric current based implementations can also be advantageous based on the device configuration.

Fig. 7 shows cross-sectional view of a system 20 according to the present disclosure for selectively controlling occlusion of an ear canal 1. The system in this embodiment comprises a device 10 for selectively controlling occlusion of an ear canal 1 as described above, and an acoustic driver 21 configured to generate acoustic waves 4 for delivery into the ear canal 1 in response to an input audio signal 5. The acoustic driver 21 comprises a front cavity 21 A and a back cavity 21 B isolated from the front cavity 21 A, and the device 10 is configured to control the occlusion of an acoustic channel between the ear canal 1 and the external environment 2 via the front cavity 21 A. The system 20 may further comprise means for receiving a control signal 6 based on a user interaction with the device 10 (such as a user turning a dial or pushing an on/off button arranged on the device 10), and an additional sensor 7 configured to detect at least one of an own voice of a user of the device 10 (such as a voice accelerometer) or a sensor 7 to detect noise level 202 of the external environment 2 (such as an external microphone or an array of external microphones arranged in a beamforming configuration). The sensor 7 may further be configured to generate a sensor signal 8 indicating the presence of said own voice or said noise level respectively.

Fig. 8 shows a flow diagram of a method according to the present disclosure for selectively controlling occlusion of an ear canal 1 using a device 10 as described above. In a first step 101 , a control signal 6 is received based on a user interaction with the device 10 (such as a user turning a dial or pushing an on/off button arranged on the device 10). Then in a next step 102, the state of the valve member 14 is changed to open or close said aperture 13 based on said control signal 6.

Fig. 9 shows a flow diagram of a further embodiment of a method for selectively controlling occlusion of an ear canal 1 according to the present disclosure, using a system 20 as described above comprising an acoustic driver 21. In a first step 201 , the system detects whether the acoustic driver 21 is generating acoustic waves 4 for delivery into the ear canal 1 . Depending on the answer, in a following step the valve member 14 can either be instructed to open 204 said aperture 13 if the acoustic driver 21 is not generating acoustic waves 4, or to close 205 said aperture 13 if the acoustic driver 21 is generating acoustic waves 4. Only opening the valve member 14 if the acoustic driver 21 is not generating acoustic waves 4 ensures that sound isolation remains optimal when sound is played back to the user, while also enabling that the user hears the external environment 2 when there is no sound playback from the acoustic driver 21 . In a further embodiment, also illustrated in Fig. 9, at least one additional sensor 7 is provided and configured to detect at least one of an own voice of a user of the device 10 or a noise level of the external environment 2, and to generate a sensor signal 8 indicating the presence of said own voice or said noise level respectively, as described above with respect to Fig. 7. In this configuration, after the system detects whether the acoustic driver 21 is generating acoustic waves 4, the system can further detect 203 whether an own voice of a user of the device 10 is present, and generate a sensor signal 8 which is used for changing the state of the valve member 14 to only open said aperture 13 if said own voice is detected.

The system can further be configured to detect 202 noise level of the external environment 2 and compare it to a predefined noise level threshold, and generate a sensor signal 8 which is used for changing the state of the valve member 14 to only open said aperture 13 if said noise level is below the predefined threshold, or to close said aperture 13 if said noise level is above the predefined threshold.

The various aspects and implementations has been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

The reference signs used in the claims shall not be construed as limiting the scope.

Claims

1. A device (10) for selectively controlling occlusion of an ear canal (1) comprising: a sealing member (11) configured to fit into an ear canal (1 ) or to cover the opening of an ear canal (1) to acoustically separate at least one portion of the ear canal (1A) from the external environment (2); an acoustic pathway (3) arranged to allow acoustic waves (4) to propagate between said at least one portion of the ear canal (1A) and the external environment (2), said acoustic pathway (3) at least partly defined by a wall portion

(12) having therein an aperture (13); and a flat, substantially rigid valve member (14) configured to selectively open or close said aperture (13) by a rotational or translational motion relative to said aperture

(13).

2. The device according to claim 1 , wherein the thickness T of said valve member (14) measured in the direction of propagation of the acoustic waves (4) is smaller than the smallest diameter D of said aperture (13) T < D.

3. The device according to any one of claims 1 or 2, wherein said valve member

(14) comprises a lid (15) having a shape substantially corresponding to the shape of said aperture (13); and an actuator (16) configured to induce a rotational or translational motion of said lid

(15) relative to said aperture (13) using an electric current.

