Abstract: An autonomous cleaning device and a noise reduction air duct device are provided for autonomous cleaning device. The autonomous cleaning device includes a body and a motor arranged on the body, and the noise reduction air duct device is mounted on the body. The noise reduction air duct device includes an upper housing, a lower housing and a support noise reduction structure made of elastic material. The lower housing and the upper housing enclose to form an air duct, an air inlet is arranged at a position of the air duct corresponding to the motor, and an air outlet is arranged on a side of the air duct away from the air inlet; the support noise reduction structure has a first end fixed on the lower housing, and a second end abutting against a lower surface of the upper housing.

Abstract: The invention relates to an adaptive active noise cancellation apparatus and an audio playback system using the same. The adaptive active noise cancellation apparatus shapes an error signal and a noise signal according to a shape of an ideal noise. After that, the shaped noise signal and the shaped error signal are sent into a parameter adjusting unit to perform an adaptive parameter adjustment. Thus, the adaptive noise filter unit is not only can adaptively suppress noise and minimize the error signal, but also can suppress specific frequencies that are sensitive to the human ear.

Abstract: The cleaner according to the present disclosure includes a main body forming an airflow path through which air is sucked and exhausted; a dust separation unit disposed in the airflow path and configured to separate dust from the air; a fan module disposed in the airflow path and configured to move the air in the airflow path; and a noise control module including a speaker, and configured to control the output of the speaker to increase a level of the noise of at least one range of the frequency range of 2000 Hz or more and 8000 Hz or less.

Abstract: A method of thermodynamic assessment of flow through a turbomachine having a compressor, comprising: receiving sensor readings from a plurality of acoustic sensors located about an intake for the turbomachine upstream of the compressor; and receiving pressure and stagnation temperature readings for the flow into the intake. A static temperature is determined for the flow into the intake and an average velocity of the flow over a flow area of the intake upstream of the compressor using the acoustic sensor readings. A mass flow rate of the flow through the intake is determined using the average velocity of the flow and the stagnation pressure.

Abstract: Embodiments for one-way sound absorbing systems are described herein. In one example, a sound absorbing system includes a waveguide having open ends for receiving an incoming acoustic wave and wall portions defining a first port and a second port. A first electroacoustic absorber is mounted to the first port and is electrically connected to a shunting circuit, while a second electroacoustic absorber is mounted to the second port and is electrically connected to an open circuit. The sound absorption of the system is directional dependent.

Abstract: A design method for feedforward active noise control (ANC) system using analog filter. In which, at least one noise collecting system is adopted for collecting a real environmental noise for obtaining a reference signal and a target signal. According to the reference signal and the target signal, a first adaptive system identifying unit is enabled to complete a system identification process for producing a first adaptive filter. After that, a second adaptive system identifying unit is enabled to complete a system identification process based on the reference signal, the target signal and the first adaptive filter for producing a second adaptive filter. After the second adaptive filter is converted to a low-order digital filter, the digital filter is further converted to a physical analog filter circuit. Consequently, a feedforward ANC system comprising the physical analog filter circuit, a pre-amplifier unit, a reference microphone, and a mixer is established.

Abstract: An unmanned flying object, capable of suppressing an increase in overall size while having a configuration to reduce noise, is provided. The unmanned flying object includes a duct that corresponds to: at least one generator that generates airflow; at least one microphone; and at least one speaker. The duct covers the at least one generator in a direction perpendicular to an airflow direction, passes the airflow in the airflow direction, includes a space between inner and outer peripheral surfaces, and defines an opening at the end of the space in the airflow direction. A shape of the inner peripheral surface is tapered in the airflow direction. The at least one microphone is positioned in the space. The at least one speaker is positioned closer to the at least one generator than the at least one microphone.

Abstract: To improve soundproofing performance of a soundproofing wall constituted by wall members overlapping with a hollow portion therebetween. A resonance state of an outer wall member of a soundproofing wall which includes an inner wall member on the side of a sound generation source, an outer wall member outwards from the inner wall member with respect to a position of the generation source, and a hollow portion which is provided between the inner wall member and the outer wall member is detected. A pressure of the hollow portion is adjusted so that the resonance state is a minimum based on adjustment of the pressure of the hollow portion.

Abstract: An information handling system may include an air mover configured to cause movement of gaseous fluid within the information handling system in order to thermally cool one or more components of the information handling system and a dynamic noise generation system configured to receive an indication of expected acoustical energy generated by the air mover and generate sound in accordance with an output noise signal based on noise generated by the air mover.

