Method and system for detecting drowsiness and / or sleep - Patents.com

Abstract

A method and system are provided for detecting drowsiness and / or sleep and controlling the volume of audio delivered, for example, from an in-ear speaker. An outer ear pressure detected between the eardrum and the in-ear speaker is acquired and processed together with the frequency and amplitude characteristics of the delivered audio. In this manner, a baseline ear pressure over time is obtained. Drowsiness and / or sleep can be detected from the derived baseline ear pressure, so that, for example, the volume of the delivered audio can be adapted accordingly.

Description

[Technical field]

[0001] The present invention relates to the detection of drowsiness and / or sleep. For example, such detection can be used to control the sound delivered by in-ear speakers, in particular to provide automatic power-off when the listener is asleep. Such detection can also be used to control other external devices. [Background technology]

[0002] Music has always been an essential part of modern culture. Advances in digital technology have made it possible to listen to music anytime and anywhere using personal listening devices (PLDs) such as iPods, mobile phones, and tablet computers. Summary of the Invention [Problem to be solved by the invention]

[0003] Music has been shown to have beneficial effects and has been used as part of music therapy to manage many neurological and psychiatric disorders. However, recent scientific studies have found that excessive listening to music on a PLD may induce hearing loss or accelerate age-related hearing loss. The prevalence of hearing loss due to music exposure in young adults has been reported to range from 9.3% to 14%.

[0004] Furthermore, it has been observed that approximately 58% of adolescents and college students exceed the recommended maximum noise exposure while listening to music. The volume level of music as well as the total duration of exposure have been observed to be significantly correlated with hearing loss. If not detected and treated in time, hearing loss due to such exposure can be permanent.

[0005] PLDs are often used with in-ear speakers, i.e. earplugs / earphones. Many people fall asleep listening to music. In such situations, continuous and long-term exposure to music can be harmful to the ears.

[0006] It has been proposed to automatically reduce the volume of music when sleep is detected. For example, WO 2012 / 058886 and CN 109561219 each disclose using pressure detection to detect pulse and identifying sleep from pulse characteristics such as heart rate variability.

[0007] However, pulse detection may not be accurate because the heartbeat may be drowned out, for example, by the music one is listening to, which may even have a rhythm that corresponds to the pulse rate. [Means for solving the problem]

[0008] The invention is defined by the claims.

[0009] An embodiment according to one aspect of the present invention provides a method for detecting drowsiness and / or sleep comprising the steps of receiving an outer ear pressure detected between the eardrum and the in-ear speaker from a pressure sensor forming part of the in-ear speaker during delivery of audio to the in-ear speaker, processing frequency and amplitude characteristics of the delivered audio and the outer ear pressure to derive a baseline ear pressure over time, and detecting drowsiness and / or sleep from the derived baseline ear pressure.

[0010] This method uses pressure sensing to detect drowsiness and / or sleep. Instead of using pressure sensing to detect pulse in known methods, a baseline (residual) pressure is obtained by separating the pressure resulting from the subject's physiology from the pressure generated by the audio. The baseline pressure is the pressure resulting from the subject's physiology after removing the pressure effect of the music (or other audio) being listened to. The baseline pressure allows for the detection of various events such as short-term pressure changes due to yawning, or gradual pressure changes over time.

[0011] Audio data for the transmitted audio is received and frequency and amplitude characteristics of the transmitted audio are processed using the audio data. A baseline ear pressure is obtained by subtracting the pressure effect of the audio being listened to from the detected outer ear pressure.

[0012] The detected drowsiness and / or sleep can be used to control the device, for example to turn the device off or to reduce the volume. For example, in response to detected drowsiness or sleep, the volume delivered by the in-ear speaker itself can be reduced or the audio can be turned off (i.e., the volume is adapted to zero). The volume can also be gradually reduced to zero.

[0013] At its simplest level, the method can be implemented without the need for any dedicated external sensors to detect sleep or drowsiness states. Instead, basic hardware present in the in-ear speaker itself is used for sleep detection. The acoustic transducer in the earphone can be reversed to function as a microphone to detect pressure changes. To this end, a duty cycle control can be used to alternate between speaker and pressure sensor (i.e., microphone) functions.

