Communication assembly, aircraft provided with the communication assembly and method for preventing interference in communications

Description

Disclosure area

[0001] The present disclosure relates to a communication assembly comprising a breathing mask equipped with a microphone, as well as to an aircraft equipped with the communication assembly and a method, the assembly and the method being intended to avoid interference due to oxygen flow noise in communications between a user, an aircraft crew member, and another aircraft crew member or between the aircraft user and a control tower. The user is in particular a pilot or a co-pilot. Background to the disclosure

[0002] Most aircraft are equipped with breathing mask systems to provide oxygen to crew members for use in emergency situations, such as in oxygen-depleted environments during aircraft decompression. During such emergency operations, pilots, flight officers, and other flight crew members may wear a breathing mask that includes a breathing-demand regulator and a microphone. It is imperative that the breathing mask include a microphone so that communication with other crew members or with control tower personnel can be maintained during such an emergency.

[0003] In most microphone systems, sounds emitted by the user activate a microphone, which converts the received sounds into an audio signal for transmission. The sounds received by the microphone include not only the user's voice but, unfortunately, background noise as well. When the user inhales, the sound of the gas flow exiting the regulator is often particularly loud and is transmitted as noise with a large component comparable in frequency and intensity to the sounds emitted by a person when speaking. When a crew member (pilot or otherwise) wearing a breathing mask speaks, the noise generated by inhalation by other crew members can seriously impede hearing or understanding the words of the speaking crew member.Additionally, when crew members are exposed to stressful emergency conditions, their breathing rate increases, further intensifying the level of noise interference. This interference poses a very serious problem, as it is during such an emergency that effective communication between crew members and with the tower is imperative.

[0004] In practice, an audio button can be provided to allow the pilot to manually activate the microphone function only when speaking and to mute the microphone when it is not activated (no audio signal transmitted).

[0005] Furthermore, it is known, in particular from document WO2008081226A1, a communication assembly comprising a breathing mask. The breathing mask comprises a regulator delivering a breathing gas when the crew member inhales. The oxygen content of the breathing gas depends on the pressure inside the cabin (passenger compartment). Reference is generally made to the cabin altitude which is the "standard" altitude corresponding to the pressure in the cabin (inside the aircraft, where the user is located). Such a breathing mask comprises a shell placed on the face, the shell being sealed and applying in a sealed manner to the face of the crew member to prevent any entry, in particular of ambient air, inside the shell other than the breathing gas supplied on demand and regulated in oxygen content.This avoids any dilution with the cabin air and also protects the crew member from any possible smoke or harmful gases.

[0006] Due to this waterproof design, such a communication set includes a microphone arranged inside the shell and delivers an audio signal to the aircraft's audio system.

[0007] Furthermore, document WO2008081226A1 discloses a communication set equipped with a microphone for reducing the noise of injecting breathing gas into the shell, the audio signal delivered by the microphone is automatically reduced (attenuated) when a noise corresponding to the injection of oxygen into the shell is detected. In the event of speech detection, the audio signal delivered by the microphone is not reduced (not attenuated).

[0008] The microphone, called ASM (Active switch microphone), includes a breathing gas injection noise detection and a speech detection. This works perfectly satisfactorily. However, this communication set has the disadvantage compared to the audio button for activating the microphone function of complicating the verification of the correct functioning of the communication set. Indeed, during the verification, the breathing mask is generally stored in its storage box and one practice is to simultaneously verify the correct functioning of the supply of breathing gas to the shell and the microphone by listening to the flow of breathing gas in the shell via the aircraft audio system.

[0009] One solution to this problem is to provide an on / off button that inhibits the reduction (attenuation) of the audio signal, even if breathing gas flow is detected. Disclosure Statement

[0010] An ergonomic, reliable and robust communication system is proposed to overcome at least some of the aforementioned problems.

[0011] To this end, the communication set, intended to avoid interference due to oxygen flow noise in communications between a user, an aircraft crew member, and another aircraft crew member or between the user and a control tower, comprises: a) a respiratory mask comprising: a body having a face shell having a respiratory cavity, said face shell being adapted to be applied to the user's face in a use configuration in which the respiratory cavity is delimited by said face shell and by the user's face, a regulator having an inlet port for connection to an oxygen source and an outlet port delivering a respiratory gas containing oxygen, the outlet port being in flow communication with the respiratory cavity for supplying the respiratory gas to the user in a flow through the respiratory cavity upon inhalation by the user,b) a test button for supplying the breathing cavity with breathing gas (in the absence of inhalation by the user) when the communication assembly is in a stowed configuration in which the breathing cavity is not in contact with the user's face, c) a microphone mounted on the body of the breathing mask, the microphone being configured to pick up a sound signal in the breathing cavity and transmit a first electrical signal corresponding to the picked up sound signal, d) an attenuation device configured to receive the first electrical signal and operate in at least a first mode or a second mode and transmit a second electrical signal, wherein: in the first mode, the attenuation device attenuates at least a central frequency band of the first electrical signal, said central frequency band corresponding to a frequency range of the sound signal extending between 500 Hz and 1500 Hz,and in the second mode, the attenuating device does not attenuate the central frequency band of the first electrical signal; e) a sound monitoring system comprising: a first sound monitor configured to monitor the sound signal, detect a first sound intensity in a first frequency range and analyze the first sound intensity to determine whether the first sound intensity is within a first level range determined to detect a flow noise through the respiratory cavity upon inhalation by the user in the use configuration, and a second sound monitor configured to monitor the sound signal, detect a second sound intensity in a second frequency range and analyze the second sound intensity to determine whether the second sound intensity is within a second level range determined to detect a vocal sound,the second frequency range being distinct from the first frequency range; and f) a controller configured to select the operating mode of the attenuation device, in order to operate the attenuation device in: the first mode (i) when the first sound intensity analyzed by the first sound monitor is in the first determined level range and (ii) when the second sound intensity analyzed by the second sound monitor is not in the second determined level range, and the second mode when the second sound intensity analyzed by the second sound monitor is in the second determined level range; g) a transmitter arranged downstream of the attenuation device to transmit an output signal to another crew member or a transmitting antenna, , in which communication set: the sound monitoring system is configured to monitor the sound signal, detect a third sound intensity in a third frequency range, and analyze the third sound intensity to determine whether the third sound intensity is within a third level range determined to detect flow noise in the respiratory cavity in the stowed configuration, the third frequency range being distinct from the first frequency range, and the controller is configured not to operate the attenuation device in the first mode when the third sound intensity is within the third level range.

