Silent communication mask with a movable acoustic retention element

Abstract

The invention relates to a silent communication face mask (1) intended to be placed on the head of a user (5), comprising: a shell (2) configured to cover the mouth and nose of the user (5), said shell (2) having at least one exhalation vent (14), at least one microphone (3) carried by the shell (2) and arranged so as to capture and transmit the user's speech (5), an acoustic absorption device (4) extending within the shell (2), the mask (1) having at least one first movable element (20) configured to adopt an open configuration of the exhalation vent (14) under the effect of the pressure of air exhaled by the user (5) and to adopt a closed configuration of the exhalation vent (14) in the absence of exhaled air, thus rendering the user's speech (5) unintelligible. Figure for the abstract: Fig. 1

Description

Title of the invention: Silent communication mask comprising a movable acoustic retention element. Technical field

[0001] The present invention relates to the field of communication masks.

[0002] In particular, it proposes a silent communication mask allowing a user of the mask to talk to someone through the mask, without being heard by people who are geographically close. STATE OF THE ART

[0003] In recent years, nomadic work, or teleworking, which consists of working from a location different from the designated place of employment, has developed considerably. This development has been stimulated in particular by technological advances, especially in the field of mobile communication devices such as smartphones, tablets or laptops, as well as by the rise of reliable and fast means of communication such as broadband internet and online collaboration tools.

[0004] The emergence of the possibility of working from anywhere poses certain problems, particularly when the chosen workplace is a public place or one shared with other people located nearby, for example a train, a cafe or a library.

[0005] Indeed, workers may have to participate in videoconference meetings, during which they will have to discuss potentially confidential matters with colleagues or clients remotely. This situation, in addition to being problematic in terms of confidentiality for the worker, can also make those present near the worker uncomfortable.

[0006] In order to guarantee mobile workers comfortable communication, even in difficult or noisy environments, communication masks have been developed. Such devices traditionally consist of a sound capture device such as a microphone, a shell covering the user's nose and mouth, a device for attaching it to the user's head, and inhalation and exhalation vents.

[0007] To solve this problem, the company SKYTED has developed a so-called silent communication mask, incorporating an acoustic absorption device.

[0008] More specifically, the proposed mask incorporates a surface trim element which is derived from the invention described in patent FR3065570 and which ensures improved acoustic absorption.

[0009] This invention makes it possible to envision surface-absorbing acoustic wave pads that adapt to very specific sound environments. Furthermore, the effectiveness of these pads depends solely on their shape, and not on the materials used. The choice of materials is therefore flexible, depending on environmental constraints such as temperature, mass limitations, mechanical strength, etc. Finally, this freedom in the choice of shaping materials also allows for a wide range of manufacturing methods, which can be additive manufacturing or injection molding.

[0010] This invention therefore makes it possible to effectively treat acoustic waves in very harsh environments, for example on aircraft nacelles using metallic materials and additive manufacturing methods. It also makes it possible to treat industrial equipment noise and transportation noise, such as rail, automotive, aircraft, and marine noise, in a very effective and targeted manner. Finally, this freedom in materials (rigid / soft) and the possibility of injection molding allows for targeted and low-cost applications in domestic environments: household appliances (vacuum cleaners, heating or ventilation systems, tools, etc.).

[0011] We wish to further improve the confidentiality ensured by the communication mask developed with this acoustic absorption material.

[0012] Furthermore, communication masks must be compact to ensure compatibility with mobile use and allow the user freedom of movement. The need for a compact mask limits the usable surface area for acoustic absorption and therefore constitutes a limiting factor in its relative acoustic absorption effectiveness. Description of the invention

[0013] A general object of the invention is to provide a communication mask allowing for even improved confidentiality.

[0014] Communication masks include breathing vents which can allow unabsorbed acoustic waves to "radiate" and escape from the mask.

[0015] According to one aspect, the invention proposes a mask with at least a first movable element that can adopt an opening configuration of an exhalation vent under the effect of a push of air exhaled by the user and a closing configuration of said vent in the absence of exhaled air, thus rendering the user's words unintelligible.

[0016] Thus, the confidentiality of the mask is reinforced with respect to people located near the user.

[0017] This solution also has the advantage of not impacting the compactness of the mask.

[0018] To this end, the invention proposes a silent communication face mask intended to be placed on a user's head, comprising: - a shell configured to cover the user's mouth and nose, said shell having at least one exhalation vent, - at least one microphone mounted on the shell and positioned to capture and transmit the user's speech, and - a sound-absorbing device extending into the hull.

