WO1995008155A1 - Modelisation causale de bruit a impulsion previsible - Google Patents

Modelisation causale de bruit a impulsion previsible Download PDF

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Publication number
WO1995008155A1
WO1995008155A1 PCT/US1994/009711 US9409711W WO9508155A1 WO 1995008155 A1 WO1995008155 A1 WO 1995008155A1 US 9409711 W US9409711 W US 9409711W WO 9508155 A1 WO9508155 A1 WO 9508155A1
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WO
WIPO (PCT)
Prior art keywords
noise
impulse
response
isolated
model
Prior art date
Application number
PCT/US1994/009711
Other languages
English (en)
Inventor
Jeffrey N. Denenberg
Original Assignee
Noise Cancellation Technologies, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Noise Cancellation Technologies, Inc. filed Critical Noise Cancellation Technologies, Inc.
Publication of WO1995008155A1 publication Critical patent/WO1995008155A1/fr

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Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1787—General system configurations
    • G10K11/17879—General system configurations using both a reference signal and an error signal
    • G10K11/17883—General system configurations using both a reference signal and an error signal the reference signal being derived from a machine operating condition, e.g. engine RPM or vehicle speed
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17853—Methods, e.g. algorithms; Devices of the filter
    • G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/128—Vehicles
    • G10K2210/1282—Automobiles
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/128—Vehicles
    • G10K2210/1282—Automobiles
    • G10K2210/12822—Exhaust pipes or mufflers
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3012—Algorithms
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3045—Multiple acoustic inputs, single acoustic output

Definitions

  • This invention relates to the causal modeling of impulse noise.
  • Impulse noise occurs in many applications and is sometimes amenable to synchronous algorithms such as in "Selective Active Cancellation for Repetitive Phenomena", U.S. Patent No. 4,878,188 (when the repetition rate is consistent and not too slow as in Magnetic Resonance Imaging (MRI)) or the classical Feed Forward Algorithm (when a reference signal is available).
  • MRI Magnetic Resonance Imaging
  • Feed Forward Algorithm when a reference signal is available.
  • the use of a noise model is discussed in U.S. Patent No. 4,153,815 (Chaplin et al) and further refined in U.S. Patent No. 4,417,098 (Chaplin et al) which are hereby incorporated by reference herein.
  • the noise model in these patents is the noise shape for one period of a periodic noise.
  • the noise model is maintained as an isolated instance of the natural response of the noise generation system when it is triggered once.
  • MISACT single channel multiple interacting sensors and actuators
  • Figure 1 is a plot of a typical impulse noise
  • Figure 2 is the plot of Figure 1 at four times the rate
  • Figure 3 is the power spectrum plot of periodic noise
  • Figure 4 is a schematic showing adaptive feed forward impulse noise canceling system
  • FIG. 5 shows an exhaust noise cycle
  • Figure 6 is a schematic of an impulse noise canceling system
  • Figure 7 is a diagrammatic top view of an engine.
  • Impulse noise is generated by suddenly occurring, high energy events.
  • the energy released by the event then creates vibration and/or noise which tends to die out in a short time.
  • the decay time taken is a function of the losses and resonances in the physical medium through which the noise or vibration passes.
  • An example of an impulse noise with a rapid decay is firing a gun.
  • An example of an impulse noise from a low loss (or high "Q") system and therefore having a slow decay is the sound of a bell or a cymbal.
  • Figure 1 gives an example of a typical individual noise impulse.
  • the energy release at time zero causes the physical system to vibrate at a natural resonance frequency (which happens to be at one eighth of the sampling rate in this example).
  • the vibration or noise then dies out exponentially and is down 40 dB by the 72nd sample period (after the 9th ringing cycle).
  • Many noise sources create impulse noise at regular intervals.
  • the resulting tonal noise can and has been canceled by synchronous systems (MISACT).
  • MISACT synchronous systems
  • Figure 2 shows the same impulse noise as in Figure 1 but repeated four times at a rate corresponding to one fourth of the natural ringing frequency. Note that the noise shape is not consistent until the third or fourth repetition as the "tails" of the earlier impulse noises accumulate to form the steady state "Noise Cycle" that we are familiar with in repetitive systems. A delayed version of the original impulse noise shape is dotted in with the last noise cycle for comparison.
  • Figure 3 shows the steady state of the power spectrum of this periodic noise.
  • the primary noise is at the natural ringing frequency of the physical system. All of the frequency components are at multiples of the noise cycle (repeat rate) as expected in periodic noise sources. Note that the power at frequencies other than the ringing frequency is a function of the repeat rate and the decay time. If the repeat rate is fast compared to the decay time, very little energy is in the other frequencies. If the repeat rate is slow compared to the decay time, the other frequency components contain most of the noise power.
  • FIG. 4 it is shown how a classical Adaptive Feedforward (AFF) system can be used to cancel impulse noise. It will, however, be slow in adapting to changes in the noise.
  • AFF Adaptive Feedforward
  • the simplification is due to the fact that the anti-noise does not feed back to the reference signal (a trigger pulse synced to the start of each impulse). This eliminates the "B" filter which is normally used to eliminate feedback to the reference sensor in the general case.
  • the adaptive filter on the right of the diagram determines the anti-noise transfer function "C" by adding a low level test signal to the anti-noise output and correlating it with the residual signal. This measured “C” is then used to equalize the Filtered-X LMS update process in the main adaptive filter ("A") on the left of the diagram.
  • the filter tap weights in "A” then continuously adapt to minimize the noise in the residual signal.
  • ® denotes the convolution operation which is the result of passing h- ⁇ through the inverse of "C”.
  • the convolution can also be stated as the output is a weighted sum over the "memory” in the filter and the filter (c **1 ) "impulse" response quantifies the filter memory as a function of delay:
  • the AFF system described above will also cancel periodic impulse noise when allowed to adapt. It will find a solution that cancels the noise, but it will, in general, find the wrong solution. There are many solutions that will cancel the noise in the periodic case.
  • the system can be biased toward the correct answer when the general shape of the noise pulse is known at design time.
  • the weight update equations can be constrained to result in weights that follow the general shape.
  • One set of constraints is to compute a running average of the energy in the weights over a short time period (long enough to average out ringing, but short enough to follow the envelope of the noise signal). This calculation can be used dynamically to bias the result to have the known shape.
  • Constantly varying noise rate As long as the rate of the noise is constantly varying the adaptation rate can be set to average over several impulses and the system will do a good job.
  • Non-overlapping impulses When the impulses die out between repetitions the system is well behaved.
  • the amplitude of the pulse is a strong function of the engine torque.
  • the timing is fixed WRT the rotation (physical) of the crank (may need to be somewhat variable in new engines with variable valve timing). Therefore use eight repetitions of this model (one for each cylinder) tied to sync.
  • ⁇ o is the phase indeterminacy and handle for variable valve timing ki— >k N are differential output levels (cylinder compression difference, etc.) (Slowly Varying) ⁇ l ⁇ N 1S differential delays in exhaust headers (Slowly
  • krj is noise level and is related to torque (Rapidly Varying)
  • AFF filter models the exhaust pipe with compensation for the transfer function of the output transducer (Slowly Varying, mainly due to temperature).
  • the modified AFF system has only one rapidly varying parameter to deal with while the synchronous system has more than 60. It will therefore tend to behave better when engine conditions change rapidly.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

