Voice output apparatus, voice output method, and voice output program

There is provided a voice output apparatus for providing a high-quality sound to an eardrum of a user. The voice output apparatus includes a first voice output unit outputting a voice to an ear canal of a user based on an output voice signal, a first noise acquirer arranged to face outward from a body of the user and captures a mixed voice including first external noise arriving from an outside of the user to output a mixed voice signal, an echo canceler cancelling an influence, on the first external noise, of a leaked voice output from the first voice output unit and leaking to the outside of the user, and a noise canceler generating a first external noise signal corresponding to the first external noise, and processing, using the first external noise signal, an input voice signal input from the outside to generate the output voice signal.

This application is a National Stage Entry of PCT/JP2020/013850 filed on Mar. 26, 2020, which claims priority from Japanese Patent Application 2019-061289 filed on Mar. 27, 2019, the contents of all of which are incorporated herein by reference, in their entirety.

TECHNICAL FIELD

The disclosure relates to a voice output apparatus, a voice output method, and a voice output program.

BACKGROUND ART

In the above technical field, patent literature1discloses a technique of detecting, by a microphone incorporated in an ear pad provided in a ring shape in a temporal region of a user, an external sound signal and a reproduced sound signal, generating a cancel signal by inverting the phases of the detected external sound signal and the detected reproduced sound signal, and reproducing the generated cancel signal as a cancel sound from the second driver unit.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

Technical Problem

However, the technique described in the above literature assumes that there exists a ring-shaped ear pad contacting the temporal region of the user, and can thus be applied to only some headphones.

The disclosure provides a technique of solving the above-described problem.

Solution to Problem

To achieve the above object, according to the disclosure, there is provided a voice output apparatus comprising:

a first voice output unit that outputs a voice to an ear canal of a user based on an output voice signal;

a first noise acquirer that is arranged to face outward from a body of the user and captures a mixed voice including first external noise arriving from an outside of the user to output a mixed voice signal;

an echo canceler that cancels an influence, on the first external noise, of a leaked voice output from the first voice output unit and leaking to the outside of the user; and

a noise canceler that generates a first external noise signal corresponding to the first external noise, and processes, using the first external noise signal, an input voice signal input from the outside to generate the output voice signal.

To achieve the above object, according to the disclosure, there is provided a voice output method comprising:

outputting a voice to an ear canal of a user based on an output voice signal;

capturing a mixed voice including external noise arriving from an outside of the user to output a mixed voice signal;

canceling an influence, on the external noise, of a leaked voice output in the outputting and leaking to the outside of the user; and

generating a external noise signal corresponding to the external noise, and processing, using the external noise signal, an input voice signal input from the outside to generate the output voice signal.

To achieve the above object, according to the disclosure, there is provided a voice output program for causing a computer to execute a method, comprising:

outputting a voice to an ear canal of a user based on an output voice signal;

capturing a mixed voice including external noise arriving from an outside of the user to output a mixed voice signal;

canceling an influence, on the external noise, of a leaked voice output in the outputting and leaking to the outside of the user; and

generating a external noise signal corresponding to the external noise, and processing, using the external noise signal, an input voice signal input from the outside to generate the output voice signal.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the disclosure, voice output apparatuses of various forms can provide a high-quality sound to the eardrum of a user.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Example embodiments of the disclosure will now be described in detail with reference to the drawings. It should be noted that the relative arrangement of the components, the numerical expressions and numerical values set forth in these example embodiments do not limit the scope of the disclosure unless it is specifically stated otherwise. Further, in the drawings below, a unidirectional arrow simply indicates the flow direction of a given signal, and does not exclude bidirectionality. Note that the term “voice signal” in the following description refers to a direct electrical change which is generated in accordance with a voice or another sound and used to transmit the voice or the other sound, so this is not limited to a voice.