Abstract: A wearable camera includes an imaging unit; a storage unit configured to store video data imaged by the imaging unit; a sound collection unit disposed on an upper surface of a casing of the wearable camera and configured to collect a sound of a user; and a control unit configured to extract a sound of the user related to an imaging situation included in the video data, and add attribute information to the video data based on the extracted sound.

Abstract: Methods and apparatus to implement microphones in thin form factor electronic devices are disclosed. An electronic device includes a chassis having an exterior surface and an interior surface. The chassis includes a plurality of holes extending through the chassis. The plurality of holes are within a 1 mm diameter circular area of the chassis. The electronic device further includes a microphone coupled to the interior surface of the chassis adjacent the circular area of the chassis.

Abstract: A microwave irradiation device includes a housing capable of accommodating an object to be heated; a plurality of microwave resonators installed around the housing; a microwave conductor coupling the plurality of microwave resonators; a microwave generator configured to generate microwaves having different frequencies; and a microwave measurement circuit coupled to the housing or the microwave conduction unit. Each of the microwave resonators resonates a microwave having a resonance frequency of the microwave resonator generated in the microwave generator and irradiates the object placed in the housing with the resonated microwave, and one microwave resonator among the plurality of microwave resonators and another microwave resonator have different resonance frequencies.

Abstract: A ventilation device for an interior of a motor vehicle includes a ducting system with at least one air duct and a blower via which an air flow can be generated in the ducting system. To allow active ventilation of the interior at particularly low noise levels, at least one sound transducer of the ventilation device is provided via which a sound pressure in the ducting system can be detected and a signal corresponding to the sound pressure detected can be transmitted to at least one second sound transducer of the ventilation device. In order to reduce the sound pressure, a counter sound pressure depending on the signal in the ducting system can be generated by the at least one second sound transducer.

Abstract: Vehicles and methods are disclosed for enabling low power security checks to be performed on attempted access to a vehicle. An example vehicle includes a communication system having a low frequency antenna for communication with a vehicle unlocking device and a processor. The processor is configured to vary a gain in a low frequency signal transmitted to the vehicle unlocking device via the communication system, determine, based on a response from the vehicle unlocking device, that the vehicle unlocking device is a suspected attack device, responsively perform a security check on the vehicle unlocking device, and transmit an alert based on the security check.

Abstract: An active duct noise control system and a method thereof are provided, including a duct, a noise source speaker, a microphone, a plurality of noise-cancelling speakers, and a plurality of controllers. Wherein, the noise source speaker generates the primary noise, and the microphone is disposed to receive the residual noise. The plurality of noise-cancelling speakers are disposed between the noise source speaker and the microphone and respectively generate noise-cancelling audio frequencies to offset the primary noise and reduce the residual noise. The plurality of controllers are respectively connected to the plurality of noise-cancelling speakers and the noise source speaker and calculate each of the noise-cancelling audio frequencies generated by each of the plurality of noise-cancelling speakers according to the multi-channel inverse filtering principle.

Abstract: A rotor blade noise reduction system includes: a plurality of rotor blades; a plurality of first speakers disposed equidistantly on a first circumference which is opposed to one surface of a rotor blade plane; a plurality of second speakers disposed equidistantly on a second circumference which is opposed to the other surface of the rotor blade plane; at least one evaluation microphone configured to acquire noise generated from the rotating rotor blades and control sound generated from the first speakers and the second speakers; and an active sound suppression processor configured to input a plurality of first delay control signals corresponding to the first speakers, and to input a plurality of second delay control signals corresponding to the second speakers.

Abstract: An attenuation device for attenuating sound waves, and a corresponding system and method, generated by a source emitting sound waves having frequencies between f1 and f2 and wherein the pressure levels are between n1 and n2. The attenuation device comprising at least one acoustic absorber comprising at least one non-linear membrane; the attenuation device being configured in such a way that the first face of the absorber is in acoustic communication with the source. The attenuation device also comprises at least one coupling element for coupling the second face with the source, the coupling element being configured to transmit to the second face sound waves according to the sound waves emitted by the source, and of which the phase and/or the amplitude leads to a pressure differential of the sound waves arriving respectively on the first and second face at the same time.

Abstract: A device includes a housing and a core configured to be secured within the housing. The core includes a microphone configured to detect a sound signal. The core also includes a control board configured to generate a noise-canceling sound signal based on the sound signal and a set of transfer functions. The core further includes a speaker configured to deliver the noise-canceling sound signal. The device also includes a fastener configured to connect the housing to an air filter of an intake vent of an enclosure of a power generation unit.

