Active noise reduction headrest and binaural adaptive sound field control method thereof

Abstract

The application relates to an active noise reduction head pillow and a binaural adaptive sound field control method thereof, which comprises the following steps: a head resting area is formed by recessing the middle part of a pillow main body, and ear fitting areas are formed by protruding the two sides of the head resting area; two noise reduction modules are symmetrically embedded in the interiors of the two ear fitting areas; the noise reduction module comprises a sound generating unit and a processing unit, the noise reduction module further comprises a first collecting unit and a second collecting unit, the first collecting unit is arranged close to the outer side of the pillow main body and is used for collecting external incident noise to obtain a reference signal, the second collecting unit is arranged close to the position of the user's ear area and is used for collecting residual noise to obtain an error signal; and the processing unit generates a driving signal for driving the sound generating unit based on the reference signal obtained by the first collecting unit and the error signal obtained by the second collecting unit. The application can actively reduce the environmental noise near the user's ear, improve the environmental quietness during sleep, and meet the use requirements of waterproofness and washability.

Description

Technical Field

[0001] This invention relates to the field of sleep products and noise reduction equipment, and in particular to an active noise-canceling headrest with dustproof and waterproof properties and its binaural adaptive sound field control method. Background Technology

[0002] Environmental noise in the sleep and rest environment is a significant factor affecting the quality of human rest. Common interfering noises include road and rail traffic noise, air conditioner and fan noise, and other continuous low- to mid-frequency noises. These types of noises often have strong penetrating power and are not easily absorbed by ordinary soft materials, easily causing continuous psychological and physiological disturbances to users in a quiet sleep environment.

[0003] Existing noise-canceling products have significant shortcomings in addressing the aforementioned issues. First, headphone-style or earbud-style noise-canceling devices need to be worn directly on the ear or inserted into the ear canal. In sleep scenarios, especially when sleeping on one's side, the hard shell of the headphones can compress the auricle, resulting in extremely poor comfort during prolonged wear. Furthermore, these devices are prone to falling out and can cause ear canal hygiene problems, making it difficult to meet the need for continuous use throughout the night.

[0004] Secondly, while there are a few pillow products on the market that integrate noise reduction functions, most of them use an ear-cup structure or rely solely on passive sound insulation. Passive sound insulation has very limited effect on suppressing penetrating low-to-mid-frequency noise; and if a bulky ear-cup structure is used, the main body of the pillow often needs to be thickened, which in turn damages the original cervical spine support and head comfort of the pillow, making it difficult to achieve both noise reduction and a comfortable sleep experience.

[0005] In addition, since the electronic module is usually fixed to the pillow body as a whole, the entire pillow cannot be cleaned by daily washing, and its hygiene and durability under long-term use cannot be guaranteed. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides an active noise-canceling headrest and its binaural adaptive sound field control method. The active noise-canceling headrest embeds two noise-canceling modules respectively within the ear contact areas corresponding to the user's left and right ears, thereby actively controlling noise in the left and right ear regions. Simultaneously, by incorporating a power supply module, a waterproof cover, and a removable pillowcase, the active noise-canceling headrest simultaneously meets the needs for power supply, waterproof protection, and outer layer washing.

[0007] The technical solution adopted in this invention is an active noise-canceling headrest, comprising: The pillow body has a concave center to form a head support area, and protrusions on both sides of the head support area to form an ear contact area. Two noise reduction modules are symmetrically embedded inside the two ear-contacting areas. Each noise reduction module includes a sound-generating unit and a processing unit. The noise reduction module also includes a first acquisition unit and / or a second acquisition unit. The first acquisition unit is located near the outer side of the pillow body and is used to acquire external incident noise to obtain a reference signal. The second acquisition unit is located near the user's ear area and is used to acquire residual noise to obtain an error signal. The processing unit generates a driving signal for driving the sound-generating unit based on the reference signal obtained by the first acquisition unit and / or the error signal obtained by the second acquisition unit.

[0008] Preferably, each of the noise reduction modules includes a first acquisition unit, a second acquisition unit, a sound generation unit, and a processing unit; each processing unit generates a driving signal for driving the sound generation unit in its noise reduction module based on the reference signal obtained by the first acquisition unit and the error signal obtained by the second acquisition unit in its respective noise reduction module.

[0009] Preferably, the ear-fitting area has an installation cavity, the noise reduction module is fixedly installed in the installation cavity, and the thickness of the noise reduction module is not greater than half the thickness of the ear-fitting area; the installation cavity is filled with cushioning material, and the cushioning material is disposed on the surface of the noise reduction module.

[0010] Preferably, the device further includes a power supply module for supplying power to the two noise reduction modules; the bottom of the pillow body is provided with a mounting groove, the power supply module is embedded in the mounting groove, the opening of the mounting groove is provided with a cover, and a waterproof sealing ring or waterproof sealant is provided between the cover and the opening of the mounting groove; the side or bottom of the pillow body is provided with a charging interface, and the charging interface is provided with an openable and closable waterproof plug.

[0011] Preferably, the outer periphery of the pillow body is sealed with a waterproof sleeve, the outer periphery of the waterproof sleeve is covered with a pillowcase, and the pillowcase and the waterproof sleeve are detachably connected.

[0012] This invention also discloses a binaural adaptive sound field control method for an active noise-canceling headrest, used in the aforementioned active noise-canceling headrest, wherein the following steps are performed for each of the two noise-canceling modules in each sampling period: S100. External incident noise is acquired through the first acquisition unit, and the acquired external incident noise is preprocessed and converted from analog to digital to obtain a digital reference signal. S200: An adaptive filter is used to perform convolution operation on the digital reference signal according to the current filter coefficients to obtain a driving signal. The driving signal is then converted from digital to analog and amplified in power. The sound-generating unit is driven to output sound waves according to the converted and amplified driving signal. S300. The digital reference signal obtained in step S100 is filtered using a secondary path estimation model to obtain a filtered reference signal. S400: After the sound wave output by the sound-generating unit and the external incident noise are superimposed in the corresponding ear region, the residual noise in the corresponding ear region is collected by the second acquisition unit, and the residual noise is preprocessed and converted from analog to digital to obtain an error signal. S500. After obtaining the filtered reference signal and the error signal, the current filter coefficients are corrected according to the corresponding product of the filtered reference signal and the error signal and the adaptive step size to obtain the updated filter coefficients. S600: Use the updated filter coefficients as the current filter coefficients for the next sampling period, and return to step S100. The two noise reduction modules independently generate driving signals and update their respective filter coefficients based on their respective digital reference signals and error signals.

[0013] Preferably, before performing step S100 for the first time, a secondary path estimation model is established for each of the two noise reduction modules. Establishing the secondary path estimation model includes the following steps: S010. The processing unit drives the corresponding sound-emitting unit to play a known excitation signal; S020. After the known excitation signal is played by the corresponding sound unit, the response signal formed by the known excitation signal passing through the corresponding sound unit and the acoustic propagation path between the sound unit and the second acquisition unit is acquired by the corresponding second acquisition unit. S030. After obtaining the response signal, based on the known excitation signal and the response signal, identify the transmission characteristics between the signal output terminal of the corresponding processing unit and the corresponding second acquisition unit. S040. Establish a corresponding secondary path estimation model based on the transmission characteristics, store the model parameters of the secondary path estimation model in the corresponding processing unit, and use the secondary path estimation model to filter the digital reference signal in step S300.

[0014] Preferably, during the cyclic execution of steps S100 to S600, the following steps are performed continuously or periodically for each of the two noise reduction modules: S710. The low-level identification signal is superimposed on the driving signal generated in step S200, and the corresponding sound unit is driven to output sound waves according to the driving signal superimposed with the low-level identification signal. S720. After the corresponding sound unit outputs a sound wave containing the low-level identification signal, the corresponding second acquisition unit acquires the identification response signal formed after the low-level identification signal passes through the corresponding secondary path. S730. After obtaining the identification response signal, update the corresponding secondary path estimation model based on the low-level identification signal and the identification response signal. S740. After updating the corresponding secondary path estimation model, the updated secondary path estimation model is used to filter the digital reference signal in step S300 of the subsequent sampling period.

