WO1995024309A2 - Procede et dispositif non invasifs a terre virtuelle numerique et a detection d'erreurs - Google Patents

Procede et dispositif non invasifs a terre virtuelle numerique et a detection d'erreurs Download PDF

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Publication number
WO1995024309A2
WO1995024309A2 PCT/US1995/002433 US9502433W WO9524309A2 WO 1995024309 A2 WO1995024309 A2 WO 1995024309A2 US 9502433 W US9502433 W US 9502433W WO 9524309 A2 WO9524309 A2 WO 9524309A2
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WO
WIPO (PCT)
Prior art keywords
noise
cancellation
signal
sensor means
sensor
Prior art date
Application number
PCT/US1995/002433
Other languages
English (en)
Other versions
WO1995024309A3 (fr
Inventor
Dexter G. Smith
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 WO1995024309A2 publication Critical patent/WO1995024309A2/fr
Publication of WO1995024309A3 publication Critical patent/WO1995024309A3/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
    • G10K11/1785—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
    • 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
    • G10K11/17857—Geometric disposition, e.g. placement of microphones
    • 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
    • G10K11/17875—General system configurations using an error signal without a reference signal, e.g. pure feedback
    • 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
    • G10K2210/109—Compressors, e.g. fans
    • 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
    • G10K2210/112—Ducts
    • 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
    • G10K2210/3011—Single acoustic input
    • 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
    • G10K2210/3044—Phase shift, e.g. complex envelope processing

Definitions

  • the present invention relates to active cancellation systems for repetitive or non- repetitive phenomena, and, more specifically, to an active cancellation system that provides cancellation phenomena without requiring an external reference or timing signal.
  • the simplest active cancellation for phenomena is an analog negative feedback system, also referred to as "a virtual earth” system.
  • phenomena is sent to an actuator, which provides cancellation phenomena into the area in which the phenomena is to be canceled.
  • phase shifts are typically due to delays such as that resulting from the distance between the sensor and the actuator, and also by echoes.
  • the phase shifts vary by frequency and have not been amenable to a solution in the analog feedback systems except for over a very narrow range of frequencies or in a very confined environment, such as a headphone.
  • 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.
  • a m,k + l A m,k - ⁇ * e k' ⁇ C ⁇ . ⁇ k _ ⁇
  • y k is the cancellation signal value at sample k
  • ⁇ k is the error signal value at sample k
  • C is the vector of coefficients of the impulse response from the controller output to the error sensor input
  • A is the vector of coefficients of the cancellation filter
  • x j - is the value of the estimated noise signal at sample k
  • ⁇ is the LMS convergence rate coefficient
  • This form of the algorithm is only applicable to systems consisting of one channel, i.e., a single sensor and a single actuator.
  • Duct systems can take many shapes and forms but certain features are common to all. There is a prime energy converter to change primary energy (usually electricity) to mechanical energy. Next, the mechanical energy is used to move air about the structure where the system is installed. Ductwork is used to contain and direct the air to the end user location. Along with the air itself, noise from the energy conversion system propagates down the ductwork. Depending on the installation, this noise can be quite annoying to the end users especially if the fan chosen has a noticeable blade passage tonal which is the number of blades times the revolutions per second of the fan.
  • a digital virtual earth cancellation system for duct borne repetitive or non- repetitive noise is provided according to the present invention which receives a phenomena input signal from outside the duct system representing residual phenomena to be canceled and includes an adaptive filter for generating a cancellation signal.
  • the adaptive filter adapts its filtering characteristics as a function of the difference between the residual signal and the estimated effects of the cancellation signal.
  • a phase circuit maintains the adapting of the filtering characteristics and 90° phase of the phenomena signal.
  • the impulse response of the entire cancellation system which includes delays introduced by filters and other factors, is convolved with the output of the cancellation system, i.e., the cancellation signal. This value is subtracted from the externally sensed residual signal that is received by the cancellation system, to provide an estimate of the noise.
  • 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 externally sensed residual signal and the estimated noise convolved with the system response.
  • the error sensing microphone in a DVE duct cancellation system must sense the summation of noise plus anti-noise but not sense locally generated turbulence in the duct. It also must be placed so that an appropriate transfer function from speaker to microphone can be determined by the DVE algorithm and so that attenuation is maximized in the appropriate area, in this case the interior of a duct. Therefore, the microphone may be taken out of the duct if these conditions are met.
  • duct wall is not very acoustically transparent, a small section of the duct may be replaced with a more acoustically transparent material and the microphone is then mounted outside the duct.
  • This non-invasive error sensing DVE invention for duct cancellation of repetitive or non-repetitive noise takes the error residual noise sensor (microphone) out of the interior of the duct.
  • the advantage is that direct contact with turbulent air flows and/or corrosive environments is avoided.
  • the values sent to an adapter for the adaptive filter are kept within 90° phase of the residual signal to provide convergence of the adaptation.
  • An embodiment of the present invention measures the system impulse response from speaker mounted flush with the duct wall to the externally mounted microphone and includes a test signal generator for generating a test signal which is combined with the cancellation signal and provided to in the area to be monitored.
  • An adaptive filter is provided that receives a random test signal and provides a filtered signal. A difference is produced between the filtered signal and the phenomena residual signal.
  • An adapter adapts the filter weights of this adaptive filter as a function of the difference signal and a delay line of test signal values. The filter weights represent the measured impulse response of the system.
  • Figure 2 shows a typical duct system
  • Figure 3 shows a diagrammatic view of the invention.
  • FIG. 1 shows a basic block diagram of a virtual earth, negative feedback system.
  • Phenomena such as noise
  • a sensor 10 which sends out a sensing signal.
  • This sensor signal is affected by an anti-aliasing filter (not shown in Figure 1) and other factors which have an impulse response E.
  • the sensor signal as affected by the impulse response E, results in a residual signal r to a processor 11.
  • the processor 11 From the residual signal r, the processor 11 produces an output signal y, the signal being the cancellation signal y.
  • the cancellation signal y used to form the canceling phenomena, is affected by filters, transit delays, and other factors which have an impulse response S.
  • the output from the actuator 12, the cancellation phenomena combines with the original phenomena and the residual is detected at a location 13 by the sensor 10.
  • the noise n(t) convolved with the impulse response E is found by subtracting the effects of the processor output y, as convolved by S and E, from the residual signal r received by the processor 11.
  • the average power of r can be minimized by a gradient descent method, such as a known least mean square (LMS) algorithm as described in Patent No. 5,105,377.
  • LMS least mean square
  • fan 20 is the primary energy conversion system that moves air through duct 21 through air diffuser 26 to end user occupied space 25.
  • the DVE system is installed with loudspeaker 23 mounted flush in the duct along with microphone 24.
  • Controller 22 senses the noise in the duct 21 and provides an output signal to actuator 23.
  • microphone 24 senses locally generated turbulence at its location. Much effort needs to be spent trying to find a good location for it to sense noise but not turbulence. It is also very difficult to move the microphone around inside a duct 21, reseal the duct 21 and then try the cancellation system. It is a very iterative process.
  • fan 30 is the primary energy conversion system that moves air through duct 31 through air diffuser 38 to end user occupied space 35. In this embodiment, it is desired to cancel tonal noise from fan 30 before it reaches room 35.
  • the DVE system is installed with loudspeaker 33 mounted flush in the duct.
  • Microphone 34 is mounted outside the duct 31 at location 36. (Note that location 36 may be just the duct wall itself or a small section of duct wall replaced by a more acoustically transparent material). Controller 32 senses the noise in the duct 31 and provides an output signal to actuator 33.
  • microphone 34 senses tonal noise propagated through the duct 31 at location 36 and does not sense noise generated by turbulence inside the duct 31. It is now a simple matter to manually move microphone 34 around outside the duct 31 to achieve maximum noise attenuation. Having described the invention it will become apparent to those of ordinary skill in the art that many changes and modifications can be made to the invention without departing from the scope of the appended claims.