[0012] It appeared that the flow of respiratory gas in the respiratory cavity when the respiratory cavity is not blocked by a face could be discriminated from the flow in the respiratory cavity when the respiratory cavity is blocked by a face. This possibility of discrimination appears due to the absorption of sound waves by the face.

[0013] This solution has the advantage of reducing the constraints on the user. On the one hand, this solution avoids requiring the pilot to press a button each time he speaks to be heard. On the other hand, this solution prevents the button inhibiting the reduction of the audio signal from being in an incorrect position likely to cause the presence of flow noise interfering with communications or an erroneous detection of a malfunction of the communication system. Indeed, if the noise reduction function is active when the test button is pressed to check the proper functioning of the communication system, the noise of the flow of the breathing gas in the respiratory cavity will not be perceived, or at least not perceived via the aircraft's audio system.

[0014] According to another characteristic, in the second mode, preferably the attenuation device does not modify the first electrical signal.

[0015] The second electrical signal is therefore identical to the first electrical signal. Since the sound signal is considered to correspond to words, there is no need to modify the first electrical signal.

[0016] According to another feature, preferably the controller is configured to operate the attenuation device in the second mode when the third sound intensity is within the third determined level range.

[0017] Since the sound signal is considered to correspond to a flow noise in the respiratory cavity in the stowed configuration, the user must hear this noise, just as the words must be heard. The second mode can therefore be selected both when the second sound intensity analyzed by the second monitor is in the second determined level range and when the third sound intensity is in the third determined level range.

[0018] According to another feature, the third frequency range extends at least partly above 2000 Hz, preferably at least partly above 2500 Hz.

[0019] It appears that the third frequency range thus makes it possible to detect a flow noise in the respiratory cavity in the stored configuration.

[0020] According to an additional characteristic, the third frequency range preferably extends entirely below 5 kHz, more preferably below 4.5 kHz.

[0021] It appears that the third frequency range thus makes it possible to clearly distinguish a flow noise in the respiratory cavity in the stored configuration from a flow noise in the respiratory cavity in the use configuration.

[0022] According to another feature, the communication assembly further comprises a storage box configured to receive the respiratory mask in the stowed configuration.

[0023] Thus, the flow noise in the respiratory cavity in the stowed configuration has less variation due to the environment of the respiratory cavity, which improves the reliability of identifying that the sound signal corresponds to the flow of respiratory gas in the respiratory cavity in the stowed configuration.

[0024] According to an additional characteristic, preferably the third frequency range is centered (the middle of the third frequency range is located) between 2,500 Hz and 3,500 Hz.

[0025] It appears that placing the middle of the third frequency range between 2,500 Hz and 3,500 Hz is favorable to obtaining good discrimination of the noise of the flow of respiratory gas in the respiratory cavity in the stored configuration compared on the one hand to a vocal sound and on the other hand to a noise of the flow of respiratory gas in the respiratory cavity in the use configuration.

[0026] According to another characteristic, preferably the third frequency range extends entirely above 1000 Hz, more preferably above 1.5 kHz.

[0027] It appears that the third frequency range thus makes it possible to clearly distinguish a flow noise in the respiratory cavity in the row configuration of a vocal sound.

[0028] According to an alternative characteristic, the first frequency range and the third frequency range overlap.

[0029] In the case where the distinction between a flow noise in the respiratory cavity in the stowed configuration and a speech sound is not essential, this feature can be advantageous.

[0030] According to an additional characteristic, the first frequency range and the third frequency range are identical and the first level range and the third level range are identical.

[0031] Thus, the detection of a voice sound and a sound of respiratory gas flow in the respiratory cavity in the stowed configuration is carried out simultaneously, indistinctly. The communication system is therefore simpler.

[0032] According to an alternative feature, preferably the sound monitoring system comprises a third sound monitor distinct from the second sound monitor, the third sound monitor being configured to monitor the sound signal, detect the third sound intensity in the third frequency range and analyze the third sound intensity to determine if the third sound intensity is in the third level range determined to detect a flow noise in the respiratory cavity in the stowed configuration, the third frequency range being distinct from the second frequency range.

[0033] Thus, the detection of a speech sound is distinct from the detection of a flow noise in the respiratory cavity in the stowed configuration, which allows for better detection and discrimination compared to a flow noise in the respiratory cavity in the use configuration.

[0034] According to an additional feature, preferably the third sound monitor is arranged on an electronic microphone card necessary for the operation of the microphone.

