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JP2018518715

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DESCRIPTION JP2018518715
Abstract: A method and system for noise cancellation includes an amplifier in communication
with three or more speakers arranged in an area. The system controller generates a driver signal
for each of the speakers in response to signals from at least one microphone that senses sound in
the region and transmits the driver signal to the amplifier. The amplifier drives each speaker with
the driver signal generated for that speaker. In response to the driver signal, the speaker emits a
combined sound that produces a substantially uniform sound pressure field for a particular zone
in the area. The substantially uniform sound pressure field generated by the speaker has a
magnitude and phase adapted to attenuate the noise field in the region corresponding to the
sound detected by the at least one microphone.
Noise cancellation system that arranges speakers for uniform driver field
[0001]
The present invention relates to noise cancellation systems.
[0002]
TECHNICAL FIELD This specification relates generally to noise cancellation systems, and more
particularly to noise attenuation or cancellation (generally referred to as noise cancellation) in a
specific environment such as a passenger cabin of a vehicle.
[0003]
All examples and features described below can be combined in any technically possible manner.
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[0004]
In one aspect, the noise cancellation system comprises three or more speakers disposed within
the area, an amplifier in communication with the three or more speakers, and a system controller
in communication with the at least one microphone and the amplifier.
The system controller generates a driver signal for each of the three or more speakers in
response to the signal from the at least one microphone generated in response to the detected
sound in the area, and transmits the driver signal to the amplifier Do.
The amplifier applies each driver signal to drive different ones of three or more speakers.
3The one or more speakers, in response to the driver signal, emit a combined sound that
produces a substantially uniform sound pressure field for a particular zone in the area. 3The
substantially uniform sound pressure field generated by the one or more speakers has a
magnitude and phase adapted to attenuate the noise field corresponding to the sound detected
by the at least one microphone.
[0005]
Embodiments of the system can include one of the following features, or any combination
thereof.
[0006]
3
One or more speakers can be arranged along a common plane.
They can include left, center and right speakers. A particular zone may surround the expected
location of the head of the occupants of the area. The left and right speakers should be equally
spaced from the expected position of the occupant's head, and the center speaker may be closer
to the expected position of the occupant's head than the left and right speakers. it can.
03-05-2019
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[0007]
The system controller can comprise a compensator in communication with the at least one
microphone. The compensator may generate a command signal in response to the signal from
the at least one microphone. The command signal may be configured to attenuate noise in a
particular zone. An array speaker controller is in communication with the compensator to receive
the command signal, apply signal conversion to the command signal based on the predetermined
parameter value, and the combined sound emitted by the three or more speakers is specific A
driver signal can be generated that is used to drive three or more speakers to generate a
substantially uniform sound pressure field for the zone.
[0008]
Each driver signal can be generated by applying a gain to the command signal. The total gain of
the driver signal may be approximately equal to one. 3The driver signal for one of the one or
more speakers can include a delay.
[0009]
In another aspect, a method is provided for attenuating noise. The method comprises the steps of
generating a driver signal for each of three or more speakers disposed in the area in response to
a signal generated in response to sound detected in the area by the at least one microphone;
Substantially uniform sound that attenuates the noise field corresponding to the sound detected
by the at least one microphone by the combined sound emitted by the three or more speakers in
response to the driver signal within a particular zone in Generating a pressure field.
[0010]
Embodiments of the method can include one of the following features, or any combination
thereof.
[0011]
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The method may further include the step of arranging three or more speakers along a common
plane.
3The one or more speakers can include a left speaker, a center speaker, and a right speaker. A
particular zone can surround the expected position of the head of the area occupant, and the left
and right speakers are arranged at equal distances from the expected position of the head of the
occupant, and the central speaker Can be closer to the expected position of the occupant's head
than the left and right speakers. The driver signal generates a command signal configured to
attenuate noise in a particular zone within the region in response to the signal from the at least
one microphone, and converts the signal to the command signal based on the predetermined
parameter value. Are used to drive three or more speakers so that the combined sound emitted
by the three or more speakers produces a substantially uniform sound pressure field for a
particular zone The driver signal may be generated for each of the three or more speakers in
response to the signal from the at least one microphone.
[0012]
Each driver signal can be generated by applying a gain to the command signal. The sum of gains
for the set of driver signals may be approximately equal to one. One of the driver signals can
include a delay.
[0013]
In another aspect, the vehicle comprises a cabin and a noise cancellation system, the noise
cancellation system comprising at least three speakers in the cabin and at least one amplifier in
communication with the three or more speakers. System controller in communication with two
microphones and an amplifier. The system controller generates a driver signal for each of the
three or more speakers in response to the signal generated in response to the sound detected in
the area by the at least one microphone and transmits the driver signal to the amplifier . The
amplifier drives each of the three or more speakers with a driver signal for that speaker. 3The
one or more speakers emit a combined sound that responds to the driver signal to produce a
substantially uniform sound pressure field for a particular zone in the area, and the substance
generated by the three or more speakers A substantially uniform sound pressure field has a
magnitude and phase adapted to attenuate the noise field corresponding to the sound detected
by the at least one microphone.