First Example Embodiment

A voice output apparatus100according to the first example embodiment of the disclosure will be described with reference toFIG.1. As shown inFIG.1, the voice output apparatus100includes a voice output unit101, a noise acquirer102, an echo canceler103, and a noise canceler104. The voice output unit101outputs a voice112to an ear canal140of a user130based on an output voice signal111. The noise acquirer102is arranged to face outward from the body of the user130, and captures a mixed voice including external noise121arriving from the outside of the user130to output a mixed voice signal122. The echo canceler103cancels the influence, on the external noise121, of a leaked voice output from the voice output unit101and leaking to the outside of the user130. The noise canceler104generates a first external noise signal corresponding to the external noise121, and processes, using the first external noise signal, an input voice signal input from the outside to generate the output voice signal111.

According to this example embodiment, voice output apparatuses of various forms can provide a sound intended by a producer to the eardrum of the user while performing noise cancellation.

Second Example Embodiment

A voice output apparatus according to the second example embodiment of the disclosure will be described next with reference toFIGS.2A and2B.FIG.2Ais a view showing the arrangement of the voice output apparatus according to this example embodiment. A voice output apparatus200includes a loudspeaker201as a voice output unit, an external microphone202as a noise acquirer, a voice processor210, and a receiver220. The voice processor210includes an echo canceler203and a noise canceler204. The voice output apparatus200may be an inner ear headphone, a canal headphone, a two-ear headphone, a single-ear headphone, or a monaural headphone but the disclosure is not limited to them. The voice output apparatus200is not limited to a headphone, and may be an earphone or a headset.

The receiver220receives a transmission signal250via wireless or wired communication from a voice reproduction apparatus such as a smartphone. The transmission signal250received by the receiver220undergoes processing in the voice processor210to be converted into an output voice signal211, and the output voice signal211is input to the loudspeaker201. The loudspeaker201accepts the input of the output voice signal211, and outputs an output voice212to an ear canal240of a user230.

The external microphone202is arranged to face outward from the body of the user230, and captures external noise221arriving from the outside of the user230. However, when the loudspeaker201outputs a voice, the external microphone202may capture the output voice212as sound leakage. In this case, the external microphone202captures a mixed voice in which the external noise221and the output voice212are mixed, and outputs a mixed voice signal222.

The echo canceler203processes the mixed voice signal222using the output voice signal211to generate a pseudo external noise signal.

The noise canceler204processes the transmission signal250using the pseudo external noise signal to generate the output voice signal211.

FIG.2Bis a view showing the detailed arrangement of the voice processor210of the voice output apparatus200according to this example embodiment. The mixed voice signal222generated by the external microphone202is input to the echo canceler203. The echo canceler203applies echo cancellation processing to the mixed voice signal222using the output voice signal211. The echo canceler203includes an adaptive filter231and an adder232. The adaptive filter231generates a pseudo output voice signal233using the output voice signal211. The adder232subtracts the pseudo output voice signal233from the mixed voice signal222to generate a pseudo external noise signal234. The pseudo external noise signal234output from the adder232is used to update the coefficient of the adaptive filter231.

The noise canceler204includes a fixed filter241and an adder242. The pseudo external noise signal234is input to the noise canceler204. The noise canceler204uses the input pseudo external noise signal234to process an input voice signal251generated based on the transmission signal250. The noise canceler204drives the fixed filter241to generate a pseudo external noise signal243of a voice signal included in the mixed voice signal222. The adder242subtracts the pseudo external noise signal243from the input voice signal251.

The above-described contents will be explained by, for example, representing the input voice signal251as [Δ□Δ□] and the external noise221as [◯x◯]. The echo canceler203processes the external noise221[◯x◯] to generate a signal [◯◯] as the pseudo external noise signal234. The noise canceler204generates the pseudo external noise signal243[□□] using the pseudo external noise signal234[◯◯], and subtracts the pseudo external noise signal243[□□] from the input voice signal251[Δ□Δ□] to obtain the output voice signal211, and thus the loudspeaker201outputs an output voice [ΔΔ]. Furthermore, the external noise221[◯x◯] is deformed into [□□] before arriving at the ear canal240via the head of the user230. Then, the same signal [Δ□Δ□] as the input voice signal251, which is obtained by a combination of [ΔΔ] output from the loudspeaker201and the deformed external noise [□□], arrives at an eardrum270of the user230.