[0019] In addition, the mask includes at least one first movable element configured to adopt an opening configuration of the exhalation vent under the effect of a push of air exhaled by the user and to adopt a closing configuration of the exhalation vent in the absence of exhaled air, thus rendering the user's words unintelligible.

[0020] Advantageously, the first moving element is configured to close elastically in the absence of expelled air, with a return time to closed configuration such that the first moving element is back in the closed configuration of the expiration vent at each beginning of pronunciation of a syllable in a group of words.

[0021] Preferably, the first moving element is configured to switch from the open configuration to the closed configuration when the exhaled air push effort stops in a period of less than 250 ms.

[0022] Advantageously, the first movable element comprises a first edge fixed to the shell or to an edge of the expiration vent and a second opposite edge free.

[0023] Advantageously, the first movable element is intended to be located at a distance from the mouth of the user wearing the mask of between 4 and 26 centimeters.

[0024] In one embodiment, the first moving element is a membrane or comprises a bundle of flexible fibers.

[0025] In one embodiment, the mask includes a second movable element disposed opposite the first movable element, the first and second movable elements extending in a closing plane of the expiration vent when said first and second movable elements are in closed configuration.

[0026] In another embodiment, the first moving element comprises a paddle wheel.

[0027] In one embodiment, the shell includes an inhalation vent, the mask comprising a third and optionally a fourth movable element adapted to adopt an opening configuration of the inhalation vent achieved under the effect of the push of incoming air inhaled by the user and a closing configuration of the inhalation vent when the user is not inhaling air, said third and fourth moving elements being configured to close elastically in the absence of inspired air.

[0028] In such an embodiment, the mask comprises a first stop element blocking the opening of the exhalation vent under the effect of the pressure of the air inhaled by the user, and comprising a second stop element blocking the opening of the inhalation vent under the effect of the pressure of the air exhaled by the user. DESCRIPTION OF FIGURES

[0029] Other features, objectives and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0030] Fig. 1 illustrates a communication mask conforming to an embodiment of the invention worn by a user;

[0031] [Fig.2] schematically illustrates the communication mask of [Fig.1] in top view;

[0032] Fig. 3A illustrates an example of a first and a second movable elements according to a first embodiment, in front view, in closed configuration;

[0033] Fig. 3B illustrates the first and second moving elements according to the first embodiment, in top view, in open configuration;

[0034] Fig. 3C illustrates an example of a first and second movable elements according to a second embodiment, in top view, in open configuration;

[0035] Fig. 4 illustrates an example of a first and second movable elements according to a third embodiment, in front view;

[0036] Fig. 5A illustrates an example of a first and second movable elements according to a fourth embodiment, in front view, in closed configuration;

[0037] Fig. 5B illustrates an example of a first and a second movable element according to the fourth embodiment, in top view, in open configuration and in closed configuration;

[0038] Fig. 5C illustrates an example of a third and fourth movable elements according to one embodiment, in top view, in closed configuration and in open configuration;

[0039] Fig. 6A schematically illustrates an example of a sonogram of the first formant of the syllable "no" and the effects of the mask according to the invention on intelligibility for a person not wearing the mask;

[0040] Fig. 6B schematically illustrates an example of a sonogram of the first formant of the syllable "bab" and the effects of the mask according to the invention on intelligibility for a person not wearing the mask;

[0041] Fig. 6C schematically illustrates an example of a sonogram of the first formant of the syllable "gag" and the effects of the mask according to the invention on intelligibility for a person not wearing the mask;

[0042] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION Example of a general mask structure:

[0043] The communication mask 1 illustrated in figures 1 and 2 comprises a shell 2, at least one microphone 3 and an acoustic absorbing device 4. Fasteners 6 allow the mask to be held in position on the head of a user 5.

[0044] The shell 2 is configured to cover the mouth and preferably the nose of the user 5. An inner surface 8 of the shell 2 defines a cavity 12 surrounding the mouth and preferably the nose of the user 5 when the mask 1 is worn by the user, for example by means of a mouthpiece 13.

[0045] The microphone 3 is arranged in the shell 2 and configured to capture the acoustic waves emitted by the user 5 in order to transmit them remotely, for example to a mobile phone via communication electronics.