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[0014]
Vehicle embodiments may include one of the following features, or any combination thereof.
[0015]
3
One or more speakers can be arranged along a common plane.
3The one or more speakers can include a left speaker, a center speaker, and a right speaker. A
particular zone may surround the expected location of the head of the occupants of the area. The
left and right speakers can be arranged at equal distances from the expected position of the
occupant's head, and the center speaker is located at the expected position of the occupant's
head than the left and right speakers. It can be close.
[0016]
The system controller can comprise a compensator in communication with the at least one
microphone. The compensator may generate a command signal in response to the signal from
the at least one microphone. The system controller further comprises an array speaker controller
in communication with the compensator to receive command signals therefrom and to generate
driver signals used to drive the three or more speakers in response to the command signals. be
able to.
[0017]
Each driver signal can include a gain to apply to the command signal. The total gain of the driver
signal may be approximately equal to one. One of the driver signals includes a delay.
[0018]
The above and other features and advantages can be better understood by referring to the
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following description in conjunction with the accompanying drawings in which like numerals
indicate like structural elements and features in the various figures. The drawings are not
necessarily to scale, emphasis instead being placed upon illustrating the principles of features
and implementations.
[0019]
FIG. 1 is a diagram of an environment with an example noise cancellation system installed
therein. 35 is a graph showing a substantially uniform sound pressure field generated by two
array speakers. Fig. 6 is a graph showing the decreasing sound pressure field generated by three
speakers driven in phase with the same command signal. FIG. 5 illustrates an example process
for determining driver signals for driving array speakers. FIG. 7 is a flow chart illustrating an
example process for configuring a noise cancellation system to drive an array speaker to
generate a substantially uniform sound pressure field. Figure 2 is a flow diagram of an example
process for canceling noise. FIG. 5 is a block diagram of an example noise cancellation system
that switches between an arrayed speaker configuration and an in-phase speaker configuration.
FIG. 1 is a block diagram of an example noise cancellation system that mixes an arrayed speaker
configuration with an in-phase speaker configuration in response to noise related events. FIG. 7 is
a flow diagram of an example process for switching between an arrayed speaker configuration
and an in-phase speaker configuration. FIG. 2 illustrates deployment of a noise cancellation
system in an environment to an occupant.
[0020]
Conventional noise cancellation systems generally use feedback from the noise capturing
microphone so that the sound from the speaker cancels the noise at the microphone to control
the speaker. The applicant has recognized that there has been a mismatch between the noise
field containing the occupant and the driver field generated by the speaker. The noise field was
generally spatially flat (ie the sound pressure field or spectral density was relatively constant
around the occupant's head), while the driver field was 1 / r ( Similar to the 1 / radius response,
it decreased sharply from the loudspeaker position. Noise cancellation was performed at the
intersection with the noise and driver fields, but it eventually became a small area near the
occupant's ear. Outside that area, the noise cancellation system could produce an unpleasant
sensation whenever the occupant turned his head sideways to one side or the other.
[0021]
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The active noise cancellation system described herein eliminates such noise cancellation by
generating a sound pressure field that closely matches the noise field but has an inverted phase
over a relatively large spatial region. Increase the area of the noise cancellation zone around the
occupant's head compared to the system. Each active noise cancellation zone includes at least
one system microphone and a plurality of speakers. Generally, the system microphone measures
the pressure at a point and supplies the measurement to the controller. In one configuration, the
speakers are arranged. As used herein, “arranged speakers” refers to a specific arrangement
between the predetermined loudspeakers such that the loudspeakers both generate a
substantially spatially flat sound pressure field in terms of size and phase. Represents a
relationship. Furthermore, as used herein, a uniform driver field or a uniform noise field refers to
a field having a power spectrum that does not vary substantially spatially over a given region.
(The power spectrum may vary spectrally but is spatially uniform). A perfectly uniform sound
pressure field rarely occurs in practice, and some variation in amplitude is predicted across the
zone, so the driver and noise fields are substantially or nearly uniform or substantially or nearly
flat. One skilled in the art will recognize that it can be expressed as being
[0022]
In one configuration, the plurality of speakers are disposed in the vehicle headrest and arranged
in a row, with one speaker on the left side of the headrest, one speaker at the center and one on
the right side of the headrest Includes 3 speakers. Each system microphone measures sound near
or within the noise cancellation zone and provides a signal to the system controller. The system
controller drives the speaker so that the speaker produces a substantially uniform (i.e. flat) driver
field that closely matches the noise field in magnitude and has antiphase in the cancellation zone
Arranged in By matching the driver field to the noise field, the width and length of the noise
cancellation zone around the occupant's head is increased by increasing the degree of
intersection area between the noise field and the driver field.