[0015] Preferably, the left ear-side secondary path estimation model, the right ear-side secondary path estimation model, and the corresponding control parameters corresponding to multiple head positions or sleeping postures are pre-stored, and the following steps are performed before the first execution of step S300: S810: Obtain the detection results of the user's current head position or sleeping posture; S820. After obtaining the detection results, determine the secondary path estimation model and control parameters of the left ear side and the secondary path estimation model and control parameters of the right ear side corresponding to the current head position or sleeping posture. S830. Configure the determined secondary path estimation model and control parameters of the left ear to the corresponding noise reduction module of the left ear, and configure the determined secondary path estimation model and control parameters of the right ear to the corresponding noise reduction module of the right ear, so that the two noise reduction modules adopt the corresponding configured secondary path estimation model and control parameters in steps S300 and S500 respectively. During the cyclic execution of steps S100 to S600, if a change in the user's head position or sleeping posture is detected, steps S810 to S830 are re-executed before steps S300 and S500 are executed in the next sampling cycle.

[0016] Preferably, during the cyclic execution of steps S100 to S600, the following steps are performed for each of the two noise reduction modules: S910. Obtain the digital reference signal obtained in step S100 from multiple consecutive sampling periods, and perform spectrum analysis on the digital reference signal to obtain the energy frequency distribution of the external incident noise on the corresponding side in the multiple consecutive sampling periods and the change characteristics of the energy frequency distribution over time. S920. After obtaining the energy frequency distribution, determine the adaptive control target frequency band of the corresponding noise reduction module based on the energy frequency distribution; S930. After obtaining the characteristics of the change of the energy frequency distribution over time, determine the adaptive step size and / or the update frequency of the filter coefficients of the corresponding adaptive filter based on the characteristics of the change. S940. After determining the update frequency of the adaptive control target frequency band, adaptive step size and / or filter coefficients, the determined update frequency of the adaptive control target frequency band, adaptive step size and / or filter coefficients is used in steps S200 and S500 of subsequent sampling periods.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention symmetrically embeds noise-canceling modules within the ear-contact areas on both sides, eliminating the need for additional noise-canceling accessories and resolving the issues of head pressure and discomfort associated with traditional earplugs and headphones when sleeping on one's side. It achieves efficient noise reduction in both lying and sitting positions. Furthermore, the pillow's ergonomic design, with a central concave area for head support and raised sides for ear contact, perfectly conforms to the cervical spine's physiological curve, providing both noise isolation and cervical spine protection.

[0018] 2. Regarding waterproofing performance, this invention utilizes a multi-layered sealing structure comprised of a cover at the mounting slot opening, a waterproof sealing ring or sealant between the cover and the mounting slot, an openable waterproof plug at the charging port, and a waterproof sleeve sealing the outer periphery of the pillow body. This achieves comprehensive waterproofing and dustproofing for the electrical equipment. This multi-layered structure effectively resists daily water splashes, sweat, and moisture intrusion, preventing short circuits, malfunctions, or aging due to moisture, thus significantly extending the product's lifespan and making it widely suitable for various complex usage scenarios such as home, office, and travel.

[0019] 3. Regarding hygiene and maintenance, this invention employs a double-layered structure. Specifically, the pillow body is sealed with a waterproof sleeve, which in turn is covered by a pillowcase, with the pillowcase and waterproof sleeve being detachably connected. The inner waterproof sleeve secures and protects the noise reduction module and power supply module, while the outer pillowcase can be removed and washed separately. This structure effectively solves the problems of traditional integrated noise-reducing pillows being difficult to clean, prone to bacterial growth, and accumulating stains, maintaining cleanliness and hygiene even after long-term use. Furthermore, the pillowcase is replaceable to suit different aesthetic preferences and usage scenarios.

[0020] 4. Furthermore, this invention features a rational layout and comfortable use. The power supply module is embedded in the mounting slot at the bottom of the pillow body, the charging port is located on the rear side of the pillow body, and the noise reduction modules are symmetrically embedded inside the ear contact areas on both sides, achieving complete concealment of the devices and wiring. This does not affect the overall flatness of the pillow body and avoids pressure on the head and ears. Simultaneously, the power supply module embedded at the bottom effectively lowers the center of gravity of the pillow body, improving the stability of the entire pillow and accommodating both sleeping and reclining functions, achieving multiple uses and significantly enhancing practicality. Overall, this invention has a high degree of structural integration and a neat layout. Combined with a low-power processing unit and power supply module, it boasts advantages such as long battery life and convenient charging, requiring no complex user operations. It can adapt to the daily rest and sleep needs of various groups, greatly ensuring a superior user experience. Attached Figure Description

[0021] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein: Figure 1 This is a schematic diagram of the overall structure of the active noise-canceling headrest; Figure 2 This is a schematic diagram of the bottom structure of the active noise-canceling headrest; Figure 3 This is a flowchart of the binaural adaptive sound field control method for an active noise-canceling headrest; Figure 4 This is a schematic diagram of the adaptive control process of a single-sided noise reduction module.

[0022] 1. Pillow body; 2. Headrest area; 3. Ear contact area; 4. Noise reduction module; 5. Charging port; 6. Mounting slot; 6A. Power supply module; 6B. Main board of processing unit; 7. Pillowcase. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0024] In one embodiment, see Figure 1 The active noise-canceling headrest includes a pillow body 1 and two noise-canceling modules 4. The center of the pillow body 1 is recessed to form a headrest area 2 for supporting the user's head. The two sides of the headrest area 2 protrude upwards to form ear contact areas 3 corresponding to the user's left and right ears, respectively. The two noise-canceling modules 4 are respectively embedded inside the two ear contact areas 3, positioning them close to the user's ears.

[0025] Each noise reduction module 4 includes a sound-generating unit, a processing unit, and at least one of a first acquisition unit and a second acquisition unit. The first acquisition unit is located near the outer side of the pillow body 1 and is used to acquire incident noise propagating from the outside into the pillow body 1 and obtain a reference signal; the second acquisition unit is located near the user's ear area and is used to acquire residual noise in the ear area and obtain an error signal. The processing unit generates a drive signal based on at least one of the reference signal and the error signal, and controls the sound-generating unit to output sound waves for active noise reduction through the drive signal.

[0026] Therefore, this embodiment can adopt feedforward, feedback, or a combination of feedforward and feedback active noise reduction methods according to the actual configuration, so as to adapt to different product costs, control accuracy and usage environment requirements.

[0027] The noise reduction module 4 is an integrated electronic component comprising a sound-generating unit, a processing unit, and a data acquisition unit. The sound-generating unit typically uses a small, miniature dynamic loudspeaker or a piezoelectric ceramic loudspeaker; the processing unit is a digital signal processing chip integrated on a flexible circuit board; and the first and second data acquisition units can be microelectromechanical system (MEMS) microphones. The sound-generating unit, processing unit, and the first and second data acquisition units are connected via internal conductive lines.

[0028] In this embodiment, two noise-canceling modules 4 are respectively embedded in the ear-fitting areas 3 on both sides of the pillow body 1, allowing the noise-canceling modules 4 to work close to the ears when the user is not wearing headphones or earplugs. Compared with noise-canceling devices that need to be worn directly on the ears, this structure avoids continuous pressure on the auricle and ear canal from headphones or earplugs, making it especially suitable for use when lying flat, on one's side, and during long periods of sleep. The headrest area 2 is located in the middle of the pillow body 1, and the ear-fitting areas 3 on both sides are adjacent to the user's left and right ears, respectively. The shape of the pillow body 1 can both support the user's head and provide installation space for the noise-canceling modules 4 close to the ears. The noise-canceling modules 4 are embedded inside the ear-fitting areas 3, which reduces the possibility of electronic components being exposed or protruding directly from the pillow surface, reduces the direct pressure of the noise-canceling modules 4 on the user's head and ears, and helps maintain the continuity and comfort of the pillow body 1 surface.

[0029] Two noise reduction modules 4 are respectively located in the two ear contact areas 3, enabling each noise reduction module 4 to collect sound and output sound waves corresponding to one ear area of ​​the user. Since the acoustic environment of the user's left and right ears may be different, for example, noise may mainly come from one side, or when the user lies on their side, one ear is close to the pillow body 1 while the other ear faces outward. Therefore, arranging the noise reduction modules 4 on the left and right sides can provide corresponding sound collection positions and sound wave output positions for the left and right ear areas respectively, reducing the problem of long sound propagation distance and difficulty in taking into account the sound field on both sides when the noise reduction module 4 is only placed in the middle of the pillow or on one side.