[0035] Thus, the characteristics of the third sound monitor can be changed by replacing a module including the microphone and the microphone electronic board.

[0036] In a further complementary manner, the electronic microphone card carries the first sound monitor, the third sound monitor and a part of the controller returning intermediate information regarding the selection of the operating mode of the attenuation device.

[0037] According to an alternative feature, the communication assembly comprises a microphone electronic board and the first sound monitor, the second sound monitor and the third sound monitor are arranged on a monitoring electronic board separate from the microphone electronic board.

[0038] Thus, an existing communication set can be improved to avoid interference due to oxygen flow noise in communications, while allowing easy verification of proper operation, by adding the monitoring electronic card.

[0039] According to another characteristic in accordance with the present disclosure, preferably the communication assembly further comprises a bandpass filter for filtering sound signals having a frequency outside a major voice frequency band, said bandpass filter being arranged between the attenuation device and the transmitter.

[0040] Thus, the communication set makes it possible to eliminate parasitic noises picked up at the same time as the user's speech, without having a major detrimental effect on good understanding of the user's speech by the control tower or the other crew member.

[0041] According to an additional characteristic, preferably the bandpass filter has a bandwidth including (the entire) frequency range between 500 Hz and 1,500 Hz, preferably the bandpass filter has a bandwidth including (the entire) frequency range between 300 and 3,000 Hz.

[0042] According to an additional or alternative characteristic, preferably the bandpass filter cuts at least frequencies below 100 Hz and at least frequencies above 5000 Hz.

[0043] In various embodiments of the communication assembly, one and / or the other of the following arrangements may optionally be used: in the first mode, the attenuation device mutes the entire sound signal; the controller is configured to always operate the attenuation device in the second mode when the first sound intensity analyzed by the first sound monitor is not in the first determined level range; the controller is configured to operate the attenuation device in the second mode when: the second sound intensity analyzed by the second sound monitor is in the second determined level range, or when the third sound intensity is in the third determined level range;the controller is configured to operate the attenuation device in the first mode only when: the first sound intensity analyzed by the first sound monitor is in the first determined level range, the second sound intensity analyzed by the second sound monitor is not in the second determined level range, and the third sound intensity is not in the third determined level range; the first frequency range extends (entirely) above 10 kHz, preferably (entirely) above 30 kHz; the second frequency range extends (entirely) below 1000 Hz, preferably (entirely) below 500 Hz, more preferably below 300 Hz; the second frequency range extends (entirely) above 100 Hz, preferably (entirely) above 130 Hz;the first sound monitor, the second sound monitor and the third sound monitor each monitor the first electrical signal to monitor the sound signal; the respirator further includes a support harness attached to the body of the respirator.;

[0044] An aircraft equipped with the communications package is also offered.

[0045] Also provided is a method for avoiding interference due to oxygen flow noise in communications between a user, an aircraft crew member, and another aircraft crew member or between the user and a control tower.In this method, a communication assembly comprises a breathing mask, a microphone and a test button, the breathing mask comprising a body and a regulator, the body of the breathing mask having a face shell, said face shell having a breathing cavity, the regulator supplying the breathing cavity upon inhalation by the user, the microphone being mounted on the body of the breathing mask and being configured to pick up an audible signal in the breathing cavity and transmit a first electrical signal corresponding to the picked up audible signal, the test button making it possible to supply the breathing cavity with breathing gas when the communication assembly is in a stowed configuration in which the breathing cavity is not in contact with the face of the user, an attenuation device being configured to receive the first electrical signal, the method comprising: . placing the respiratory mask in a use configuration in which the face shell is applied to the user's face, the respiratory cavity being delimited by said face shell and by the user's face or placing the face shell of the respiratory mask in the stowed configuration and actuating the test button, monitoring, in a first frequency range, a first sound intensity of the sound signal picked up by the microphone, analyzing the first sound intensity and determining whether the first sound intensity is in a first level range determined to detect a flow noise through the respiratory cavity during inhalation by the user in the use configuration; monitoring, in a second frequency range, a second sound intensity of the sound signal picked up by the microphone, the second frequency range being distinct from the first frequency range,analyzing the second sound intensity and determining whether the second sound intensity is within a second determined level range to detect a vocal sound, monitoring, in a third frequency range, a third sound intensity of the sound signal picked up by the microphone, the third frequency range being distinct from the first frequency range and analyzing the third sound intensity to determine whether the third sound intensity is within a third determined level range to detect a flow noise in the respiratory cavity in the stowed configuration, attenuating at least a central frequency band of the first electrical signal to generate an output signal,the center frequency band of the first electrical signal corresponding to a frequency range of the sound signal extending between 500 Hz and 1,500 Hertz when the first sound intensity analyzed by a first sound monitor is in the first determined level range and when the second sound intensity analyzed by a second sound monitor is not in the second determined level range and the third sound intensity is not in the third level range, not attenuating the center frequency band of the first electrical signal to generate the output signal, when the second sound intensity analyzed by the second sound monitor is in the second determined level range, and transmitting the output signal to another crew member or a transmitting antenna. Brief description of the figures

[0046] Other features and advantages will become apparent from the following detailed description, with reference to the accompanying drawings in which: Fig. 1 is a schematic view of a communication assembly in a use configuration, the communication device comprising a breathing mask, a storage box equipped with a test button and a microphone assembly; Fig. 2 is a schematic view of the communication assembly in a stowed configuration; Fig. 3 schematically represents the microphone assembly comprising a microphone transmitting a first electrical signal; Fig. 4 illustrates a spectral analysis of the first electrical signal in a usage configuration, and Fig. 5 illustrates a spectral analysis of the first electrical signal in a row configuration. Detailed Description of Disclosure

[0047] THE figures 1 And 2illustrate a communication assembly 1 arranged in an aircraft cabin 5. The communication assembly 1 essentially comprises a breathing mask 10, an oxygen source 4, a storage box 40, a test button 8 and a microphone assembly 30. The microphone assembly 30 comprises a microphone 20, a sound monitoring system 28, a controller 32, an attenuation device 34 and a transmitter 38.

