VARIABLE GAIN ACTIVE NOISE CANCELLATION SYSTEM WITH IMPROVED RESIDUAL NOISE DETECTION.

摘要

AN ACTIVE NOISE CANCELLATION SYSTEM INCLUDES A SERIES OF CHARACTERISTICS FOR A MORE EFFECTIVE CANCELLATION, GREATER RELIABILITY AND BETTER STABILITY. A PARTICULAR FEATURE ADAPTED TO HEADPHONE SYSTEMS INCLUDES THE LOCATION OF A RESIDUAL MICROPHONE RADIALLY DEVIVED FROM THE CENTER OF A SOUND GENERATOR, TO DETECT A MORE SIMILAR SIGNAL TO THAT INCIDING ON THE USER'S AUDITIVE PAVILION. IN ADDITION, A DESIGN OF HEADPHONE WITH THE OPEN BACK INCLUDES PERFORATIONS IN THE SIDE OF THE HEADPHONE, INSTEAD OF BEING MADE IN THE BACK, SO THAT THE PERFORATIONS ARE LESS SUSPENDABLE TO AN INADVERTED BLOCK. THE SYSTEM ALWAYS INCLUDES A MECHANISM TO DETECT CHANGES IN THE ACOUSTIC CHARACTERISTICS OF THE ENVIRONMENT THAT MAY BE CAUSED, FOR EXAMPLE, BY PRESSURE EXERCISED ON THE HEADPHONES, AND THAT COULD UNEMPLOY THE CANCELLATION SYSTEM. THE SYSTEM AUTOMATICALLY RESPONDS TO SUCH CHANGES, FOR EXAMPLE, REDUCING THE PROFIT OR FREQUENCY RESPONSE OF THE SYSTEM IN ORDER TO PRESERVE STABILITY. THE SYSTEM ALSO INCLUDES OTHER PROCEDURES TO DETECT THE IMMINENTLY INSTABILITY, AND TO COMPENSATE, FOR EXAMPLE, TO DETECT THE APPEARANCE OF SIGNS WITHIN CHARACTERISTIC FREQUENCIES OF THE START OF THE STABILITY, AND ADJUST THE SUITABILITY OF THE FOLLOWING THE REINFORCED SIGNS. THE SYSTEM ALSO INCLUDES A MECHANISM TO CONSERVE THE DURATION OF THE BATTERIES BY DISCONNECTING THE SYSTEM WHEN THE SOUND LEVELS ARE LOW, OR ADJUSTING THE POWER SUPPLY TO THE WAY SYSTEM THAT COINCIDES WITH THE SYSTEM FEEDING REQUIREMENTS.