JP2015506155

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DESCRIPTION JP2015506155
Abstract A method of virtually adjusting an audio system incorporating an acoustic compensation
system, wherein the audio system is adapted to reproduce an audio signal in a listening
environment via one or more acoustic transducers. is there. The acoustic compensation system
has an audio sensor located at a sensor location in the listening environment. The transfer
function from each acoustic transducer to the audio sensor position is unique. The method
contemplates recording the noise at the sensor location and creating a virtual transfer function
from each acoustic transducer to the sensor location based on the unique transfer function from
each acoustic transducer to the sensor location. Do. The audio signal is processed to a sensor
position transfer function through a virtual acoustic transducer. The virtual sensor signal is
created by combining the audio signal processed to the sensor position transfer function through
a virtual acoustic transducer and the noise recorded at the sensor position.
Virtual audio system adjustment
[0001]
The present disclosure relates to the adjustment of audio systems.
[0002]
The audio system may include the ability to change one or more parameters of the audio signal
to produce a desired effect on the sound perceived by the listener in the listening environment.
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The effect that results is generally a change in signal level within the listening environment and /
or sound equalization. Designers of audio systems who are developing systems for use in noisy
environments such as car cabins, airports, restaurants etc. have developed a system that aims to
develop systems that perform well under different conditions of the listening environment We
hope to use the system in a real environment, while retaining the ability to adjust the dynamic
parameters of the. This task requires repeated and extensive use of the listening environment
under actual use conditions, which can be difficult and costly.
[0003]
In order to account for changes in noise, some audio systems for the listening environment
where noise in the listening environment may change are dynamically adjusted. One example of
such an environment is a car cabin. Noise from other conditions in the listening environment
such as engine noise, road noise, and wind noise associated with the condition of the window of
the vehicle (up, partially open, or fully open) Affect the perception of the sound being played
through the audio system. Some acoustic compensation systems sense the sound inside the car,
extract noise from the sensed sound, and adjust the audio signal in a predetermined manner to
account for the noise. For example, playback levels, dynamic range, and frequency response can
be changed based on analysis of noise.
[0004]
It may also be desirable to alter their perception, for example by canceling or enhancing engine
noise within the vehicle cabin. An audio system incorporating an acoustic compensation system
can achieve this by creating an audio signal based on engine harmonics.
[0005]
Systems are known that allow for virtual evaluation of certain aspects of audio systems. For
example, virtual listening via headphones can be used to assess subjectively. Such virtual
listening systems can include adding pre-recorded noise to the audio output to mimic the actual
environment.
[0006]
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In order for the audio system incorporating the acoustic compensation system to operate
efficiently, the audio system needs to be adjusted. That is, it is necessary to establish the value of
the dynamic parameter based on the actual usage condition. For a vehicle audio system, the
adjustment requires that the vehicle be operated under various vehicle operating conditions that
mimics the conditions that the user is likely to experience. This is generally at one or more noise
sensor locations inside the vehicle when the vehicle is operating under various conditions such as
engine RPM, vehicle speed, road surface conditions, and vehicle window conditions. Need to
measure noise. Thus, proper adjustment of the audio system incorporating the acoustic
compensation system requires extended substantial access to a particular listening environment
such as, for example, a vehicle.
[0007]
In contrast to conventional approaches, certain embodiments of the present innovation record
sound at one or more sensor locations in the listening environment, while at the same time one
or more in the listening environment It is contemplated to simultaneously record the sound in
mono or binaural mode at the sound evaluation position. It is desirable to calibrate the recording
so that the recorded sounds can be played back at the same level as they were during the
recording. Additional non-acoustic signals relating to sounds in the listening environment can
also be recorded. Examples of such signals include engine RPM, throttle position, and / or engine
torque associated with vehicle engine noise. The engine RPM signal defines the engine harmonic
frequency while the throttle position and / or engine torque serves to define the level of engine
noise for harmonic enhancement. The transfer function from each loudspeaker to each acoustic
sensor position and each sound evaluation position is virtualized. The acoustic sensor signal can
then be virtualized and fed back to the acoustic compensation system controller. This allows the
audio system to be adjusted without operating the vehicle during the adjustment process. It is
desirable to calibrate the measurement and virtualization of the transfer function so that the
signal reproduced through the virtualization system is output at an appropriate level relative to
the recorded noise level. As a result, once the vehicle is operated under the desired operating
conditions, to record sound and non-acoustic signals at the sensor and evaluation positions, the
adjustment engineer can adjust the system anytime or anywhere .