[0048] The breathing mask 10 is intended to be used by a user 2, generally a crew member piloting the aircraft. The breathing mask 10 comprises a body 14, a harness 6, a goggle 13 and a regulator 16. The body 14 comprises a face shell 11 having a breathing cavity 12. The face shell 11 has a peripheral edge coming into contact with the face of the user 2, around the mouth and nose of the user, in the configuration of use illustrated in figure 1The peripheral edge is generally covered with foam or a similar flexible material, in order to apply in a substantially sealed manner to the face of the user 2. In the configuration of use, the respiratory cavity 12 is substantially closed, delimited by the facial shell 11 and the face of the user 2. The user inhales and exhales into the respiratory cavity 12.

[0049] In the illustrated embodiment, the face shell 11 is of the oronasal type. The goggle 13 is optional and removably mounted on the face shell 11. The goggle 13 comprises a secondary shell extending around the eyes and a transparent screen arranged opposite the eyes. The secondary shell defines a secondary cavity. Alternatively, the face shell could be of the so-called full-face type and extend around the mouth, nose and eyes, forming a single cavity.

[0050] The harness 6 is connected to the body 14 and extends around the head of the user 2. In the use configuration, the harness 6 keeps the face shell 11 applied to the face of the user 2. In the illustrated embodiment, the harness 6 is formed by two tubes that are expandable when inflated under pressure. The tubes are held on the body 14 at their ends.

[0051] The regulator 16 is rigidly mounted on the body 14. The regulator has an inlet orifice 15 and an outlet orifice 17. The inlet orifice 15 is connected to an oxygen source 4 by a flexible hose 18. The outlet orifice 17 is in communication with the respiratory cavity 12. As is well known, the regulator has several operating modes including a so-called normal mode, a so-called 100% oxygen mode and an emergency mode. In the 100% oxygen mode, the regulator 16 supplies the respiratory cavity 12 with respiratory gas consisting solely of the gas coming from the oxygen source 4. The supply is carried out on demand, in other words when the user 2 inhales, the user creates a slight depression in the respiratory cavity 12 relative to the ambient pressure in the cabin 5 and the regulator supplies the respiratory cavity 12 until the pressure in the respiratory cavity reaches the ambient pressure.In the normal mode, the regulator 16 supplies the respiratory cavity 12 with a respiratory gas consisting of a mixture of oxygen from the oxygen source and ambient air, the oxygen content of the respiratory gas increasing as the ambient pressure decreases, the pressure in the respiratory cavity 12 being maintained substantially equal to the ambient pressure. In the emergency mode, the regulator 16 supplies the respiratory cavity 12 with respiratory gas consisting of the gas from the oxygen source 4 and a slight overpressure is maintained in the respiratory cavity 12 relative to the ambient pressure. The oxygen is stored under pressure in the oxygen source 4 or produced under pressure in the oxygen source 4. The gas supplied by the oxygen source 4 preferably comprises at least 95% oxygen, preferably at least 99% oxygen.

[0052] The breathing mask 10 further allows the gas exhaled by the user 2 into the breathing cavity 12 to escape. Preferably, the regulator 16 comprises a valve opening due to overpressure in the breathing cavity 12 to allow the gases exhaled by the user 2 to be discharged into the ambient air.

[0053] The storage box 40 has a storage space 42 in which the respiratory mask 10 is received in the stowed configuration illustrated in figure 2. In the illustrated embodiment, the storage box 40 comprises four side walls 44, a bottom wall 46 and doors 48 delimiting the storage space 42. The storage box 40 is metallic. The storage box 40 has an access opening allowing the insertion of the respiratory mask 10 into the storage space 42, or on the contrary to remove the respiratory mask from the storage box 42. The doors 48 are arranged opposite the bottom wall 46. The doors 48 substantially close the access opening when they are closed and release the access opening when they are open. In the stowed configuration, the regulator 16 is in the emergency mode which is the most protective for the user. Generally, the storage box 40 is equipped with a supply valve (not shown) which is closed when the doors 48 are closed so as to prevent oxygen from escaping through the breathing cavity 12.The supply valve opens when the doors 48 are opened or a similar means allows the supply valve to be opened automatically when the breathing mask is removed from the storage box 40.

[0054] The test button 8 allows the supply valve to be opened while maintaining the communication assembly in the stowed configuration and the doors 48 closed, in particular while maintaining the breathing mask 10 in the storage space 42 (and the doors 48 closed). In the embodiment, the test button 8 is mounted on the storage box 40 near the access opening.

[0055] The microphone 20 is mounted on the body 14, picks up the sound signal in the respiratory cavity 12 and converts the sound signal into a first electrical signal 52.