[0030] The first acquisition unit is positioned near the outer side of the pillow body 1, allowing it to collect noise before it reaches the user's ear area, providing a reference for the processing unit to generate a drive signal. This arrangement ensures that the obtained reference signal effectively characterizes the external noise source or incident noise, providing a signal basis for the sound-generating unit to output corresponding sound waves in advance. This is suitable for noises with a certain degree of continuity and predictability, such as those from air conditioners, fans, and road traffic. The second acquisition unit is positioned near the user's ear area, collecting residual noise that remains after the external noise is superimposed on the sound waves output by the sound-generating unit. Therefore, the error signal obtained by the second acquisition unit directly reflects the actual noise reduction state in the ear area. The processing unit can adjust the output of the sound-generating unit based on this error signal, reducing the problem of generating a drive signal solely based on external noise without knowing the actual noise reduction result in the ear area. When the noise reduction module includes both the first and second acquisition units, the processing unit can control the sound-generating unit by combining the reference signal and the error signal; when only one type of acquisition unit is used, a feedforward or feedback active noise reduction structure can be formed, respectively.

[0031] The sound-generating unit is positioned within the ear-contact area 3, close to the user's ears. This shortens the acoustic propagation distance between the sound-generating unit and the target noise reduction area, concentrating the sound waves output by the unit near the user's ears without creating a noise reduction field throughout the room or a large space. This localized sound field control method reduces the power requirements of the sound-generating unit and facilitates targeted suppression of persistent low-to-mid-frequency noise. In this embodiment, by combining the head support structure of the pillow body 1, the bilateral ear-contact structure, and the active noise reduction module 4, noise acquisition, signal processing, and sound wave output can all be completed near the user's ears without adding any additional ear-wearing components. This balances head support, sleep comfort, and localized active noise reduction requirements.

[0032] In one embodiment, each noise reduction module 4 includes a first acquisition unit, a second acquisition unit, a sound generation unit, and a processing unit. Each processing unit is connected to the first acquisition unit, the second acquisition unit, and the sound generation unit in its respective noise reduction module 4, and generates a driving signal based on the reference signal and error signal obtained on its side to drive the sound generation unit on its side to output sound waves. Thus, the left and right noise reduction modules 4 form independent noise acquisition, signal processing, and sound wave output paths, respectively.

[0033] This embodiment enables each processing unit to control its corresponding sound-emitting unit based on the acoustic signal from the corresponding ear side, avoiding the trade-off problem that occurs when the left and right sides share the same reference signal, error signal, or drive signal. When noise mainly comes from one side, or when the user is lying on their side and the acoustic environment of the left and right ears is different, the two noise reduction modules 4 can process the reference signal and error signal of their respective sides, so that the left and right ear areas can obtain noise reduction control corresponding to their actual acoustic environment.

[0034] In one embodiment, each of the two ear-fitting areas 3 has an installation cavity, and the two noise-canceling modules 4 are fixedly installed in their respective installation cavities. The dimension of the noise-canceling module 4 along the thickness direction of the ear-fitting area 3 is no greater than half the thickness of the ear-fitting area 3, allowing the noise-canceling module 4 to be embedded inside the ear-fitting area 3. The installation cavity is filled with cushioning material, which is disposed on the surface of the noise-canceling module 4. Specifically, it can be disposed on the side of the noise-canceling module 4 facing the user's head or the outer surface of the ear-fitting area 3, or it can cover part or all of the surface of the noise-canceling module 4. The cushioning material can be made of high-resilience sponge or silicone, etc.

[0035] By providing an installation cavity within the ear-fitting area 3, the noise-canceling module 4 can be positioned and fixed, reducing the possibility of displacement when the pillow body 1 is squeezed, flipped, or moved, and ensuring that the two noise-canceling modules 4 remain in positions corresponding to the user's ears. Limiting the thickness of the noise-canceling module 4 to no more than half the thickness of the ear-fitting area 3 allows for sufficient flexible material space between the noise-canceling module 4 and the outer surface of the ear-fitting area 3, preventing the noise-canceling module 4 from protruding directly from the surface of the pillow body 1 or being too close to the user's contact surface. A cushioning material is placed on the surface of the noise-canceling module 4, separating the rigid electronic components from the user's head, dispersing the pressure applied to the area where the noise-canceling module 4 is located when the user leans against the pillow, and cushioning the impact and compression received by the noise-canceling module 4. Simultaneously, the cushioning material can fill and level the installation cavity, reducing the formation of local depressions, hard spots, or discontinuous areas on the surface of the ear-fitting area 3 due to the installation cavity, thus balancing the fixed installation of the noise-canceling module 4 with the supportive comfort of the pillow body 1.

[0036] In one embodiment, the active noise-canceling headrest further includes a power supply module 6A, which is electrically connected to two noise-canceling modules 4 to supply power to the first acquisition unit, the second acquisition unit, the processing unit, and the sound-generating unit. The bottom of the pillow body 1 has a mounting groove 6, in which the power supply module 6A is embedded. A cover is provided at the opening of the mounting groove 6, covering the opening, and a waterproof sealing ring or waterproof sealant is provided between the cover and the opening of the mounting groove 6. The side or bottom of the pillow body 1 also has a charging interface 5 electrically connected to the power supply module 6A, and a closable waterproof plug is provided at the charging interface 5. The waterproof plug is opened during charging and closed when not charging.

[0037] By placing the power supply module 6A at the bottom of the pillow body 1, it avoids the headrest area 2 and the ear contact areas 3 on both sides, reducing the space occupied by relatively rigid components such as batteries and circuit boards on the head and ear support areas, and preventing the power supply module 6A from directly bearing the user's head pressure. The bottom location of the power supply module 6A also concentrates its weight in the lower part of the pillow body 1, reducing the possibility of the pillow body 1 tilting or flipping due to the noise reduction modules 4 on both sides.

[0038] The cover is used to seal the opening of the mounting groove 6. A waterproof sealing ring or waterproof sealant is placed between the cover and the opening of the mounting groove 6 to reduce the entry of sweat, water stains, and moisture into the mounting groove 6 through the mating gap between the cover and the mounting groove 6. The waterproof sealing ring facilitates the formation of a seal by pressing the cover together, while the waterproof sealant fills the small gaps at the mating position. Both provide waterproof protection for the area where the power supply module 6A is located.

[0039] The charging port 5 is located on the pillow body 1, which is connected to the outside world, making it easy for moisture to enter. By providing an openable and closable waterproof plug, the charging port 5 can be sealed when not charging without affecting the charging operation. The sealing structure of the mounting slot 6 opening works in conjunction with the waterproof plug of the charging port 5 to protect both the installation position and the charging position of the power supply module 6A, reducing the risk of moisture, short circuits, or corrosion to the power supply module 6A and its connecting circuits.

[0040] In another feasible implementation, see Figure 2 The motherboard 6B of the processing unit is not limited to being embedded inside the ear contact area 3, but can also be located in the mounting slot 6 at the bottom of the pillow body 1. In this case, the motherboard 6B of the processing unit shares the receiving space of the bottom mounting slot 6 with the power supply module 6A, and establishes an electrical connection with the sound-emitting unit, the first acquisition unit, and the second acquisition unit embedded inside the ear contact area 3 through a flexible ribbon cable. This variant solution can further reduce the weight of the noise reduction module 4.

[0041] In one embodiment, the power supply module includes a rechargeable battery, which can be a rechargeable lithium battery pack or a polymer lithium battery. Its capacity can be set according to the power consumption of the two noise reduction modules and the predetermined battery life, for example, 5000-10000mAh. A mounting bracket for fixing the power supply module can be provided in the mounting slot. The power supply module is installed in the mounting bracket by a snap-fit ​​method, facilitating the assembly, replacement, and maintenance of the power supply module. The charging interface can be a Type-C interface and is located on the side or bottom of the pillow body, in a location that is not easily contacted by the user and is not prone to water accumulation. Placing the power supply module at the bottom of the pillow body avoids the head support area and the ear contact area, reducing the space occupied by the power supply module on the head support and bringing the center of gravity of the pillow body closer to the bottom, improving placement stability.

[0042] In one embodiment, the noise reduction module, the power supply module, and the connection circuit between them can be sealed with waterproof sealant, waterproof sealing ring, or waterproof housing, respectively.

