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    DIGITAL VIRTUAL EARTH ACTIVE CANCELLATION SYSTEM
    145.
    发明公开
    DIGITAL VIRTUAL EARTH ACTIVE CANCELLATION SYSTEM 失效
    有源数字ANNULATIONSSYSTEM“虚拟地球”。

    公开(公告)号：EP0521868A1

    公开(公告)日：1993-01-13

    申请号：EP91904237.0

    申请日：1991-02-07

    Applicant: NOISE CANCELLATION TECHNOLOGIES, INC.

    Inventor： ZIEGLER, Eldon, W., Jr.

    IPC: G10K11 ,  H03H21 ,  H04B3

    CPC classification number: H03H21/0012 ,  G10K11/178 ,  G10K2210/3011

    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.

    ACTIVE SOUND ATTENUATION SYSTEM FOR ENGINE EXHAUST SYSTEMS AND THE LIKE
    146.
    发明公开
    ACTIVE SOUND ATTENUATION SYSTEM FOR ENGINE EXHAUST SYSTEMS AND THE LIKE 失效
    用于发动机排气系统的主动声衰减系统

    公开(公告)号：EP0373188A4

    公开(公告)日：1990-09-19

    申请号：EP89902911

    申请日：1989-02-17

    Applicant: NOISE CANCELLATION TECHNOLOGIES, INC.

    Inventor： GARDNER, JOHN, W. ,  ZIEGLER, ELDON, W., JR.

    IPC: F01N1/00 ,  F01N1/06 ,  F01N1/08 ,  F01N1/22 ,  G10K11/178

    CPC classification number: F01N1/22 ,  F01N1/065 ,  G10K11/178 ,  G10K2210/12822 ,  G10K2210/3227 ,  G10K2210/32272

    Abstract: An active sound attenuation system for combustion engine exhaust systems and the like is disclosed. The system includes counter-noise acoustic wave generators (19) that are protected from the environment of a medium propagating undesireable noise by an acoustically tuned anti-noise chamber (5, 11) interposed between the wave generators (19) and the medium with the undesirable noise. To provide for noise cancellation at an outlet end (4) of an exhaust pipe (10) the anti-noise chamber (5, 11) has an annular opening disposed substantially in the plane of the exhaust pipe outlet thereby giving an effective common point source for the propagated undesirable noise and the counter-noise acoustic wave.

    Abstract translation: 公开了一种用于内燃机排气系统等的主动声音衰减系统。 该系统包括抗噪声声波发生器（19），该发声器通过介于波发生器（19）和介质之间的声学​​调谐的抗噪声室（5,11）来保护传播无用噪声的介质的环境， 不良噪音。 为了在排气管（10）的出口端（4）处提供噪声消除，防噪声室（5,11）具有大致在排气管出口的平面中设置的环形开口，从而提供有效的公共点源 对于传播的不良噪声和反噪声声波。

    Variable gain active noise cancellation system with improved residual noise sensing
    147.
    发明授权
    Variable gain active noise cancellation system with improved residual noise sensing 失效
    活性Lärmunterdruckungsanordnung可变增益和改善的残余噪声测量

    公开(公告)号：EP0967592B1

    公开(公告)日：2007-01-24

    申请号：EP99203047.8

    申请日：1994-06-23

    Applicant: NOISE CANCELLATION TECHNOLOGIES, INC.

    Inventor： Jones, Owen

    IPC: G10K11/178

    CPC classification number: G10K11/17857 ,  A61F2011/145 ,  G10K11/17855 ,  G10K11/17881 ,  G10K11/17885 ,  G10K2210/108 ,  G10K2210/1081 ,  G10K2210/3011 ,  G10K2210/3013 ,  G10K2210/3019 ,  G10K2210/3028 ,  G10K2210/3056 ,  G10K2210/3214 ,  G10K2210/503

    Abstract: An active noise cancellation system includes a series of features for more effective cancellation, greater reliability, and improved stability. A particular feature adapted for headset systems includes locating a residual microphone radially offset from the centre of a sound generator to detect a signal more similar to that incident upon the eardrum of the user. In addition, an open back headset design includes perforations on the side of the headset instead of the back, so that the perforations are less susceptible to inadvertent blockage. The system also includes a mechanism for detecting changes in the acoustic characteristics of the environment that may be caused, for example, by pressure exerted upon the earpieces, and that may destabilize the cancellation system. The system automatically responds to such changes, for example, by reducing the gain or the frequency response of the system to preserve stability. The system further includes other methods for detecting imminent instability and compensating, such as detecting the onset of signals within enhancement frequencies characteristic of the onset of instability, and adjusting the gain of frequency response of the system or suppressing the enhanced signals. The system further includes a mechanism for conserving battery life by turning the system off when sound levels are low, or adjusting the power supply to the system to correspond to the current power requirements of the system.

    DECORATIVE SPEAKER COVER
    149.
    发明公开
    DECORATIVE SPEAKER COVER 审中-公开
    烤花扬声器盖

    公开(公告)号：EP1053541A1

    公开(公告)日：2000-11-22

    申请号：EP99902986.1

    申请日：1999-01-06

    Applicant: NOISE CANCELLATION TECHNOLOGIES, INC.

    Inventor： CLAYBAUGH, David ,  O'BRIEN, Sean

    IPC: G10K11/00

    CPC classification number: H04R1/023

    Abstract: A decorative speaker cover is disclosed that transforms any loudspeaker into a work of art. The decorative speaker cover of the invention consists of a sheet of material (1) stretched across and adhered to a support frame (2). The sheet of material (1) contains an artistic work like a picture, design, custom photograph, print, etc. The invention also includes methods for attaching the decorative speaker covers to a loudspeaker cabinet (3). The disclosed methods allow speaker covers to be readily changed.

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