[0056] The attenuating device 34 receives the first electrical signal 52 from the microphone and transmits a second electrical signal 54. The attenuating device 34 comprises at least a first (operating) mode and a second (operating) mode. Preferably, the first mode is an active mode and the second mode is an inactive mode. The second mode is advantageously of the "pass-through" type in which the attenuating device 34 does not modify the first electrical signal 52 coming from the microphone 30, so that the second electrical signal 54 is identical to the first electrical signal 52. At least, in the first mode, a central frequency band is not attenuated. The central frequency band extends between 500 Hz and 1500 Hz. In the first mode, the attenuating device 34 reduces the sound intensity of the first electrical signal 52, at least the central frequency band, by at least half.Preferably, the attenuation device 34 cuts the first electrical signal 52, at least the central frequency band. More preferably, in the first mode, the attenuation device 32 acts on the entire audible sound frequency range and cuts the first electrical signal. In one embodiment, the attenuation device 34 may be a switch, the first mode consisting of cutting the first electrical signal 52 and the second mode consisting of transmitting the first electrical signal 52 without modifying it. In an alternative embodiment, the attenuation device 34 may comprise an electronic component or software designed to reduce the intensity of the first electrical signal in the first mode.

[0057] In the illustrated embodiment, the second electrical signal 54 is received by a bandpass filter 36 which is optional. The bandpass filter 36 transmits a third electrical signal 56 to the transmitter 38. The bandpass filter 36 is therefore disposed between the attenuation device 34 and the transmitter 38. The bandpass filter 36 has a bandwidth preferably included in a major voice frequency range, the major voice frequency range extending between 300 Hz and 3,500 Hz, preferably between 300 Hz and 3,000 Hz. Thus, when the attenuation device 34 is in the second mode, unwanted noises outside the major voice frequency range are eliminated by the bandpass filter 36.

[0058] The frequency range of speech is essentially between 300 Hz and 3000 Hz. In telephony, the transmitted frequency range is generally between 300 Hz and 3400 Hz. 99% of the power of speech is at a frequency below 3000 Hz. Therefore, the bandpass filter 36 essentially excludes unwanted noise, not speech.

[0059] In the illustrated embodiment, the transmitter 38 transmits an output signal 58 to other crew members and / or to the control tower, preferably via the aircraft audio system.

[0060] In the illustrated embodiment, the sound monitoring system 28 comprises a first sound monitor 22, a second sound monitor 24 and a third sound monitor 26. The first sound monitor 22, the second sound monitor 24 and the third sound monitor 26 are connected in parallel to the output of the microphone 20. More precisely, the first sound monitor 22, the second sound monitor 24 and the third sound monitor 26 receive the first electrical signal 52.

[0061] The first sound monitor 22 monitors a first frequency range to determine whether the first electrical signal 52 corresponds to a flow noise through the respiratory cavity 12 during inhalation by the user 2 while the respiratory mask 10 is in the use configuration. In other words, the first frequency range is chosen to achieve satisfactory discrimination in particular between, on the one hand, a flow noise of the pressurized respiratory gas in the respiratory cavity 12 in the use configuration and, on the other hand, a speech sound or a flow noise of the pressurized respiratory gas in the respiratory cavity 12 in the stowed configuration. Other noises may be picked up by the microphone 20, in particular a flow noise from the respiratory cavity 12 to the ambient air of the cabin 5 when the user exhales.However, in the illustrated embodiment, these other noises are not discriminated, given that their overall sound level appeared sufficiently low not to significantly hinder the proper understanding of the words.

[0062] In the use configuration, the breathing cavity 12 is substantially closed (the breathing gas flows through the breathing cavity 12 to the lungs of the user 2), delimited on the one hand by the face shell 11 and on the other hand by the face of the user 2. In the stowed configuration, the breathing cavity 12 is open, so that the breathing gas flowing into the breathing cavity 12 can escape into the ambient air of the cabin 5.

[0063] There figure 4illustrates a first curve 62 representing the sound intensity of a flow noise through the respiratory cavity 12 in the configuration of use picked up by the microphone 20 as a function of the frequency. In other words, the first curve 61 is a frequency representation of the first electrical signal 52 during inhalation by the user 2.

[0064] There Figure 5 illustrates a second curve 64 representing the sound intensity of a flow noise through the respiratory cavity 12 in the stowed configuration as a function of frequency. In other words, the second curve 62 is a frequency representation of the first electrical signal 52 during a test with the respiratory mask 10 inside the storage box 40.

[0065] The difference between the first curve 62 illustrated in the figure 4 and the second curve 64 illustrated in the Figure 5appears due in particular to the fact that the respiratory gas flows into the closed respiratory cavity 12 versus the respiratory cavity 12 is open to the ambient air and to the fact that the user's face has different sound absorption characteristics from the storage box 40 or the ambient air.

[0066] A spectral analysis of the first curve 62 and the second curve 64 shows that the flow noise of the respiratory gas in the respiratory cavity 12 is composed of white noise both in the use configuration and in the stowed configuration, i.e., the flow noise of the respiratory gas in the respiratory cavity 12 has approximately the same intensity over a wide frequency range. Despite this, differences appear between the first curve 62 and the second curve 64. The analysis shows in particular a high intensity component of the first curve 62 above 10 kHz and more particularly 30 kHz.

[0067] When the first sound monitor 22 detects that the first electrical signal 52 has, in the first frequency range, a first intensity which is included in a first determined level range, the first sound monitor 22 sends a first message 23 to the controller 32 which corresponds to the detection of a flow noise through the respiratory cavity 12 in the use configuration. Otherwise, the first message 23 sent by the first sound monitor 22 to the controller 32 corresponds to an absence of detection of flow noise through the respiratory cavity 12 in the use configuration. The first message 23 sent to the controller 32 is therefore binary.

