Patent Application
20190251948
The present disclosure relates to a signal processing device, a signal processing method, and a program.
With the development of voice synthesis technologies and the like, user interfaces (UIs) enabling users to recognize notification target information without confirming screens or the like when various information processing devices read the notification target information aloud by voice have recently become popular. The technologies are also applied to in-vehicle devices such as car navigation devices or the like.
Patent Literature 1: Japanese Patent No. 4882773
Incidentally, in situations in which in-vehicle devices such as car navigation devices are used, various kinds of noise such as driving sounds of engines, motors, or the like or road noise caused by vibration or the like received from road surfaces by vehicles can be assumed to occur. Therefore, desired is an introduction of structures that further reduce the influence of noise, such as so-called noise cancellation, into in-vehicle devices. For example, Patent Literature 1 discloses an example of a technology called noise cancellation.
On the other hand, in situations in which users (for example, drivers) use in-vehicle devices such as car navigation devices, the users hear a voice guidance output from acoustic devices such as speakers installed in vehicles, unlike cases in which users hear voice via headphones, earphones, or the like. In environments in which users hear acoustic sounds output to open spaces in this way, for example, acoustic sounds from other acoustic devices are collected by sound collection units (for example, microphones) installed to reduce noise of acoustic sounds output from certain acoustic devices in some cases. In these cases, sound collection results of acoustic sounds from other acoustic devices have an influence on processes of reducing noise and are manifested as, for example, a phenomenon such as so-called howling in some cases.
Accordingly, the present disclosure proposes a signal processing device, a signal processing method, and a program capable of reducing the influence of noise in a more preferred aspect even in an environment in which a user hears an acoustic sound output to an open space.
According to the present disclosure, there is provided a signal processing device including: a generation unit configured to generate a first noise reduction signal for driving a first acoustic device which outputs a first acoustic sound for reducing noise; and an acquisition unit configured to acquire a sound collection result of an acoustic sound collected by a predetermined sound collection unit, the acoustic sound including the first acoustic sound propagating from the first acoustic device via a first propagation path and a second acoustic sound propagating from a second acoustic device different from the first acoustic device via a second propagation path. The generation unit generates the first noise reduction signal on a basis of the sound collection result and a cancellation signal based on a second noise reduction signal for driving the second acoustic device.
In addition, according to the present disclosure, there is provided a signal processing method including: by a processor, generating a first noise reduction signal for driving a first acoustic device which outputs a first acoustic sound for reducing noise; and acquiring a sound collection result of an acoustic sound collected by a predetermined sound collection unit, the acoustic sound including the first acoustic sound propagating from the first acoustic device via a first propagation path and a second acoustic sound propagating from a second acoustic device different from the first acoustic device via a second propagation path. The first noise reduction signal is generated on a basis of the sound collection result and a cancellation signal based on a second noise reduction signal for driving the second acoustic device.
In addition, according to the present disclosure, there is provided a program causing a computer to execute: generating a first noise reduction signal for driving a first acoustic device which outputs a first acoustic sound for reducing noise; and acquiring a sound collection result of an acoustic sound collected by a predetermined sound collection unit, the acoustic sound including the first acoustic sound propagating from the first acoustic device via a first propagation path and a second acoustic sound propagating from a second acoustic device different from the first acoustic device via a second propagation path. The first noise reduction signal is generated on a basis of the sound collection result and a cancellation signal based on a second noise reduction signal for driving the second acoustic device.
According to the present disclosure, as described above, it is possible to provide a signal processing device, a signal processing method, and a program capable of reducing the influence of noise in a more preferred aspect even in an environment in which a user hears an acoustic sound output to an open space.
Note that the effects described above are not necessarily limitative. With or in the place of the above effects, there may be achieved any one of the effects described in this specification or other effects that may be grasped from this specification.
Hereinafter, (a) preferred embodiment(s) of the present disclosure will be described in detail with reference to the appended drawings. Note that, in this specification and the appended drawings, structural elements that have substantially the same function and structure are denoted with the same reference numerals, and repeated explanation of these structural elements is omitted.
Note that the description will be made in the following order.
First, an example of an overall configuration of a noise reduction system according to an embodiment of the present disclosure will be described with reference to
A noise reduction system 1 according to the embodiment is mainly assumed to be used in an environment in which a user hears an acoustic sound output from an acoustic device such as a speaker to an open space, unlike a case in which a user hears a voice via a headphone, an earphone, or the like.
A specific application example of the noise reduction system 1 according to the embodiment is to reduce the influence of the driving sound of an engine, a motor, or the like or noise such as road noise caused due to vibration or the like received from a road surface by a vehicle on a voice or an acoustic sound from an in-vehicle device such as a car navigation device. More specifically, in the noise reduction system 1 according to the embodiment, an acoustic device 11 and a sound collection unit 13 are held to be located near right and left ears of a user U11 sitting on a seat installed in a vehicle. Note that in the following description, in a case in which the acoustic device 11 and the sound collection unit 13 held near the left ear of the user U11 are explicitly indicated, the acoustic device 11 and the sound collection unit 13 are referred to as “an acoustic device 11a and a sound collection unit 13a.” Similarly, in a case in which the acoustic device 11 and the sound collection unit 13 held near the right ear of the user U11 are explicitly indicated, the acoustic device 11 and the sound collection unit 13 are referred to as “an acoustic device 11b and a sound collection unit 13b.” For example, in the example illustrated in
For example,
As illustrated in
In addition, in the example illustrated in
On the basis of the foregoing configuration, the noise reduction system 1 according to the embodiment reduces the influence of noise on the acoustic sound output from each of the acoustic devices 11a and 11b through a noise reduction process based on a so-called feedback (FB) scheme. Note that an overview of the noise reduction process based on the FB scheme will be separately described below.