According to this example embodiment, it is possible to eliminate the influence that sound leakage output from the loudspeaker is mixed in the external microphone, thereby providing a high-quality sound to the eardrum of the user.

Third Example Embodiment

A voice output apparatus according to the third example embodiment of the disclosure will be described next with reference toFIGS.3A and3B.FIG.3Ais a view showing the detailed arrangement of a voice processor of the voice output apparatus according to this example embodiment. The voice output apparatus according to this example embodiment is different from that according to the above-described second example embodiment in that an internal microphone301and a controller360are provided and the fixed filter241is replaced by an adaptive filter341. The remaining components and operations are similar to those in the second example embodiment. Hence, the same reference numerals denote similar components and operations, and a detailed description thereof will be omitted.

The internal microphone301is an internal microphone arranged to face an ear canal240of a user230. The internal microphone301captures external noise313obtained when part of external noise221spatially passes through the voice output apparatus and is transmitted to the ear canal240. The external noise313captured by the internal microphone301is used as an error signal312to update the coefficient of the adaptive filter341. A noise canceler204processes an input voice signal251using an input pseudo external noise signal234.

The controller360controls the update timing of the coefficients of the adaptive filter341and an adaptive filter231.

FIG.3Bis a graph for explaining the coefficient processing of the controller of the voice output apparatus according to this example embodiment. As described above, an echo canceler203and a noise canceler204perform echo cancellation processing and noise cancellation processing using the adaptive filters231and341, respectively. InFIG.3B, the ordinate represents an update amount (learning amount) and the abscissa represents an S/N (Signal-to-Noise ratio). A graph320indicates the update amount of the coefficient of the adaptive filter341of the noise canceler204. A graph330indicates the update amount of the coefficient of the adaptive filter231of the echo canceler203. As indicated by graphs320and330, the controller360simultaneously performs filter update for the adaptive filters231and341while changing the update amount by the S/N ratio. Furthermore, as indicated by graphs340and350inFIG.3C, the controller360can accelerate filter convergence by stopping filter update of the adaptive filter, whose update amount is smaller, based on the S/N ratio and the update curve. Instead of turning on/off the echo canceler203and the noise canceler204, update (learning) of each of adaptive filters231and341is turned on/off, thereby alternately updating the adaptive filters231and341. After the adaptive filters231and341are updated to some extent, each filter coefficient hardly changes. In this state, the controller360does not reupdate the adaptive filters231and341in principle but if the device is detached or the device is passed to another user while the power is ON, the controller360performs filter update to adopt the device to the other user.

The timing when the controller360updates the adaptive filter341is the timing when the internal microphone301does not capture an output voice212. Furthermore, the timing when the controller360updates the adaptive filter231is the timing when a loudspeaker201outputs the output voice212.

Furthermore, the internal microphone301may capture a main voice311of the user230transmitted through the ear canal from the vocal cord of the user230in addition to the external noise313, thereby generating a main voice signal. At the timing when the main voice311is captured and the loudspeaker201outputs an output voice, the adaptive filter231is not updated.

According to this example embodiment, it is possible to eliminate the influence that sound leakage output from the loudspeaker is mixed in the external microphone, and provide a sound intended by a producer to the eardrum of the user while performing noise cancellation. Since the adaptive filters are updated, it is possible to deal with a change in external noise and a change in voice output from the loudspeaker.

Fourth Example Embodiment

A voice output apparatus according to the fourth example embodiment of the disclosure will be described next with reference toFIG.5A.FIG.5Ais a view showing the detailed arrangement of a voice processor of the voice output apparatus according to this example embodiment. The voice output apparatus according to this example embodiment is different from that according to the above-described third example embodiment in that a loudspeaker502is further provided. The remaining components and operations are similar to those in the second example embodiment. Hence, the same reference numerals denote similar components and operations, and a detailed description thereof will be omitted.