[0014] The method may include, for example, applying a time stamp to the audio and the detected ear pressure using a shared clock, so that the different signals can be synchronized for analysis.

[0015] Detecting drowsiness and / or sleep may include detecting a yawning event from the baseline ear pressure and / or detecting an increase in middle ear pressure associated with sleep from the baseline ear pressure.

[0016] Yawning indicates the onset of sleep. The frequency of yawning events can be monitored, for example, over time. Middle ear pressure is known to increase during sleep, and this can be detected from the measured outer ear pressure by separating the audio pressure from the baseline pressure.

[0017] The method may further comprise detecting correct fitting of the in-ear speaker to the ear and generating an output signal indicative of when the fit is not correct.

[0018] Pressure sensing requires that a closed cavity be formed to allow accurate measurement and interpretation of baseline pressure measurements, so that in the event of an incorrect fit, a warning can be provided and / or controls based on sleep detection can be overridden.

[0019] The method may further comprise sensing outer ear pressure during the calibration phase to determine a subject-specific pressure characteristic.

[0020] This allows the analysis of the baseline pressure to be more accurate for a particular subject. The calibration phase may, for example, involve the subject performing tasks such as (simulated) yawning, swallowing, and / or jaw movements. This calibration phase may also be used to detect ear pathologies.

[0021] Deriving the baseline ear pressure over time can include using an analytical model of the ear canal, which takes into account the volume and shape of the ear canal cavity.

[0022] The analytical model is constructed for the subject, for example, by sensing one or more ear canal size or shape characteristics.

[0023] Proximity or ultrasonic sensors can be used for this purpose. The model can also take into account, for example, the age and sex of the subject.

[0024] The method may further include sensing motion of the subject using the inertial monitoring unit and additionally detecting drowsiness and / or sleep from the sensed motion.

[0025] This monitors head movement while listening to audio. As a person becomes drowsy, their head movement is expected to decrease and eventually the head will stabilize in a particular position for a period of time. Head movement can then be correlated with baseline pressure changes to detect drowsiness or sleep. The inertial monitoring unit can form part of the in-ear speaker.

[0026] The invention provides a method of controlling a device, comprising the steps of detecting drowsiness and / or sleep and controlling the device dependent on the detection of drowsiness and / or sleep. The controlled device may be the in-ear speaker itself (e.g. by controlling a source sending audio to the in-ear speaker), an external device such as a television, or a non-audio device such as a lighting device, a heating device, a device putting a mobile phone into "sleep mode", etc.

[0027] Thus, in one example, the device has in-ear speakers and controlling the device includes adapting the volume (or on / off state) of audio delivered in response to detection of drowsiness and / or sleep.

[0028] The method may further comprise detecting an awakening from sleep and controlling the delivery of audio by the in-ear speaker to improve sleep quality. The awakening from sleep may be detected by an inertial monitoring unit of the mobile phone or other sensors such as an EEG sensor. When an awakening is detected, other devices may be controlled, for example a coffee machine.

[0029] The method may further comprise controlling a valve to vent a space between the eardrum and the in-ear speaker to an ambient environment in response to detecting drowsiness and / or sleep.

[0030] The valve provides a physical connection that, when opened, creates an air passage between the ear canal and the outside, so that the ear canal is no longer a closed cavity. This connection can be opened when the audio volume is turned down or off. This reduces humidity in the ear canal and establishes a near-normal airflow, thus reducing the risk of infection.

[0031] The invention also provides a computer program having a computer program code configured to perform the method described above, when the computer program is run on a computer.

[0032] The present invention further provides a drowsiness and / or sleep detection system comprising an in-ear speaker having a pressure sensor for detecting outer ear pressure between the eardrum and the in-ear speaker, the system being configured to perform the steps of receiving the detected outer ear pressure from the pressure sensor, processing frequency and amplitude characteristics of audio delivered to the in-ear speaker and the corresponding detected outer ear pressure to derive a baseline ear pressure over time, and detecting drowsiness and / or sleep from the derived baseline ear pressure.