Procédé et système (10) pour la modélisation causale de bruit à impulsion prévisible, comprenant un capteur permettant de détecter le bruit à impulsion, des moyens permettant de traiter le signal de détection, ces moyens comprenant un circuit pour modéliser une réponse isolée afin de commander la réponse acoustique anti-bruit.
PCT/US1994/009711 1993-09-17 1994-09-02 Modelisation causale de bruit a impulsion previsible WO1995008155A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US12263493A 1993-09-17 1993-09-17
US08/122,634 1993-09-17

Publications (1)

Publication Number Publication Date
WO1995008155A1 true WO1995008155A1 (fr) 1995-03-23

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009070476A1 (fr) * 2007-11-27 2009-06-04 David Clark Company Incorporated Annulation active de bruit à l'aide d'une approche de modèle de prédiction

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4987598A (en) * 1990-05-03 1991-01-22 Nelson Industries Active acoustic attenuation system with overall modeling
US5033082A (en) * 1989-07-31 1991-07-16 Nelson Industries, Inc. Communication system with active noise cancellation
US5117401A (en) * 1990-08-16 1992-05-26 Hughes Aircraft Company Active adaptive noise canceller without training mode
US5140640A (en) * 1990-08-14 1992-08-18 The Board Of Trustees Of The University Of Illinois Noise cancellation system
US5146505A (en) * 1990-10-04 1992-09-08 General Motors Corporation Method for actively attenuating engine generated noise
US5187692A (en) * 1991-03-25 1993-02-16 Nippon Telegraph And Telephone Corporation Acoustic transfer function simulating method and simulator using the same
US5251262A (en) * 1990-06-29 1993-10-05 Kabushiki Kaisha Toshiba Adaptive active noise cancellation apparatus
US5278780A (en) * 1991-07-10 1994-01-11 Sharp Kabushiki Kaisha System using plurality of adaptive digital filters
US5313407A (en) * 1992-06-03 1994-05-17 Ford Motor Company Integrated active vibration cancellation and machine diagnostic system

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5033082A (en) * 1989-07-31 1991-07-16 Nelson Industries, Inc. Communication system with active noise cancellation
US4987598A (en) * 1990-05-03 1991-01-22 Nelson Industries Active acoustic attenuation system with overall modeling
US5251262A (en) * 1990-06-29 1993-10-05 Kabushiki Kaisha Toshiba Adaptive active noise cancellation apparatus
US5140640A (en) * 1990-08-14 1992-08-18 The Board Of Trustees Of The University Of Illinois Noise cancellation system
US5117401A (en) * 1990-08-16 1992-05-26 Hughes Aircraft Company Active adaptive noise canceller without training mode
US5146505A (en) * 1990-10-04 1992-09-08 General Motors Corporation Method for actively attenuating engine generated noise
US5187692A (en) * 1991-03-25 1993-02-16 Nippon Telegraph And Telephone Corporation Acoustic transfer function simulating method and simulator using the same
US5278780A (en) * 1991-07-10 1994-01-11 Sharp Kabushiki Kaisha System using plurality of adaptive digital filters
US5313407A (en) * 1992-06-03 1994-05-17 Ford Motor Company Integrated active vibration cancellation and machine diagnostic system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009070476A1 (fr) * 2007-11-27 2009-06-04 David Clark Company Incorporated Annulation active de bruit à l'aide d'une approche de modèle de prédiction

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