Abstract: A method for measuring performance of a noise cancellation system that is operable to cancel noise is provided. The method includes generating a first model of a target noise. The first model represents the target noise in a form that is received at a location remote from a noise source of the target noise and within a defined environment. The method also includes generating a second model of a cancellation noise. The cancellation noise is configured to at least partially cancel the target noise when combined with the target noise. The second model represents the cancellation noise in a form that is received at the location. The method also includes determining, using the first model and the second model, a cancellation error value indicative of only a portion of the target noise that remains when the target noise and the cancellation noise are combined.

Abstract: A method for detecting failure in a noise cancellation system is provided. The noise cancellation system is operable to at least partially cancel an unwanted noise produced by a noise source. The method includes receiving a cancellation noise signal from the noise cancellation system. The cancellation noise signal represents a cancellation noise that, when combined with a target noise, is operable to at least partially cancel the target noise. The method also includes receiving an error signal approximately representing a portion of the target noise that remains after the cancellation noise and the target noise are combined. The method also includes determining whether the signal level changed or remains unchanged for each of the received cancellation noise signal and the error signal. The method also includes assigning a failure state of the noise cancellation system based on the determination and initiating a remedial measure that corresponds with the assigned failure state.

Abstract: A method for controlling a noise cancellation system having an adaptive control portion is provided. The noise cancellation system is operable to generate a cancellation noise configured to at least partially cancel an unwanted noise in a defined environment. The adaptive control portion is operable to adjust the operation of the noise cancellation system based on a level of unwanted noise that remains when the cancellation noise and the unwanted noise are combined. The method includes receiving an error signal representing a portion of a noise not cancelled by a cancellation noise, where the cancellation noise is generated from the noise cancellation system. The method also includes determining whether the level of the error signal exceeds a first threshold value for a first predetermined period of time. The method also includes calculating a crest factor using the error signal. The method also includes determining whether the crest factor exceeds a second threshold value.

Abstract: A machine is provided having an engine system wherein at least one engine system component with an acoustic reflective surface is surrounded by a jacket configured to absorb sound from at least one sound producing device of the engine system. The jacket includes a sound absorbing material such as fibrous thermal insulation and an acoustic permeable covering between the acoustic reflective surface and the engine compartment of the machine. The acoustic permeable covering of the jacket may comprise a micro-perforated skin, whereby acoustic energy from the at least one sound producing device of the engine system can enter a volume defined by the jacket wherein it is absorbed by the sound absorbing material. A method of operating an engine system includes dissipating engine sound within a jacket surrounding an engine system component, the jacket including an acoustic permeable covering and a sound absorbing material positioned within the covering.

Abstract: A method for measuring performance of a noise cancellation system that is operable to cancel noise is provided. The method includes generating a first model of a target noise. The first model represents the target noise in a form that is received at a location remote from a noise source of the target noise and within a defined environment. The method also includes generating a second model of a cancellation noise. The cancellation noise is configured to at least partially cancel the target noise when combined with the target noise. The second model represents the cancellation noise in a form that is received at the location. The method also includes determining, using the first model and the second model, a cancellation error value indicative of only a portion of the target noise that remains when the target noise and the cancellation noise are combined.

Abstract: A method for detecting failure in a noise cancellation system is provided. The noise cancellation system is operable to at least partially cancel an unwanted noise produced by a noise source. The method includes receiving a cancellation noise signal from the noise cancellation system. The cancellation noise signal represents a cancellation noise that, when combined with a target noise, is operable to at least partially cancel the target noise. The method also includes receiving an error signal approximately representing a portion of the target noise that remains after the cancellation noise and the target noise are combined. The method also includes determining whether the signal level changed or remains unchanged for each of the received cancellation noise signal and the error signal. The method also includes assigning a failure state of the noise cancellation system based on the determination and initiating a remedial measure that corresponds with the assigned failure state.

Abstract: A method for controlling a noise cancellation system having an adaptive control portion is provided. The noise cancellation system is operable to generate a cancellation noise configured to at least partially cancel an unwanted noise in a defined environment. The adaptive control portion is operable to adjust the operation of the noise cancellation system based on a level of unwanted noise that remains when the cancellation noise and the unwanted noise are combined. The method includes receiving an error signal representing a portion of a noise not cancelled by a cancellation noise, where the cancellation noise is generated from the noise cancellation system. The method also includes determining whether the level of the error signal exceeds a first threshold value for a first predetermined period of time. The method also includes calculating a crest factor using the error signal. The method also includes determining whether the crest factor exceeds a second threshold value.

Abstract: A machine is provided having an engine system wherein at least one engine system component with an acoustic reflective surface is surrounded by a jacket configured to absorb sound from at least one sound producing device of the engine system. The jacket includes a sound absorbing material such as fibrous thermal insulation and an acoustic permeable covering between the acoustic reflective surface and the engine compartment of the machine. The acoustic permeable covering of the jacket may comprise a micro-perforated skin, whereby acoustic energy from the at least one sound producing device of the engine system can enter a volume defined by the jacket wherein it is absorbed by the sound absorbing material. A method of operating an engine system includes dissipating engine sound within a jacket surrounding an engine system component, the jacket including an acoustic permeable covering and a sound absorbing material positioned within the covering.

Abstract: A method and apparatus for providing an audible alarm signal. The method and apparatus includes creating a rectangular pulse signal having a desired period and a desired first amplitude, adding a shaped modulation component to the rectangular pulse signal from the desired first amplitude to a desired second amplitude to create a modulating waveform, creating a carrier signal, and combining the carrier signal and the modulating waveform to create the audible alarm signal.

Abstract: A noise suppression louver for an enclosure, in particular, an apparatus for suppressing sound at the openings which allow air to enter or exit an internal combustion engine enclosure. The louver comprises a matrix of intersecting horizontal and vertical passive sound absorptive slats.

Abstract: A method for locating and identifying defects in a variable geometry workpiece using first and second transceivers positioned of a preselected distance apart adjacent opposite surfaces of the workpiece and aligned to direct ultrasonic signals toward each other through the workpiece. An ultrasound signal is transmitted from each transceiver toward the workpiece. Signal reflections from each adjacent workpiece surface are detected and used to compute workpiece thickness. Signals from one transceiver are detected at the other transceiver and their intensity determined. The signal intensity is normalized in proportion to the obtained workpiece thickness to establish a signal intensity independent of workpiece thickness. In one form, at least three signal processing paths, each having a different preselected gain, provide three signals of different amplified intensities for each measurement point.