Abstract: An active noise cancellation system and method, in which an active noise controller generates an anti-noise signal based on an error signal, and a loudspeaker operatively coupled to the active noise controller converts the anti-noise signal into anti-noise sound. An acoustic error sensor operatively coupled to the active noise controller picks up sound and converts the picked-up sound into the error signal. The acoustic error sensor is disposed at a front face of the loudspeaker.

Abstract: A centrifugal blower system includes a centrifugal blower assembly for generating airflow. The centrifugal blower assembly includes a housing, a motor coupled to the housing, and at least one impeller coupled to the motor. A motor controller is coupled to the motor. The motor controller is configured to receive at least one feedback parameter and to transmit instructions to the motor to control an operation of the motor based on the at least one feedback parameter. The operation of the motor is configured to reduce noise in the centrifugal blower system.

Abstract: An acoustic device that has a neck loop that is constructed and arranged to be worn around the neck. The neck loop includes a housing with a first acoustic waveguide having a first sound outlet opening, and a second acoustic waveguide having a second sound outlet opening. There is a first open-backed acoustic driver acoustically coupled to the first waveguide and a second open-backed acoustic driver acoustically coupled to the second waveguide.

Abstract: The present invention discloses a fan noise controlling system, comprising: at least one cylinder-shaped limiter, a plurality of error sensors, a noise controlling module, and at least one loudspeaker. According to the particular design of the present invention, the cylinder-shaped limiter is connected to a fan device for confining the transmission path of at least one fan noise signal. On the other hand, the error sensors are disposed in the internal of the cylinder-shaped limiter, and the loudspeaker is disposed at an axis position of the fan device. When this fan controlling system normally works, the noise controlling module is able to generate at least one anti-noise signal according to a plurality of error signals collected by the error sensors at consecutive previous time points, and then the loudspeaker is driven to broadcast the anti-noise signal for carrying out an outstanding efficacy on the cancellation of the fan noise.

Abstract: An initial operating speed of a cooling fan at an information handling system is determined. A microphone is located at the system to favor acquisition of ambient sound relative to acquisition of sound emanating from the cooling fan. An audio signal is received from the microphone. The operating speed of the cooling fan is adjusted based on a level of the audio signal.

Abstract: An inlet apparatus for a gas turbine engine includes: a fan duct adapted to surround at least one row of rotating fan blades, the fan duct having a circular frontal area, and defining a first inlet plane; and an outer duct surrounding the fan duct, the outer duct including: a first frontal area shape at the first inlet plane which defines, cooperatively with an exterior of the fan duct, at least one lobe through which air can pass; and a second frontal area shape at a second inlet plane located axially downstream from the forward end which is circular, and which defines, cooperatively with an exterior of the fan duct, an annulus through which air can pass.

Abstract: An active noise reduction earphone includes a speaker, a plurality of microphones and a feedback system. Each microphone is displaced from the speaker and the other microphones, and each microphone generates a microphone signal responsive to received acoustic noise. The feedback system receives a combination of the microphone signals and generates an inverse noise signal that is applied to the speaker. The speaker generates an inverse acoustic noise signal that substantially cancels the acoustic noise signal at a predetermined location relative to the speaker and the microphones. The feedback system can include a microphone signal combiner in communication with the microphones. The microphone signal combiner generates a signal that may be a sum or weighted sum of the microphone signals and can be used to generate the inverse noise signal. The earphone has an increased noise reduction bandwidth and improved cancellation capability relative to conventional earphones.

Abstract: An adaptive equalization system that adjusts the spectral shape of a speech signal based on an intelligibility measurement of the speech signal may improve the intelligibility of the output speech signal. Such an adaptive equalization system may include a speech intelligibility measurement module, a spectral shape adjustment module, and an adaptive equalization module. The speech intelligibility measurement module is configured to calculate a speech intelligibility measurement of a speech signal. The spectral shape adjustment module is configured to generate a weighted long-term speech curve based on a first predetermined long-term average speech curve, a second predetermined long-term average speech curve, and the speech intelligibility measurement. The adaptive equalization module is configured to adapt equalization coefficients for the speech signal based on the weighted long-term speech curve.