A voice output apparatus500includes the loudspeaker502. That is, the voice output apparatus500has a structure including two microphones and two loudspeakers in an ear canal240of a user230. An external microphone202and the loudspeaker502are made to face outward from the user230.

The loudspeaker502is a loudspeaker made to face outward from the user230. By outputting an opposite-phase voice signal521(“−X”) having a phase opposite to that of sound leakage “X” from the loudspeaker502, the sound leakage “X” is controlled in advance in the outer space of the user230(active noise control). Then, by controlling the sound leakage “X”, the external microphone202captures high-quality external noise221which the sound leakage hardly influences.

An internal microphone301captures part of an output voice212output from the loudspeaker201, and an adaptive filter531generates the opposite-phase voice signal521corresponding to the part of the output voice212captured by the internal microphone301. The loudspeaker502outputs an opposite-phase voice based on the opposite-phase voice signal521.

The update amount of an adaptive filter341is large when the difference between a pseudo external noise signal234and the output voice212is sufficiently small. That is, the difference between the pseudo external noise signal234and the output voice212represents detailed information of an environmental change, and is an S/N ratio (Signal-to-Noise Ratio). It is considered that when the difference approaches 0 (lim→0), the S/N ratio approaches infinite (lim→∞). The update amount of the adaptive filter531is large when the output voice212captured by the internal microphone301is sufficiently large. That is, this is because in the adaptive filter531, it is considered that when the output voice212captured by the internal microphone301is sufficiently large, the S/N ratio approaches infinite (lim→∞). A case in which the output voice212captured by the internal microphone301is large corresponds to a case in which a transmission signal250is received and the user utters.

According to this example embodiment, since it is possible to extract a high-quality pseudo external noise signal, it is possible to improve the quality of a sound that arrives at the eardrum of the user. Furthermore, since the opposite-phase sound is output from the loudspeaker, it is possible to reduce sound leakage to the periphery. That is, in this example embodiment, the ear canal240of the user230is regarded as a one-dimensional acoustic tube, and the external microphone202and the loudspeaker502are arranged at the end of the ear canal240, thereby making it possible to prevent sound leakage. When a pipe is exemplified as a one-dimensional acoustic tube, a sound radially spreads but the sound travels straight in the pipe without radially spreading. Even if one point of the radially spreading sound is captured and a sound having an opposite phase is output, the sound cannot be canceled in the space. However, since sound pressure is equally applied to a cross section in the one-dimensional acoustic tube, one point of the cross section is captured to make a sound having an opposite phase to collide, thereby canceling the sound in the space. For example, the muffler of an automobile or the like can perform silencing by this scheme.

Fifth Example Embodiment

A voice output apparatus according to the fifth example embodiment of the disclosure will be described next with reference toFIG.5B.FIG.5Bis a view showing the arrangement of the voice output apparatus according to this example embodiment. The voice output apparatus according to this example embodiment is different from that according to the above-described fourth example embodiment in that an output voice signal input to a loudspeaker201is used for filter update of an adaptive filter531. The remaining components and operations are similar to those in the fourth example embodiment. Hence, the same reference numerals denote similar components and operations, and a detailed description thereof will be omitted.

An output voice212captured by an internal microphone301and output from a loudspeaker201is used to update the filter coefficient of an adaptive filter341. The adaptive filter531generates an opposite-phase voice signal521using an output voice signal511input to the loudspeaker201. A loudspeaker502outputs an opposite-phase sound based on the opposite-phase voice signal521.

The update amount of the adaptive filter341is large when the difference between a pseudo external noise signal243and the output voice212is sufficiently small. The update amount of an adaptive filter231is large when the output voice212output from the loudspeaker201is sufficiently large. A case in which the output voice212output from the loudspeaker201is sufficiently large corresponds to a case in which a transmission signal250is received.