[0043] In one embodiment, the outer periphery of the pillow body 1 is sealed with a waterproof sleeve, forming a waterproof isolation layer covering the pillow body 1 and the electronic components inside the pillow body 1. A pillowcase 7 is detachably connected to the waterproof sleeve. Specifically, the pillowcase 7 can be detachably attached to the waterproof sleeve using a zipper, snap, or hook and loop fastener, allowing it to be removed. The waterproof sleeve can be made of waterproof fabric, high-density waterproof polyester fiber, or thermoplastic polyurethane film composite fabric, and connected using a heat-sealing process to reduce water seepage channels at the seams, forming a complete sealed isolation layer. The outer pillowcase 7 can be made of skin-friendly and breathable materials such as pure cotton, Tencel, or blends, and its overall outer contour closely matches the outer contour of the waterproof sleeve, forming a smooth and soft surface after being wrapped around the waterproof sleeve. The pillowcase and the electronic components inside the pillow body are independent of each other, and insulating material can also be provided between the pillowcase and the electronic components.

[0044] A waterproof cover seals the outer perimeter of the pillow body 1, isolating the noise reduction module 4, power supply module 6A, and connecting circuitry inside the pillow body 1 from sweat, water stains, and moisture, reducing water penetration from the outer surface of the pillow body 1 to the internal electronic components. The pillowcase 7, located outside the waterproof cover, serves as an outer layer covering that comes into direct contact with the user's skin and hair. The pillowcase 7 is detachably connected to the waterproof cover, allowing it to be removed for washing or replacement without disassembling the noise reduction module 4, power supply module 6A, or the waterproof cover, avoiding repeated disassembly and reassembly of the internal electronic components when cleaning the pillowcase 7. This double-layer structure assigns different functions to different covering layers: the inner waterproof cover seals and protects the pillow body 1 and electronic components, while the outer pillowcase 7 provides a surface for human contact and meets daily washing needs. Thus, while maintaining the fixed installation and waterproof isolation of the electronic components, it allows for independent cleaning of the parts in contact with the user, alleviating the conflict between the inability of the electronic components in the electronic pillow to come into contact with water and the need for frequent cleaning of the pillow's outer layer.

[0045] In a more specific embodiment, the pillow body can be made of an elastic material to provide cushioning for the head and neck while supporting the user's head. Furthermore, the headrest area has a recess depth of 7–10 cm, and the ear-contact area has a protrusion height of 9–12 cm relative to the headrest area, creating a curved support structure with a lower center and higher sides. The pillow body can be used flat as a headrest, or upright or adjusted for use as a neck support pillow, making it suitable for various scenarios such as home sleep, office naps, and sofa rests.

[0046] The two noise reduction modules employ an independent zone control architecture for the left and right ears. Each module independently handles noise acquisition, signal processing, drive signal generation, and error feedback for its corresponding side, thereby controlling the local sound field of the left and right ear regions respectively. Since the acoustic environments of the user's left and right ears may differ—for example, noise may primarily originate from one side, or when the user is lying on their side, one ear may be close to the pillow while the other faces outwards—independent control allows the two noise reduction modules to process the sound according to the actual acoustic conditions of their respective ear regions, reducing the mutual interference that occurs when a single control path simultaneously considers both ears.

[0047] Each noise reduction module may include a first acquisition unit, a second acquisition unit, an analog front-end circuit, a processing unit, and a sound generation unit. The first and second acquisition units may employ microelectromechanical systems (MEMS) microphones. The analog front-end circuit performs pre-amplification, anti-aliasing filtering, and analog-to-digital conversion on the acquired signals, and performs digital-to-analog conversion on the drive signal generated by the processing unit. The processing unit may employ a digital signal processor (DSP) to perform calculations on the reference signal and / or error signal and generate the drive signal. The sound generation unit outputs sound waves based on the drive signal. Depending on the configuration of the acquisition units, the noise reduction module may employ a feedforward, feedback, or feedforward-feedback hybrid active noise reduction structure.

[0048] In the feedforward active noise cancellation structure, the noise cancellation module includes a first acquisition unit. This unit is positioned near the outer side of the pillow body and is used to acquire the external incident noise and obtain a reference signal before it propagates to the user's ear area. The processing unit generates a drive signal based on the reference signal, and the sound-generating unit outputs a sound wave based on the drive signal. The feedforward active noise cancellation structure can obtain information about external incident noise in advance and is suitable for relatively continuous low-to-mid-frequency noise such as traffic noise, air conditioning noise, and fan noise; however, its control results are affected by the correlation between the reference signal and the actual noise in the ear area, and it cannot directly perform feedback correction based on the residual noise in the ear area.

[0049] In a feedback-based active noise cancellation structure, the noise cancellation module includes a second acquisition unit. This second acquisition unit is positioned close to the user's ear area to collect residual noise in that area and obtain an error signal. The processing unit adjusts the drive signal of the sound-generating unit based on the error signal. While the feedback-based active noise cancellation structure can perform closed-loop adjustment based on the actual residual noise in the ear area, its response to noise changes has a certain lag, and the control parameters need to be set appropriately to reduce the possibility of howling or self-oscillation in the control loop.

[0050] In the feedforward-feedback hybrid active noise cancellation structure, the noise cancellation module simultaneously incorporates a first acquisition unit and a second acquisition unit. The processing unit generates a driving signal based on the reference signal obtained from the first acquisition unit and adjusts the driving signal based on the error signal obtained from the second acquisition unit. Thus, the noise cancellation module can utilize both the reference signal to obtain information about external incident noise and the error signal to acquire the actual residual noise in the corresponding ear region, thereby combining feedforward control and feedback control to perform active noise cancellation on the corresponding ear region.

[0051] Considering that users may toss and turn, move their heads, and deform the pillow body under pressure during sleep, and that ambient noise may change over time, this embodiment preferably adopts a feedforward-feedback hybrid active noise cancellation structure. In a simplified implementation, depending on the product's structural complexity, processing capabilities, and usage requirements, a feedforward active noise cancellation structure may be used with only a first acquisition unit, or a feedback active noise cancellation structure may be used with only a second acquisition unit.

[0052] In one embodiment, the processing unit may have low-power management functionality. When the noise intensity detected by the first acquisition unit and / or the second acquisition unit is lower than a preset noise threshold, the processing unit reduces the signal processing frequency or enters standby mode; when the active noise-canceling headrest is detected to be unused, the processing unit enters sleep mode. The active noise-canceling headrest may also be equipped with a switch connected to the processing unit, allowing the user to activate or deactivate the two noise-canceling modules.

[0053] When the remaining power of the power supply module is lower than a preset power threshold, it can output a low power warning and reduce the output power of the sound unit. The power supply module can also be equipped with over-temperature protection circuit, over-current protection circuit, and over-voltage protection circuit to limit or cut off power supply when the rechargeable battery is in an abnormal state.

[0054] To limit abnormal sound output during active noise cancellation, the processing unit can limit the maximum output sound pressure of the sound-generating unit and perform abnormal howling detection based on the error signal obtained by the second acquisition unit. When self-excitation is detected in the control loop, the processing unit stops outputting the corresponding drive signal or silences the corresponding sound-generating unit.

[0055] An insulation layer and a heat insulation layer can also be provided between the noise reduction module and the power supply module and the filling material of the pillow body. A dustproof and moisture-proof structure can be provided at the acoustic openings corresponding to the first acquisition unit, the second acquisition unit and the sound-emitting unit to reduce the entry of dust and moisture into the noise reduction module through the acoustic openings.

[0056] In a more specific implementation, the bottom of the pillow body adopts a heat balance design, which, together with the heat dissipation of the battery area, prevents the temperature from getting too high during long-term use, thereby ensuring both noise reduction function and battery life and safety.

[0057] In one embodiment, a binaural adaptive sound field control method for an active noise-canceling headrest is provided. The headrest has two noise-canceling modules, one corresponding to the user's left ear region and the other to the right ear region. These modules independently generate drive signals and update filter coefficients based on digital reference signals and error signals acquired from the corresponding sides. See also... Figure 3 and Figure 4 In each sampling period, the following steps are performed for each of the two noise reduction modules: S100: External incident noise is acquired through the first acquisition unit, and the acquired external incident noise is preprocessed and converted from analog to digital to obtain a digital reference signal. The preprocessing may include pre-amplification and anti-aliasing filtering, and the left and right noise reduction modules respectively obtain the digital reference signal on the corresponding side.