[0068] Therefore, if the first sound monitor 22 detects a sound with frequencies above 10 kHz and with an intensity above 60 dBa in this frequency range, it can be deduced that the first electrical signal 52 corresponds to the noise of the respiratory gas inhaled by the user 2 in the use configuration.

[0069] The second sound monitor 24 monitors a second frequency range to determine whether the first electrical signal 52 corresponds to a vocal sound. In other words, the second frequency range is chosen to achieve satisfactory discrimination, in particular between, on the one hand, a speech sound and, on the other hand, a noise of oxygen flow under pressure in the respiratory cavity 12 in the use configuration or in the stowed configuration. Here again, other noises can be picked up by the microphone 20. Vocal sound is understood to mean human speech, in particular the speech of the user 2.

[0070] When the second sound monitor 24 detects that the first electrical signal 52 has a second intensity in the second frequency range that is within a second determined level range, the second sound monitor 24 sends a second message 25 to the controller 32 that corresponds to the detection of a vocal sound. Otherwise, the second message 25 sent by the second sound monitor 24 to the controller 32 corresponds to an absence of detection of vocal sound. The second message 25 sent to the controller 32 is also binary.

[0071] The second monitor 24 is configured to detect a sound in a second frequency range characteristic of a vocal sound. Preferably, the second frequency range extends below 1000 Hz, for example below 500 Hz and more preferably between 130 Hz and 230 Hz. Alternatively, the second frequency range could be centered on 180 Hz plus or minus 25 Hz and have an amplitude between 50 Hz and 250 Hz.

[0072] In the illustrated embodiment, the second intensity extends above a second level, for example above 60 dBa.

[0073] The third sound monitor 26 monitors a third frequency range to determine whether the first electrical signal 52 corresponds to a flow noise through the respiratory cavity 12 when the respiratory mask 10 is in the stowed configuration. In other words, the third frequency range is chosen to achieve satisfactory discrimination in particular between, on the one hand, a flow noise of pressurized respiratory gas in the respiratory cavity 12 in the stowed configuration and, on the other hand, a speech sound or a flow noise of pressurized respiratory gas in the respiratory cavity 12 in the use configuration. Other noises that can be picked up by the microphone 20 are not discriminated in the illustrated embodiment.

[0074] It has been found that in order to perform good discrimination between a speech sound and a respiratory gas flow noise in the respiratory cavity 12 in the stowed configuration, the third frequency range is preferably selected above 1000 Hz, more preferably above 1500 Hz. Furthermore, the third frequency range should preferably extend (at least in part) above 2000 Hz, more preferably above 2500 Hz.

[0075] Furthermore, to perform good discrimination between a respiratory gas flow noise in the respiratory cavity 12 in the stowed configuration and a respiratory gas flow noise in the respiratory cavity 12 in the use configuration, the third frequency range is preferably selected (entirely) below 5000 Hz, more preferably below 4500 Hz.

[0076] Furthermore, it has been found that when the breathing mask is in the storage box 40, an intensity peak appears in a range of approximately 2,500 Hz to 3,500 Hz depending on the characteristics of the storage box 40. Therefore, the third frequency range is preferably centered between 2,500 Hz and 3,500 Hz and the width of the second frequency range is preferably less than 2,000 Hz, more preferably less than 500 Hz.

[0077] In the illustrated embodiment, preferably the third frequency range is centered at 2800 Hz, and extends 200 Hz on either side, in other words, the second frequency range extends between 2600 Hz and 3000 Hz.

[0078] Preferably, the third frequency range monitored by the third sound monitor 26 is determined by a filter of order greater than or equal to 2, preferably greater than or equal to 4.

[0079] In the illustrated embodiment, the third intensity extends above a third level, for example above 60 dBa.

[0080] The controller 32 receives the first message 23 from the first sound monitor 22, the second message 25 from the second sound monitor 24 and the third message 27 from the third sound monitor 26.

[0081] When the second message 25 corresponds to the detection of vocal sound, the controller 32 sends a control message 33 to the attenuation device 32 to place it in the second mode, regardless of the first message 23 and the third message 27. In other words, the second message 25 takes precedence over the first message 23 and the third message 27.

[0082] When the third message 27 corresponds to the detection of respiratory gas flow noise in the respiratory cavity 12 in the stowed configuration, the controller 32 sends a control message 33 to the attenuation device 32 to place it in the second mode, regardless of the first message 23. In other words, the third message 27 takes precedence over the first message 23. Thus, even if the first sound monitor 22 detects respiratory gas flow noise in the respiratory cavity 12 in the flow configuration, while in reality the communication assembly is in the stowed configuration, the communication assembly 1 can be tested (the sound is not attenuated).Alternatively, it could be provided that the first message 23 takes precedence over the third message 27, in other words that when the second message 25 corresponds to the absence of detection of vocal sound and the first message corresponds to the detection of noise of respiratory gas flow in the respiratory cavity 12, the controller places the attenuation device 34 in the first mode regardless of the third message 27.

[0083] When the first message 23 corresponds to the detection of respiratory gas flow noise in the respiratory cavity 12 in a use configuration and the second message 25 corresponds to the absence of detection of vocal sound and the third message corresponds to the absence of detection of respiratory gas flow noise in the respiratory cavity 12 in a stowed configuration, the controller 32 sends a control message 33 to the attenuation device 32 to place it in the first mode.