According to this example embodiment, in addition to the above-described fourth example embodiment, the convergence of the adaptive filter531is fast and the adaptive filter531is also stable.

Sixth Example Embodiment

A voice output apparatus according to the sixth example embodiment of the disclosure will be described next with reference toFIG.6.FIG.6is a view showing the arrangement of the voice output apparatus according to this example embodiment. The voice output apparatus according to this example embodiment is different from that according to the above-described fifth example embodiment in that no internal microphone301is provided. The remaining components and operations are similar to those in the second example embodiment. Hence, the same reference numerals denote similar components and operations, and a detailed description thereof will be omitted.

An output voice signal511input to a loudspeaker201is used to update the filter coefficient of a fixed filter641. Furthermore, an adaptive filter531generates an opposite-phase voice signal521of the output voice signal511. A loudspeaker502outputs an opposite-phase sound (“−X”) based on the opposite-phase voice signal521.

According to this example embodiment, since the internal microphone is unnecessary, as compared to the fourth and fifth example embodiments, it is possible to improve, by a simple arrangement, the quality of a sound that arrives at the eardrum of the user. In addition, since the fixed filter641is used, no coefficient convergence time is required, thereby implementing stable sound quality.

Other Example Embodiments

While the disclosure has been particularly shown and described with reference to example embodiments thereof, the disclosure is not limited to these example embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the claims. A system or apparatus including any combination of the individual features included in the respective example embodiments may be incorporated in the scope of the disclosure.

The disclosure is applicable to a system including a plurality of devices or a single apparatus. The disclosure is also applicable even when an information processing program for implementing the functions of example embodiments is supplied to the system or apparatus directly or from a remote site. Hence, the disclosure also incorporates the program installed in a computer to implement the functions of the disclosure by the computer, a medium storing the program, and a WWW (World Wide Web) server that causes a user to download the program. Especially, the disclosure incorporates at least a non-transitory computer readable medium storing a program that causes a computer to execute processing steps included in the above-described example embodiments.

FIG.4Ais a block diagram showing the arrangement of a computer400that executes a signal processing program when forming the third example embodiment by the signal processing program. The computer400includes an input unit410, a CPU (Central Processing Unit)420, an output unit430, and a memory440.

The CPU420controls the operation of the computer400by loading the signal processing program stored in the memory440. That is, after executing the signal processing program, the CPU420outputs, in step S401, an output voice212from the output unit430. In step S403, the CPU420captures a mixed voice in which external noise221from the input unit410and the output voice212from a loudspeaker201are mixed, and outputs a mixed voice signal222. In step S407, the CPU420performs echo cancellation processing for the mixed voice signal222using an output voice signal211input to the loudspeaker201, generates a pseudo external noise signal234, and outputs it. In step S409, the CPU420performs noise cancellation processing for an input voice signal251using the pseudo external noise signal234.

FIG.4Bis a flowchart illustrating the procedure of processing executed by the CPU420. In step S421, the CPU420determines whether an internal microphone301captures a main voice311. If it is determined that the main voice311is acquired (YES in step S421), the CPU420ends the processing. If it is determined that the main voice311is not acquired (NO in step S421), the CPU420advances to step S423. In step S423, the CPU420determines whether the loudspeaker201outputs the output voice212. If it is determined that the output voice212is output (YES in step S423), the CPU420ends the processing. If it is determined that the output voice212is not output (NO in step S423), the CPU420advances to step S425. In step S425, the CPU420updates an adaptive filter341of a noise canceler204.

FIG.4Cis a flowchart illustrating the procedure of processing executed by the CPU420. In step S431, the CPU420determines whether the loudspeaker201outputs the output voice212. If it is determined that the output voice212is not output (NO in step S431), the CPU420ends the processing. If it is determined that the output voice212is output (YES in step S431), the CPU420advances to step S433. In step S433, the CPU420determines whether the main voice311is captured. If it is determined that the main voice311is captured (YES in step S433), the CPU420ends the processing. If it is determined that the main voice311is not captured (NO in step S433), the CPU420advances to step S435. In step S435, the CPU420updates an adaptive filter231of an echo canceler203.