[0058] S200: An adaptive filter is used to convolve the digital reference signal according to the current filter coefficients to obtain a driving signal. The driving signal is then converted from digital to analog and amplified in power. The converted and amplified driving signal is used to drive the sound-generating unit to output sound waves. The left and right processing units generate driving signals according to their respective digital reference signals.

[0059] S300: The digital reference signal obtained in step S100 is filtered using a secondary path estimation model to obtain a filtered reference signal. The secondary path includes the propagation path of the driving signal after it is output from the processing unit, sequentially passing through digital-to-analog conversion, power amplification, sound generation unit, air, and the pillow body, and finally reaching the second acquisition unit. By processing the digital reference signal using the secondary path estimation model, the influence of this propagation path on the signal amplitude, phase, and delay can be considered when updating the filter coefficients subsequently.

[0060] Both steps S200 and S300 are executed based on the digital reference signal obtained in step S100, and there is no fixed order between them.

[0061] S400: After the sound wave output by the sound-generating unit and the external incident noise are superimposed in the corresponding ear region, the residual noise in the corresponding ear region is acquired by the second acquisition unit, and the residual noise is preprocessed and converted from analog to digital to obtain an error signal. The left second acquisition unit and the right second acquisition unit respectively acquire the residual noise in the corresponding ear region, so that the two noise reduction modules obtain their respective error signals.

[0062] S500: After obtaining the filtered reference signal and the error signal, the current filter coefficients are corrected according to the corresponding product of the filtered reference signal and the error signal and the adaptive step size to obtain updated filter coefficients. The adaptive step size is used to determine the correction magnitude of the filter coefficients; it can be a fixed step size or adjusted according to the energy of the digital reference signal or the magnitude of the error signal.

[0063] S600: Use the updated filter coefficients as the current filter coefficients for the next sampling period, and return to step S100. In this process, the two noise reduction modules independently generate driving signals and update their respective filter coefficients based on their respective obtained digital reference signals and error signals. Thus, steps S100 to S600 are executed cyclically during the active noise reduction process, enabling the two noise reduction modules to continuously adjust their respective driving signals based on the external incident noise and residual noise on their respective sides.

[0064] Using the above method, the left and right noise reduction modules each form an independent adaptive control path, which can be controlled separately for the different acoustic environments of the left and right ears. For example, when the noise mainly comes from one side, or when the user is lying on their side and the positional relationship between the left and right ears and the main body of the pillow is different, the two noise reduction modules can update the filter coefficients according to the digital reference signal and error signal of the corresponding side, reducing the mutual trade-offs caused by sharing the same control parameter.

[0065] Simultaneously, external incident noise is acquired through the first acquisition unit, and residual noise in the ear region is acquired through the second acquisition unit. This allows the processing unit to both generate a driving signal using external noise information and perform feedback correction based on the actual residual noise in the ear region. The secondary path estimation model ensures that the filter coefficient updates take into account the influence of propagation links such as the sound-generating unit, air, and the pillow body on the signal, thereby matching the adaptive control process with the actual acoustic propagation state of the active noise-canceling headrest.

[0066] In one embodiment, before the first execution of step S100, secondary path estimation models are established for each of the two noise reduction modules. The secondary path refers to the transmission path from the signal output of the processing unit, through digital-to-analog conversion, power amplification, electroacoustic conversion of the sound-generating unit, and the acoustic propagation space between the sound-generating unit and the second acquisition unit, ultimately collected by the second acquisition unit. Since the installation positions of the left and right noise reduction modules, the relative positions between the sound-generating unit and the second acquisition unit, and the influence of the pillow body on sound wave propagation may differ, separate secondary path estimation models are established for each of the two noise reduction modules. Establishing the secondary path estimation model includes the following steps: S010. The processing unit drives the corresponding sound-generating unit to play a known excitation signal. The known excitation signal can be white noise, a frequency sweep signal, or other test signals with predetermined signal characteristics, used to excite the actual secondary path of the corresponding noise reduction module.

[0067] S020. After the known excitation signal is played by the corresponding sound-emitting unit, the response signal formed by the known excitation signal passing through the corresponding sound-emitting unit and the acoustic propagation path between the sound-emitting unit and the second acquisition unit is acquired by the corresponding second acquisition unit. After being output by the sound-emitting unit, the known excitation signal propagates through the air between the sound-emitting unit and the second acquisition unit, the pillow body, and related electroacoustic components, and is acquired by the corresponding second acquisition unit to obtain the response signal. This response signal includes the effects of the actual secondary path on the known excitation signal, such as amplitude attenuation, phase change, and time delay.

[0068] S030. After obtaining the response signal, based on the known excitation signal and the response signal, identify the transmission characteristics between the signal output terminal of the corresponding processing unit and the corresponding second acquisition unit. Specifically, the amplitude, phase, and delay relationships between the known excitation signal and the response signal can be compared to obtain model parameters that can characterize the actual secondary path.

[0069] S040. A corresponding secondary path estimation model is established based on the transmission characteristics. The model parameters of the secondary path estimation model are stored in the corresponding processing unit. In step S300, the secondary path estimation model is used to filter the digital reference signal. The left and right noise reduction modules respectively use their established secondary path estimation models to process the digital reference signal on the corresponding side.

[0070] By performing secondary path calibration on the left and right noise reduction modules before active noise reduction operation, the established secondary path estimation model can correspond to the actual assembly position and acoustic propagation path of each noise reduction module, reducing path mismatch caused when directly using a unified model or a preset model.

[0071] Meanwhile, the reference signal processed by the secondary path estimation model is used during the filter coefficient update process. This allows for the inclusion of the influence of the sound-generating unit, air, pillow body, and second acquisition unit on the signal, making the update direction of the filter coefficients more closely match the actual acoustic response of the ear region, thereby improving the stability and accuracy of adaptive control. Separate calibration on the left and right sides also accommodates the differences in structural position and acoustic propagation conditions between the left and right ear regions, providing a corresponding initial model basis for independent adaptive control of the two noise reduction modules.

[0072] In one embodiment, during the cyclic execution of steps S100 to S600, the secondary path estimation models of the two noise reduction modules are continuously or periodically corrected online. The left and right noise reduction modules each perform the online correction process to ensure that their respective secondary path estimation models correspond to the actual acoustic propagation paths on the corresponding sides. Specifically, the following steps are continuously or periodically executed for the two noise reduction modules: S710. The low-level identification signal is superimposed on the driving signal generated in step S200, and the corresponding sound-generating unit is driven to output sound waves according to the driving signal superimposed with the low-level identification signal. The amplitude of the low-level identification signal can be set lower than the amplitude of the normal active noise cancellation signal to reduce the impact of the identification process on the user's normal use.

[0073] S720. After the corresponding sound-emitting unit outputs a sound wave containing the low-level identification signal, the corresponding second acquisition unit acquires the identification response signal formed after the low-level identification signal passes through the corresponding secondary path. The identification response signal reflects the amplitude change, phase change, and time delay of the low-level identification signal caused by the current secondary path.

[0074] S730. After obtaining the identification response signal, the corresponding secondary path estimation model is updated based on the low-level identification signal and the identification response signal. The left and right noise reduction modules update their respective secondary path estimation models based on their respective obtained identification response signals, avoiding the two noise reduction modules sharing the same update result.

[0075] S740. After updating the corresponding secondary path estimation model, the updated secondary path estimation model is used to filter the digital reference signal in step S300 of the subsequent sampling period. The updated secondary path estimation model does not reverse the processing of the completed current sampling period, so that the model update process is consistent with the execution order of the main control loop.

[0076] The aforementioned online correction process can be executed continuously during active noise cancellation or periodically at preset time intervals. Continuous execution is suitable for situations where secondary paths change relatively frequently; periodic execution can reduce the computational burden on the processing unit while tracking changes in secondary paths. The specific execution method can be set according to the processing capabilities and usage status of the active noise cancellation headrest.

[0077] When a user rolls over, moves their head, or applies different pressures to the pillow body, the relative position between the sound-generating unit and the second acquisition unit, the deformation state of the pillow body, and the sound wave propagation space may all change, causing the actual secondary path to deviate from the pre-established secondary path estimation model. By injecting a low-level identification signal and acquiring the corresponding identification response signal during active noise cancellation operation, the change information of the current secondary path can be obtained, and the secondary path estimation model can be corrected accordingly.