[0033] The processor is configured to detect drowsiness and / or sleep, for example by detecting a yawn event from the baseline ear pressure and / or detecting an increase in middle ear pressure associated with sleep from the baseline ear pressure.

[0034] The present invention further provides an audio delivery system having a drowsiness and / or sleep detection system as defined above, wherein a processor is configured to adapt the volume (or on / off state) of the delivered audio in response to detection of drowsiness and / or sleep.

[0035] The system (for drowsiness detection or audio delivery) may further comprise a sensor device for detecting correct fitting of the in-ear speaker to the ear, the processor being configured to generate an output signal indicative of when a correct fit has not been achieved.

[0036] The system (for drowsiness detection or audio delivery) may further comprise an inertial monitoring unit, the processor being configured to additionally detect drowsiness and / or sleep from the detected movements.

[0037] The audio delivery system may further comprise a sensor device for detecting arousal from sleep, in which case the processor is configured to control the delivery of the audio in response to detecting arousal from sleep to improve sleep quality.

[0038] The system (for drowsiness detection or audio delivery) may further comprise a valve for venting the space between the eardrum and the in-ear speaker to the surrounding environment, in which case the processor is configured to control the valve in response to detection of drowsiness and / or sleep.

[0039] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0040] For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which: [Brief description of the drawings]

[0041] [Figure 1] FIG. 1 illustrates an audio transmission system. [Diagram 2] FIG. 2 illustrates a calibration phase of a method for controlling the volume of audio delivered through an in-ear speaker. [Diagram 3] FIG. 13 illustrates a volume control method after a calibration phase. [Figure 4] FIG. 1 shows a plot of baseline pressure over time and a single yawn event. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] The present invention will now be described with reference to the drawings.

[0043] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the devices, systems and methods, are for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects and advantages of the devices, systems and methods of the present invention will become better understood from the following description, the appended claims and the accompanying drawings. It should be understood that the drawings are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to denote the same or similar parts.

[0044] The present invention provides a method and system for detecting drowsiness and / or sleep and then controlling the volume of audio delivered, for example, from an in-ear speaker. The outer ear pressure detected between the eardrum and the in-ear speaker is acquired and processed together with the frequency and amplitude characteristics of the delivered audio. In this way, a baseline ear pressure over time is obtained. Drowsiness and / or sleep can be detected from the derived baseline ear pressure and, for example, the volume of the delivered audio can be adapted accordingly.

[0045] FIG. 1 shows an audio delivery system 10 that includes an in-ear speaker 20 having a pressure sensor 22 that detects the outer ear pressure between the eardrum and the in-ear speaker 20 .

[0046] Audio is sent to the system 10 from an audio source 30. Typically, the audio source 30 is a mobile phone or music player, and communication between the audio source and the system 10 is via short-range wireless communication such as Bluetooth®. Of course, a wired connection is also possible.

[0047] A processor 24 of the system receives the sensed outer ear pressure from the pressure sensor 22 and also analyses the frequency and amplitude characteristics of the audio sent to the in-ear speakers. Optionally, the system further comprises an inertial monitoring unit IMU 26.

[0048] The processor functions are shown in Figure 1.

[0049] A first module 40 receives the sensed outer ear pressure from the pressure sensor 22 and also receives the audio data. A second module 42 extracts from the sensed outer ear pressure a component resulting from the audio itself. In this way, a baseline ear pressure over time is derived. This baseline ear pressure is derived from the listener's physiology.

[0050] A second module 42 processes the baseline ear pressure to detect drowsiness and / or sleep, and a third module 44 of the processor 24 then generates a volume control signal V to adapt the volume of the delivered audio depending on the detection of drowsiness and / or sleep. The volume control signal V is returned to the audio source 30.

[0051] 1 shows a single in-ear speaker, but of course a system would typically have a pair of in-ear speakers, and sleep detection can be implemented in one or both in-ear speakers.

[0052] Figure 2 shows a first step of a method for controlling the volume of audio delivered through in-ear speakers. The steps of Figure 2 can be considered as part of a calibration phase before a user of the system uses the speakers to listen to audio.

[0053] In use, at step 50, the in-ear speaker is inserted into the outer ear, sealing the ear canal from the outside air. This essentially creates a closed cavity. The pressure sensor 22 is on one side of the cavity and the eardrum is on the other side of the cavity.