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

Abstract

La présente invention concerne un procédé et un dispositif d'annulation des phénomènes de pression au moyen d'un seul capteur (10) qui a) génère un bruit atténuateur et b) mesure le résultat sonore du bruit original ainsi que du bruit atténué sans capter le bruit généré par la turbulence locale; dispositif à terre virtuelle numérique (32), un haut-parleur (33) et un microphone (34) sont utilisés.
PCT/US1995/002433 1994-03-02 1995-03-01 Procede et dispositif non invasifs a terre virtuelle numerique et a detection d'erreurs WO1995024309A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US20460494A 1994-03-02 1994-03-02
US08/204,604 1994-03-02

Publications (2)

Publication Number Publication Date
WO1995024309A2 true WO1995024309A2 (fr) 1995-09-14
WO1995024309A3 WO1995024309A3 (fr) 1995-10-05

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1162599A2 (fr) * 2000-06-05 2001-12-12 Siemens Canada Limited Recalibration d'un système actif de suppression du bruit

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4122303A (en) * 1976-12-10 1978-10-24 Sound Attenuators Limited Improvements in and relating to active sound attenuation
US4153815A (en) * 1976-05-13 1979-05-08 Sound Attenuators Limited Active attenuation of recurring sounds
US4417098A (en) * 1979-08-16 1983-11-22 Sound Attenuators Limited Method of reducing the adaption time in the cancellation of repetitive vibration
US4829590A (en) * 1986-01-13 1989-05-09 Technology Research International, Inc. Adaptive noise abatement system
US4878188A (en) * 1988-08-30 1989-10-31 Noise Cancellation Tech Selective active cancellation system for repetitive phenomena
US5105377A (en) * 1990-02-09 1992-04-14 Noise Cancellation Technologies, Inc. Digital virtual earth active cancellation system
US5293425A (en) * 1991-12-03 1994-03-08 Massachusetts Institute Of Technology Active noise reducing

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4153815A (en) * 1976-05-13 1979-05-08 Sound Attenuators Limited Active attenuation of recurring sounds
US4122303A (en) * 1976-12-10 1978-10-24 Sound Attenuators Limited Improvements in and relating to active sound attenuation
US4417098A (en) * 1979-08-16 1983-11-22 Sound Attenuators Limited Method of reducing the adaption time in the cancellation of repetitive vibration
US4829590A (en) * 1986-01-13 1989-05-09 Technology Research International, Inc. Adaptive noise abatement system
US4878188A (en) * 1988-08-30 1989-10-31 Noise Cancellation Tech Selective active cancellation system for repetitive phenomena
US5105377A (en) * 1990-02-09 1992-04-14 Noise Cancellation Technologies, Inc. Digital virtual earth active cancellation system
US5293425A (en) * 1991-12-03 1994-03-08 Massachusetts Institute Of Technology Active noise reducing

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1162599A2 (fr) * 2000-06-05 2001-12-12 Siemens Canada Limited Recalibration d'un système actif de suppression du bruit
EP1162599A3 (fr) * 2000-06-05 2012-06-27 Siemens VDO Automotive Inc. Recalibration d'un système actif de suppression du bruit

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