Abstract: A system and method for providing an aircraft noise advisory during departure and/or arrival of an aircraft are disclosed. In one embodiment, predefined allowable aircraft noise level information associated with a plurality of aircraft noise sensors located in the vicinity of airports are obtained. Further, predefined allowable aircraft noise level information associated with one or more of the plurality of aircraft noise sensors is presented on a display device in the aircraft, based on a current location of the aircraft, upon receiving noise data request from a pilot. Furthermore, current aircraft noise level information is obtained from one of the one or more aircraft noise sensors. In addition, the current aircraft noise level information is compared with predefined allowable aircraft noise level information associated with the one of the one or more aircraft noise sensors. Also, the aircraft noise advisory is displayed based on an outcome of the comparison.

Abstract: An operation noise control method for an air conditioner includes: a step (S1) of detecting an operation mode of the air conditioner; a step (S2) of operating an air flow guide panel (20) in accordance with the detected operation mode and controlling the air flow guide panel (20) so as to form a duct-like outlet passage (10) in a vicinity of an outlet (5); a step (S3) of selecting a sound wave which is preset in accordance with the operation mode; and a step (S4) of radiating the selected sound wave in the duct-like outlet passage (10) from a speaker (21).

Abstract: A control signal generating unit in an active sound effect generating apparatus adjusts the amplitude of a control signal by varying the amplitudes of reference signals in accordance with an amount of change in frequency and a load of a driving source.

Abstract: A sound generator, for a system for influencing sound waves propagating through an exhaust system of a vehicle driven by an internal combustion engine, includes an enclosure comprised of an upper shell and a lower shell. A bell mouth, supported by the lower shell and penetrating the lower shell, is configured for a fluid communication with the exhaust system. A loudspeaker is disposed in the enclosure and supported by the bell mouth. The lower shell of the enclosure supports the upper shell of the enclosure. The bell mouth is solely supported by the lower shell of the enclosure. The lower shell may include at least one air-tight feed-through for a control wire connected to the loudspeaker and/or at least one pressure equalizing valve. An anti-sound system is provided that includes the sound generator and a vehicle is provided with the anti-sound system.

Abstract: A second error microphone may be incorporated in a mobile device to allow computation of additional parameters for modifying an adaptive noise cancellation (ANC) algorithm. For example, a first and second acoustic pressure may be calculated from a first and second error microphone of the mobile device. The first and second acoustic pressure may be input to an algorithm for determining an acoustic intensity vector. The ANC algorithm may receive the acoustic intensity vector as an input, and adapt an anti-noise signal to reduce the acoustic intensity vector. Additionally, an input impedance for the error microphones may be calculated from the acoustic pressure to determine coupling between a speaker and a user's ear. The anti-noise algorithm may be adjusted or disabled when the input impedance indicates the user has removed the phone from the user's ear.

Abstract: A computer-implemented method obtains a correlation between percent utilization and noise level for a plurality of compute node types, and obtains an inventory of a plurality of compute nodes in a cluster, wherein the inventory identifies each compute node by a compute node type, and wherein the plurality of compute nodes includes two or more compute node types. The method further includes determining a percent utilization of each compute node, and, for each compute node of an identified compute node type, determining a noise level using the determined percent utilization for the compute node as input into the correlation between percent utilization and noise level for the identified compute node type. An overall noise level in the cluster is calculated using the noise level determined for each compute node, and workload is distributed among the plurality of compute nodes to reduce the calculated overall noise level in the cluster.

Abstract: A low power microphone circuit for a vehicle is provided that includes: at least one microphone transducer; a digital signal processor for receiving output signals from the at least one microphone transducer and for generating a digitally processed audio signal; an output amplifier for amplifying the audio signal from the digital signal processor and modulating an input voltage with the audio signal; and a DC power supply for supplying power to the digital signal processor. The output amplifier and the DC power supply may be electrically coupled in series. The DC power supply and the output amplifier may be powered by the input current, where the input current is no greater than about 6 mA.

Abstract: An arrangement (1) of an electroacoustic actuator (2) on a vehicle structure (3) of a motor vehicle, has a housing (4), in which at least one loudspeaker (7) is arranged, which separates a front volume (8) from a rear volume (9) in the housing (4). The actuator (2) has a sound emission pipe (5), which projects outwards from the housing (4) and which is fluidically coupled with the front volume (8). A reduced introduction of noise into the vehicle arises when the actuator (2) is held on the vehicle structure (3) with a plurality of holding devices (19), which are arranged on the housing (4) in a circumferential direction (20) of the housing (4) spaced apart from one another. Each holding device (19) is designed as springy in a holding direction (21) and as rigid transversely thereto.