[0046] The acoustic absorbing device 4 is disposed on a portion of the inner surface 8 of the shell 2. More precisely, the acoustic absorbing device 4 forms an inner lining of the cavity 12. It is thus positioned to be in the path of the sound waves emitted by the user 5 wearing the mask 1 while speaking and is, for example, made up of a surface lining element as described in document FR3065570. The acoustic absorbing device 4 thus makes it possible to at least partially absorb the acoustic waves emitted by the user 5 while not being airtight against the air exhaled by the user 5, which can escape from the cavity 12 by passing through said acoustic absorbing device 4. Vent(s) and moving parts:

[0047] The hull 2 ​​includes one or more exhaust vents 14, for example arranged on lateral surfaces 10, 11 of the hull 2, other locations of the hull 2 ​​being of course conceivable such as for example an external surface 9 of the hull 2 ​​opposite the internal surface 8.

[0048] An exhalation vent 14 consists, for example, of an opening in the shell 2 leading to the outside of the mask 1 on one side and communicating with the cavity 12 via the acoustic absorber device 4 on the other, so that the air exhaled by the user 5 can escape from the mask 1 after escaping from the cavity 12 by passing through the acoustic absorber device 4. For example, and as shown in the figures, the exhalation vent 14 can be rectangular in shape with a length between 1 and 3 centimeters, and a width between 2 and 4 millimeters.

[0049] In addition, the mask 1 includes at its vent(s) 14 at least one movable element 20 configured to chop up the sound likely to come out of the vent 14 and to make the words escaping from the mask 1 at least partially unintelligible to a person located near the user 5 wearing the mask 1.

[0050] More specifically, the movable element 20 is configured to adopt an open configuration of the expiration vent 14 under a push effect of the air exhaled by the user 5, and to adopt a closed configuration of the expiration vent 14 in the absence of exhaled air.

[0051] Alternatively, the movable element 20 is disposed in the shell 2 between the cavity 12 and the expiration vent 14, and extends in a closing plane of the expiration vent 14 in closed configuration, as shown for example in Figures 1 and 2.

[0052] In one embodiment, the movable element 20 is deformable in bending and comprises, for example, a flexible membrane or a bundle of flexible fibers. One of its edges 20a is attached to the edge of the exhalation vent 14 or to an inner wall of the shell 2; its other opposite edge 20b is free. In the unloaded configuration, the movable element 20 closes all or part of the exhalation vent 14 and thus occupies the closed configuration; furthermore, the movable element 20 deforms in bending under the effect of the pressure of the air exhaled by the user 5 to allow said exhaled air to escape. Several movable elements may also be provided to close the same vent, for example, a first movable element 20 and a second movable element 23 formed by two membranes (as illustrated in Figures 3A, 3B and 3C, for example) or two bundles of membranes (as illustrated in [Fig.4] for example) one opposite the other and each attached to an edge of the expiration vent 14 or to an inner wall of the shell 2 located between the cavity 12 and the expiration vent 14 in the obturation plane of the expiration vent 14. An embodiment with two movable elements 20 and 23 is shown in Figures 3A (in closed configuration), 3B and 3C (in open configuration), in which the second movable element 23 comprises an edge 23a attached to the edge of the expiration vent 14 opposite to the edge bearing the edge 20a of the first movable element 20, and a second opposite free edge 23b.

[0053] Thus, when the user 5 speaks or is exhaling, the air exhaled by the user 5 causes a flexural movement of the moving element 20 (or, where applicable, the moving elements 20, 23), which opens the exhalation vent 14. The moving element 20 is then in the configuration of the exhalation vent 14 being open, as is the second moving element 23, where applicable. Figures 3B and 3C illustrate the moving elements 20, 23 in two extreme flexural positions when they are subjected to the exhalation of the user 5.

[0054] Conversely, when the user 5 stops speaking, or is in the inspiration phase, the exhaled air is stopped, stopping the pushing effort previously exerted on the moving element(s) 20, 23. Consequently, the moving element 20 resumes the closing configuration of the expiration vent 14, as does the second moving element 23 where applicable, as shown in [Fig.3A].

[0055] Typically, the moving element 20, and where applicable the second moving element 23, is configured to return to the closed configuration from the open configuration in less than 250 milliseconds. This duration corresponds to the minimum non-audible pause time generally observed after a series of syllables composing a word or group of words. In this way, the moving element 20, and where applicable the second moving element 23, returns to the closed configuration from the open configuration quickly enough so that at the beginning of each syllable spoken by the user 5 during the pronunciation of a group of words, the moving element 20, and where applicable the second moving element 23, is in the closed configuration.