4. The device according to claim 3, wherein said actuator (16) comprises a a magnet bar (17) comprising two opposite magnetic poles fixed to the lid (15); and a solenoid (18) arranged near the aperture (13) and configured to provide alternating magnetic fields and thereby attracting one of said two opposite magnetic poles, depending on the charge from said electric current.

5. The device according to any one of claims 3 or 4, wherein said valve member (14) is configured to be bi-stable by preventing free rotation of the lid (15) relative to said aperture (13) when no electric current is fed to the actuator (16).

6. The device according to any one of claims 3 to 5, wherein both said aperture (13) and said lid (15) are half-disk shaped, and wherein the lid (15) comprises a solid material and is configured to rotate around a pivot axis between a closed state of the valve member (14) where the lid (15) completely covers the aperture (13) and an open state of the valve member (14) where there is no overlap between the lid (15) and the aperture (13).

7. The device according to claim 6, wherein said actuator (16) comprises a a straight magnet bar (17A), comprising two opposite magnetic poles, fixed to the straight edge of the lid (15); and at least one solenoid (18) arranged near an end of the straight end of the aperture (13) and configured to provide alternating magnetic fields to attract one of said two opposite magnetic poles, depending on the charge from said electric current, and thereby rotate said lid (15) around said pivot axis.

8. The device according to any one of claims 3 to 5, wherein both said aperture (13) and said lid (15) are disk-shaped, and wherein said lid (15) comprises at least two mesh layers (19A,19B), each mesh layer comprising parallel slits, wherein the slits of the mesh layers (19A,19B) are arranged correspondingly, so that relative motion between the mesh layers (19A,19B) can result in closed state where the mesh layers (19A,19B) completely block air flow through said aperture (13) and in an open state where the mesh layers (19A,19B) only partially block airflow through said aperture (13).

9. The device according to claim 8, wherein the slits of said mesh layers (19A, 19B) are arranged to result in a fine mesh resolution that allows air flow but prevents passage of at least one of dust particles or liquids through said aperture (13) in an open state.

10. The device according to any one of claims 8 or 9, wherein said actuator (16) comprises a an L-shaped magnet bar (17B), comprising two opposite magnetic poles at its two ends, fixed to a first mesh layer, with the corner of the L-shaped magnet bar (17B) arranged at the center of the disk-shaped first mesh layer; and a solenoid (18) arranged near the aperture (13) and configured to provide alternating magnetic fields to attract one of said two opposite magnetic poles, depending on the charge from said electric current, and thereby induce a relative rotational motion between said first mesh layer (19A) and a second mesh layer (19B) around a pivot axis so that in an open state the mesh layers (19A,19B) form a grid with perpendicular slits and in a closed state the slits of the mesh layers (19A, 19B) are aligned to block air flow.

11. The device according to any one of claims 8 or 9, wherein the slits of the mesh layers (19A, 19B) are arranged in a parallel fashion, and wherein said actuator (16) is configured to induce a translational motion between said mesh layers (19A,19B) so that in an open state the slits of the mesh layers (19A,19B) are arranged to create pathways to allow air flow through and in a closed state the slits are offset to block air flow.

12. An earphone system (20) for selectively controlling occlusion of an ear canal (1) comprising: an acoustic driver (21) configured to generate acoustic waves (4) for delivery into the ear canal (1) in response to an input audio signal (5); and a device (10) according to any one of claims 1 to 11.

13. A method for selectively controlling occlusion of an ear canal (1) comprising: providing a device (10) according to any one of claims 1 to 11 ; receiving (101) a control signal (6) based on a user interaction with the device (10); and changing (102) the state of the valve member (14) to open or close said aperture (13) based on said control signal (6).

14. A method for selectively controlling occlusion of an ear canal (1) comprising: providing an earphone system (20) according to claim 12; detecting (201) whether the acoustic driver (21) is generating acoustic waves (4) for delivery into the ear canal (1 ); and changing the state of the valve member (14) to open (204) said aperture (13) if the acoustic driver (21) is not generating acoustic waves (4) or to close (205) said aperture (13) if the acoustic driver (21) is generating acoustic waves (4).

15. A method according to any one of claims 13 or 14, further comprising providing at least one additional sensor (7) configured to detect at least one of an own voice (203) of a user of the device (10) or a noise level (202) of the external environment (2) and generate a sensor signal (8) indicating the presence of said own voice or said noise level respectively; changing the state of the valve member (14) based on said sensor signal (8) to only open (204) said aperture (13) if said noise level is below a predefined threshold or if said own voice is detected, and to close (205) said aperture (13) if said noise level is above a predefined threshold.