[0078] Therefore, this embodiment can track and update the secondary paths on the left and right sides online while the active noise-canceling headrest is working normally, so that the secondary path estimation model used in subsequent sampling cycles is adapted to the current acoustic propagation state, reducing model mismatch caused by user head movement, changes in sleeping posture or deformation of the pillow body under pressure, and improving the stability and accuracy of the filter coefficient update process.

[0079] In one embodiment, for multiple head positions or sleeping postures, corresponding left-ear secondary path estimation models, right-ear secondary path estimation models, and control parameters are pre-established and stored. Different head positions or sleeping postures can include lying flat, lying on the left side, lying on the right side, and states where the head is offset to varying degrees relative to the headrest area. Control parameters can include at least one of adaptive step size, initial values ​​of filter coefficients, target control frequency band, and filter coefficient update frequency.

[0080] Because the relative positions of the user's left and right ears with the corresponding sound-emitting unit and the second acquisition unit, as well as the pressure pattern of the pillow body, may differ under different head positions or sleeping postures, secondary path estimation models are provided for the left and right ear sides respectively for the same head position or sleeping posture. Each pre-stored secondary path estimation model can be obtained through secondary path calibration under the corresponding state.

[0081] The left ear-side secondary path estimation model and the right ear-side secondary path estimation model, along with their corresponding control parameters, are pre-stored for multiple head positions or sleeping postures. The following steps are then performed before the first execution of step S300: S810. Obtain the detection result of the user's current head position or sleeping posture. The detection result is used to characterize whether the user is currently lying flat, on their left side, on their right side, or with their head turned to one side.

[0082] S820. After obtaining the detection results, determine the secondary path estimation model and control parameters for the left ear and the right ear corresponding to the current head position or sleeping posture. Since the acoustic environment of the left and right ears may be different under the same sleeping posture, the corresponding models and control parameters are determined separately for the left and right ears, instead of sharing the same set of models and parameters.

[0083] S830: Configure the determined left-ear secondary path estimation model and control parameters to the corresponding left-ear noise reduction module, and configure the determined right-ear secondary path estimation model and control parameters to the corresponding right-ear noise reduction module, so that the two noise reduction modules respectively use the corresponding configured secondary path estimation model and control parameters in steps S300 and S500. The determined left-ear secondary path estimation model and control parameters are configured to the corresponding left-ear noise reduction module, and the determined right-ear secondary path estimation model and control parameters are configured to the corresponding right-ear noise reduction module. In subsequent execution of step S300, the two noise reduction modules respectively use the corresponding configured secondary path estimation model to filter their respective digital reference signals; in execution of step S500, the corresponding configured control parameters are used to correct their respective filter coefficients.

[0084] During the cyclic execution of steps S100 to S600, if a change in the user's head position or sleeping posture is detected, steps S810 to S830 are re-executed before steps S300 and S500 are executed in the next sampling cycle.

[0085] During the cyclic execution of steps S100 to S600, the detection results of the user's head position or sleeping posture can be continuously or periodically acquired. When it is detected that the user turns over, moves their head, or changes from one sleeping posture to another, before executing steps S300 and S500 in the next sampling cycle, steps S810 to S830 are re-executed to switch the left and right noise reduction modules to the secondary path estimation model and control parameters corresponding to the changed state.

[0086] By pre-establishing the correspondence between head position or sleeping posture and secondary path estimation models on both sides, the model corresponding to the current state can be directly invoked after the user's posture changes, reducing secondary path mismatch caused by always using the same model. Compared to relying solely on adaptive filters to gradually readjust after posture changes, this method can shorten the process required to match control parameters with the current acoustic propagation state.

[0087] Meanwhile, secondary path estimation models and control parameters are configured for the left and right ear sides respectively for the same head position or sleeping posture. This can adapt to the asymmetrical acoustic state when one ear is close to the main body of the pillow and the other ear is facing the outside when lying on the side. This allows the two noise reduction modules to process signals according to the actual propagation conditions of the corresponding sides, improving the adaptability of the independent sound field control of the two ears to changes in the user's turning over and head position.

[0088] In one embodiment, during the cyclic execution of steps S100 to S600, spectral analysis is performed on the digital reference signals obtained from multiple consecutive sampling periods for both the left and right noise reduction modules. This is to adjust the control strategy for subsequent sampling periods based on the frequency distribution and variation of the external incident noise on the corresponding side. The left and right noise reduction modules perform analysis and parameter adjustments respectively, ensuring that their respective target frequency bands and control parameters match the noise characteristics on the corresponding side. Specifically, the following steps are performed for each of the two noise reduction modules: S910. Obtain the digital reference signal obtained in step S100 for multiple consecutive sampling periods, and perform spectrum analysis on the digital reference signal to obtain the energy frequency distribution of the external incident noise on the corresponding side within the multiple consecutive sampling periods and the time-varying characteristics of the energy frequency distribution. The energy frequency distribution is used to characterize the frequency band where the noise energy is mainly concentrated, and the time-varying characteristics are used to characterize whether the noise is relatively stable, periodic, or undergoes rapid changes.

[0089] S920. After obtaining the energy frequency distribution, determine the adaptive control target frequency band for the corresponding noise reduction module based on the energy frequency distribution. For example, when the energy of external incident noise is mainly concentrated in the mid-low frequency band, this mid-low frequency band is determined as the adaptive control target frequency band, so that the processing unit generates and adjusts the drive signal within this frequency band. When the energy frequency distributions of the noise on the left and right sides are different, different adaptive control target frequency bands can be determined respectively.

[0090] S930. After obtaining the time-varying characteristics of the energy frequency distribution, determine the adaptive step size and / or the update frequency of the filter coefficients for the corresponding adaptive filter based on the changing characteristics. When the energy frequency distribution of the noise is relatively stable, a relatively stable adaptive step size and update frequency can be used; when the noise changes rapidly, the update frequency of the filter coefficients and / or the adaptive step size can be increased to enhance the tracking ability of noise changes.

[0091] S940. After determining the update frequency of the adaptive control target frequency band, adaptive step size, and / or filter coefficients, the determined update frequency of the adaptive control target frequency band, adaptive step size, and / or filter coefficients is used in steps S200 and S500 of subsequent sampling periods. Thus, spectrum analysis and parameter determination are performed for multiple consecutive sampling periods that have been obtained, and the determination results are used for subsequent sampling periods without reverse processing of completed sampling periods.

[0092] The following is a more specific example.

[0093] Working Mechanism of Active Noise Control Algorithm. To ensure that the aforementioned hybrid noise reduction structure can automatically achieve and maintain good noise reduction performance in actual acoustic environments, this invention preferably employs the Filtered-x Least Mean Square (FxLMS) algorithm as the core active noise control algorithm. The basic task of the FxLMS algorithm is to automatically and continuously adjust the coefficients of a digital adaptive filter without prior knowledge of the specific noise waveform, so that the inverted sound wave generated by the filter and played through the speaker can maximally cancel out environmental noise near the ear where the error microphone is located.

[0094] The working process of this algorithm can be described as follows.

[0095] Reference signal acquisition. The external incident noise acquired by the reference microphone (i.e., the first acquisition unit) is preprocessed and converted from digital to digital (A / D) to obtain a digital reference signal x(n), which represents the source information of the noise about to reach the ear. The adaptive filter takes this reference signal as input, performs convolution operation with the current filter coefficients w(n), generates a drive signal, and after D / A conversion and power amplification, it is emitted by the loudspeaker (i.e., the sound-emitting unit) to form an anti-phase sound wave.

[0096] The secondary path refers to the entire transmission path of the anti-phase acoustic signal, starting from the output of the controller (i.e., the processing unit), passing through D / A conversion, power amplification, speaker electroacoustic conversion, and acoustic propagation through the air and the main structure of the pillow between the speaker and the error microphone (i.e., the second acquisition unit), until it is picked up again by the error microphone and converted into an electrical signal. The secondary path is not an ideal straight-through channel; it has its own amplitude attenuation, frequency response, and time delay, which alters the phase and amplitude of the signal output by the controller. Therefore, if the original reference signal is directly used to drive the standard least mean square (LMS) weight update, the signal actually applied to the error microphone after the secondary path alteration will no longer match the phase of the reference signal and the error signal, potentially causing the algorithm to fail to converge correctly or even diverge. The core improvement of the FxLMS algorithm is that in the branch used for weight update, a model obtained by estimating the secondary path is first used. The reference signal x(n) is filtered to obtain the "filtered reference signal" x′(n), which is then used in the weight update. This is the origin of "Filtered-x": the object being filtered is the reference signal x(n). Through this process, the reference branch is matched with the actual secondary path in terms of phase and amplitude characteristics, thereby ensuring the stable convergence of the algorithm.