[0008]
In some embodiments, the invention comprises the application of virtualization to the adjustment
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of an acoustic compensation system in conjunction with an audio system to reproduce a signal in
a listening environment. The sound compensation system may also change the operating
parameters of the audio system, change the signal reproduced by the audio system, or both. An
acoustic compensation system is used to dynamically alter in some way the signal rendered by
the audio system in the listening environment in response to changes in the operating conditions
of the system affecting the listening environment. The acoustic compensation system receives
one or more inputs. At least some of the inputs are from sensors (acoustic or non-acoustic) with
non-stationary statistics. That is, the sensor output signal statistics change with time. In general,
sensor output signal statistics vary with the operating characteristics of the environment. In one
embodiment adapted for use in a vehicle, the sensor output statistics change with the operating
conditions of the vehicle (speed, transmission gear, vehicle window conditions, etc.). The acoustic
sensor is virtualized. Non-acoustic sensors and / or other system inputs that are not affected by
the output from the audio system (e.g., engine RPM) are recorded. A controller in the acoustic
compensation system forms an output based on the received input. The controller may have a
feedforward or feedback topology, or may exhibit characteristics of both. The controller may
operate open loop or may operate closed loop. The controller may be time invariant or may be
time adaptive. The output of the controller can also change the operating parameters of the audio
system, change the signal reproduced by the audio system, or both.
[0009]
In one example where the listening environment is a passenger cabin of a vehicle, an acoustic
compensation system changes operating parameters of the audio system to render the desired
audio program information in a listening area (cabin). The parameters are modified based on
ambient noise present in the environment to improve the audibility of the rendered audio signal
in the presence of noise. The parameters are dynamically changed in response to dynamic
changes in noise.
[0010]
Also in another example where the listening environment is the passenger cabin of a vehicle, an
acoustic compensation system alters the characteristics of the signal that correlates with the
vehicle's engine signature and outputs this signal through the audio system. The dynamically
changing output signal interferes with the engine signal present in the listening environment to
change the perception of the engine signature by the listener located in the listening
environment (vehicle cabin). In one example, the altered signal destructively interferes with
engine noise and in another example constructively. The modified signal may be a wideband
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replica of the engine noise signature or may represent one or more individual harmonics of the
fundamental frequency of the engine signature. The signal can destructively interfere with one
harmonic and constructively interfere with the other harmonic.
[0011]
The acoustic compensation system has one or more sensors located somewhere in the listening
environment. At least some of these sensors are generally acoustic sensors, such as microphones.
The system also includes one or more non-acoustic inputs for noise, such as one or more nonacoustic sensors that sense parameters related to environmental noise, and / or an engine RPM
signal received from an automotive engine controller. It can have. Non-acoustic sensors or other
non-acoustic inputs may include engine RPM, throttle position, or engine load for vehicle engine
noise. The system can use these inputs to determine how to modify the system or process signals
to reach some desired state.
[0012]
Audio system virtualization is known. The synthesis of the interaction between the audio system
and the listening environment makes it possible for the individual to physically locate the signal
within the listening environment and represent the signal present when listening to the actual
physical audio system. It is possible to allow people to listen. The signal may be reproduced via
headphones or loudspeakers. Until now, such virtualized audio systems have been static, so
changing conditions could not be considered dynamically. Virtualization was performed only at
the evaluation position. That is, it was performed only at the position of the listener's ear.
[0013]
The invention herein is that the use of an acoustic compensation system requires the use of a
sensor to sense some conditions in the space that the system is trying to compensate. In order to
virtually adjust such a system, it is not sufficient to virtualize only the evaluation points, but also
record sensor signals or other system inputs related to the listening environment or sensors used
by the system Must be virtualized. In addition to generating a virtual signal representing the
signal present at the evaluation point, the virtualized acoustic compensation system also needs to
access sensor signals present in the actual environment. Only then does the virtual version of the
acoustic compensation system output a signal representing the actual signal output by the
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physical system exposed to the same environment. There is a need for virtualization of sensor
signals that may be affected by the acoustic compensation system.
[0014]
Several methods for virtualizing assessment points are described herein. In a first example of a
system used to change audio system parameters in order to improve the audibility of the desired
signal rendered by the system in the presence of noise, the engineer adjusting the system
actually It is desirable to listen to the audio system as if it were in the vehicle. This is best done
by virtualizing the binaural signal at the score, as is known for simple virtual listening of static
(non time-varying) audio systems. In the second example, where the engine sound features are
modified by the acoustic compensation system, it is not necessary to use binaural virtualization
at the score. Virtualization of the signal present at a single point near the listener's head is
sufficient to determine if the engine sound has the correct features. It is also possible to
determine this objectively in the case of EHC (engine harmonic cancellation), and an objective
measurement of the desired reduction of SPL (sound pressure level) may be available. It is not
necessary to use binaural virtualization for EHC and EHE (engine harmonic enhancement)
applications, but of course it can be used, and in some cases, a tuning engineer may want to hear
a modified engine sound. Furthermore, because EHC and EHE can be used simultaneously in the
audio system, the coordination engineer may want to listen to the virtual vehicle cabin system in
both systems running simultaneously.
[0015]
In general, one aspect of the present disclosure is a method of virtually adjusting an audio system
incorporating an acoustic compensation system, the audio system including an audio signal
through one or more acoustic transducers in a listening environment. It features the method used
to play. The acoustic compensation system has a sensor located at a sensor location in the
listening environment. Transfer functions from each acoustic transducer to the sensor location
are measured and stored. The method contemplates recording noise at the sensor location. A
virtual transfer function from each acoustic transducer to the sensor position is created based on
the measured transfer function from each acoustic transducer to the sensor position. The audio
signal is then processed to a sensor position transfer function through a virtual acoustic
transducer. A virtual sensor signal is created by combining the audio signal processed to the
sensor position transfer function through all virtual acoustic transducers and the noise recorded
at the sensor position. This virtual sensor signal may then be used in audio system adjustment
tasks, or as the actual noise sensor output as used in a real audio system.
