372 results about "Acoustic noise reduction" patented technology

A disk drive is disclosed employing either back electromotive force (BEMF) spindle speed control mode or wedge spindle speed control mode. A BEMF detector monitors the BEMF voltage generated by the windings of the spindle motor to generate a BEMF speed error. The BEMF spindle speed control mode is used to spin up the disk to an operating speed, and the wedge spindle speed control to maintain the disk at the operating speed. While in the wedge spindle speed control mode, a BEMF detection window is disabled to reduce acoustic noise.

A disk drive is disclosed comprising a disk, an actuator arm, a head connected to a distal end of the actuator arm, and a voice coil motor (VCM) for rotating the actuator arm about a pivot to actuate the head over the disk, wherein the VCM rotates the actuator arm into a latched positioned when the disk drive is idle. Disk drive control circuitry unlatches the actuator arm by applying a driving current to the VCM according to an open-loop current profile. The open-loop current profile comprises an acceleration pulse having an acceleration magnitude and an acceleration interval, and a deceleration pulse having a deceleration magnitude and a deceleration interval. The deceleration magnitude is substantially smaller than the acceleration magnitude, and the deceleration interval is substantially longer than the acceleration interval, to thereby attenuate acoustic noise when unlatching the actuator arm.

An aircraft engine nacelle comprises: (a) an inlet lip and a skin having internal and external surfaces; (b) a noise abatement structure such as an acoustic panel located on the internal surface of the nacelle skin; and (c) an electrically powered de-icing system located on the external surface of the nacelle skin and in electrical connection to a power source. A method for de-icing and abating noise from an aircraft nacelle comprises: (a) providing a noise abatement structure such as an acoustic panel located on the internal surface of the nacelle skin; (b) providing an electrically powered de-icing system on the external surface of the nacelle skin; and (c) applying an electric current to the electrically powered de-icing system. The nacelle skin may be a perforated skin, and the de-icing system comprises a wire mesh bonded to the external surface of the perforated skin. The method and nacelle permit the use of noise abatement structures such as acoustic panels for noise reduction while advantageously avoiding detrimental high temperatures associated with conventional de-icing systems.

An acoustic noise reduction accessory apparatus attachable or made integral to a personal computer or other electronics equipment. The apparatus reduces acoustic noise emitted from the rear of the computer and in particular reduces the acoustic noise from circulating fans. The apparatus comprises an acoustic barrier or shielding member. The barrier is shaped in various forms externally of the computer or integrally extending from the back of the computer around one or more fans of the computer; the acoustic barrier member allows for minimum airflow reduction. Acoustic absorbing material is layered upon the acoustic barrier and may be combined with vibration absorbing material. The barrier may be shaped from solid or flexible members to accommodate different sized electronics and formed to include baffles and structures to direct airflow while absorbing noise; and may be made adjustable by one or more slidable members. The apparatus is easily assembled and collapsible for storage.

A transducer, a headphone and a method reduce noise and/or ambient sounds. The headphone has a microphone, a transducer and/or an electrical circuit for producing and/or for transmitting an anti-noise sound wave and/or a noise compensation signal inside an ear cup of the headphone. The anti-noise sound wave and/or the noise compensation signal cancels, dampens and/or reduces a sound wave of the noise and/or of the ambient sounds inside the ear cup. The transducer produces and/or transmits an audio signal which is received by an ear of a user. The microphone and the transducer are connected to, are attached to and/or are in communication with the electrical circuit within the headphone. The transducer has a double-sided diaphragm with concentric circular corrugations and/or foil spiral conductors on each side of the diaphragm. The microphone inside the ear cup is covered by and/or is connected to a sound absorbing material inside the ear cup of the headphone. An ear cushion having a inner side and an outer side is attached to and/or is connected to the ear cup for receiving an ear of a user. The inner side and the outer side of the ear cushion are made from an acoustically resistive material and an acoustically isolating material.

Described are metallized biaxially oriented polylactic acid (BOPLA) films with a novel formulation that exhibits a softer feel and quieter sound, without jeopardizing film making stability. It has been found that when these films are metallized, moisture barrier properties are surprisingly improved compared to conventional metallized BOPLA films. Specifically, the moisture barrier of the films may be 2.0 g/m²/day or less at 38° C. and 90% relative humidity. The films can be used, for example, in packaging applications. The films have characteristics that are beneficial to converting processes, are economical, and maintain bio-compostability similar to typical BOPLA films.