Abstract: An active noise control system for exhaust systems of a combustion engine operated vehicle comprises an anti-sound control connectable to an engine control of the vehicle and a loudspeaker connected to the control for receiving control signals and designed for generating an anti-sound in a sound generator, fluidically connectable to the exhaust system. In the control, at least two curves are stored in order to cancel airborne sound conducted in the exhaust system through outputting the signal to the loudspeaker. The curves cover different temperature ranges of the exhaust gas, which temperature ranges overlap one another by pairs or directly adjoin one another. The control is furthermore designed to select a curve suitable for a respective temperature of the exhaust gas conducted in the exhaust system from the available curves by means of signals output by the engine control and output signals to the loudspeaker making use of this curve.

Abstract: Provided are methods and systems for noise suppression within multiple time-frequency points of spectral representations. A multi-feature cluster tracker is used to track signal and noise sources and to predict signal versus noise dominance at each time-frequency point. Multiple features, such as binaural and monaural features, may be used for these purposes. A Gaussian mixture model (GMM) is developed and, in some embodiments, dynamically updated for distinguishing signal from noise and performing mask-based noise reduction. Each frequency band may use a different GMM or share a GMM with other frequency bands. A GMM may be combined from two models, with one trained to model time-frequency points in which the target dominates and another trained to model time-frequency points in which the noise dominates. Dynamic updates of a GMM may be performed using an expectation-maximization algorithm in an unsupervised fashion.

Abstract: An active sound generation device for exhaust gas systems of motor vehicles having a housing and a sound generation means arranged in the housing, in particular a loudspeaker, with a closed sound generation surface and a margin sealingly surrounding the sound generation surface, wherein, for the reduction of the manufacturing costs, the housing has an at least sectionally cylindrical shape and the inner diameter of the cylindrical shape corresponds to the projection of the outer periphery of the margin surrounding the sound generation surface onto a surface perpendicular to the cylinder axis such that the sound generation means can be inserted in a gas-tight manner at any desired point of the cylindrical section.

Abstract: An active noise control apparatus for an intake system of a vehicle may include a filter mounted on a portion of the intake system for blocking foreign materials; and a speaker assembly detachably installed at the portion to which the filter is mounted.

Abstract: The dual resonator chamber with variable volume includes first and second housings. The second housing is slidably mounted within the first housing such that a second inner neck portion of the second housing is slidably mounted about the first inner neck portion of the first housing and forms a fluid-tight seal therewith. A sliding wall is slidably mounted within the second housing, dividing the interior thereof into upper and lower resonator chambers. At least one first actutator selectively adjusts the height of the sliding wall with respect to the second lower end of the second housing to selectively adjust volumes of the upper and lower resonator chambers. At least one second actuator selectively adjusts the height of the second housing with respect to the first housing to selectively adjust the neck length of the lower resonator chamber.

Abstract: An active noise control (ANC) system may be implemented to both sides of a fan, such that both directions of the noise emitting are treated to reduce the overall noise. The impact on airflow is minimal, and the technique is very effective in a broad range of low frequencies. Passive sound-absorbing materials may be included for attenuation of high frequencies. The resulting quiet fan produces a low level of noise compared to any other device based on fan, which produces the same capacity of airflow. The quiet fan may be incorporated in any mechanical system which requires airflow induction such as: computers, air conditioners, machines, and more.

Abstract: A noise cancellation system for transporting a fluid (M) from an inlet in one space (RM1) to an outlet in another space (RM2). A noisy element (VF, HA), e.g. a ventilation fan (VF) or a turbulent noise source (HA), generates acoustic noise. A loudspeaker (L) with a diaphragm (D) is arranged such that a first side (S1) of the diaphragm (D) is in contact with the fluid (M) on a first side (P1) of the noisy element(VF), and a second side (S2) of the diaphragm (D) is in contact with the fluid (M) on a second side (P2) of the noisy element (VF). The loudspeaker diaphragm (D) is arranged to move substantially in anti-phase with at least a part of the noise generated by the noisy element (VF), hereby cancelling the noise from the noisy element (VF). The noisy element may be placed inside a duct system. Especially, the system may be a decentral ventilation system with a noisy ventilation fan (VF) for transporting air between two spaces, e.g. two rooms, or between one room and “free air”.

Abstract: There is provided a method of controlling a noise cancellation system, the noise cancellation system being for use in a device comprising a speaker for receiving a wanted signal and generating a sound signal therefrom, and the noise cancellation system comprising: a digital filter, for generating a noise cancellation signal from an input signal representative of ambient noise; and an output for applying the noise cancellation signal to the speaker in addition to the wanted signal to generate a sound signal from which the ambient noise has been at least partially cancelled. The method comprises: determining a resonant frequency of the speaker; based on the determined resonant frequency, selecting a set of filter coefficients; and applying the selected set of filter coefficients to the digital filter.