The example of the schematic configuration of the noise reduction system according to the embodiment of the present disclosure has been described above with reference to
Next, an overview of the noise reduction process based on the FB scheme will be described and problems of the noise reduction system 1 according to the embodiment will be summarized with reference to
First, a principle of the noise reduction process based on the FB scheme will be described with reference to
As illustrated above, the noise reduction process based on the FB scheme has a purpose for reducing (furthermore, silences) noise at the position of the sound collection unit 13, and a noise reduction effect is restricted to the vicinity of the sound collection unit 13. That is, ideally, in order to improve the noise reduction effect at the position of the head (eardrum) of a hearer (a user), it is more preferable to install the sound collection unit 13 at a position close to the eardrum. Note that phase rotation caused by a time delay increases as a distance between the acoustic device 11 and the sound collection unit 13 is farther. Therefore, there is a tendency of difficulty in controlling the noise reduction process. Therefore, it is more preferable to install the sound collection unit 13 near the acoustic device 11.
On the other hand, in a case in which acoustic sounds from the different acoustic devices 11a and 11b are caused to be heard by the left and right ears of the user as in the noise reduction system 1 according to the embodiment, there are a plurality of systems of series of feedback for noise reduction. Accordingly, an example of a system in a case in which a plurality of systems for noise reduction based on the FB scheme (that is, systems of feedback) are provided will be described with reference to
For example,
In addition, the system 9 includes feedback noise cancellation filters (hereinafter also referred to as “FB-NC filters”) 101a and 101b. The FB-NC filters 101a and 101b have a configuration in which a noise reduction signal is generated. More specifically, the FB-NC filter 101a generates a noise reduction signal for driving the acoustic device 11a to output an acoustic sound for reducing noise from the acoustic device 11a on the basis of a sound collection result by the sound collection unit 13a. That is, the acoustic device 11a, the sound collection unit 13a, and the FB-NC filter 101a are equivalent to a system of a series of feedback for achieving a noise reduction effect near the left ear of the user U11. Similarly, the FB-NC filter 101b generates a noise reduction signal for driving the acoustic device 11b to output an acoustic sound for reducing noise from the acoustic device 11b on the basis of a sound collection result by the sound collection unit 13b. That is, the acoustic device 11b, the sound collection unit 13b, and the FB-NC filter 101b are equivalent to a system of a series of feedback for achieving a noise reduction effect near the right ear of the user U11.
Here, in the system 9 according to the comparative example, as illustrated in
However, as illustrated in
Accordingly, the present disclosure proposes an example of a structure capable of suppressing an influence associated with formation of the above-described figure-eight-shaped closed loop which can occur in an environment in which a user hears acoustic sounds output to an open space and reducing the influence of noise in a more preferred aspect.
Next, technical characteristics of the noise reduction system 1 according to the embodiment will be described.
First, an example of a functional configuration of the noise reduction system 1 according to the embodiment will be described with reference to
As illustrated in
As illustrated in
Similarly, a gain of an acoustic signal based on a sound collection result by the sound collection unit 13b is adjusted by the microphone amplifier 105b, and the acoustic signal is input to the subtractor 107b. In addition, a cancellation signal output from the loop canceller 109b to be described below is input to the subtractor 107b. The subtractor 107b subtracts the cancellation signal output from the loop canceller 109b from an acoustic signal (that is, an acoustic signal based on the sound collection result by the sound collection unit 13b) output from the microphone amplifier 105b and inputs the acoustic signal obtained as a subtraction result to the FB-NC filter 101b. The FB-NC filter 101b generates a noise reduction signal by executing a noise reduction process in accordance with a feature of a propagation environment between the acoustic device 11b and the sound collection unit 13b on the input acoustic signal and outputs the noise reduction signal as a driving signal for driving the acoustic device 11a. That is, a gain of the noise reduction signal output from the FB-NC filter 101b is adjusted by the power amplifier 103b to drive the acoustic device 11b. Note that the noise reduction signal output from the FB-NC filter 101b is partially split by a splitter or the like to be input to the loop canceller 109a.
Next, the loop cancellers 109a and 109b will be described. The loop cancellers 109a and 109b generate cancellation signals for reducing an influence associated with the formation of the figure-eight-shaped closed loop described with reference to
Note that the functional configuration of the above-described noise reduction system 1 is merely exemplary and the present disclosure is not necessarily limited to only the configuration illustrated in
The example of the functional configuration of the noise reduction system 1 according to the embodiment has been described above with reference to
Next, an example of signal processing of the noise reduction system 1 according to the embodiment will be described with reference to
In
In addition, reference numerals β1 and β2 schematically denote filter coefficients for generating noise reduction signals by executing a noise reduction process on acoustic signals input by the FB-NC filters 101a and 10b. In addition, reference numerals G′1 schematically denotes a filter coefficient used for the loop canceller 109b to generate a cancellation signal to be input to the subtractor 107b by executing a filtering process on the input noise reduction signal. Similarly, reference numerals G′2 schematically denotes a filter coefficient used for the loop canceller 109a to generate a cancellation signal to be input to the subtractor 107a by executing a filtering process on the input noise reduction signal.