An aircraft window configuration utilizes a laminate build-up of the primary pane to increase damping and reduce the structural response to the turbulent boundary layer outside the aircraft. The laminate may consist of several acrylic layers or a combination of acrylic and glass layers. Noise dampening results from the introduction of a transparent visco-elastic material or a urethane. A vacuum layer may be introduced between the primary pane and a middle, or fail-safe pane. The vacuum layer decouples the panes over a broad frequency range resulting in a lower response of the inner pane that radiates noise into the passenger cabin. Such a window configuration reduces weight and improves noise performance. A damped laminate also reduces pane deflections into the air stream and improves aerodynamic performance of the aircraft.

The system provides a technique for suppressing or eliminating tonal noise in and input signal. The system operates on the input signal at a plurality of frequency bins and uses information generated at a prior bin to assist in calculating values at subsequent bins. The system first identifies peaks in a signal and then determines if the peaks are from tonal effects. This can be done by comparing the estimated background noise of a current bin to the smoothed background noise of the same bin. The smoothed background noise can be calculated using an asymmetric IIR filter. When the ratio of the current background noise estimate to the currently calculated smoothed background noise is far greater than 1, tonal noise is assumed. When tonal noise is found, a number of suppression techniques can be applied to reduce the tonal noise, including gain suppression with fixed floor factor, an adaptive floor factor gain suppression technique, and a random phase technique.

A two-way voice communication device which provides a high-level of acoustic noise reduction is disclosed. A resilient ear tip provides acoustic isolation and secures the earphone within the ear canal of the user. The ability to rotate the earphone within the ear canal allows the user to easily position an attached microphone. The audio signals may be conveyed by an included radio frequency receiver and radio frequency transmitter, or the earphone may be connected to an electrical audio device using a multi-conductor cable. Audio signals may be conveyed to one or both ears of a user. A switch to mute the audio signal from the microphone, or for supporting a push-to-talk mode of operation, may be included in the earphone housing, or on the cable.

A system for reducing the emissions produced by an engine affixed to a body during operation and reducing noise and vibration. The present invention is particularly related to a small form factor active/passive Diesel Particulate Filter system having an exhaust backpressure sensor, a heating element, a Diesel Oxidation Catalyst, a power relay switch, a filter and an electronic control unit for controlling the heating element based on backpressure detected by the sensor.

The invention provides a composite material silencing and noise-reducing acoustic liner and a preparation method thereof, belongs to the technical field of structural/functional integrated composite material molding, and mainly relates to a composite material microporous panel honeycomb sandwich structure silencing and noise-reducing acoustic liner assembly, a molding process method and applications thereof, specifically to layer spreading of aramid fiber and glass fiber reinforced epoxy resin-based composite prepreg, application of a polymer acoustic separation membrane material, and hot press tank curing molding. According to the present invention, a large number of micro-pores are processed on the composite material layer plate through the laser processing method; and the Nomex aramid paper honeycomb core, the composite material panel and the back plate are adhered and cured by the film-like adhesive to form the micro perforated plate composite material silencing and noise-reducingacoustic liner, wherein the silencing and noise-reducing acoustic liner can be the single-freedom-degree acoustic liner structure and the multi-freedom-degree acoustic liner structure, and can achievethe acoustic noise reduction function of aero engines.

A method and apparatus is disclosed for acoustic noise reduction using fan speed control. The acoustic noise reduction using fan speed control includes a plurality of temperature detectors disposed at a plurality of locations within an electronics equipment enclosure, each detector having an associated setpoint temperature. An error value is determined for each temperature detector, the error consisting of the difference between the detected temperature and the associated setpoint temperature. The maximum error among all error values is then identified and the operating speed of a cooling fan in is set in response to this maximum error. Advantages include providing a fan speed directly related to electronics temperature which inherently accounts for higher ambient temperatures, enclosure altitude, electronics power consumption, and air filter clogging. The acoustic noise reduction using fan speed control is particularly useful for overcoming the need to overcompensate fan speed, thereby resulting in higher than necessary noise levels in order to accommodate worse-case conditions known in the art.

A vented cover includes a pair of cross-flow ventilation ducts each including an acoustic noise reduction lining. The ducts are “cross-flow” in that they cross and bypass one another. The cover is affixed to an enclosure containing components of a computer system and abuts against a panel of the enclosure having an airflow aperture. An air moving device (AMD) passes air through the enclosure from the ducts if the cover is an intake cover, and/or into the ducts if the cover is an exhaust cover. The ducts increase the air path length, and the acoustic absorbing surface, thereby increasing acoustic attenuation. Airflow resistance is reduced by reducing surfaces perpendicular and close to the area where air enters and by reducing sharp turns in the ducts. The cover has a relatively thin depth because the ducts cross and bypass each other in a very space efficient manner.