[0056] Such a deformable movable element 20, 23 (membrane, fiber bundle, etc.) is made of an elastic material sufficiently flexible to be pushed and bend under the force of the air exhaled by the speaking user 5, and sufficiently rigid to return to its closed configuration otherwise. Thus, such a movable element 20, 23 is, for example, made of rubber, silicone, or an elastomer in general. Such a movable element 20, 23 can therefore be an elastic material characterized by a Young's modulus between 500 and 2500 MPa. The thickness of such a movable element 20, 23 can be between 0.4 and 1 millimeter, so as to be thin enough to move to an open configuration under the force of the air exhaled by the speaking user 5.

[0057] It should also be noted that, when the user 5 speaks, the emitted acoustic waves propagate at a speed of approximately 340 meters per second. Since the air exhaled by the speaking user 5 propagates at an initial speed of approximately 1.3 meters per second, the acoustic waves reach the first moving element 20, and where applicable also the second moving element 23, well before the exhaled air exerts a pushing force on said first moving element 20, and where applicable also the second moving element 23, at the beginning of each syllable due to the sufficiently rapid return time of the first moving element 20 and where applicable the second moving element 23 to the closed configuration.Thus, the acoustic waves emitted by the user 5 while speaking and arriving at the level of the moving element 20 (after passing through the acoustic absorber device 4) before the exhaled air are reflected by the first moving element 20 in closed configuration obstructing the expiration vent 14, if necessary by both moving elements 20, . 23. In this way, the acoustic waves are retained within the mask 1, thus improving the overall acoustic attenuation of the mask 1. This improved acoustic attenuation remains effective until the air exhaled by the user 5 comes into contact with the first moving element 20, or with both moving elements 20 and 23 as applicable, and exerts a pushing force on it / them. The moving element 20, and as applicable the second moving element 23, then switches to an open configuration and allows the exhaled air and the incoming acoustic waves to escape from that moment onward, as long as the moving element 20, and as applicable the second moving element 23, is subjected to such a pushing force and has not returned to its closed configuration upon cessation of said pushing force. In this way, each syllable spoken by the user 5 is rendered partially unintelligible.Indeed, words or syllables that can be perceived in the absence of such a moving element 20 are "chopped up" so that a person near the user 5 will not be able to clearly understand said words or syllables. This unintelligibility will vary and be more or less significant depending on the syllable pronounced, each syllable provoking a more or less early and longer exhalation depending on the language. For example, the duration of a syllable in French is between 200 and 250 milliseconds, while the duration of a syllable in Chinese is between 200 and 400 milliseconds.

[0058] In French, the average duration of a vowel is about 100 to 200 milliseconds (ms) while the average duration of a consonant is about 30 to 100 milliseconds (ms).

[0059] If the first letter, vowel or consonant, is pronounced in part or entirely before the mobile element 20 is pushed by the airflow, the syllable will potentially be unintelligible.

[0060] In order to optimize the unintelligibility effects, it is necessary to respect distance conditions between the mouth and the expiration vent 14.

[0061] Indeed, the distance between the mouth and the first moving element 20, or the two moving elements 20 and 23 as appropriate, must allow for the shortest duration provided by a vowel or consonant uttered in a conversation, which is on the order of 30 milliseconds. Due to the velocity of exhaled air being approximately 1.3 m / s, the moving element 20, and as appropriate the second moving element 23, must be located at a minimum distance of 4 cm from the mouth, so that the exhalation of air is complete by the time the pressure of the exhaled air begins to act on the first moving element 20.

[0062] Similarly, a maximum distance between the moving element 20 and the mouth can be determined in order to prevent the first moving element 20, and where applicable the second moving element 23, from being in an open configuration at the end of a The syllable is closed and remains open until the next syllable. However, this maximum distance is relatively large and is generally incompatible with the need for a compact mask. For example, for the pronunciation of the syllable "le" or the syllable "no," whose respective emission durations are 200 milliseconds, the maximum distance is 26 cm.

[0063] In order to illustrate the effects on the intelligibility of sounds escaping from mask 1, some elements of speech physics are recalled below.

[0064] In particular, vowels are the longest sounds and are easily identifiable. When a sound is emitted from the glottis of user 5, harmonics appear and are filtered by the vocal tract of user 5. A frequency spectrum of this sound is then in the form of modulated harmonics called "formants".

[0065] The presence of a vowel indicates the presence of consonants before or after said vowel, by a modification of the trajectory of the formants during the transitions before and after the vowel.