Here, y is an acoustic sound output from the acoustic device 11a and z is an acoustic sound output from the acoustic device 11b. Here, the acoustic sound y is equivalent to an acoustic sound output by driving the acoustic device 11a on the basis of the noise reduction signal from the FB-NC filter 101a. Similarly, the acoustic sound z is equivalent to an acoustic sound output by driving the acoustic device 11b on the basis of the noise reduction signal from the FB-NC filter 101b. At this time, the acoustic sound y is expressed in (Expression 2) below.
Here, in (Expression 2) above, by setting a feature (that is, the filter coefficient G′2) of the loop canceller 109a to substantially match the spatial feature G2 (that is, G′2=G2), it is possible to exclude an influence of the acoustic sound z output from the acoustic device 11b from the acoustic sound y output from the acoustic device 11a. Thus, it is possible to improve independency of the system of feedback including the system on the left ear side (that is, the system of feedback including the acoustic device 11a, the sound collection unit 13a, and the FB-NC filter 101a). That is, since the influence associated with the formation of the figure-eight-shaped closed loop is suppressed, an improvement in design easiness, an improvement in a noise reduction effect, or the like can be expected.
Note that in a case in which the system on the left ear side is focused on, the acoustic sound (in other words, the acoustic sound for reducing noise) output from the acoustic device 11a and collected by the sound collection unit 13a is equivalent to an example of a “first acoustic sound.” In addition, the acoustic sound output from the acoustic device 11b and collected by the sound collection unit 13a is equivalent to an example of a “second acoustic sound.” In addition, the propagation path (the propagation environment) between the acoustic device 11a and the sound collection unit 13a is equivalent to an example of a “first propagation path” and the propagation path (the propagation environment) between the acoustic device 11b and the sound collection unit 13a is equivalent to an example of a “second propagation path.” In addition, the noise reduction signal for driving the acoustic device 11a is equivalent to an example of a “first noise reduction signal” and the noise reduction signal for driving the acoustic device 11b is equivalent to an example of a “second noise reduction signal.”
In addition, in the foregoing description, the acoustic sound y output from the acoustic device 11a has been focused on, but an influence of the acoustic sound y output from the acoustic device 11a can also be excluded on the basis of a similar idea with regard to the acoustic sound z output from the acoustic device 11b.
The example of the signal processing of the noise reduction system 1 according to the embodiment has been described above with reference to
Next, conditions for installation positions of the acoustic devices 11 and the sound collection units 13 will be described in more detail. As described above, in the noise reduction system 1 according to the embodiment, an influence of noise is reduced through the noise reduction process based on the FB scheme. Therefore, it is more preferable to restrict the noise reduction effect to the vicinities of the sound collection units 13 and install the sound collection units 13 near the acoustic devices 11. That is, in the noise reduction system 1 according to the embodiment, the acoustic devices 11 and the sound collection units 13 are each preferably held near the ears (eardrums) of the hearer.
Here, conditions for a positional relation between the acoustic devices 11, the sound collection units 13, and the ears of the hearer for obtaining the noise reduction effect in a more preferred aspect will be examined in more detail with reference to
For example,
Next, a phase change in accordance with the distance between the acoustic device 11 and the sound collection unit 13 will be focused on. For example,
Here, in a case in which the phase rotation caused by the time delay is set to 45 deg or less and an upper limit of the frequency of the acoustic sound for reducing noise is set to 300 Hz, a limit of the distance between the acoustic device 11 and the sound collection unit 13 is 15 cm from the simulation result illustrated in
On the basis of the above, conditions of a positional relation among the acoustic device 11, the sound collection unit 13, and an ear of the hearer in order to obtain the noise reduction effect in a more preferred aspect will be described with reference to
As described above, the acoustic device 11 and the sound collection unit 13 may each be installed with a positional relation in which the phase rotation at the position of each of the sound collection unit 13 and the ear U13 of the hearer in an acoustic sound for reducing noise output from the acoustic device 11 is 45 deg or less in both the sound collection unit 13 and the ear U13. More specifically, as illustrated in
Note that the installation positions of the acoustic device 11 and the sound collection unit 13 are not particularly limited as long as the acoustic device 11 and the sound collection unit 13 are each installed so that the above-describe conditions are satisfied. For example,
For example, in the example illustrated in
In addition, in the example illustrated in
The conditions for the installation positions of the acoustic devices 11 and the sound collection units 13 have been described above in more detail with reference to
Next, modification examples of the noise reduction system 1 according to the embodiment will be described.
First, an example of a case in which features of the above-described loop cancellers 109a and 109b are adaptively controlled in response to a change in a feature of an environment in which the acoustic sounds output from the acoustic devices 11a and 11b propagate will be described as Modification Example 1.
