Abstract: An actively controlled mount system to control vibration which permits static forces from a machine while decoupling transmission of dynamic vibration forces. The mount system includes opposed force chamber (156, 160) with pistons which control movement of an engine connected bushing (3) to allow compensatory force generated by the opposed chambers to transfer thereto to attenuate vibration from the engine.

Abstract: An active high transmission loss panel for quieting either one or two way sound radiation which incorporates a number of cells (11) which contain sensors and actuators (12) adapted to be controlled independently or interactively so as to attenuate noise attempting to pass through said panel.

Abstract: An apparatus and method of actively cancelling undesirable acoustic noise generated by a patient diagnosing apparatus during a diagnosis operation which includes a remotely located active noise cancellation unit. The undesirable acoustic noise is transferred via hollow tubes from the patient diagnosing apparatus to the remote location to be detected thereat. A control unit thereafter generates cancellation waves based upon the detected undesirable acoustic noise. The cancellation waves are transferred to the patient area via additional hollow tubes to cancel the undesirable acoustic noise. The use of hollow tubes of non-magnetic, non-metallic material ensures that the undesirable acoustic noise and the cancellation waves do not interfere with the diagnosis of operation.

Abstract: A method and system by which the number of samples used to characterize the noise cycle of an active noise cancellation system varies dynamically as a function of the fundamental operating frequency of the system.

Abstract: An active force cancellation system adapted to contain vibrations in flexible structures which utilizes co-located vibration sensors and counter-vibration devices to offset linear disturbances without setting off sub-structure vibrations.

Abstract: A mount assembly is provided for mounting a component, such as an engine, to a vehicle for active control of vibration. The assembly includes first and second mounting members and, an intermediate insert with first and second elastomeric systems connecting said first and second mounting members with the intermediate insert in between. An actuator in parallel with said first elastomeric system provides vertical force to said first elastomeric system to provide a relatively soft vertical rate. A controller operates the actuator in response to sensed vibration so that the vertical force tends to avoid or cancel it. A relatively high fore/aft and lateral dynamic rate of the first system protects the actuator. The second elastomeric system connects the second mounting member with the intermediate insert and exhibits a relatively high vertical rate and a relatively soft fore/aft and lateral rate. One or more sensors feeds data to a controller that analyzes the vibrations to determine the harmonics thereof.

Abstract: An in wire active cancelling system cancels undesirable repetitive signal components from a primary electronics signal controlling desired intelligent signal components and undesirable repetitive signal components. The primary electronic signal is fed as an input to an electronic mixer. A second input to the electronic mixer is a repetitive cancelling signal which is applied by the mixer to cancel the undesirable repetitive signal component from the primary signal without interfering with passage of the primary signal intelligent signal components. The repetitive cancellation signal is developed from a residual signal developed by the mixer and a timing signal obtained from a timing signal generator.

Abstract: A digital virtual earth active cancellation system which receives a phenomena input signal representing residual phenomena to be cancelled and has an adaptive filter which generates a cancellation signal. A system impulse response is convolved with the cancellation signal and is subtracted from the input signal to produce an estimate of noise. This substantially eliminates the problems associated with destructive feedback due to phase shifts. The residual signal is used to control an adaptive filter that receives the estimated noise as an input. The adaptive filter produces the cancellation signal by filtering the estimated noise with filter weights that are adapted using the residual signal and the estimated noise convolved with the system impulse response.

Abstract: An active sound attenation system for combustion engine exhaust systems and the like is disclosed. To protect the counter-noise acoustic wave generator from the environment of the medium propagating the undesirable noise, an acoustically tuned anti-noise chamber is interposed between the wave generators 19, 19A and the location of the medium with the undesirable noise. To provide for global cancellation at the outlet end 4, of the exhaust pipe 10, the anti-noise chamber 11, 11A has an annular opening disposed substantially in the plane 4 of the exhaust pipe outlet thereby giving the undesirable noise and the cancelling noise an apparent common source.

Abstract: A hybrid type vibration isolation mounting apparatus for supporting a first member at a second member, and including a passive vibration absorbing device, such as a typical rubberized engine mount, located between the first and second members, and an active vibration actuator for applying counter vibration isolation forces in parallel in response to the detected relative vibration of the first and second members, wherein the actuator is located on a support mount frame attached to the second member. The support mount frame provides a structure for the actuator force application, with continuous transfer of static loads between the first and second member being provided by the passive device. In its preferred embodiment, the apparatus is utilized in conjunction with vehicle engine mounts wherein the first member comprises the engine and the second member comprises the vehicle frame.

Abstract: A sound cancellation system wherein a pair of sensors and actuators are positioned immediately adjacent an associated ear of an inhabitant of an enclosure so as to provide a cancellation zone immediately adjacent an associated ear without interfering with adjacent zones. A controller receives a synchronization signal so as to cancel a selected noise associated with a synchronization signal. The sensors and actuators are mounted to a seat which is to be occupied by an inhabitant of the enclosure.

Abstract: A monitoring capability may be provided integral with or separate from a vibration cancellation system to monitor or display input and output signals and transfer functions as well as spectral waveforms. Testing is performed by monitoring and displaying the input and generating appropriate test signals while further monitoring and displaying the input. The ability to modify the characteristics of the vibration cancellation system is included.

Abstract: A confined system of sound transmission from a frequency attenuation compensated source through plastic pneumatic tubes in series with liquid tubes of considerable length, transmitting audio to and through pneumatic headphones to the ear canals of the user. It is an audio system suitable for use in Nuclear Magnetic Resonance scanning environments and for use in CAT scan environments. The system includes a stereo program source playing into a stereo frequency compensation amplifier driving right and left loudspeaker pneumatic drivers feeding audio to and through long liquid tubes in series with pneumatic tubes extended to left and right earphones of plastic headphones worn by a patient in a scan room environment.