[0084] When the first message 23 corresponds to the absence of detection of respiratory gas flow noise in the respiratory cavity 12 in a use configuration, the second message 25 corresponds to the absence of detection of vocal sound and the third message corresponds to the absence of detection of respiratory gas flow noise in the respiratory cavity 12 in a stowed configuration, the controller 32 places the attenuation device 32 in the second mode. However, alternatively, the controller 32 could send a control message 33 to the attenuation device 32 to place it in the first mode, if it were found that such a situation corresponds to another parasitic noise, such as the exhalation of the user 2 through the respiratory cavity 12.

[0085] The controller 2 can be configured to perform logic tests two by two between the first message 22, the second message 24 and the third message 26, the control message 33 being the result of the different logic tests.

[0086] The microphone assembly 30 comprises a microphone electronics board 21 and a monitoring electronics board 35 connected by an electrical cable 19. The microphone electronics board 21 is arranged in the body 14 of the breathing mask 10. The monitoring electronics board 35 is arranged away from the breathing mask 10, in particular on the storage box 40 or another location in the cabin 5 of the aircraft. The attenuation device 34, the filter 36 and the transmitter 38 are arranged on the monitoring electronics board 35.

[0087] In one embodiment, the controller 32 comprises a first logic unit and a second logic unit. The first logic unit performs a test between the first message 23 and the third message 27, the result of which is tested by the second logic unit with the second message 25 to obtain the control message 33 sent to the attenuation device 32 according to one of the logics explained above. Furthermore, the first sound monitor 22, the third sound monitor 26 and the first logic unit are preferably arranged on the microphone electronics board 21, while the second sound monitor 24 and the second logic unit are arranged on the monitoring electronics board 35. Alternatively, the first sound monitor 22, the second sound monitor 24, the third sound monitor 26, the first logic unit and the second logic unit could all be arranged on the monitoring electronics board 35.

[0088] In another embodiment, the first logic unit performs a test between the first message 23 and the second message 25, the result of which is tested by the second logic unit with the third message 27 to obtain the control message 33 sent to the attenuation device.

[0089] Although the present disclosure has been illustrated and described in detail in the drawings and the preceding description, this illustration and description should be considered as an illustrative and not a limiting example. For example, the microphone transmitting the first electrical signal 52 could be a second microphone to which the second sound monitor 24 is connected, the first sound monitor 22 being connected to a first microphone different from the second microphone and / or the third sound monitor 26 could be connected to a third microphone different from the second microphone, the different microphones possibly having different acoustic responses. Therefore, the first electrical signal 52 could be notably different from the electrical signal received by the first sound monitor 22.

[0090] In particular, the second microphone could be selected to be particularly sensitive to speech signals and with little distortion within the speech bandwidth. The first microphone and / or the third microphone could be chosen to achieve a wide bandwidth response, but a low requirement regarding distortion.

[0091] The microphone circuit board 21 and / or the monitoring circuit board 35 may be in the form of a printed circuit board using discrete analog components such as a filter, operational amplifiers used to amplify the signals and compare them to predetermined levels, and logic components to control the behavior of the board.

[0092] The microphone electronics board 21 and / or the monitoring electronics board 35 may be in the form of a digital board or a mixed analog / digital board, using software and a digital signal processor (DSP) to embody the functions described above. For example, an analog-to-digital converter may convert the signals emitted by the microphone 20 into a stream of integers representative of the captured sounds. The stream of integers is processed by a software-controlled processor to analyze the characteristics of the captured sounds and determine the attenuation to be applied as explained above.

Claims

1. A communication assembly (1) for avoiding interferences due to oxygen flow noise in communications between a user (2), an aircrew member, and another aircrew member or between the user and a control tower, said communication assembly comprising: a) a breathing mask (10) including: a body (14) having a face shell (11) having a breathing cavity (12), said face shell (11) being adapted to be applied on the face of the user (2) in a use configuration in which the breathing cavity (12) is delimited by said face shell (11) and by the face of the user (2), a regulator (16) including an inlet orifice (15) intended to be connected to an oxygen source (4) and an outlet orifice (17) delivering a breathing gas containing oxygen, the outlet orifice (17) being in flow communication with the breathing cavity (12) for supplying the breathing gas to the user (2) in a flow through the breathing cavity (12) during inhalation by the user (2), b) a test button (8) for supplying the breathing cavity with breathing gas when the communication assembly is in a stowed configuration in which the breathing cavity (12) is not in contact with the face of the user (2), c) a microphone (20) mounted on the body (14) of the breathing mask (10), the microphone (20) being configured to capture a sound signal in the breathing cavity (12) and transmit a first electrical signal (52) corresponding to the captured sound signal, d) an attenuation device (34) configured to receive the first electrical signal (52) and operate in at least a first mode or a second mode and transmit a second electrical signal (54), wherein: in the first mode, the attenuation device (34) attenuates at least one central frequency band of the first electrical signal (52), said central frequency band corresponding to a frequency range of the sound signal extending between 500 Hz and 1,500 Hz, and in the second mode, the attenuation device (34) does not attenuate the central frequency band of the first electrical signal (52); e) a sound monitoring system (28) comprising: a first sound monitor (22) configured to monitor the sound signal, detect a first sound intensity in a first frequency range and analyse the first sound intensity to determine whether the first sound intensity is within a first determined level range to detect a flow noise through the breathing cavity (12) during inhalation by the user in the use configuration, and a second sound monitor (24) configured to monitor the sound signal, detect a second sound intensity in a second frequency range and analyse the second sound intensity to determine whether the second sound intensity is within a second determined level range to detect a vocal sound, the second frequency range being distinct from the first frequency range; and f) a controller (32) configured to select the operating mode of the attenuation device, in order to make the attenuation device operate in: the first mode (i) when the first sound intensity analysed by the first sound monitor (22) is within the first determined level range and (ii) when the second sound intensity analysed by the second sound monitor is not within the second determined level range, and the second mode when the second sound intensity analysed by the second sound monitor is within the second determined level range; g) a transmitter (38) disposed downstream of the attenuation device (34) for transmitting an output signal (58) to another crew member or an emitter antenna, wherein: the sound monitoring system (28) is configured to monitor the sound signal, detect a third sound intensity in a third frequency range and analyse the third sound intensity to determine whether the third sound intensity is within a third determined level range to detect a flow noise in the breathing cavity (12) in the stowed configuration, the third frequency range being distinct from the first frequency range, and the controller (32) is configured not to make the attenuation device (34) operate in the first mode when the third sound intensity is within the third level range.