[0023]
Driving the loudspeakers in an array configuration generally produces satisfactory noise
cancellation for occupants whose head is in the cancellation zone. However, to achieve a flat
driver field, part of the output from one speaker will erase the other output, making the array
system less efficient. Despite the satisfactory results, the applicant has recognized certain noise
related events. For example, driving the vehicle over a crack or tar in the road could cause the
03-05-2019
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system controller to generate a high output (voltage) that would result in audible clipping of the
amplifier. To avoid audible clipping, some examples of noise cancellation systems transition from
driving the speakers in alignment mode to the in-phase configuration mode, but with no
cancellation between the speakers, so It is efficient for the array configuration mode in response
to the detection of noise related events in real time. As used herein, a speaker driven in the "in
phase" configuration mode means that all of the speakers are driven by the same command
signal. Since driving the speaker in the in-phase configuration mode has a smaller zone noise
cancellation than the alignment mode, the transition is instantaneous to avoid audible artifacts,
and the noise cancellation system terminates some noise generation event It shifts to the array
configuration mode again in real time later.
[0024]
FIG. 1 illustrates a generalized example of an environment 10 having a noise cancellation system
12 installed therein to attenuate or cancel noise in the environment. The principles described
herein apply to feed forward and feedback noise cancellation systems. The noise cancellation
techniques described herein can extend to a variety of specific environments, whether such
environments are open or enclosed. For example, the deployment of the noise cancellation
system 12 can be in a vehicle (e.g. car, truck, bus, train, plane, boat, ship), living room, cinema,
public hall, and generally, strategic placement of array speakers Wherever possible, noise
cancellation can be achieved for occupants of such environments, as described below. For
example, within a vehicle, the noise cancellation system 12 may serve to attenuate road noise at
low frequencies (eg, 40 Hz to 200 Hz), and for this purpose it is advantageous to weight certain
areas of the vehicle. Can reduce the need for
[0025]
In the illustrated example, the noise cancellation system 12 includes a plurality of speakers 16-1,
16-2, 16-3 (generally, the speakers 16), one or more microphones 18, an amplifier 20, and a
system controller 22. And. The system controller 22 is in communication with one or more
system microphones 18 to receive the signal 23 therefrom, and in communication with the
amplifier 20 to send driver signals 25 thereto in response to the signals. The amplifier 20
communicates with the plurality of speakers 16 to drive each speaker 16 according to the driver
signal 25.
[0026]
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In this example, the speakers 16 are arranged. The array loudspeakers 16 may be incorporated
together in a single unit 30, for example, in the headrest of the vehicle (for example, behind the
occupant's head and facing the occupant) or distributed separately (for example, the occupant's
Around the speaker ring), or some together, others separately (for example, two speakers on the
front side of the headrest, another speaker on the other side of the headrest in front of the
occupant) can do. All loudspeakers can be on the same plane (horizontal or vertical), ie an
imaginary plane passes through the center of all loudspeakers.
[0027]
In one configuration example, the plurality of speakers 16 includes three speakers 16-1, 16-2,
and 16-3. All of the speakers 16 are disposed behind the occupant's head, and the speakers 16
face forward towards the occupant and are on the same imaginary horizontal plane. The left
speakers 16-1 are spatially aligned with the right speakers 16-3 (they are equidistant from the
forward side of the unit 30). The speaker 16-2 is moved by a predetermined distance, and is
closer to the front side of the unit 30 than the speakers 16-1 and 16-3 on both sides of the
speaker 16-2. The unit 30 is behind the occupant's head, and the central speaker 16-2 is closer
to the head than the other two outer speakers 16-1, 16-3. Since the simulation shows that this
arrangement produces a more uniform pressure field than aligning all the speakers 16 in a row,
the central speaker 16-2 is closer to the head.
[0028]
1
One or more system microphones 18 are disposed within the environment 10 occupied by the
individual. Each system microphone 18 can detect sound in the listening area and in response
can generate a signal. In response to the signals, system controller 22 generates command
signals that are sent to the array speakers. The array loudspeakers are designed such that the
acoustic transfer function from the loudspeaker to the system microphone 18 corresponds to the
acoustic transfer function measured from the loudspeaker to various points in the desired noise
cancellation zone. In general, the acoustic transfer function corresponds to the measured
response at a given position for a sound source (e.g. a loudspeaker) at another position. This
measurement response captures the relationship between the output (i.e. the sound detected at a
given position) and the input (i.e. the driver voltage). The measured relationship is a function of
frequency and has magnitude and phase components.
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[0029]
In one configuration example, each microphone 18 is disposed in the environment 10, in which
case the acoustic transfer function of the sound radiated from the plurality of speakers 16 to the
position of the microphone 18 is the ear of the occupant from the plurality of speakers 16 Is
substantially equal to the acoustic transfer function of up to the sound. An example technique for
identifying such locations of microphones has been filed on August 1, 2014, entitled "System and
Method of Microphone Placement for Noise Attenuation" in US Patent Application No. 14 /
449,325. And are incorporated herein by reference in their entirety.
[0030]
System controller 22, which may be embodied in amplifier 20, includes a compensator 24 in
communication with array speaker controller 26. Compensator 24 generates command signal 27
based on one or more signals 23 received from one or more system microphones 18.
[0031]
In general, the array speaker controller 26 uses the command signal 27 received from the
compensator 24 to generate a driver signal 25 adapted to generate a spatially flat driver field.