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[0016]
Various implementations may include one or more of the following features. There may be sound
evaluation locations in the listening environment, and transfer functions from each acoustic
transducer to the evaluation locations may be measured. The method comprises recording noise
at the sensor location at the same time as recording noise at the sound estimation location, and
evaluating position from each acoustic transducer based on a unique transfer function from each
acoustic transducer to the evaluation position. The steps of creating a virtual transfer function to
the next step, processing the audio signal to the evaluation position transfer function through the
virtual acoustic transducer, the audio signal processed into the evaluation position transfer
function through all the virtual acoustic transducers, and the sound evaluation And D. combining
the position-recorded noise with the audio evaluation signal.
[0017]
The acoustic compensation system may further comprise a processor for processing the audio
signal, the method comprising the step of inputting a virtual sensor signal into the processor,
wherein the virtual sensor signal is reproduced as part of the audio evaluation signal ( That is,
the method may further comprise the steps used by the processor to cause the modification of
the audio signal (played back in the virtualized listening environment). The method includes
inputting to the processor one or more acoustic compensation system inputs selected from a
group of inputs including an engine RPM signal, a music signal, a signal representative of vehicle
speed, and a signal representative of vehicle functional status. And even further. These acoustic
compensation system inputs may be used by the processor to cause correction of the audio
signal reproduced in a virtualized listening environment.
[0018]
The noise may be recorded in a binaural manner, the recorded noise may comprise the sound in
the vehicle cabin, and the sound may be recorded in a vehicle operating under various different
vehicle operating conditions. The method may further comprise the step of associating (e.g. in a
database) the recorded sound with the particular vehicle operating conditions at the time of
recording. The method takes out the recorded sound under such conditions, and uses such
extracted sound and the recorded acoustic system input to create a virtual sensor signal and an
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audio evaluation signal. Still further may include querying the database for specific vehicle
operating conditions.
[0019]
The acoustic compensation system may comprise multiple sensors located at multiple sensor
locations in the listening environment, in which case noise may be recorded simultaneously at all
sensor locations. There may be multiple evaluation locations within the listening environment,
and noise may be recorded simultaneously for all sensor locations and all evaluation locations.
The method may further comprise the step of analyzing the audio evaluation signal, which can be
realized by applying the audio evaluation signal to the headphones. The sensor may be either a
microphone or an accelerometer.
[0020]
The recorded noise may comprise the sound in the listening environment, and the sound may be
recorded under various environmental conditions of the listening environment. The method may
further comprise, in the database, associating the recorded sound with the specific environmental
conditions at the time of recording. The method may further comprise the step of querying a
database for specific environmental conditions and retrieving the sound recorded under such
conditions. The method may still further comprise the step of creating a virtual sensor signal and
an audio evaluation signal using the extracted sound.
[0021]
In general, in another aspect of the present disclosure, a method of virtually adjusting an audio
system with an acoustic compensation system, the audio system comprising an audio signal via
one or more acoustic transducers in a vehicle cabin It features the method used to play. The
acoustic compensation system comprises an adaptive processor for processing the audio signal
and a microphone located at a sensor location in the vehicle cabin. In the vehicle cabin there is a
sound evaluation position. Transfer functions from each acoustic transducer to the sensor
position are measured and stored, and transfer functions from each acoustic transducer to the
evaluation position are measured and stored. The method comprises the steps of recording sound
at the sensor position and recording sound at the sound evaluation position simultaneously with
recording at the sensor position, the sound being recorded at a vehicle operating under various
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specified vehicle operating conditions And the step of The recorded sound may be associated in
the database with the particular vehicle operating conditions at the time of recording. A virtual
transfer function from each acoustic transducer to the sensor position is created based on a
unique transfer function from each acoustic transducer to the sensor position. A virtual transfer
function from each acoustic transducer to the evaluation position is created based on a unique
transfer function from each acoustic transducer to the evaluation position. The audio signal is
processed to a sensor position transfer function through a virtual acoustic transducer, and the
audio signal is processed to an estimated position transfer function through a virtual acoustic
transducer. The virtual sensor signal is created by combining the audio signal processed to the
sensor position transfer function through a virtual acoustic transducer and the sound recorded at
the sensor position. The audio evaluation signal is created by combining the audio signal
processed to the evaluation position transfer function through the virtual sound transducer and
the sound recorded at the sound evaluation position. The virtual sensor signal is input to the
processor, and the virtual sensor signal is used by the processor to cause correction of the audio
signal to be reproduced in the virtualized vehicle cabin. Also input to the processor is one or
more acoustic compensation system inputs selected from the group of acoustic compensation
system inputs including an engine RPM signal, a music signal, a signal representative of vehicle
speed, and a signal representative of vehicle functional status . These acoustic compensation
system inputs are recorded simultaneously with the recording of noise at the sensor and
evaluation positions. The acoustic compensation system input is used by the processor to cause
correction of the audio signal to be reproduced in the virtualized vehicle cabin.