For example,
As illustrated in
In the noise reduction system 2 illustrated in
On the other hand, in the noise reduction system 2 illustrated in
Accordingly, a configuration in which a plurality of filters with different features are provided in advance and a filter to be used as a loop canceller is selected quasi-adaptively among the plurality of filters in accordance with an environment or a situation is proposed as another example of a schematic configuration of the noise reduction system according to Modification Example 1. For example,
As illustrated in
The filter banks 301a and 301b correspond to the FB-NC filters 101a and 101b in the noise reduction system 1 described with reference to
In addition, the filter banks 309a and 309b correspond to the loop cancellers 109a and 109b in the noise reduction system 1 described with reference to
Note that in the noise reduction system 3 illustrated in
Here, a change in a propagation environment of an acoustic sound output from each of the acoustic devices 11a and 11b in accordance with the position of the head of the user will be described with reference to
For example, in the example of the case in which the head of the user U11 is close to the headrest 81, as illustrated in
As understood from comparison between
The same applies to a relation between the acoustic device 11b and the sound collection unit 13a. For example, in the example illustrated in
In addition, the example in which the loop canceller is selected in accordance with the position of the head of the user U11 has been described. The same applies to the NC-FB filter. That is, the head position estimation unit 35 may control the switching between the NC-FB filters in the filter banks 301a and 301b on the basis of an estimation result of the head of the user.
In addition, as described above, the change in the spatial feature between the acoustic device 11 and the sound collection unit 13 in accordance with the position of the head of the user U11 has been mainly focused on. However, a factor changing the spatial feature between the acoustic device 11 and the sound collection unit 13 is not necessarily limited to only the position of the head of the user U11. For example, in a case in which a space inside a vehicle is assumed, the spatial feature between the acoustic device 11 and the sound collection unit 13 is also changed in accordance with an opened or closed state of a window or a door. Therefore, the head position estimation unit 35 may select the loop canceller or the NC-FB filter, for example, by acquiring information indicating the opened or closed state of a window or a door via a controller area network (CAN) and using the acquired information along with an estimation result of the position of the head.
In addition, when the noise reduction process in accordance with the spatial feature between the acoustic device 11 and the sound collection unit 13 can be realized, the configuration of each of the filter banks 301a, 301b, 309a, and 309b is not limited to the configuration in which the plurality of filters described above is selectively switched. Specifically, at least one of a gain and a phase of an input acoustic signal may be able to be controlled in accordance with the spatial feature between the acoustic device 11 and the sound collection unit 13. Therefore, for example, a configuration in which a gain can be controlled, such as a variable gain amplifier or a variable resistor may be applied as at least one of the filter banks 301a, 301b, 309a, and 309b. Accordingly, in the present disclosure, a process of controlling at least one of the gain and the phase of an input signal is assumed to be indicated in a case in which a “filtering process” is called. In addition, in a case in which the spatial feature between the acoustic device 11a and the sound collection unit 13a and between the acoustic device 11b and the sound collection unit 13b is stable, the filter banks 301a and 301b may be switched and the above-described NC-FB filters 101a and 101b may be installed.
Next, an example of signal processing by the noise reduction system 3 according to Modification Example 1 will be described with reference to
In
Here, since a sound pressure at the position of the head of the user U11 can be obtained by adding the acoustic sounds y and z output from the acoustic devices 11a and 11b to the noise d3, the sound pressure is expressed in a conditional expression shown in (Expression 3) below.
Note that information indicating correlation between the noise d1 and the noise d2 collected by the sound collection units 13a and 13b and the noise d3 at a point at which a reduction in the noise is realized (that is, an assumed position of the head of the user U11) may be calculated on the basis of, for example, a result of advance measurement, simulation, or the like and may be stored in a desired recording unit (for example, a database). Thus, for example, by configuring the noise reduction system 3 so that the NC-FB filter is selected quasi-adaptively, it is possible to expect an improvement in the noise reduction effect at the position of the head of the user U11. Note that, for a relationship among the noise d1, the noise d2, and the noise d3, it is more preferable to contain an amplitude difference and a phase difference by a stationary wave, for example, in consideration of the fact that the space inside the vehicle is a closed space. The information may be calculated, for example, on the basis of the result of the advance measurement, the simulation, or the like and may be stored in the desired recording unit. In addition, as another example, the information may be estimated using a sound pressure estimation technology such as a so-called virtual microphone.
Next, examples of configurations and methods for estimating the position of the head of the user U11 will be described with reference to
For example, in the example illustrated in
In addition, in the example illustrated in
In addition, in the example illustrated in
In addition, in the example illustrated in
The example of the configuration in which the features of the above-described loop cancellers 109a and 109b are adaptively controlled in accordance with a change of the feature of the environment in which the acoustic sound output from each of the acoustic devices 11a and 11b propagates has been described as Modification Example 1.
Next, an example of control in a case in which the FB-NC filters or the loop cancellers are switched in the noise reduction system 3 described with reference to
For example,
In the example illustrated in
Specifically, in a case in which the loop canceller in the filter bank 309 is switched, both the loop canceller L1 which is a switching source and the loop canceller LM which is a switching destination are connected to both an input side and an output side. In addition, at this time, volumes of signals output from the loop cancellers L1 and LM are controlled by faders 311-1 and 311-2 and are added by an adder 313 to be output.