2. The communication assembly according to claim 1, wherein the third frequency range extends at least partially above 2,000 Hz, preferably at least partially above 2,500 Hz.

3. The communication assembly according to any one of the preceding claims, wherein the third frequency range extends entirely below 5 kHz, preferably below 4.5 kHz.

4. The communication assembly according to any one of the preceding claims, wherein the communication assembly further comprises a storage box (40) configured to receive the breathing mask (10) in the stowed configuration.

5. The communication assembly according to the preceding claim, wherein the third frequency range is centred between 2,500 Hz and 3,500 Hz.

6. The communication assembly according to any one of the preceding claims, wherein the third frequency range extends entirely above 1,000Hz, preferably entirely above 1.5 kHz.

7. The communication assembly according to any one of the preceding claims, wherein the sound monitoring system (28) comprises a third sound monitor (26) distinct from the second sound monitor (22), the third sound monitor (26) being configured to monitor the sound signal, detect the third sound intensity in the third frequency range and analyse the third sound intensity to determine whether the third sound intensity is within the third level range determined to detect flow noise in the breathing cavity (12) in the stowed configuration, the third frequency range being distinct from the second frequency range.

8. The communication assembly according to any one of the preceding claims, wherein, in the first mode, the attenuation device (34) silences all of the sound signal.

9. The communication assembly according to the preceding claim, wherein the controller (32) is configured to make the attenuation device (34) operate in the first mode only when: the first sound intensity analysed by the first sound monitor (22) is within the first determined level range, the second sound intensity analysed by the second sound monitor (24) is not in the second determined level range, and the third sound intensity is not in the third determined level range.

10. An aircraft equipped with a communication assembly according to any one of the preceding claims.

11. A method for avoiding interferences due to oxygen flow noise in communications between a user (2), an aircrew member, and another aircrew member or between the user and a tower control, wherein a communication assembly (1) comprises a breathing mask (10), a microphone (20) and a test button (8), the breathing mask (10) including a body (14) and a regulator (16), the body (14) of the breathing mask (10) having a face shell (11), said face shell (11) having a breathing cavity (12), the regulator (16) supplying the breathing cavity (12) during inhalation by the user (2), the microphone (20) being mounted on the body (14) of the breathing mask (10) and being configured to capture a sound signal in the breathing cavity (12) and to transmit a first electrical signal (52) corresponding to the captured sound signal, the test button (8) allowing supplying the breathing cavity (12) with breathing gas when the breathing mask (10) is in a stowed configuration in which the breathing cavity (12) is not in contact with the face of the user (2), an attenuation device (34) being configured to receive the first electrical signal (52), the method comprising: placing the breathing mask (10) in a use configuration in which the face shell (11) is applied on the face of the user (2), the breathing cavity (12) being delimited by said face shell (11) and by the face of the user (2) or placing the face shell (11) of the breathing mask (12) in the stowed configuration and actuate the test button (8), monitoring, in a first frequency range, a first sound intensity of the sound signal captured by the microphone (20), analysing the first sound intensity and determining whether the first sound intensity is within a first determined level range to detect a flow noise through the breathing cavity (12) during inhalation by the user (2) in the use configuration, monitoring, in a second frequency range, a second sound intensity of the sound signal captured by the microphone (20), the second frequency range being distinct from the first frequency range, analysing the second sound intensity and determining whether the second sound intensity is in a second determined level range to detect a vocal sound, monitoring, in a third frequency range, a third sound intensity of the sound signal captured by the microphone (20), the third frequency range being distinct from the first frequency range and analysing the third sound intensity to determine whether the third sound intensity is within a third determined level range to detect a flow noise in the breathing cavity (12) in the stowed configuration, attenuating at least a central frequency band of the first electrical signal (52) to generate an output signal (58), the central frequency band of the first electrical signal (52) corresponding to a frequency range of the sound signal extending between 500 Hz and 1,500 Hertz when (i) the first sound intensity analysed by a first sound monitor (22) is within the first determined level range and (ii) when the second sound intensity analysed by a second sound monitor (24) is not within the second determined level range and (iii) the third sound intensity is not within the third level range, not attenuating the central frequency band of the first electrical signal to generate the output signal (58), when the second sound intensity analysed by the second sound monitor (24) is within the second determined level range, and transmitting the output signal to another crew member or an emitter antenna.