[0097] Error signal processing. The definition of the error signal comes from the error microphone: the error microphone collects the residual sound pressure after the ambient noise and the out-of-phase sound wave output by the speaker are superimposed near the ear. After preprocessing and A / D conversion, the error signal e(n) is obtained. e(n) directly reflects the part of the noise that has not yet been canceled at the ear position at the current moment, and is the target quantity that the algorithm needs to continuously reduce.

[0098] At each sampling time, the algorithm makes minor adjustments to the filter coefficients according to the least mean square criterion, following the direction that causes the error signal energy (instantaneous squared error) to decrease the most. The weight update process can be described by the following expression: w(n+1) = w(n) +μ·x′(n)·e(n) Where: w(n) -- the coefficient vector of the adaptive filter at the current time; w(n+1) -- The updated coefficient vector; x′(n) -- The filtered -x reference signal vector obtained after filtering the reference signal through the secondary path estimation model; e(n) -- Residual noise error signal acquired and processed by the error microphone; μ -- Adaptive step size (also known as convergence factor).

[0099] The physical meaning of this expression is that the coefficient adjustment is proportional to the product of the filtered reference signal and the current error signal. That is, when the error is large and its correlation with the reference signal is strong, the coefficient adjustment is large; as the error gradually decreases, the adjustment also decreases, eventually stabilizing the system. Through such iterative processes, the adaptive filter continuously approaches the optimal coefficients that can maximally cancel noise at the error microphone, thereby continuously reducing residual noise near the ear.

[0100] The value of the step size μ has a crucial impact on the algorithm's performance, requiring a trade-off between convergence speed and stability. When μ is large, the correction of coefficients in each iteration is larger, resulting in faster convergence and more rapid tracking of changes in noise and the acoustic environment. However, an excessively large step size can cause coefficients to oscillate around the optimal value, increase steady-state error, and even lead to algorithm divergence and system instability. When μ is small, the algorithm converges more slowly and is less responsive to environmental changes, but the steady-state error is smaller and the operation is more stable.

[0101] Therefore, in one implementation, a suitable fixed step size can be selected based on the measured noise intensity and convergence, or alternatively, improved strategies such as normalized step size or variable step size can be adopted to enable the step size to be adaptively adjusted according to the reference signal energy or error magnitude, thereby achieving a better balance between fast convergence and steady-state accuracy.

[0102] The secondary path estimation model includes offline pre-calibration, online correction, and responses to path changes. As mentioned above, the secondary path estimation model... The accuracy of the secondary path directly affects the stable convergence of the FxLMS algorithm and the final noise reduction effect. Therefore, the identification and maintenance of the secondary path is a crucial step in the algorithm's engineering implementation. In one embodiment, the present invention preferably performs offline pre-calibration of the secondary path before the product leaves the factory: On the assembled neck pillow, a known excitation signal (e.g., white noise or a swept frequency signal) is played by the controller through a speaker, while an error microphone collects the response signal after passing through the actual secondary path. A digital model of the transmission characteristics from the speaker output to the error microphone is estimated using an adaptive identification method, and the model parameters are pre-stored in the noise reduction chip as the basis for filtering the reference signal during the FxLMS algorithm's operation. This ensures that the product has a secondary path model that matches its actual structure in its initial state upon leaving the factory.

[0103] However, in practical use, the secondary path is not static. When the user's head position changes, they turn over to change their sleeping posture, or the pillow body deforms under pressure, the relative position between the speaker and the error microphone, the shape of the acoustic cavity, and the propagation path will all change, causing the actual secondary path to deviate from the factory-calibrated model. If left unaddressed, this deviation will reduce the noise reduction effect and, in severe cases, affect the stability of the algorithm. To address this issue, this invention optionally introduces an online correction mechanism for the secondary path: during normal system operation, a low-level identification signal that is essentially inaudible to the user is superimposed and injected, and the secondary path estimation model is continuously or periodically updated accordingly to track the slow changes in the actual path; simultaneously, the FxLMS adaptive filter itself will also continuously update the coefficients of the main filter based on the error signal. Therefore, when the secondary path or noise environment changes, the algorithm can gradually reconverge to a new optimal state through continuous iteration, thus possessing a certain degree of adaptability to changes in the sound field caused by head movement and pillow body deformation. In one implementation, the detection results of head position or sleeping posture can be combined to switch or modify the corresponding secondary path model and control parameters between different position states, so as to further improve the stability and accuracy of local sound field control.

[0104] Noise spectrum analysis and control strategy adjustment under different noise scenarios. To make the noise reduction effect more targeted, the DSP digital signal processing unit of this invention performs spectrum analysis on the collected noise while executing adaptive control, identifies the frequency distribution of noise energy and its time-varying characteristics, thereby determining the current noise scenario and adjusting the control strategy accordingly. For noise with energy concentrated in the low to mid frequency and relatively stable (e.g., traffic noise, mechanical noise from air conditioners and fans), the system can focus the adaptive control on the corresponding low to mid frequency band and use a relatively stable step size to achieve stable and sufficient cancellation. For mechanical noise with strong periodicity, the system can utilize its periodicity to improve the accuracy of cancellation. When the noise changes rapidly, the system can appropriately improve the adaptive tracking capability while ensuring stability, so as to respond to noise changes more quickly. It should be noted that the above-mentioned division of noise scenarios and corresponding adjustment of control strategies are intended to illustrate the control idea that can be implemented in engineering. The specific frequency band division threshold, discrimination rules and parameter values ​​can be determined according to actual tuning, and this invention does not impose specific numerical limitations on them.

[0105] The effectiveness of the algorithm against low- and mid-frequency noise and its inherent limitations against high-frequency and sudden noise. It should be objectively pointed out that active noise cancellation technology and the FxLMS adaptive control method used in this invention have relatively good suppression capabilities against low- and mid-frequency noise, but inherent limitations against high-frequency and sudden noise. The fundamental reason is that active noise cancellation relies on precisely aligning the phase of the anti-phase sound wave with the noise at a specific spatial location to achieve cancellation. The higher the noise frequency, the shorter its wavelength, and the faster the phase changes with spatial location. Maintaining precise phase matching within the user's ear, a region with a certain spatial range, becomes increasingly difficult. Furthermore, unavoidable time delays exist in the system's acquisition, processing, conversion, and sound generation stages, significantly increasing the difficulty of effectively canceling high-frequency noise. For sudden, non-stationary noise, because its occurrence time and spectrum are difficult to predict, the adaptive algorithm requires a certain convergence time to track it. Often, the noise has already ended before the algorithm has fully converged, making it difficult to achieve ideal cancellation results. Therefore, in one embodiment, the present invention preferably sets the effective frequency band of active noise cancellation to the mid-low frequency range of approximately 20~2000 Hz to leverage the advantages of active noise cancellation in this frequency band. For high-frequency noise and sudden noise outside the aforementioned frequency band, passive attenuation is mainly achieved through passive methods such as the passive sound absorption of the pillow's main filling material and the outer cover, as well as the ear-blocking effect of the raised structures on both sides. The present invention does not claim that active noise cancellation can achieve the same degree of elimination across the entire frequency band, thus avoiding exaggeration of the noise cancellation effect.

[0106] When using this invention, the user can lie flat or on their side on the pillow body. The noise reduction modules on both sides correspond to the position of the human ear. Turning on the noise reduction function will enable quiet rest. Alternatively, the pillow body can be placed vertically and used as a support pillow against the back and neck. For daily cleaning, only the outer cover needs to be removed for washing. The inner waterproof cover and the built-in device do not need to be treated. Daily water stains and sweat stains can be wiped directly, making it convenient to use.