For example,
As illustrated in
Note that in the foregoing description, the case in which the switching between the loop cancellers in the filter bank 309 is controlled has been focused on, but the same applies to a case in which the NC-FB filters in the filter bank 301 are switched.
The example of the control in the case in which the FB-NC filters or the loop cancellers are switched in the above-described noise reduction system 3 has been described with reference to
Next, an example of a configuration of a noise reduction system in a case in which 3 or more systems of feedback reducing noise are provided has been described as Modification Example 3. The example of the case in which the system of feedback reducing noise near the left ear of the user and the system of feedback reducing noise near the right ear of the user are provided has been mainly described above. On the other hand, the number of systems of feedback reducing noise is not limited to 2 described above, but 3 or more systems of feedback may be provided. For example,
As illustrated in
Reference numerals F1 to F3 schematically denote transfer functions of propagation environments in which an acoustic sound output from each acoustic device 11 arrives at the sound collection unit 13 forming the system of feedback along with the acoustic device 11. As a specific example, the transfer function F3 denotes the transfer function of the propagation environment between the acoustic device 11c and the sound collection unit 13c.
Reference numerals G12, G13, G21, G23, G31, and G32 schematically denote transfer functions of propagation environments in which an acoustic sound output from each acoustic device 11 arrives at the other sound collection units 13 different from the sound collection unit 13 forming the system of feedback along with the acoustic device 11. Specifically, the transfer function G12 indicates a transfer function of a propagation environment between the acoustic device 11a and the sound collection unit 13b, and the transfer function G13 indicates a transfer function of a propagation environment between the acoustic device 11a and the sound collection unit 13c. In addition, the transfer function G21 indicates a transfer function of a propagation environment between the acoustic device 11b and the sound collection unit 13a, and transfer function G23 indicates a transfer function of a propagation environment between the acoustic device 11b and the sound collection unit 13c. In addition, the transfer function G31 indicates a transfer function of a propagation environment between the acoustic device 11c and the sound collection unit 13a, and transfer function G32 indicates a transfer function of a propagation environment between the acoustic device 11c and the sound collection unit 13b.
Reference numerals β1 to β3 schematically illustrate filter coefficients used for each of the FB-NC filters 401a to 401c to generate the above-described noise reduction signal. In addition, reference numerals G′12, G′13, G′21, G′23, G′31, and G′32 schematically denote filter coefficients used for each of the loop cancellers 409e, 409c, 409a, 409f, 409d, and 409b to generate the above-described cancellation signal.
For example, an acoustic sound output from the acoustic device 11a is collected by the sound collection unit 13a and an acoustic signal based on the sound collection result is input to the subtractor 407a. In addition, the cancellation signal output from each of the loop cancellers 409a and 409d is input to the subtractor 407a. The subtractor 407a subtracts the cancellation signal output from each of the loop cancellers 409b and 409d from the acoustic signal based on the sound collection result by the sound collection unit 13a and inputs an acoustic signal obtained as a subtraction result to the FB-NC filter 401a. The FB-NC filter 401a generates a noise reduction signal by executing the noise reduction process on the input acoustic signal in accordance with the feature (the transfer function F1) of the propagation environment between the acoustic device 11a and the sound collection unit 13a and outputs the noise reduction signal as a driving signal for driving the acoustic device 11a. In addition, the noise reduction signal output from the FB-NC filter 401a is partially split by a splitter or the like to be input to each of the loop cancellers 409c and 409e.
In addition, an acoustic sound output from the acoustic device 11b is collected by the sound collection unit 13b and an acoustic signal based on the sound collection result is input to the subtractor 407b. In addition, the cancellation signal output from each of the loop cancellers 409b and 409e is input to the subtractor 407b. The subtractor 407b subtracts the cancellation signal output from each of the loop cancellers 409b and 409e from the acoustic signal based on the sound collection result by the sound collection unit 13b and inputs an acoustic signal obtained as a subtraction result to the FB-NC filter 401b. The FB-NC filter 401b generates a noise reduction signal by executing the noise reduction process on the input acoustic signal in accordance with the feature (the transfer function F2) of the propagation environment between the acoustic device 11b and the sound collection unit 13b and outputs the noise reduction signal as a driving signal for driving the acoustic device 11b. In addition, the noise reduction signal output from the FB-NC filter 401b is partially split by a splitter or the like to be input to each of the loop cancellers 409a and 409f.
Similarly, an acoustic sound output from the acoustic device 11c is collected by the sound collection unit 13c and an acoustic signal based on the sound collection result is input to the subtractor 407c. In addition, the cancellation signal output from each of the loop cancellers 409c and 409f is input to the subtractor 407c. The subtractor 407c subtracts the cancellation signal output from each of the loop cancellers 409c and 409f from the acoustic signal based on the sound collection result by the sound collection unit 13c and inputs an acoustic signal obtained as a subtraction result to the FB-NC filter 401c. The FB-NC filter 401c generates a noise reduction signal by executing the noise reduction process on the input acoustic signal in accordance with the feature (the transfer function F3) of the propagation environment between the acoustic device 11c and the sound collection unit 13c and outputs the noise reduction signal as a driving signal for driving the acoustic device 11c. In addition, the noise reduction signal output from the FB-NC filter 401c is partially split by a splitter or the like to be input to each of the loop cancellers 409b and 409d.