[0054] While the outer ear pressure is detected and monitored over time in step 52, the subject is asked to perform several simple actions, such as swallowing, yawning, and dropping the chin, in step 54. These actions produce pressure changes in the outer ear that are analyzed in step 56. This information is used as a baseline for subsequent processing.

[0055] This information is further used to detect that the in-ear speakers are correctly positioned and functioning, and to allow measurement of the baseline pressure in the ear canal, step 58. If the in-ear speakers are not working properly, this can be indicated using an audio-visual indicator, step 60.

[0056] Existing pathologies of the outer ear can also be checked by analyzing pressure changes in the outer ear. If any pre-existing pathologies are present, this can again be indicated by an audiovisual indicator.

[0057] For example, detection of a tympanic membrane perforation is performed in step 62 and, if present, this is indicated by an audiovisual indicator in step 64 .

[0058] Detection of other pathologies is performed at step 66 and, if present, this is indicated by an audiovisual indicator at step 68 .

[0059] The above calibration steps are optional: while calibration is preferred to adapt the system to an individual subject, detection of pathologies is entirely optional.

[0060] FIG. 3 illustrates the volume control method after the calibration phase.

[0061] In step 70, the user turns on the audio, which automatically activates the pressure sensor, which then measures pressure in step 72. The pressure in the outer ear is monitored in real time and is denoted P_Measured.

[0062] The audio being played creates sound waves that travel through the air by displacing a nearby column of air, which is sealed in the ear canal by the in-ear speaker on one end and the eardrum on the other, changing the pressure within the ear canal.

[0063] The pressure change in the ear canal depends on both the frequency and amplitude of the sound waves resulting from the reproduced audio, and the physical dimensions of the ear canal. The ear canal is generally an elliptical cylinder, approximately 25 mm long and 7 mm in diameter. To measure the pressure change, a lossless cylindrical tube model was proposed as an approximation of the ear canal. Therefore, the volume of the occluded cavity created by an in-ear speaker can be calculated as follows: V = πr2h (1) where h is the distance between the pressure sensor and the eardrum, and r is the radius of the ear canal. Standard values ​​can be used for h and r, for example based on age and gender. However, precise values ​​can also be used by using appropriate sensors such as proximity sensors, ultrasonic sensors, etc.

[0064] The audio characteristics, particularly frequency and amplitude, are analyzed by the processor in step 74. Using an anatomical model of the outer ear as described above, the change in outer ear pressure for a particular subject using the system can be derived for a given frequency and amplitude of the audio being played. The resulting pressure from the audio, denoted as P_Music, is obtained in step 76 using the frequency and amplitude information of the audio.

[0065] The processor receives the pressure measurements P_Measured as well as the audio being played. By using, for example, timestamps, the pressure waveform over time can be aligned with the audio data that was played to give the pressure waveform.

[0066] The measured pressure depends on both the baseline pressure in the ear canal (P_BL) and the pressure change due to the audio (P_Music), which can be expressed as: P_Measured = f(P_BL, P_Music) (2)

[0067] Based on empirical or experimental data, it is possible to derive a mathematical model for deriving a baseline outer ear pressure (P_BL) from the pressure P_Measured measured in the presence of audio in the outer ear (with a corresponding pressure P_Music).

[0068] Thus, in step 80, a baseline outer ear pressure can be obtained based on a mathematical model that can be expressed as follows: P_BL = f(P_Measured,P_Music) (3)

[0069] The baseline outer ear pressure is obtained, for example, using a machine learning algorithm. Experimental data is used for training, and standard machine learning tools such as linear regression are used to derive the relationship in equation (3).

[0070] For a linear regression model, this can be written as: P_BL=β0+β1(P_Measured)+β2(P_Music), where β0 is a constant term, and β1 and β2 are coefficients derived using experimental data.

[0071] The baseline outer ear pressure is used to detect drowsiness and / or sleep.