The compensator 24 does not compensate for the operation of the arrayed speaker controller 26
when calculating the command signal 27, regardless of whether the algorithm executed by the
compensator 24 is configured as an array or in phase. A command signal 27 is generated. Based
on the command signal 27, the array speaker controller 26 generates a separate driver signal 25
for each speaker 16 of the plurality of speakers. The driver signal 25 is adjusted to drive the
speaker 16 such that the speaker 16 generates a spatially flat driver field of a particular
magnitude and phase to cancel the noise field. The arrayed speaker controller 26 sends these
driver signals 25 to the amplifier 20 to drive the loudspeakers 16 accordingly.
[0032]
FIG. 2 shows a three-dimensional graph 35 of an example of a substantially uniform (flat) sound
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pressure field 40 that can be generated by array speakers 16 driven with equal amplitude
voltage. The magnitude of the sound pressure in dB (referenced to any pressure) is measured on
the vertical axis (z-axis) and the distance (in inches) is measured on the x and y axes. 4Two
vertical lines 42 correspond to the temporary positions of the four test microphones, and a
substantially constant (ie, uniform) sound pressure magnitude is desired, as will be described in
more detail in connection with FIG. Used to define the field 40 to be The test microphones do not
stay in these positions when the noise cancellation system 12 is operating. The approximate
positions of the speakers 16-1, 16-2, and 16-3 generally coincide with the three large peaks in
the graph 35. From each of these peaks, the magnitude of the sound pressure drops sharply and
levels off in the substantially flat sound pressure field 40. In this example, the x and y dimensions
of the flat sound pressure field 40 are approximately 4.5 inches by 4.5 inches, starting
immediately in front of the center speaker 16-2. A flat sound pressure field 40, designed to
intersect and cancel the substantially flat noise field, corresponds to the noise cancellation zone.
[0033]
FIG. 3 shows a three-dimensional graph 45 of an example of a sound pressure field 48 that can
be generated by the loudspeaker 16 driven in phase with equal amplitude voltage. Similar to FIG.
2, the magnitude of the sound pressure in dB (based on any pressure) is measured on the vertical
axis (z-axis) and the distance (in inches) is on the x and y axes It is measured. 4Four vertical lines
42, corresponding to the temporary position of one test microphone, are only shown to provide a
reference point for comparing the graph 35 of FIG. Also shown are the approximate positions of
the speakers 16-1, 16-2, and 16-3. From the peak levels at these loudspeaker locations, the
magnitude of the sound pressure gradually decreases with increasing distance from the
loudspeakers. Driving the loudspeaker 16 in the in-phase configuration is generally suboptimal
because the sound pressure field 48 is generally tilted with respect to the flat noise field, and
thus generated by the flat sound pressure field 40 of FIG. Generate a relatively small area of
erasure (ie, along the line where the noise and driver fields intersect) as compared to the
intersection area. Nevertheless, the in-phase configuration can provide higher response than the
same driver voltage array configuration.
[0034]
FIG. 4 shows an example process that is pre-configured such that array loudspeaker controller
26 modifies input command signal 27 to generate driver signal 25 for each of speakers 16 to
achieve a desired flat driver field. The process places four test microphones 50-1, 50-2, 50-3, and
50-4 (generally 50) apart in the environment 10 surrounding the occupant's expected head area
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52. Accompanied by The position of the test microphone 50 substantially defines a twodimensional noise cancellation zone 54 that internally produces the desired flat driver field.
Microphones 50-1 and 50-3 both correspond to the head position of the occupant turned 45
degrees to the right, and microphones 50-2 and 50-4 both turned 45 degrees to the left
Correspond to the position of the occupant's head.
[0035]
The optimization routine (algorithm) measures the frequency response from the input of the
array speaker controller 26 to each of the microphones 50. The purpose of the optimization
routine is to apply a transformation (eg, to the driver signal 25) such that the frequency response
(in magnitude and phase) for all of the test microphones 50 from the input of the arrayed
speaker , Gain and delay). Thus, the perceptual effect of noise cancellation is the same
throughout the noise cancellation zone 54.
[0036]
In one example implementation, the optimization routine may have a fixed gain on one of the
three speakers (eg, 16-1) and three free on the other two speakers (eg, 16-2, 16-3). Calculate the
set 25 of driver signals by using the parameters. 3One free parameter is the gain of each of the
other two speakers (eg, 16-2, 16-3), the delay of one of the other two speakers (eg, 16-2, 16-3)
Corresponds to One example solution generated by the optimization routine generates a driver
signal 25 sent to the center speaker 16-2 with a fixed gain of 1 to generate the driver signal 25
sent to the left speaker 16-1. In order to generate a gain and a delay of approximately -1 and a
fixed gain of 1 to the command signal 27 to generate the driver signal 25 sent to the right
speaker 16-3. The optimization routine takes into account the physical movement of the central
speaker 16-2. The side speakers 16-1 and 16-3 operate in phase, so the outputs of the side
speakers 16-1 and 16-3 are summed. The central speaker 16-2 works individually. By bringing
the center speaker 16-2 closer to the head of the occupant than the side speakers 16-1 and 16-3,
the driver field is flattened. Array speaker controller 26 is pre-generated by the solution
generated by the optimization routine used during operation of noise cancellation system 12 to
generate driver signal 25 based on command signal 27 received from compensator 24.