Here, the acoustic sound output from the acoustic device 11a will be focused on. In this case, the feature (the transfer function G′21) of the loop canceller 409a is set to substantially match the spatial feature G21 and the feature (the transfer function G′31) of the loop canceller 409d is set to substantially match the spatial feature G31. In this configuration, it is possible to exclude an influence of the acoustic sound output from each of the acoustic devices 11b and 11c from the acoustic sound output from the acoustic device 11a. Therefore, it is possible to improve independency of the system of feedback formed by the acoustic device 11a, the sound collection unit 13a, and the NC-FB filter 401a.
Here, the acoustic sound output from the acoustic device 11b will be focused on. In this case, the feature (the transfer function G′32) of the loop canceller 409b is set to substantially match the spatial feature G32 and the feature (the transfer function G′12) of the loop canceller 409e is set to substantially match the spatial feature G12. In this configuration, it is possible to exclude an influence of the acoustic sound output from each of the acoustic devices 11a and 11c from the acoustic sound output from the acoustic device 11b. Therefore, it is possible to improve independency of the system of feedback formed by the acoustic device 11b, the sound collection unit 13b, and the NC-FB filter 401b.
Similarly, the acoustic sound output from the acoustic device 11c will be focused on. In this case, the feature (the transfer function G′13) of the loop canceller 409c is set to substantially match the spatial feature G13 and the feature (the transfer function G′23) of the loop canceller 409f is set to substantially match the spatial feature G23. In this configuration, it is possible to exclude an influence of the acoustic sound output from each of the acoustic devices 11a and 11b from the acoustic sound output from the acoustic device 11c. Therefore, it is possible to improve independency of the system of feedback formed by the acoustic device 11c, the sound collection unit 13c, and the NC-FB filter 401c.
Note that the example of the case in which the number of systems of feedback is 3 has been described above. Even in a case in which the number of systems of feedback is 4 or more, the noise reduction system may be configured on the basis of the same idea. That is, a loop canceller that generates a cancellation signal in accordance with a feature of a propagation environment may be provided in each of the propagation environments between the plurality of acoustic devices 11 and the plurality of sound collection units 13.
In addition, in a case in which 3 or more systems of feedback are provided, at least two or more of the plurality of systems of feedback may be selectively caused to be operated. As a specific example, the plurality of systems of feedback are assumed to be provided so that 3 or more acoustic devices 11 are disposed around the user. In this case, for example, by causing the systems of feedback reducing noise to operate near the left and right ears of a user in accordance with a detection result of a position of the head of the user, operations of the other systems of feedback may be caused to stop.
The example of the configuration of the noise reduction system in a case in which 3 or more systems of feedback reducing noise are provided has been described with reference to
Next, a hardware configuration of an information processing device 900 that forms the noise reduction system 1 according to the embodiment will be described in detail with reference to
The information processing device 900 constituting the noise reduction system 1 according to the present embodiment is equipped primarily with a CPU 901, ROM 903, and RAM 905. Additionally, the information processing device 900 may also be equipped with a host bus 907, a bridge 909, an external bus 911, an interface 913, an input device 915, an output device 917, a storage device 919, a drive 921, a connection port 923, and a communication device 925.
The CPU 901 serves as an arithmetic processing device and a control device, and controls the overall operation or a part of the operation of the information processing device 900 according to various programs recorded in the ROM 903, the RAM 905, the storage device 919, or a removable recording medium 927. The ROM 903 stores programs, operation parameters, and the like used by the CPU 901. The RAM 905 primarily stores programs that the CPU 901 uses and parameters and the like varying as appropriate during the execution of the programs. These are connected with each other via the host bus 907 configured from an internal bus such as a CPU bus or the like. Note that the FB-NC filter 101a and the loop cancellers 109a and 109b described above with reference to
The host bus 907 is connected to the external bus 911 such as a PCI (Peripheral Component Interconnect/Interface) bus via the bridge 909. Additionally, the input device 915, the output device 917, the storage device 919, the drive 921, the connection port 923, and the communication device 925 are connected to the external bus 911 via the interface 913.
The input device 915 is an operation mechanism operated by a user, such as a mouse, a keyboard, a touch panel, buttons, a switch, a lever, or a pedal. Also, the input device 915 may be a remote control mechanism (a so-called remote control) using, for example, infrared light or other radio waves, or may be an externally connected device 929 such as a mobile phone or a PDA conforming to the operation of the information processing device 900. Furthermore, the input device 915 generates an input signal based on, for example, information which is input by a user with the above operation mechanism, and is configured from an input control circuit for outputting the input signal to the CPU 901. The user of the information processing device 900 can input various data to the information processing device 900 and can instruct the information processing device 900 to perform processing by operating this input device 915.