[0072] The state of drowsiness before sleep is characterized by frequent yawning. During yawning, the pressure in the nasopharyngeal cavity increases. The middle ear is connected to the nasopharynx via the Eustachian tube. The change in middle ear pressure leads to a displacement (bulging or retraction) of the tympanic membrane. In particular, during yawning, the increase in middle ear pressure leads to a transient bulging of the tympanic membrane towards the outer surface.

[0073] As a result, in step 82, the occurrence of a yawn can be detected based on the pressure change in the outer ear baseline pressure. Measurements on a sufficiently large sample population can be used to generate a database of expected pressure changes in the outer ear during a yawn (in the presence of audio). Every occurrence of a yawn that is detected based on the pressure signal characteristics is time-stamped for further processing. In step 84, it is detected whether the frequency of yawning increases for a predetermined period of time (above a predetermined threshold). This analysis can be used to indicate a state of drowsiness in step 86.

[0074] This information is then used in step 88 to either lower the audio volume or turn the audio off completely.

[0075] Instead of, or as well as, detecting drowsiness based on yawning, pressure monitoring can also be used to detect sleep. It is known that during sleep, middle ear pressure slowly increases. An increase in middle ear pressure leads to an outward bulging of the eardrum. This leads to a slow increase in baseline pressure in the outer ear if it creates a blocked cavity. Thus, in step 89, the baseline pressure P_BL is monitored and in step 90, it is determined whether a gradual increase in this baseline outer ear pressure is detected. If there is a gradual increase, this is used in step 92 to determine that the individual has fallen asleep, which causes the audio volume to be lowered again or switched off completely in step 88.

[0076] If neither drowsiness nor sleep is detected, the method returns to step 72 for the next analysis.

[0077] Figure 4 shows a plot of baseline pressure over time, illustrating a single yawning event. There are various features (labeled k-s) that can be used to enable reliable detection of yawning from pressure changes.

[0078] The in-ear speaker may further include an inertial measurement unit (IMU) that monitors head movements while listening to audio. As a person becomes drowsy, head movements are expected to decrease and eventually the head will stabilize in a particular position for an extended period of time. Thus, head movements are correlated with pressure changes in the outer ear to detect drowsiness or sleep and control the audio accordingly.

[0079] Additional sensing can be performed, for example, using sensors already present in the audio source, for example a cell phone, which has an IMU and other sensors such as an electroencephalography (EEG) sensor can be used to sense drowsiness or sleep.

[0080] The system can further detect arousal from sleep, for example, based on pressure changes and IMU measurement patterns, and if an impending awakening is detected, the system plays an appropriate masking noise (such as white noise, brown noise, pink noise, etc., at a predetermined intensity) to improve sleep quality.

[0081] In another example, the in-ear speaker can have a valve to vent the space between the eardrum and the in-ear speaker to the surrounding environment. When the valve is opened, the ear canal is no longer a closed space. The system can then be configured to open this connection when lowering the audio volume based on drowsiness detection. This helps to reduce humidity in the ear canal and establish a near-normal airflow, thus reducing the risk of infection.

[0082] The above examples show the pressure sensor as a separate component added to the in-ear speaker, however the speaker itself can be used as the pressure sensor (i.e. functioning as a microphone), e.g., with duty cycle control to alternate between pressure sensing and speaker functions.

[0083] The main example of interest is controlling the audio delivered by the in-ear speakers. However, other devices, such as lighting, heating, or other sound sources such as a television or an external audio device, can be controlled based on the detection of sleep or drowsiness. The control can include level control (e.g. volume or light level) or on-off control. Thus, more generally, the invention provides a method for detecting drowsiness or sleep using the pressure cavity created by the in-ear speakers, and this detected information can then be used in any desired way to control the audio delivery by external devices and / or the in-ear speakers themselves.

[0084] The above examples detect yawning events from the baseline ear pressure as an indicator of drowsiness and / or detect sleep-related increases in middle ear pressure, however, any suitable analysis of the baseline pressure that allows information regarding sleep or drowsiness to be determined may be performed and these are merely possible examples.

[0085] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, 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.

[0086] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0087] The 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 telecommunications systems.

[0088] When the term "adapted to" is used in the claims or the description, the term "adapted to" is meant to be equivalent to the term "configured to." When the term "arrangement" is used in the claims or the description, the term "arrangement" is intended to be equivalent to the term "system," and vice versa.