The database may be queried for such conditions to retrieve sounds recorded under certain
vehicle operating conditions. The extracted sound is then used to create virtual sensor signals
and audio evaluation signals. The audio evaluation signal can then be analyzed, for example by
applying the audio evaluation signal to the headphones. This analysis can alternatively be
performed objectively.
[0022]
Various implementations of this aspect of the disclosure may include one or more of the
following features. The acoustic compensation system may comprise a plurality of microphones
located at a plurality of sensor locations within the vehicle cabin, and sound may be recorded
simultaneously at all sensor locations. There may be multiple rating locations within the vehicle
cabin, and sound may be recorded in all sensor locations simultaneously and in a binaural
manner at all rating locations.
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[0023]
Generally, another aspect of the present disclosure virtually adjusts an acoustic compensation
system that is part of an audio system used to create an audio signal that cancels or enhances
engine harmonics in a vehicle cabin. A method, wherein an acoustic compensation system
comprises a processor for processing an audio signal and a microphone located at a sensor
location in a vehicle cabin, there is a sound evaluation location in the vehicle cabin, and each
sensor location from each acoustic transducer The method is characterized in that the transfer
functions to and from are measured and stored, and the transfer functions from each acoustic
transducer to the evaluation position are measured and stored. The method comprises the steps
of simultaneously recording sound at the sensor position, recording sound at the sound
evaluation position and recording one or more engine related signals. Recordings are performed
on vehicles operating under various engine operating conditions. A virtual transfer function from
each acoustic transducer to the sensor position is created based on a unique transfer function
from each acoustic transducer to the sensor position. A virtual transfer function from each
acoustic transducer to the evaluation position is created based on a unique transfer function
from each acoustic transducer to the evaluation position. The audio signal is processed to a
sensor position transfer function through a virtual acoustic transducer. The audio signal is
processed to an estimated position transfer function through a virtual acoustic transducer. The
virtual sensor signal is created by combining the audio signal processed to the sensor position
transfer function through a virtual acoustic transducer and the sound recorded at the sensor
position. The audio evaluation signal is created by combining the audio signal processed to the
evaluation position transfer function through the virtual sound transducer and the sound
recorded at the sound evaluation position. The virtual sensor signal is input to the processor, and
the virtual sensor signal is adapted to cause the correction of the audio signal to be reproduced
in the virtualized vehicle cabin to cancel or enhance one or more engine harmonics Used by An
engine RPM signal is also input to the processor. The engine RPM signal is recorded
simultaneously with the recorded sound and is used by the processor to cause a correction of the
audio signal reproduced in the virtualized vehicle cabin. The extracted sound is used to create
virtual sensor signals and audio evaluation signals. The audio evaluation signal is analyzed, which
can be realized by applying the audio evaluation signal to the headphones.
[0024]
The foregoing and other objects, features, and advantages will be apparent from the following
description of specific embodiments of the invention, as illustrated in the accompanying
drawings. Like reference characters refer to the same parts throughout the different views. The
drawings are not necessarily to scale, emphasis instead being placed upon illustrating the
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principles of various embodiments of the invention.
[0025]
FIG. 1 is a schematic view of a listening environment used to record noise and / or non-acoustic
signals and adapted to use a type of dynamic audio system capable of simulating adjustments
according to the present invention. FIG. 1 is a schematic diagram of a system for use in simulated
tuning of a dynamic audio system. It is an alternative system for use in simulated tuning of
dynamic audio systems.
[0026]
Embodiments of the present invention contemplate recording sound at one or more sensor
locations within the listening environment and simultaneously recording sounds at one or more
sound evaluation locations within the listening environment. Non-acoustic engine related signals
such as engine RPM, throttle position, engine load, and / or engine torque can be recorded
simultaneously with the sound recording. If desired, non-acoustic sensors can be used to sense
such signals. Alternatively, such signals can be provided by existing vehicle components or
subsystems. The recording at the evaluation position may be binaural, but it does not have to be.
The transfer function from each loudspeaker to each sound sensor position and each sound
evaluation position is virtualized. The sound sensor signal can then be virtualized and fed back to
the controller of the sound compensation system. This makes it possible to adjust the audio
system incorporating the acoustic compensation system without operating the vehicle during the
adjustment process. As a result, once the vehicle is operated under the desired operating
conditions, to record sound at the sensor position and evaluation position, and simultaneously to
record non-sound signals, the coordination engineer may, at any time or anywhere, You will be
able to adjust the system.
[0027]
The recording and sound system 10 of FIG. 1 illustrates a listening environment 12. The listening
environment 12 is adapted to use an audio system 14 that plays audio within the listening
environment 12 via one or more loudspeakers, such as the loudspeakers 16 and 18. The
invention herein allows for the adjustment of an acoustic compensation system that may be part
of audio system 14.
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[0028]
The listening environment 12 may be a closed environment, a partially closed environment, or an
open environment. An example of a closed listening environment is a car cabin. The partially
closed listening environment may be a room with an opening such as a doorway or other indoor
location, including, for example, a public space such as a restaurant. The open listening
environment may be an outdoor location where music or other audio is played, or a large open
indoor space or location such as an airport concourse.