Configured
[0037]
The optimization routine may use other parameters instead of, or in addition to, gain and delay,
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examples of which include linear and non-linear filters, pole frequencies, and zero frequencies,
among them It should be understood that it is not limited.
[0038]
FIG. 5 applies to the command signal 27 to generate a driver signal that is used to drive the
speaker 16 to cancel noise in the area, for example in the passenger's head of the vehicle, in the
cabin of the vehicle An example of a process 100 for configuring the noise cancellation system
12 using the parameter values being
In the description of process 100, reference is made to the elements of FIG. Process 100 includes
the step of defining a two-dimensional noise cancellation zone 54 (step 102), which is occupied
by the prospective occupant and produces a desired flat driver field therein. In order to define
this zone, at least three test microphones 50 spatially separated are placed in front of the
loudspeaker 16 to generate a two-dimensional area (e.g. an isosceles triangle, a rectangle, a
parallelogram) . 3The position of the two speakers 16 preferably corresponds to the expected
position of the speakers during operation of the noise cancellation system 12.
[0039]
The speaker 16 emits a sound having a range of frequencies of interest (ie, the original form of
the audio signal is predetermined) (step 104). For example, the design of the noise cancellation
system 12 may be to attenuate low frequency noise (5 to 150 Hz) and the speech signal includes
frequencies over the desired frequency range. The transfer function (i.e., the magnitude and
phase response) of each of the test microphones 50 from the input of the amplifier 20 is
measured (step 106). The optimization routine arranges the loudspeakers to drive the
loudspeakers 16 in order to converge on a set of parameter values that produce substantially the
same frequency response in magnitude and phase over the desired frequency range from the
loudspeakers 16 to all of the test microphones 50 Adjust certain parameters of the controller 26
(step 108). The solution found by the optimization routine achieves with the speaker the
generation of a substantially flat driver field which closely matches the substantially flat noise
field in the cancellation zone. Array speaker controller 26 is configured with parameter values
(eg, gain and delay) found by the optimization routine for use in driving speaker 16 during the
operation phase (step 110).
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[0040]
FIG. 6 shows an example of a process 150 for providing noise cancellation in the noise
cancellation zone 54 defined as described in connection with FIG. In the description of process
150, reference is made to the elements of FIG. During operation of the noise cancellation system
12, at least one system microphone 18 disposed near the occupied area detects sound that may
include frequency components that are considered noise (step 152). In response to the sound,
each microphone 18 generates a signal (step 154).
[0041]
In response to the signal (or signals) from the at least one system microphone 18, the
compensator 24 of the system controller 22 executes an algorithm that generates a command
signal 27 (step 156). The purpose of the algorithm is to achieve a visible reduction (eg, at least 4
dB) in the occupant's ear. In general, the implemented algorithm applies one or more filters to
the signal generated by each system microphone 18. In the case of multiple microphones 18, the
implemented algorithm may apply different filters to the signal generated by each microphone
18 and combine the results to generate a command signal. The applied filters may be digital or
analog, linear or non-linear.
[0042]
The array speaker controller 26 of the system controller 22 receives the command signal 27 and
generates a set of driver signals in response to the command signal 27 (step 158). Each driver
signal 25 is associated with a different one of the speakers 16. With arrayed speakers, at least
two of the speakers receive different driver signals 25 (eg, different gains, delays, or both), and
typically all of the speakers receive different driver signals 25. Array speaker controller 26 sends
driver signal 25 to amplifier 20. Amplifier 20 drives each speaker 16 according to the driver
signal associated with that speaker (step 160). The sounds emitted by the speaker 16 are both
opposite (i.e., approximately equal in magnitude, 180 degrees in phase to the substantially flat
noise field corresponding to the noise detected by the at least one system microphone 18).
Offset) producing a substantially flat sound pressure field.
[0043]
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FIG. 7 shows an example of a noise cancellation system 12 'adapted to alternate between an
arrayed speaker configuration and an in-phase speaker configuration. The noise cancellation
system 12 ′ includes a system controller 22 ′ in communication with the amplifier 20.
Amplifier 20 communicates with a plurality of speakers 16-1, 16-2, and 16-3 positioned as
described in connection with FIG.
[0044]
System controller 22 'includes a compensator 24 in communication with switch 170 (also
considered as a signal director module). Compensator 24 generates command signal 27 based on
one or more signals 23 received from one or more system microphones 18. The switch 170 is in
communication with the array loudspeaker controller 26 and the in-phase loudspeaker controller
172. In the first state, the switch 170 passes the command signal 27 received from the
compensator 24 as a whole to the array speaker controller 26, and the in-phase speaker
controller 172 does not receive any part of the command signal 27. In the second state, the
switch 170 passes the command signal 27 as a whole to the in-phase speaker controller 172, and
the array speaker controller 26 does not receive any part of the command signal 27.