[0066] Consonants can be plosive, such as "b" or "g", in which case the passage of air is momentarily blocked by an occlusion of the vocal tract during their pronunciation.

[0067] Consonants can also be oral, such as "1", in which case the soft palate is raised (or lowered in the case of so-called restrictive consonants) and air passes through the mouth.

[0068] Finally, consonants can be nasal, such as "n", in which case the vocal tract is momentarily closed by a lowering of the soft palate while the nasal cavities allow a continuous flow of air.

[0069] Although oral and nasal consonants involve a more or less restricted expiration, the pronunciation of such a consonant may be totally or partially unintelligible depending on its duration. For example, and as illustrated in [Fig.6A] which schematically represents the 1st formant from a sonogram of the vowel "no", the duration of the consonant "n", which extends between the instants t0 and t1, is greater than the opening delay of the expiration vent 14 (which corresponds to the time it takes for the exhaled air from the beginning of the pronunciation of the syllable to exert a pushing force on the moving element 20 or the moving elements 20, 23 as appropriate, and thus open the expiration vent 14, the opening time of the expiration vent 14 being represented by the window F), so that this consonant is partially retained by a person near the user 5 wearing the mask 1.

[0070] Conversely, as illustrated in [Fig. 6B], which represents the first formant from a sonogram of the vowel "bab", the duration of the consonant "b" (between times t4 and t5) is slightly less than the opening delay of the expiratory vent 14 illustrated through window F (t4 and t5 being outside window F), so that the letter "b" is totally retained in mask 1, as well as the beginning of the vowel "a", which is pronounced between t5 and t6, and part of which is located outside window F.

[0071] Similarly, in [Fig.6C] which represents the 1st formant from a sonogram of the vowel "gag", the duration of the consonant "g" (between times t8 and t9) is slightly greater than the opening delay of the expiration vent 14 illustrated by the window F (t9 being inside the window F in the opposite direction to t8), so that the letter "g" is partially retained in the mask 1.

[0072] Thus, depending on the syllables pronounced, the words are retained more or less by at least one mobile element 20, so that the unintelligibility for a person near the user 5 is increased.

[0073] In one embodiment, the shell 2 further includes an inhalation vent 16 similar to the exhalation vent 14. The inhalation vent 16 may be made on one of the lateral surfaces 10, 11, for example on the second lateral surface 11, or in other words on the lateral surface opposite the lateral surface on which the exhalation vent 14 is made. Alternatively, the inhalation vent 16 may be made anywhere on the outer surface 9 of the shell 2. The inhalation vent 16 consists, for example, of an opening in the shell 2, so that the user 5 can inhale outside air into the mask 1, this inhaled air entering the mask through the inhalation vent 16. For example, the inhalation vent 16 may be rectangular in shape with a length and width similar to those of the exhalation vent 14.Alternatively, the mask 1 may, like the expiration vent 14, comprise a plurality of inspiration vents 16. Preferably, the total area of ​​the inspiration vent(s) 16 is identical to the total area of ​​the expiration vent(s) 14.

[0074] In an alternative embodiment, the expiration vent 14 and the inspiration vent 16 are combined.

[0075] In an embodiment in which the exhalation vent 14 and the inspiration vent 16 are not coincident, and advantageously in this case, the mask 1 comprises, analogously to the exhalation vent 14, at least one third movable element 25 similar to the first movable element 20, and optionally a fourth movable element 26 similar to the second movable element 23, the third and fourth movable elements 25, 26 being on opposite edges of the inspiration vent 16, or alternatively on opposing inner walls of the mask 1 located between the cavity 12 and the inspiration vent 16 (as illustrated in [Fig. 2], but not in [Fig. 1] for reasons of clarity). In such an embodiment, the movable elements 20, 23 on the exhalation vent 14 side may comprise a first stop element 27 configured to block the opening of said elements mobile elements 20, 23 from the obturation plane towards the cavity 12, i.e. to block the opening of said mobile elements 20, 23 during inhalation by the user 5. Similarly, the mobile elements 25, 26 on the inhalation vent side 16 may include a second stop element 28 configured to block the opening of said mobile elements 25, 26 from the obturation plane towards the inhalation vent 16, i.e. to block the opening of said mobile elements 25, 26 during expiration by the user 5. The stop elements 27, 28 may be similar, and for example include protrusions 30 extending from an edge of the vent 14, 16 corresponding or from an inner wall of the mask 1.