[0029]
It is desirable to use virtual listening techniques to adjust an audio system that includes an
acoustic compensation system. One aspect of acoustic compensation system performance that
requires adjustment is the use of such a system for vehicle noise compensation. One type of
vehicle noise compensation system contemplated herein is disclosed in US Pat. No. 5,434,922,
the disclosure of which is incorporated herein by reference. In this system, the volume and / or
equalization of the audio reproduced in the vehicle cabin is corrected to compensate for the noise
in the cabin. Another use of the in-vehicle acoustic compensation system is for EHC / EHE, where
engine noise in the vehicle cabin is canceled or enhanced. Such systems also need to be
coordinated.
[0030]
In order to tune the acoustic compensation system to operate properly, the system is operated
under all relevant operating conditions and operating parameters of the listening environment.
Since the listening environment is exposed to various conditions in which the system is to be
adjusted, audio engineers generally listen to the output of the audio system while in the listening
environment. At least some of these conditions are generally time-varying. Engineers can modify
the acoustic compensation system parameters to achieve optimal audio results. Thus,
coordination requires both substantial access to the listening environment and the presence of
coordinating engineers in the listening environment.
[0031]
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Audio system and listening so that the individual can listen to a signal that is physically located
within the listening environment and present when listening to the actual physical audio system
It is possible to synthesize interactions with the environment. The signal may be reproduced via
headphones or loudspeakers. Until now, such virtualized audio systems were static, so it was not
possible to consider dynamically changing conditions. Virtualization was performed only at the
evaluation position. That is, it was performed only at the position of the listener's ear. For
example, audio system performance in the presence of noise can be achieved by recording the
noise in the actual listening environment in advance and then mixing the recorded noise with the
output of the audio system to create a mixed signal via headphones The coordination engineer
was virtualized by playing back. Such a system is disclosed in US Patent Publication No. US
2008/0212788 A1, the disclosure of which is incorporated herein by reference.
[0032]
The acoustic compensation system may use one or more sensors to sense temporally varying
conditions in or reaching the space that the system intends to compensate. An example of such a
space is a listening environment such as a vehicle cabin. The sensor may include a vibration
sensor such as a microphone for sensing sound or an accelerometer for sensing vibration. In
order to virtually adjust such a system, both the evaluation position and the sensor output need
to be virtualized. Thus, in order to be able to adjust the acoustic compensation system remotely
from the listening environment (referred to herein as "virtual adjustment"), the acoustic signal
present at each sensor location is evaluated for the purpose of the adjustment. It must be
recorded at the same time as the recording of the noise at the location within the listening
environment (referred to herein as the "evaluation location"). Time-varying engine related signals
such as RPM, throttle position, and / or engine torque can be recorded simultaneously with the
sound signal recording.
[0033]
FIG. 1 discloses a system that achieves simultaneous recording of noise and engine related
signals in the listening environment 12 at one or more sensor locations and one or more sound
evaluation locations. Sound sensor 20, which is typically a microphone, is located at a first
sensed location within environment 12 (eg, which may be at the location of one of the listener's
ears). Sound sensing system 24 is located at a first sound evaluation position within environment
12. Engine related non-audio signals may be sensed by non-acoustic sensors 25, such sensors
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being located either in the listening environment or elsewhere. If engine related signals (e.g.
RPM, throttle position, transmission settings) are already present in the car, they need not be
sensed by another sensor but may instead be directly input from the vehicle into the acoustic
compensation system . With respect to RPM, in some cases, analog RPM pulses can be retrieved
from the engine controller, and the acoustic compensation system can derive RPM based on the
timing of the pulses. In other cases, the engine controller provides a digital signal representative
of the RPM value. This signal may be used directly by the acoustic compensation system. The
second sound sensor 22 is located at a second sensor position (eg, may be at the other ear of the
listener) and the second sound sensing system 26 is located at a second sound evaluation
position The second non-acoustic sensor 27 is located in the listening environment or elsewhere.
[0034]
Although two sets of sensors are shown in FIG. 1, it is not a limitation of the present invention,
but of at least one of the sensors, including zero or more acoustic sensors, and zero or more nonacoustic sensors. Including use. Certain embodiments of the invention contemplate one or more
sound sensors at one or more sound sensor positions, and also contemplate one or more sound
evaluation positions all located in a particular listening environment. . However, the invention is
not limited to any particular type of listening environment. For example, for a virtual assessment
of an audio system for a vehicle cabin, one may want to assess the sound on different seats.
Vehicle cabins are asymmetric and may result in an imbalance. Systems engineers currently
evaluate the system by listening on various sheets. In EHE and EHC systems, the way in which
the signal from the audio system interacts with engine noise may vary from sheet to sheet.
Multiple seats may be evaluated to ensure that all locations within the vehicle achieve the desired
performance goals.