[0045]
In response to receiving the command signal 27, the array speaker controller 26 generates the
flat sound pressure field, as described above in connection with FIG. A signal 25 is generated.
The amplifier 20 receives the driver signal 25 and drives each speaker according to the driver
signal 25 for that speaker.
[0046]
An example of the gain 174-1 applied to the driver signal 25 to generate a flat sound pressure
field is a gain of 1 for the left speaker 16-1 and a gain of -1 for the center speaker 16-2 (and And
the right speaker 16-3 includes a gain of one. The net sum of these gains is equal to one speaker
(1 + (-1) +1).
[0047]
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15
Elimination of noise events using large pressure amplitudes requires equally large pressure from
the speaker 16, and the relatively low pressure response of the arrayed speakers to the driver
voltage when the amplifier output voltage reaches its limit, Clip as a result. Because the
constellation mode may overdrive the amplifier, the noise cancellation system 12 'transitions to
the in-phase mode when certain noise related events occur. 3By driving the two speakers 16-1,
16-2, 16-3 in the in-phase configuration mode, the acoustic gain is increased by a factor of three.
Thus, amplifier 20 drives speaker 16 to a smaller output voltage to achieve the noise cancellation
output intended by compensator 24 when the speaker is in the in-phase configuration mode than
when in the configuration mode. Need. In response to the command signal 27, the in-phase
speaker controller 172 generates a common in-phase driver signal 175 sent to all of the speakers
16, but the in-phase speaker controller 172 is 1/3 of each speaker 16. Apply the gain. Similar to
the array configuration mode, the net total gain is one speaker (1/3 + 1/3 + 1/3), but the
voltages required to achieve the noise cancellation speaker output are in the array configuration
mode Is one third of the voltage required by Thus, when operating in the in-phase configuration
mode, amplifier 20 does not clip. It should be understood that the gain and gain net sum
generated by the array speaker controller 26 and the in-phase speaker controller 172 are
examples of values provided to illustrate the principle.
[0048]
The system controller 22 ′ further includes a signal magnitude monitor 176 coupled to the
outputs of the array loudspeaker controller 26 and the in-phase loudspeaker controller 172 and
to the switch 170. The signal magnitude monitor 176 causes the switch 170 to cause the arrayed
speaker controller 26 to overdrive the amplifier 20 and in-phase the command signal 27 in
response to detecting noise related events that may cause clipping. Turn to the speaker controller
172. A signal magnitude monitor 176 monitors the output of the array loudspeaker controller
26, compares the magnitude of the driver signal 25 to a threshold, and initiates a transition from
array configuration to in-phase configuration when the magnitude exceeds the threshold. Do. In
response to the passage of a predetermined time, or in response to the monitoring output of the
in-phase speaker controller 172 falling below a predetermined threshold, the signal magnitude
monitor 176 causes the switch 170 to A transition is also made to directing the whole to the
arrayed speaker controller 26.
[0049]
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16
FIG. 8 shows another of the noise cancellation system 12 ′ ′ adapted to transition between the
array loudspeaker configuration and the in-phase loudspeaker configuration in response to noise
related events to avoid overdriving the amplifier. It is a block diagram of the example of. The
noise cancellation system 12 "includes a system controller 22" configured to cancel noise in the
two noise cancellation zones 54-1, 54-2. To eliminate noise in the noise cancellation zone 54-2 to
show that such features are optional and that the principles described in connection with FIG. 8
apply to noise cancellation only in a single noise cancellation zone The components to do this are
shown in phantom. In general, instead of distributing the command signal 27 as a whole in one
configuration mode or the other as described in FIG. 7, the noise cancellation system 12 ′ ′
command signal between the array speaker configuration mode and the in-phase speaker
configuration mode Allocate 27.
[0050]
The system controller 22 "is in communication with the first amplifier 20-1 and optionally with
the second amplifier 20-2. Each amplifier 20-1 and 20-2 communicates with a pair of speakers
16A and 16B, respectively. The system controller 22 "includes a first signal divider 180-1 and
optionally a compensator 24 in communication with a second signal divider 180-2. Compensator
24 optionally selects command signal 27-1 based on one or more signals 23 received from one
or more system microphones 18 (not shown) associated with the first zone 54-1. A command
signal 27-2 is generated based on one or more signals 23 received from one or more system
microphones 18 (not shown) associated with the second noise cancellation zone 54-2. Command
signal 27-1 is passed to signal divider 180-1, and optionally, command signal 27-2 is passed to
signal divider 180-2.
[0051]
In one implementation, the signal divider 180-1 extracts the arrayed speaker signal 183-1 from
the command signal 27, and the bandwidth modulated filter passes the arrayed speaker signal
183-1 to the arrayed speaker controller 26-1 And the cut-off frequency of the high pass filter is
modulated by the output of the signal director module 188. Signal divider 180-1 may use a high
pass filter to pass higher frequencies of command signal 27 to arrayed speaker controller 26-1.