The output device 917 is configured from a device capable of visually or audibly notifying acquired information to a user. Examples of such device include display devices such as a CRT display device, a liquid crystal display device, a plasma display device, an EL display device and lamps, audio output devices such as a speaker and a headphone, a printer, and the like. For example, the output device 917 outputs a result obtained by various processing performed by the information processing device 900. More specifically, the display device displays, in the form of texts or images, a result obtained by various processes performed by the information processing device 900. On the other hand, the audio output device converts an audio signal such as reproduced voice data and sound data into an analog signal, and outputs the analog signal. Note that the acoustic devices 11a and 11b described above with reference to
The storage device 919 is a device for storing data configured as an example of a storage unit of the information processing device 900 and is used to store data. The storage device 919 is configured from, for example, a magnetic storage device such as a HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device. This storage device 919 stores programs to be executed by the CPU 901, and various data.
The drive 921 is a reader/writer for recording medium, and is embedded in the information processing device 900 or attached externally thereto. The drive 921 reads information recorded in the attached removable recording medium 927 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, and outputs the read information to the RAM 905. Furthermore, the drive 921 can write in the attached removable recording medium 927 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory. The removable recording medium 927 is, for example, a DVD medium, an HD-DVD medium, or a Blu-ray (a registered trademark) medium. The removable recording medium 927 may be a CompactFlash (CF; a registered trademark), a flash memory, an SD memory card (Secure Digital Memory Card), or the like. Alternatively, the removable recording medium 927 may be, for example, an IC card (Integrated Circuit Card) equipped with a non-contact IC chip or an electronic appliance.
The connection port 923 is a port for allowing devices to directly connect to the information processing device 900. Examples of the connection port 923 include a USB (Universal Serial Bus) port, an IEEE1394 port, a SCSI (Small Computer System Interface) port, and the like. Other examples of the connection port 923 include an RS-232C port, an optical audio terminal, an HDMI (a registered trademark) (High-Definition Multimedia Interface) port, and the like. By the externally connected device 929 connecting to this connection port 923, the information processing device 900 directly obtains various data from the externally connected device 929 and provides various data to the externally connected device 929.
The communication device 925 is a communication interface configured from, for example, a communication device for connecting to a communication network 931. The communication device 925 is, for example, a wired or wireless LAN (Local Area Network), Bluetooth (registered trademark), a communication card for WUSB (Wireless USB), or the like. Alternatively, the communication device 925 may be a router for optical communication, a router for ADSL (Asymmetric Digital Subscriber Line), a modem for various communications, or the like. This communication device 925 can transmit and receive signals and the like in accordance with a predetermined protocol such as TCP/IP on the Internet and with other communication devices, for example. The communication network 931 connected to the communication device 925 is configured from a network and the like, which is connected via wire or wirelessly, and may be, for example, the Internet, a home LAN, infrared communication, radio wave communication, satellite communication, or the like.
Heretofore, an example of the hardware configuration capable of realizing the functions of the information processing device 900 constituting the noise reduction system 1 according to the embodiment of the present disclosure has been shown. Each of the structural elements described above may be configured using a general-purpose material, or may be configured from hardware dedicated to the function of each structural element. Accordingly, the hardware configuration to be used can be changed as appropriate according to the technical level at the time of carrying out the present embodiment. Note that, although not illustrated in
Note that it is also possible to develop a computer program for realizing the respective functions of the information processing device 900 constituting the noise reduction system 1 according to the present embodiment as described above, and implement the computer program in a personal computer or the like. In addition, a computer-readable recording medium storing such a computer program may also be provided. The recording medium may be a magnetic disc, an optical disc, a magneto-optical disc, or flash memory, for example. Furthermore, the above computer program may also be delivered via a network, for example, without using a recording medium. In addition, the number of computers that causes the computer program to be executed is not particularly limited. For example, a plurality of computers (for example, a plurality of servers and the like) may cooperate with each other and execute the computer program.
As described above, the noise reduction system according to the embodiment includes a generation unit (that is, the NC-FB filter) that generates a first noise reduction signal for driving a first acoustic device which outputs a first acoustic for reducing noise. In addition, the noise reduction system according to the embodiment acquires a sound collection result of an acoustic sound including the first acoustic sound propagating from the first acoustic device via a first propagation path and a second acoustic sound propagating from a second acoustic device different from the first acoustic device via a second propagation path by a predetermined sound collection unit. Then, the generation unit generates the first noise reduction signal on a basis of the sound collection result by the sound collection unit and a cancellation signal based on a second noise reduction signal for driving the second acoustic device. In this configuration, the noise reduction system according to the embodiment can improve independency of each of a plurality of systems of feedback. Therefore, it is possible to suppress an influence associated with formation of a figure-eight-shaped closed loop which can occur and is not originally assumed under an environment in which a user hears acoustic sounds output to open spaces and reducing an influence of noise in a more preferred aspect.
The preferred embodiment(s) of the present disclosure has/have been described above with reference to the accompanying drawings, whilst the present disclosure is not limited to the above examples. A person skilled in the art may find various alterations and modifications within the scope of the appended claims, and it should be understood that they will naturally come under the technical scope of the present disclosure.
Further, the effects described in this specification are merely illustrative or exemplified effects, and are not limitative. That is, with or in the place of the above effects, the technology according to the present disclosure may achieve other effects that are clear to those skilled in the art from the description of this specification.