[0035]
The outputs of all the acoustic and non-acoustic sensors and the output of the sound sensing
system are provided to the recording system 28. The input to the recording system 28 may also
be physical operating conditions / environmental conditions for a particular listening
environment. For example, in a vehicle noise compensation system, it is desirable to relate the
operating conditions of the vehicle to the sensed sound and the sensed non-acoustic signal. The
parameters of the operation of the vehicle that may be input to the recording system 28 include
an engine RPM signal, a signal representative of the speed of the vehicle, and a signal
representative of the state of another vehicle function. Certain vehicle functions include the
condition that each of the windows of the vehicle is closed, fully open, or partially open. In the
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EHC / EHE system, the engine RPM is the relevant operating parameter that can be associated
with the recorded noise signal and can be recorded at the same time. When used, the recording
system 28 can associate specific operating conditions with sensor signals and sounds recorded
under such conditions.
[0036]
A sound sensor is located within the listening environment and detects sound at the location of
the sensor. If a microphone is used, the sensed sound is a combination of the desired sound (the
output of the audio system) and the noise present at the sensor location. The sensor output is fed
back to the acoustic compensation system where the desired audio is removed from the signal to
create a noise estimate that represents noise through an adaptive process such as an adaptive
noise canceler commonly known in the art. Do. This noise estimate is used by the controller of
the acoustic compensation system to generate a control signal for the audio system that results
in a change in the output of the desired audio system designed to compensate for the noise
present in the environment. Ru. For example, the volume and / or equalization of the audio can
be modified such that the audio remains audible over noise.
[0037]
Another example of a sensor is a vibration sensor. The vibration signal may be used when
correlating with the noise being compensated or altered. For example, an accelerometer of a
vehicle engine may have a signature that correlates with an acoustic signature present in the
vehicle cabin. The accelerometer can be mounted on other noise sources, such as the
transmission housing. An accelerometer mounted on the wheel suspension strut can provide a
signal representative of road noise in the vehicle cabin. The higher the correlation between
sensor signals in the environment and ambient noise, the more non-acoustic sensors may be
useful. The accelerometer output signal may also be less sensitive to the output from the audio
system as compared to the microphone. When trying to form an estimate of the noise present in
the vehicle cabin, the vibration signal is more useful than the microphone signal, as long as the
vibration signal is better correlated with the acoustic noise, as the vibration signal is not
corrupted by the output of the audio system It may be.
[0038]
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The system 50 of FIG. 2 may be used, for example, to achieve a virtual assessment of an audio
system that includes an acoustic compensation system for the purpose of virtual coordination. In
one example, the virtual evaluation 62 is achieved by creating a virtual audio signal 61 that is
played back to a person such as a coordination engineer via headphones or loudspeakers. A
virtual audio signal is a signal that is similar to the sound that a person located at the associated
evaluation position listens to in an audio system operating under the associated operating
conditions. For the vehicle noise compensation system, the evaluation position is the position in
the vehicle cabin. The selected operating conditions may include one or more of the conditions
described above, such as engine RPM, vehicle speed, road surface conditions, and window
conditions. The virtual audio signal 61 comprises a combination of the audio signal corrected by
the acoustic compensation system 52 to account for noise and the noise recorded at the relevant
evaluation position under certain selected vehicle operating conditions. For a vehicle EHC / EHE
system, the virtual audio signal 61 is an audio signal modified by the system 52 to cancel or
enhance engine harmonics, and the noise recorded at the associated evaluation position at the
associated engine RPM. A combination of
[0039]
In the virtual evaluation system 50, the transfer function from each loudspeaker to each sensor
position and evaluation position must be predetermined and stored in the system. It is known in
the art to determine the transfer function from the loudspeaker to the sensor and / or the
listener's ear (i.e. the evaluation position). For example, the filter may be synthesized to have a
transfer function that matches the measured transfer function from a source to a position (sensor
or evaluation position). Such a filter may be synthesized for each sensor and loudspeaker to each
evaluation position. For example, the transfer function from the left front speaker to the
microphone sensor may be measured. The filter is then synthesized to have the same impulse
response as the measured transfer function (as practical as possible in the art). The signal
supplied to the left front speaker is then filtered to form an output signal representing the actual
signal present at the microphone for the input signal to the left front speaker being reproduced
by the left front speaker into the listening environment It is convoluted with an impulse
response. Such transfer functions, and the method by which they are used by the invention
herein, are referred to as "virtual transfer functions."
[0040]
In system 50, virtual sensor output signal 57 comprises a combination 56 of the noise recorded
by the acoustic sensor and the audio signal 54 output by acoustic compensation system 52 that
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has been processed to sensor virtual transfer function 55 through the loudspeaker. Thus, the
signal 57 is similar to the output of an actual microphone placed at a sensor location in the
listening environment where the noise was recorded. System 52 can use signal 57 as an input in
a manner suitable for adaptation to an audio signal responsive to such input. System 52
preferably includes a controller 53. System 52 may or may not be adaptive. The input to system
52 can include parameters that can cause system 52 to modify the audio signal.