Signal divider 180-1 creates complementary high and low pass filters to send higher frequencies
to array speaker controller 26-1 and lower frequencies to in-phase speaker controller 172-1. The
signal divider 180-1 may have other implementations, such as frequency independent gain
adjustment, in which case a percentage of the signal is sent to the array speaker controller 26-1
and the remainder is in phase speaker control Is sent to the container 172-1.
03-05-2019
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[0052]
The array loudspeaker controller 26-1 is pre-configured to generate a set 25 of driver signals
(one for each speaker) designed to produce a flat driver field as described in FIG. 1 The
parameter values are applied to the array loudspeaker signal 183-1.
[0053]
The signal divider 180-1 also generates an in-phase loudspeaker signal 185-1 from the
command signal 27-1.
The in-phase speaker controller 172-1 applies a 1/3 gain to the in-phase speaker signal 185-1 to
generate the in-phase driver signal 175 (the same driver signal 175) for each speaker 16, as
described in FIG. Do.
[0054]
An adder 184-1 combines the set 25 of driver signals from the arrayed speaker controller 26-1
with the in-phase driver signal 175 to generate a hybrid command signal 187 for each speaker
16. The sum of these hybrid command signals 187-1 is equal to the command signal 27-1
generated by the compensator 24.
[0055]
Between the second noise cancellation zone 54-2, ie, the components in the signal divider 180-2,
the adder 184-2, the array loudspeaker controller 26-2, and the in-phase loudspeaker controller
172-2 The connectivity of the components and the operation of the components are similar to
their corresponding components involved in eliminating the noise in the first noise cancellation
zone 54-1.
[0056]
The system controller 22 "further includes a signal magnitude monitor 186 in communication
03-05-2019
18
with the signal director module 188.
A signal magnitude monitor 186, in communication with the output of the adder 184-1 and
optionally the output of the adder 184-2, is based on the hybrid command signal 187-1 passed
to the amplifier 20-1. And optionally, the magnitude is also calculated based on the hybrid
command signal 187-2 passed to the amplifier 20-2. In one implementation, signal magnitude
monitor 186 squares the magnitude of hybrid command signal 187-1. In another example
implementation, signal magnitude monitor 186 calculates the magnitude by multiplying the
magnitude of hybrid command signal 187-1 by the magnitude of hybrid command signal 187-2.
The calculated magnitudes are passed to the signal director module 188.
[0057]
In response to the calculated magnitude, the signal director module 188 passes any portion of
the command signal 27-1 to the array speaker controller 26-1 and which portion of the
command signal 27-1 is an in-phase speaker controller 172. Determine if it will be passed to -1.
Generally, to drive the loudspeaker without clipping, a larger portion of the command signal is
directed to the in-phase loudspeaker controller as the calculated magnitude approaches the
amplifier's limit. The signal director module 188 may, for example, calculate the calculated
magnitude to adjust the corner frequency used by the signal divider 180-1 to distribute the
command signal between the alignment mode and the in-phase configuration mode. It can be
used. For example, the corner frequency may be reduced to 0 Hz to direct the entire command
signal to the arrayed speaker controller 26-1, and conversely, the corner may be directed to
direct the entire command signal to the in-phase speaker controller 172-1. The frequency can be
raised to the maximum value of signal divider 180-1 (eg, 200 Hz). Therefore, the signal director
module 188 passes the frequency range of the command signal 27-1 to the in-phase speaker
controller 172-1 and determines which range of frequencies to pass to the array speaker
controller 26-1. Implement "sliding scale".
[0058]
FIG. 9 illustrates an example process 190 for transitioning between an array speaker
configuration mode and an in-phase speaker configuration mode. In the description of process
190, reference is made to the elements of FIGS. As a convenient starting point to illustrate the
process 190, consider the system controller (22 'or 22 ") driving a set of speakers in an array
configuration mode (step 192). Certain noise related events are detected (step 194). In the noise
03-05-2019
19
cancellation system 12 'of FIG. 7, the signal magnitude monitor 176 determines that the
magnitude of the driver signal 25 exceeds a threshold corresponding to the limit of the amplifier
20 for driving the loudspeaker without clipping. Can. As another example, detection of this noise
related event may correspond to the signal director module 188 of the noise cancellation system
12 "of FIG. 8 receiving an increase in the calculated magnitude value from the signal magnitude
monitor 186. Can.
[0059]
In response to detecting the noise related event, the system controller adjusts the speaker
configuration mode in real time (step 196). For example, in the noise cancellation system 12 'of
FIG. 7, the system controller 22' switches to driving all speakers in the in-phase configuration
mode in response to a detected noise event. As another example, in the noise cancellation system
12 "of FIG. 8, the system controller 22" increases the distribution of the command signal sent to
the in-phase speaker controller 172-1, but conversely, the array speaker controller 26- Decrease
the distribution of the command signal passed to 1.