[0089] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. 1. A method for detecting drowsiness and / or sleep in a subject, comprising: receiving, during delivery of audio to the in-ear speaker, a sensed outer ear pressure between the eardrum and the in-ear speaker from a pressure sensor forming part of the in-ear speaker; receiving audio data for the transmitted audio; (i) processing the frequency and amplitude characteristics of the delivered audio obtained using the audio data, and (ii) the detected outer ear pressure to remove pressure effects of the audio being listened to from the detected outer ear pressure to derive a baseline ear pressure over time; detecting drowsiness and / or sleep from the derived baseline ear pressure; How to do it.

2. The processor, Detecting a yawn event from the baseline ear pressure; and / or detecting an increase in middle ear pressure associated with sleep from said baseline ear pressure; The method of claim 1 further comprising:

3. The processor, Detecting a correct fitting of the in-ear speaker to an ear; generating an output signal indicative of any cases of erroneous fitting; The method of claim 1 or 2, further comprising:

4. The processor, Detecting outer ear pressure during a calibration phase and determining subject-specific pressure characteristics. The method of claim 1 , further comprising:

5. 5. The method of claim 1, wherein the step of deriving a baseline ear pressure over time comprises using an analytical model of the ear canal.

6. an inertial monitoring unit detecting motion of the subject; the processor additionally detecting drowsiness and / or sleep from the detected movements; The method of claim 1 , further comprising:

7. 1. A method of controlling an apparatus, comprising: Detecting drowsiness and / or sleep using a method according to any one of claims 1 to 6; controlling the device in response to detection of drowsiness and / or sleep; The method according to claim 1,

8. the device having an in-ear speaker; 8. The method of claim 7, wherein the step of controlling the device comprises adapting a volume of the audio delivered by the in-ear speaker, or an on / off state of the audio delivery, in response to detection of drowsiness and / or sleep.

9. detecting an arousal from sleep; controlling the delivery of audio by said in-ear speakers to improve sleep quality; The method of claim 8 further comprising:

10. 10. The method of claim 1, further comprising the step of controlling a valve to vent a space between the eardrum and the in-ear speaker to the surrounding environment in response to detection of drowsiness and / or sleep.

11. A computer program having computer program code which, when run on a computer, causes the method of any one of claims 1 to 10 to be carried out.

12. A drowsiness and / or sleep detection system for detecting drowsiness and / or sleep in a subject, comprising: an in-ear speaker having a pressure sensor for detecting outer ear pressure between the eardrum and the in-ear speaker; A processor; wherein the processor: receiving audio data for audio to be delivered to the in-ear speaker; receiving the detected outer ear pressure from the pressure sensor; (i) processing the frequency and amplitude characteristics of the delivered audio obtained using the audio data, and (ii) the corresponding detected outer ear pressure to derive a baseline ear pressure over time by removing the pressure effect of the audio being listened to from the detected outer ear pressure; detecting drowsiness and / or sleep from the derived baseline ear pressure; A system configured to execute the

13. The processor, Detecting a yawn event from the baseline ear pressure; and / or Detecting sleep-associated increases in middle ear pressure from said baseline ear pressure. Detecting drowsiness and / or sleep by The system of claim 12 further configured to:

14. 14. An audio delivery system comprising a drowsiness and / or sleep detection system according to claim 12 or 13, wherein the processor: adapting the volume of audio delivered or the on / off state of delivery of said audio in response to said detection of drowsiness and / or sleep. An audio distribution system configured to:

15. a sensor device for detecting a correct fitting of an in-ear speaker to an ear, the processor being configured to generate an output signal indicative of when there is an incorrect fitting; an inertial monitoring unit, the processor being configured to additionally detect drowsiness and / or sleep from detected movements; a valve for venting a space between the eardrum and an in-ear speaker to an ambient environment, the processor being configured to control the valve in response to detection of drowsiness and / or sleep; and a sensor device for detecting an arousal from sleep, the processor being configured to: control delivery of audio in response to detecting an arousal from sleep to improve sleep quality; 15. The audio distribution system of claim 14, comprising one or more of:

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