[0041]
There are at least two ways in which system 50 can be used for virtual coordination. One use is a
subjective assessment 62, without the need for the person realizing the adjustment to be present
in the listening environment, or during the adjustment procedure (eg while the car is traveling),
in the normal form the environment Allows one to adjust the audio system without having to be
open. This is provided via an audio evaluation signal 61 which is a combination 60 of the noise
signal recorded at a particular evaluation position and the audio signal 54 processed to an
evaluation position virtual transfer function 58 through a loudspeaker. In this case, the signal 61
is binaural and is therefore provided to a set of headphones commonly worn by a coordination
engineer, taking into account two evaluation positions (both ears). Signal 61 emulates the sound
that would be heard if a person were sitting in the car and the ear was in the evaluation position
listening to audio signal 54 with noise in the vehicle cabin present under selected vehicle
operating conditions And the noise in this case was previously recorded. The evaluation signals
provided to the headphones are generally a pair of binaural signals, one signal per ear. At each
ear, a signal is formed from the recorded binaural signal and a virtual transfer function
associated with the position of that ear. Each ear has its own virtual transfer function.
[0042]
As an alternative to such subjective assessment, an objective assessment 62 may be performed.
An objective assessment can be realized by iteratively modifying each of the tuning parameters
for a particular audio system. The assessment 62 then makes an objective determination or
measurement of the resulting change in the signal 61. For example, for a vehicle noise
compensation system, the result may be the sound level in the vehicle cabin at various
frequencies or frequency bands. As another example, in order to objectively assess the vehicle
EHC or EHE system, the objective assessment relates to the parameters of the modified audio
system to determine the parameter settings that achieve the maximum performance of the EHC /
EHE system. The desired sound spectrum can be determined, the desired performance being so
predefined. For example, if one or more engine harmonics in a vehicle cabin should be canceled
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or reduced by such a system, the objective measurement is the SPL of that frequency. In another
example, in an EHE system designed to enhance engine harmonics in a particular way, the
objective system measures SPL at the relevant frequency and compares that measurement to the
desired result.
[0043]
Engine noise has a fundamental (ie, lowest frequency component) associated with the engine
RPM. The signature of the engine is mainly composed of some higher harmonic components in
addition to this fundamental wave. A harmonic is a frequency related to the fundamental wave by
an integral multiple of the usual frequency. Half integer multiple harmonics are also possible.
The EHC and EHE systems select some finite number of harmonics (and possibly the
fundamental) to change (increase or decrease the magnitude) in some way. The final goal is
determined subjectively. The virtual adjustments herein provide the ability to vary the harmonics
in a manner designed to reach the desired endpoint. The complete signature of the engine is
determined by the magnitude and phase of all harmonics, where phase refers to the phase
relationship to the reference harmonic. The acoustic compensation system 52 changes the
signature by changing the magnitude and / or phase of some harmonics. Objective criteria can be
developed a priori, and the system can be virtually evaluated to obtain this objective measure.
The characteristics of system 52 are varied to achieve the highest desired end state.
[0044]
EHC or EHE systems use engine RPM signals to determine the frequency of engine harmonics.
The engine RPM signal may be recorded along with the noise and may be input to the system 52.
Other inputs may be, for example, throttle position or engine load. The EHC or EHE system can
be pre-configured to cancel, enhance or modify harmonics in some other way to achieve the
desired engine noise in the vehicle cabin. EHC or EHE systems produce sound at the appropriate
frequency and magnitude. The sound is reproduced through the cabin loudspeakers to achieve
the desired result. System 52 adjusts the loudness and phase of the sound to achieve the desired
result. In the case of cancellation, the in-cabin sensor (microphone), which is ideally at the
evaluation position or very close to the evaluation position, is adjusted in magnitude and phase to
minimize the level of sound at that frequency . The sound sensed by the sensor is the acoustic
sum of the noise at this frequency (usually exclusively or mainly the noise generated by the
engine at this frequency) and the sound produced by the EHC loudspeaker is there. Thus, the
EHC microphone sensor signal is an error signal that is minimized by the EHC system in case of
cancellation. System 52 modifies the sound to achieve the desired harmonic signature for EHE. In
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the EHE system, there may be no sensors or feedback. Engine signals such as RPM, throttle
position, and engine torque may be input to system 52, which then determines and outputs an
appropriate audio voice signal to achieve the desired engine harmonic enhancement. The
assessment of the EHC or EHE system may be a single point or may be binaural.
[0045]
In the present invention, in order to record noise measurements, it is necessary to access the
vehicle and either a test track or dynamometer that the vehicle is performing once only. For EHC
or EHE systems, non-acoustic signals such as engine RPM can be recorded. System 50 generally
uses engine RPM as one input to system 52. The predefined virtual transfer function replaces the
acoustic path actually present from the loudspeaker to the audio sensor and the evaluation
microphone. Thus, signals 57 and 61 will closely match the actual performance. In the case of
EHC, the amount of noise cancellation can be determined objectively. Thus, the assessment 62
achieved by iteratively adjusting the relevant system parameters can be automated. This can be
achieved using an optimization program that iteratively modifies each EHC adjustment parameter
one at a time to determine the adjustment that maximizes the EHC performance with the
measurement microphone (ie at the evaluation position) .
[0046]
In some instances of the acoustic compensation system, virtual sensor signal 57 is not fed back
to system 52. In such a case, signal 57 can be considered to be the output of the system. In the
EHC system, the signal 57 is fed back to the adaptation system 52. The EHE system can not use
an audio sensor, in which case no signal 57 is present. In that case, the output of block 58 is the
output of system 50.