Abstract: The invention relates to an air conditioning unit having an air duct, having a fan for conveying an airflow through the air duct, having a heat exchanger for the thermal conditioning of the airflow and having an apparatus for noise reduction, which apparatus has a microphone, a loudspeaker and an evaluation and control unit, the microphone being arranged in a housing indentation of the duct wall of the air duct, the housing indentation having a wall and the loudspeaker being arranged at least partially in an opening of the duct wall of the air duct in a manner which is spaced apart from the microphone in the direction of the noise emission, wherein the wall of the housing indentation is curved at least partially, the housing indentation of the microphone being covered with a porous acoustically transparent material.

Abstract: An acoustic management system configured to compensate for acoustical dampening is provided. The system includes a microphone configured to detect a first acoustic signal from an acoustic environment and a logic circuit. The logic circuit detects an onset of the acoustical dampening between the acoustic environment and the microphone. The logic circuit generates an acoustic damping compensation filter, which is applied to the first acoustic signal to generate a drive signal.

Abstract: An encoding apparatus comprises a frame processor (105) which receives a multi channel audio signal comprising at least a first audio signal from a first microphone (101) and a second audio signal from a second microphone (103). An ITD processor 107 then determines an inter time difference between the first audio signal and the second audio signal and a set of delays (109, 111) generates a compensated multi channel audio signal from the multi channel audio signal by delaying at least one of the first and second audio signals in response to the inter time difference signal. A combiner (113) then generates a mono signal by combining channels of the compensated multi channel audio signal and a mono signal encoder (115) encodes the mono signal. The inter time difference may specifically be determined by an algorithm based on determining cross correlations between the first and second audio signals.

Abstract: An earpiece (100) and a method (300) personalized voice operable control can include capturing (302) an ambient sound from an Ambient Sound Microphone (111) to produce an electronic ambient signal (426), delivering (304) audio content (402) to an ear canal (131) by way of an Ear Canal Receiver (125) to produce an acoustic audio content (404) and capturing (306) in the ear canal an internal sound (402) from an Ear Canal Microphone (123) to produce an electronic internal signal (410). The electronic internal signal includes an echo of the acoustic audio content and a spoken voice generated by a wearer of the earpiece. The Method also includes detecting (312) the spoken voice in the electronic internal signal in the presence of the echo, and controlling (314) a voice operation of the earpiece when the spoken voice is detected.

Abstract: An earpiece of an ANR device incorporates one or more of feedforward-based ANR; feedback-based ANR; passive noise reduction (PNR) of environmental noise sounds in the environment external to the casing of the earpiece in higher audible frequencies; a controlled leak acoustically coupling the front cavity to the environment external to the casing of the ANR device where the coupling may be through another cavity that is closable to the environment external to the casing with a leaky cover; a combination of an acoustically resistive port and a mass port coupling a rear cavity to the environment external to the casing where the coupling may be through another cavity that is closable to the environment external to the casing with a leaky cover; a feedforward microphone given acoustic access to the environment external to the casing through an aperture that is overlain with a leaky cover or that is enclosed within a cavity that is acoustically coupled to the environment external to the casing with a leak.

Abstract: An apparatus for damping acoustic waves that includes a volume of fluid having actively excited acoustic waves, an enclosure disposed in the volume of fluid including delimiting surfaces which define a cavity, at least one of the delimiting surfaces being permeable to the fluid, such that fluid may be exchanged between the cavity and the volume, and at least one sound producer disposed proximate the cavity to actively excite the actively excited acoustic waves in the fluid disposed in the cavity such that acoustic waves are damped in the volume.

Abstract: A method, system and computer program product are provided for implementing dynamic noise elimination. A system frame includes a plurality of acoustical sensory devices monitoring the system for problem frequencies. The system frame includes a plurality of tubes. When the tube is open, airflow is allowed. When identified tubes are closed, quarter-wavelength attenuation is provided for a frequency in a range of frequencies, based upon a length of the tube when closed. Each of the plurality of tubes is selectively controlled to be operable open or closed at a particular length, responsive to identified problem frequencies.

Abstract: An active noise control apparatus for an intake system of a vehicle may include a filter mounted on a portion of the intake system for blocking foreign materials; and a speaker assembly detachably installed at the portion to which the filter is mounted.