Additionally, the present technology may also be configured as below.
(1)
A signal processing device including:
a generation unit configured to generate a first noise reduction signal for driving a first acoustic device which outputs a first acoustic sound for reducing noise; and
an acquisition unit configured to acquire a sound collection result of an acoustic sound collected by a predetermined sound collection unit, the acoustic sound including the first acoustic sound propagating from the first acoustic device via a first propagation path and a second acoustic sound propagating from a second acoustic device different from the first acoustic device via a second propagation path,
in which the generation unit generates the first noise reduction signal on a basis of the sound collection result and a cancellation signal based on a second noise reduction signal for driving the second acoustic device.
(2)
The signal processing device according to (1), including:
a signal processing unit configured to generate the cancellation signal by executing a filtering process based on a feature of the second propagation path on the second noise reduction signal.
(3)
The signal processing device according to (2),
in which the first acoustic device and the sound collection unit are held near one ear different from another ear near which the second acoustic device is held among right and left ears of a hearer, and
the signal processing unit executes the filtering process on the second noise reduction signal in accordance with the feature of the second propagation path based on a positional relation among the sound collection unit, the second acoustic device, and a head of the hearer.
(4)
The signal processing device according to (3), including:
a detection unit configured to detect the positional relation among the sound collection unit, the second acoustic device, and the head of the hearer,
in which the signal processing unit generates the cancellation signal by executing the filtering process based on the feature of the second propagation path corresponding to a detection result of the positional relation on the second noise reduction signal.
(5)
The signal processing device according to (4), in which the signal processing unit selects a filter corresponding to the feature of the second propagation path corresponding to the detection result of the positional relation among a plurality of filters with different features, and generates the cancellation signal by executing the filtering process on the second noise reduction signal on a basis of the selected filter.
(6)
The signal processing device according to (4) or (5), in which the detection unit detects the positional relation on a basis of a light reception result obtained by a predetermined light-receiving element that receives light projected from a predetermined light source and reflected from the head of the hearer.
(7)
The signal processing device according to (4) or (5), in which the detection unit detects the positional relation on a basis of an image of the head of the hearer captured by a predetermined imaging unit.
(8)
The signal processing device according to (4) or (5), in which, on a basis of a sound collection result of an ultrasonic wave output from a predetermined acoustic device and collected by a predetermined sound collection unit, the detection unit detects the positional relation among the head of the hearer, the sound collection unit, and the second acoustic device which are located in an environment in which the ultrasonic wave propagates.
(9)
The signal processing device according to (4) or (5), in which the detection unit detects the positional relation on a basis of a delay time until an acoustic sound output from a predetermined acoustic device is collected by a predetermined sound collection unit worn on the head of the hearer.
(10)
The signal processing device according to any one of (3) to (9), in which the first acoustic device, the second acoustic device, and the sound collection unit are held to have a predetermined positional relation with respect to a headrest supporting the head of the hearer.
(11)
The signal processing device according to (10), in which the first acoustic device and the second acoustic device are provided in the headrest.
(12)
The signal processing device according to (10) or (11), in which the headrest is provided in a seat installed in a vehicle.
(13)
The signal processing device according to any one of (2) to (12), in which the filtering process includes a noise reduction process based on a feedback scheme.
(14)
The signal processing device according to any one of (2) to (13), in which the filtering process is a process of controlling at least any of a gain and a phase of the second noise reduction signal.
(15)
The signal processing device according to any one of (1) to (14), including:
another acquisition unit configured to acquire a sound collection result of an acoustic sound collected by another sound collection unit different from the sound collection unit, the acoustic sound including the second acoustic sound propagating from the second acoustic device via a third propagation path and the first acoustic sound propagating from the first acoustic device via a fourth propagation path; and
another generation unit configured to generate the second noise reduction signal on a basis of another cancellation signal based on the sound collection result acquired by the other acquisition unit and the first noise reduction signal.
(16)
The signal processing device according to any one of (1) to (15), including:
at least any of the first acoustic device, the second acoustic device, and the sound collection unit.
(17)
A signal processing method including: by a processor,
generating a first noise reduction signal for driving a first acoustic device which outputs a first acoustic sound for reducing noise; and
acquiring a sound collection result of an acoustic sound collected by a predetermined sound collection unit, the acoustic sound including the first acoustic sound propagating from the first acoustic device via a first propagation path and a second acoustic sound propagating from a second acoustic device different from the first acoustic device via a second propagation path,
in which the first noise reduction signal is generated on a basis of the sound collection result and a cancellation signal based on a second noise reduction signal for driving the second acoustic device.
(18)
A program causing a computer to execute:
generating a first noise reduction signal for driving a first acoustic device which outputs a first acoustic sound for reducing noise; and
acquiring a sound collection result of an acoustic sound collected by a predetermined sound collection unit, the acoustic sound including the first acoustic sound propagating from the first acoustic device via a first propagation path and a second acoustic sound propagating from a second acoustic device different from the first acoustic device via a second propagation path,
in which the first noise reduction signal is generated on a basis of the sound collection result and a cancellation signal based on a second noise reduction signal for driving the second acoustic device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-076100 | May 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/002219 | 1/24/2017 | WO | 00 |