[0047]
FIG. 3 discloses a system 80 specifically adapted to enable virtual adjustment of a vehicle cabin
noise compensation system. The adaptive acoustic compensation system 82 comprises an audio
system control signal algorithm 84 and an audio system 86. The virtual sensor signal 91
comprises a combination 90 of an audio signal 87 reproduced through the loudspeaker to the
sensor virtual transfer function 88 and the recorded sensor noise signal. The virtual sensor signal
91 is input to the algorithm 84 and may be part of a signal processor that implements the vehicle
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noise cancellation process. The output of the algorithm 84 is provided to the audio system 86
and audio as needed so that the simulated system modifications made by the vehicle noise
compensation system 80 are similar to those experienced in the actual vehicle cabin Control
system playback parameters.
[0048]
In one non-limiting example, the system 10 of FIG. 1 pre-populates a large number of recordings
in the vehicle cabin under various vehicle operating conditions such as different road surfaces,
different vehicle speeds, different engine RPM values, different window conditions, etc. To be
done. The test suite or database can then be created as described above. The database contains
noise recordings. The database can also include recording conditions and is associated with each
recording. The test suite may be part of the adaptation system 82. The system 80 may then be
used by a coordination engineer for subjective adjustment. System 80 may alternatively be used
more automatically, ie for objective adjustment. Specific vehicle operating conditions to be tested
can be selected, and corresponding sensor and binaural evaluation position noise signals are
retrieved from the database. These recorded noise signals are then input to couplers 90 and 94,
respectively. The audio signal 87 is reproduced to the estimated position virtual transfer function
92 through a loudspeaker and provided to the adder 94.
[0049]
There is no need to obtain information about road surface, speed, and other test conditions.
Virtual adjustment can be realized as long as recording is performed in all relevant operating
states. However, knowing where a particular condition has occurred (eg, a window was opened)
during recording can be very useful. For example, if opening the window causes an air flow noise
in the microphone and the microphone signal is strongly fluctuating, the behavior of the adaptive
system under this condition will probably not be correct. If noise recording also indicates that the
window was opened when this behavior was confirmed, it would be useful in troubleshooting
system behavior.
[0050]
The simulated coordination innovation can simplify and accelerate the coordination of the audio
system at a lower cost than the manual coordination currently performed. The simulated
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adjustments described herein do not depend on the listening environment (e.g., the intended
vehicle and dynamometer and / or test track) and the availability of other equipment and support
staff. Furthermore, the present invention enables off-site adjustment and provides the ability to
quickly switch between different vehicle operating conditions. None of that is possible with
physical vehicles. These factors can save a great deal of time and money in the audio system
adjustment task. Furthermore, the noise is exactly the same for each adjustment run of the audio
system, as the invention is more consistent because the simulated performance is performed on a
single set of baseline noise measurements. Also, the present invention allows for easy and rapid
interplay between various audio system control signal algorithms in the development of noise
compensation systems, EHC or EHE systems, or other audio systems using adaptive or nonadaptive audio processing systems Comparison is possible. The present invention allows easy
and quick comparisons of system performance at various listening positions and eliminates the
need to physically move between positions.
[0051]
The invention may be used for an acoustic compensation system adapted to be used in a listening
environment other than a vehicle cabin. In this case, the input to the acoustic compensation
system may comprise the operating conditions of the particular listening environment that affect
the sound heard at the evaluation position.
[0052]
Although the invention has been described as using a single set of virtual transfer functions
associated with each evaluation position, in some embodiments, a family of transfer functions can
be obtained and a family of evaluation positions The members of are associated with different
states of the physical system. For example, to virtually adjust the dynamic behavior of the audio
system of a convertible car, a transmission representing a first vehicle state with the top of the
vehicle above and a second vehicle state with the top of the vehicle below It may be necessary to
get separate sets of functions. Similarly, different transfer functions can be obtained that
represent other states, such as various window conditions.
[0053]
Several embodiments and options have been described herein. Modifications may be made
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without departing from the spirit and scope of the present invention. Accordingly, other
embodiments are within the scope of the claims.
[0054]
10 Recording and sound system 12 Listening environment 14 Audio system 16 Loudspeaker 18
Loudspeaker 20 Sound sensor 22 Second sound sensor 24 Sound sensing system 25 Nonacoustic sensor 26 Second sound sensing system 27 Second non-acoustic sensor 28 Recording
system 50 System 52 Acoustic Compensation System 52 Adaptive System 53 Controller 54
Audio Signal 55 Sensor Virtual Transfer Function 56 Combination 57 Virtual Sensor Output
Signal 58 Evaluation Position Virtual Transfer Function 58 Block 60 Combination 61 Virtual
Audio Signal 62 Objective Evaluation 80 System 82 Adaptive Acoustic Compensation System 84
audio system control signal algorithm 86 audio system 87 audio signal 88 sensor virtual transfer
function 90 coupler 91 virtual sensor signal 92 evaluation position virtual transfer function 94
adder
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