[0076] In an alternative embodiment, the first moving element 20 is a paddle wheel. In such a case, the first moving element 20 is disposed in a housing formed in the mask between the cavity 12 and the exhalation vent 14, such that the paddle wheel, which includes an axis of rotation passing through its center, is set in rotation by the pressure of the air exhaled by the user 5. Thus, the first moving element 20 is disposed such that the axis of rotation of the paddle wheel is perpendicular to an axis of the housing connecting an upstream portion of the housing and a downstream portion of the housing, the downstream portion communicating with the exhalation vent 14 and the upstream portion communicating with the cavity 12 via the acoustic absorber device 4.

[0077] The diameter of the impeller is chosen so that, when stationary, almost no air passes between the upstream and downstream sides of the impeller; that is, a diameter of at least 95% of the minimum distance separating two opposite walls of the housing parallel to the axis of rotation of the impeller. In other words, the diameter of the impeller is chosen so that, when stationary, no air passes between the blade tips and an opposite wall of the housing.

[0078] The closing configuration of the first moving element 20 therefore corresponds to the stopping of the paddle wheel, that is to say in a position of the blades blocking the passage of air between the upstream and downstream of the paddle wheel, in other words between the blade ends and a wall of the housing opposite.

[0079] When the user speaks or exhales, the exhaled air exerts a thrust force on the vanes of the impeller, causing the first moving element 20 to rotate around its axis of rotation. Thus, the air trapped between the vanes can pass from an upstream portion of the housing to a downstream portion of the housing, and escape from the mask 1 by reaching the exhalation vent 14. The opening configuration of the exhalation vent 14 of the first moving element 20 therefore corresponds to the rotation of the impeller.

Claims

Demands

1. A silent communication face mask (1) intended to be placed on the head of a user (5), comprising: - a shell (2) configured to cover the mouth and nose of the user (5), said shell (2) having at least one exhalation vent (14), - at least one microphone (3) carried by the shell (2) and arranged to capture and transmit the user's (5) speech, - an acoustic absorption device (4) extending into the shell (2), - at least one first movable element (20) configured to adopt an open configuration of the exhalation vent (14) under the effect of pressure from air exhaled by the user (5) and to adopt a closed configuration of the exhalation vent (14) in the absence of exhaled air, thus rendering the user's (5) speech unintelligible, characterized in that the first movable element (20) is configured to close elastically in the absence of expelled air,with a return time to the closed configuration such that the first moving element (20) returns to the closed configuration of the expiration vent (14) at the beginning of each pronunciation of a syllable in a group of words.

2. Mask (1) according to claim 1, wherein the first movable element (20) is configured to switch to closed configuration from open configuration upon cessation of the exhaled air thrust effort in a time of less than 250 ms.

3. Mask (1) according to any one of claims 1 to 2, wherein the first movable element (20) comprises a first edge (20a) fixed to the shell (2) or to an edge of the exhalation vent (14) and a second opposite free edge (20b).

4. Mask (1) according to any one of claims 1 to 3, wherein the first movable element (20) is intended to be located at a distance from the mouth of the user (5) wearing the mask of between 4 and 26 centimeters.

5. Mask (1) according to any one of claims 1 to 4, wherein the first movable element (20) is a membrane or comprises a bundle of flexible fibers.

6. Mask (1) according to any one of claims 1 to 5, comprising a second movable element (23) disposed opposite the first movable element (20), the first and second movable elements (20 and 23) extending in a closing plane of the expiration vent (14) when said first and second movable elements (20 and 23) are in closed configuration.

7. Mask (1) according to claim 1 or 2, wherein the first movable element (20) comprises a paddle wheel.

8. Mask (1) according to any one of claims 1 to 7, wherein the shell (2) includes an inhalation vent (16), the mask (1) having a third and optionally a fourth movable element (25 and 26) adapted to adopt an opening configuration of the inhalation vent (16) achieved under the effect of a push of incoming air inspired by the user (5) and a closing configuration of the inhalation vent (16) when the user (5) is not inspiring air, said third and fourth movable elements (25 and 26) being configured to close elastically in the absence of inspired air.

9. Mask (1) according to claim 8 in combination with claim 6, comprising a first stop element (27) blocking the opening of the expiration vent (14) under the effect of the pressure of the air inspired by the user (5), and comprising a second stop element (28) blocking the opening of the inhalation vent (16) under the effect of the pressure of the air exhaled by the user (5).

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