[0060]
After the noise related event is over, the system controller also transitions to driving the speaker
in the configuration mode (step 198). For example, in the noise cancellation system 12 'of FIG. 7,
the system controller 22' arranges all the loudspeakers after the magnitude of the in-phase driver
signal 175 falls below a threshold (or after a predetermined time has elapsed). Switch to driving
again. As another example, in the noise cancellation system 12 "of FIG. 8, the system controller
22" reduces the distribution of the command signal passed to the in-phase speaker controller
but, conversely, it is calculated by the signal magnitude monitor In response to the reduction of
the magnitude value, the distribution of command signals passed to the array speaker controller
is increased in real time.
[0061]
In general, the transfer function from the command signal of the in-phase loudspeaker
configuration to the system microphone closely matches the transfer function of the array
loudspeaker configuration at low frequencies (between 0 and 350 Hz) (in phase and magnitude).
This close match virtually hides the distribution of the command signal between the in-phase
03-05-2019
20
speaker controller and the array speaker controller from the compensator 24 (ie, the generator
of the command signal). Regardless of the particular division of the command signal between the
in-phase speaker controller and the array speaker controller, the transfer function to the system
microphone is virtually the same and the system controller sees virtually the same control object
There is.
[0062]
The transfer function is modified by changing the distribution of the command signal allocated to
the array speaker controller and the command signal allocated to the in-phase speaker controller
(ie the system controller now looks at different control targets) Control module (eg, linear or nonlinear filter) in front of the array speaker controller to ensure that the distribution change does
not alter the transfer function so badly in an implementation) Can be placed in front of the vessel
or in front of both.
[0063]
FIG. 10 shows an example of an environment 10 'in which a noise cancellation system can be
deployed.
In this example, a plurality of speakers 16 (only one shown) is disposed behind the occupant's
200 head in the environment 10 ', eg, a vehicle headrest, headliner, rear panel, or other interior
surface It can be mounted on top. Other example locations of speakers may be in the headliner
202 and on the back side of the headrest 204, provided that such speakers are arranged as
described herein.
[0064]
1
One system microphone 18 may be disposed, for example, on a unit 30 that includes a speaker
16, and another system microphone 18 (shown in phantom) may be disposed within the
headliner 202. The amplifier 20 and system controller 22 (with compensator, array speaker
controller, in-phase speaker controller, etc.) can be disposed, for example, in the trunk of the
vehicle. Controller 22 is in electrical communication with one or more system microphones 18 to
receive signals generated by each system microphone.
03-05-2019
21
[0065]
Examples of systems and methods described above include computer components and computer
implemented steps that will be apparent to those skilled in the art. For example, it should be
understood by those skilled in the art that computer implemented steps may be stored as
computer executable instructions on computer readable media such as, for example, floppy disks,
hard disks, optical disks, flash ROMs, non-volatile ROMs, and RAMs.
[0066]
Further, it should be understood by those skilled in the art that computer executable instructions
may be executed on various processors, such as, for example, microprocessors, digital signal
processors, gate arrays, and the like. Although not every step or element of the above-described
systems and methods is described as part of a computer system for ease of explanation, each
step or element corresponds to a corresponding computer system. Those skilled in the art will
recognize that they can have software components. Accordingly, such computer systems and / or
software components are effective by describing their corresponding steps or elements (ie, their
functionality) and are within the scope of the present disclosure.
[0067]
Several implementations have been described. Nevertheless, additional modifications can be
made without departing from the scope of the inventive concept described herein, and it is
therefore understood that other embodiments are within the scope of the following claims. It will
be done. For example, a ring of loudspeakers equidistant around the occupant can produce a
substantially uniform sound pressure field without being arranged.
[0068]
10 Environment 10 'Environment 12 Noise Canceling System 12' Noise Canceling System 12
"Noise Canceling System 16 Speaker 16-1 Speaker 16-2 Speaker 16-3 Speaker 16A Speaker Set
16B Speaker Set 18 Microphone, System Microphone 20 Amplifier 20-1 First amplifier 20-2
Second amplifier 22 System controller 22 'system controller 22 "system controller 23 signal 24
compensator 25 driver signal 26 array speaker controller 26-1 array speaker controller 26-2
array speaker Controller 27 command signal 27-1 command signal 27-2 command signal 30
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single unit 35 3D graph 40 sound pressure field 42 vertical line 45 3D graph 48 sound pressure
field 50 test microphone 50-1 test microphone 50-2 test Microphone 50-3 Test microphone 504 Test microphone 52 Predicted head area 54 Two-dimensional noise cancellation zone 54-1
Noise cancellation zone, first zone 54-2 noise cancellation zone, second erasure End zone 100
process 150 process 170 switch 172 in-phase speaker controller 172-1 in-phase speaker
controller 172-2 in-phase speaker controller 174-1 gain 175 in-phase driver signal 176 signal
magnitude monitor 180-1 first signal division 180-2 Second signal divider 183-1 Array speaker
signal 184-1 Adder 184-2 Adder 185-1 In-phase speaker signal 186 Signal size monitor 187-1
Hybrid command signal 187-2 Hybrid command Signal 188 Signal director module 190 Process
example 200 Occupant 202 Headliner 204 Headrest
03-05-2019
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