[0107] In the description of this specification, the use of terms such as "Embodiment 1," "this embodiment," or "in one embodiment" indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example; moreover, the specific features, structures, materials, or characteristics described may be combined in any appropriate manner in one or more embodiments or examples.

[0108] In the description of this specification, the terms "connection," "installation," "fixing," "setting," and "having" are interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0109] In the description of this specification, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0110] The above description of the embodiments is intended to enable those skilled in the art to understand and apply the technology of this invention. Those skilled in the art can readily make various modifications to these examples and apply the general principles described herein to other embodiments without creative effort. Therefore, this invention is not limited to the above embodiments. Modifications in the following situations should be within the scope of protection of this invention: ① New technical solutions implemented based on the technical solution of this invention and combined with existing common knowledge, where the technical effects of the new technical solution do not exceed the technical effects of this invention; ② Equivalent substitutions of some features of the technical solution of this invention using known technology, resulting in the same technical effects as those of this invention; ③ Extendable technical solutions based on the technical solution of this invention, where the substantive content of the extended technical solution does not exceed the technical solution of this invention; ④ Equivalent transformations made using the content of this specification and drawings, directly or indirectly applied to other related technical fields.

Claims

1. An active noise-canceling headrest, characterized in that, include: The pillow body has a concave center to form a head support area, and protrusions on both sides of the head support area to form an ear contact area. Two noise reduction modules are symmetrically embedded inside the two ear-contacting areas. Each noise reduction module includes a sound-generating unit and a processing unit. The noise reduction module also includes a first acquisition unit and / or a second acquisition unit. The first acquisition unit is located near the outer side of the pillow body and is used to acquire external incident noise to obtain a reference signal. The second acquisition unit is located near the user's ear area and is used to acquire residual noise to obtain an error signal. The processing unit generates a driving signal for driving the sound-generating unit based on the reference signal obtained by the first acquisition unit and / or the error signal obtained by the second acquisition unit.

2. The active noise-canceling headrest according to claim 1, characterized in that, Each of the noise reduction modules includes a first acquisition unit, a second acquisition unit, a sound generation unit, and a processing unit; each processing unit generates a driving signal for driving the sound generation unit in its respective noise reduction module based on the reference signal obtained by the first acquisition unit and the error signal obtained by the second acquisition unit.

3. The active noise-canceling headrest according to claim 2, characterized in that, An installation cavity is provided inside the ear contact area, and the noise reduction module is fixedly installed in the installation cavity. The thickness of the noise reduction module is no more than half the thickness of the ear contact area. The installation cavity is filled with cushioning material, which is disposed on the surface of the noise reduction module.

4. The active noise-canceling headrest according to any one of claims 1-3, characterized in that, It also includes a power supply module for supplying power to the two noise reduction modules; the bottom of the pillow body is provided with a mounting groove, the power supply module is embedded in the mounting groove, the opening of the mounting groove is provided with a cover, and a waterproof sealing ring or waterproof sealant is provided between the cover and the opening of the mounting groove; the side or bottom of the pillow body is provided with a charging interface, and the charging interface is provided with an openable and closable waterproof plug.

5. The active noise-canceling headrest according to claim 4, characterized in that, The outer periphery of the pillow body is sealed with a waterproof sleeve, and the outer periphery of the waterproof sleeve is covered with a pillowcase, which is detachably connected to the waterproof sleeve.

6. A binaural adaptive sound field control method for an active noise-canceling headrest, used in any one of claims 1-5, characterized in that, Within each sampling period, the following steps are performed for each of the two noise reduction modules: S100. External incident noise is acquired through the first acquisition unit, and the acquired external incident noise is preprocessed and converted from analog to digital to obtain a digital reference signal. S200: An adaptive filter is used to perform convolution operation on the digital reference signal according to the current filter coefficients to obtain a driving signal. The driving signal is then converted from digital to analog and amplified in power. The sound-generating unit is driven to output sound waves according to the converted and amplified driving signal. S300. The digital reference signal obtained in step S100 is filtered using a secondary path estimation model to obtain a filtered reference signal. S400: After the sound wave output by the sound-generating unit and the external incident noise are superimposed in the corresponding ear region, the residual noise in the corresponding ear region is collected by the second acquisition unit, and the residual noise is preprocessed and converted from analog to digital to obtain an error signal. S500. After obtaining the filtered reference signal and the error signal, the current filter coefficients are corrected according to the corresponding product of the filtered reference signal and the error signal and the adaptive step size to obtain the updated filter coefficients. S600: Use the updated filter coefficients as the current filter coefficients for the next sampling period, and return to step S100. The two noise reduction modules independently generate driving signals and update their respective filter coefficients based on their respective digital reference signals and error signals.

7. The binaural adaptive sound field control method according to claim 6, characterized in that, Before the first execution of step S100, a secondary path estimation model is established for each of the two noise reduction modules. Establishing the secondary path estimation model includes the following steps: S010. The processing unit drives the corresponding sound-emitting unit to play a known excitation signal; S020. After the known excitation signal is played by the corresponding sound unit, the response signal formed by the known excitation signal passing through the corresponding sound unit and the acoustic propagation path between the sound unit and the second acquisition unit is acquired by the corresponding second acquisition unit. S030. After obtaining the response signal, based on the known excitation signal and the response signal, identify the transmission characteristics between the signal output terminal of the corresponding processing unit and the corresponding second acquisition unit. S040. Establish a corresponding secondary path estimation model based on the transmission characteristics, store the model parameters of the secondary path estimation model in the corresponding processing unit, and use the secondary path estimation model to filter the digital reference signal in step S300.

8. The binaural adaptive sound field control method according to claim 7, characterized in that, During the cyclic execution of steps S100 to S600, the following steps are performed continuously or periodically for each of the two noise reduction modules: S710. The low-level identification signal is superimposed on the driving signal generated in step S200, and the corresponding sound unit is driven to output sound waves according to the driving signal superimposed with the low-level identification signal. S720. After the corresponding sound unit outputs a sound wave containing the low-level identification signal, the corresponding second acquisition unit acquires the identification response signal formed after the low-level identification signal passes through the corresponding secondary path. S730. After obtaining the identification response signal, update the corresponding secondary path estimation model based on the low-level identification signal and the identification response signal. S740. After updating the corresponding secondary path estimation model, the updated secondary path estimation model is used to filter the digital reference signal in step S300 of the subsequent sampling period.

9. The binaural adaptive sound field control method according to claim 6, characterized in that, The left ear-side secondary path estimation model and the right ear-side secondary path estimation model, along with their corresponding control parameters, are pre-stored for multiple head positions or sleeping postures. The following steps are then performed before the first execution of step S300: S810: Obtain the detection results of the user's current head position or sleeping posture; S820. After obtaining the detection results, determine the secondary path estimation model and control parameters of the left ear side and the secondary path estimation model and control parameters of the right ear side corresponding to the current head position or sleeping posture. S830. Configure the determined secondary path estimation model and control parameters of the left ear to the corresponding noise reduction module of the left ear, and configure the determined secondary path estimation model and control parameters of the right ear to the corresponding noise reduction module of the right ear, so that the two noise reduction modules adopt the corresponding configured secondary path estimation model and control parameters in steps S300 and S500 respectively. During the cyclic execution of steps S100 to S600, if a change in the user's head position or sleeping posture is detected, steps S810 to S830 are re-executed before steps S300 and S500 are executed in the next sampling cycle.

10. The binaural adaptive sound field control method according to claim 6, characterized in that, During the cyclic execution of steps S100 to S600, the following steps are performed for each of the two noise reduction modules: S910. Obtain the digital reference signal obtained in step S100 from multiple consecutive sampling periods, and perform spectrum analysis on the digital reference signal to obtain the energy frequency distribution of the external incident noise on the corresponding side in the multiple consecutive sampling periods and the change characteristics of the energy frequency distribution over time. S920. After obtaining the energy frequency distribution, determine the adaptive control target frequency band of the corresponding noise reduction module based on the energy frequency distribution; S930. After obtaining the characteristics of the change of the energy frequency distribution over time, determine the adaptive step size and / or the update frequency of the filter coefficients of the corresponding adaptive filter based on the characteristics of the change. S940. After determining the update frequency of the adaptive control target frequency band, adaptive step size and / or filter coefficients, the determined update frequency of the adaptive control target frequency band, adaptive step size and / or filter coefficients is used in steps S200 and S500 of subsequent sampling periods.

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