Other Expressions of Example Embodiments

Some or all of the above-described example embodiments can also be described as in the following supplementary notes but are not limited to the followings.

There is provided a voice output apparatus comprising:

a first voice output unit that outputs a voice to an ear canal of a user based on an output voice signal;

a first noise acquirer that is arranged to face outward from a body of the user and captures a mixed voice including first external noise arriving from an outside of the user to output a mixed voice signal;

an echo canceler that cancels an influence, on the first external noise, of a leaked voice output from the first voice output unit and leaking to the outside of the user; and

a noise canceler that generates a first external noise signal corresponding to the first external noise, and processes, using the first external noise signal, an input voice signal input from the outside to generate the output voice signal.

There is provided the voice output apparatus according to supplementary note 1, wherein

the echo canceler processes the mixed voice signal using the output voice signal to generate a pseudo external noise signal, and

the noise canceler processes the input voice signal using the pseudo external noise signal.

There is provided the voice output apparatus according to supplementary note 1 or 2, further comprising a second external noise acquirer that captures, as second external noise, part of the first external noise transmitted to the ear canal, wherein the noise canceler processes the input voice signal additionally using the second external noise.

There is provided the voice output apparatus according to supplementary note 3, wherein the second external noise acquirer further captures a main voice of the user transmitted through the ear canal from a vocal cord of the user to generate a main voice signal.

There is provided the voice output apparatus according to supplementary note 2 or 3, wherein the noise canceler performs noise cancellation processing using a first adaptive filter, and updates the first adaptive filter using a second external noise signal corresponding to the captured second external noise.

There is provided the voice output apparatus according to any one of supplementary notes 1 to 5, wherein the noise canceler performs noise cancellation processing using the first adaptive filter, the echo canceler performs echo cancellation processing using a second adaptive filter, the second adaptive filter is not updated when updating the first adaptive filter, and the first adaptive filter is not updated when updating the second adaptive filter.

There is provided the voice output apparatus according to supplementary note 3, wherein the noise canceler performs noise cancellation processing using a first adaptive filter, and updates the first adaptive filter at a timing when the second external noise acquirer acquires no second external noise and the voice output unit outputs no output voice.

There is provided the voice output apparatus according to supplementary note 6, wherein the echo canceler updates the second adaptive filter at a timing when the voice output unit outputs an output voice.

There is provided the voice output apparatus according to supplementary note 6 or 7, wherein the noise canceler and the echo canceler do not update the first adaptive filter and the second adaptive filter at a timing when the second external noise acquirer acquires the main voice.

There is provided the voice output apparatus according to any one of supplementary notes 1 to 9, wherein the echo canceler includes

a voice signal generator that generates a voice signal of an opposite-phase voice having a phase opposite to a phase of a voice output from the voice output unit, and

a second voice output unit that outputs the opposite-phase voice for canceling the leaked voice to the outside of the user based on the voice signal of the opposite-phase voice.

There is provided the voice output apparatus according to supplementary note 10, wherein the second external noise acquirer captures the voice output from the second voice output unit to the ear canal.

There is provided the voice output apparatus according to supplementary note 11, wherein the voice signal generator further includes an adaptive filter that generates the voice signal of the opposite-phase voice using an in-ear canal voice signal output from the second external noise acquirer.

There is provided the voice output apparatus according to any one of supplementary notes 10 to 12, wherein

the noise canceler performs noise cancellation processing using the first adaptive filter, and

the first adaptive filter updates a coefficient based on the in-ear canal voice signal.

There is provided a voice output method comprising:

outputting a voice to an ear canal of a user based on an output voice signal;

capturing a mixed voice including external noise arriving from an outside of the user to output a mixed voice signal;

canceling an influence, on the external noise, of a leaked voice output in the outputting and leaking to the outside of the user; and

generating an external noise signal corresponding to the external noise, and processing, using the external noise signal, an input voice signal input from the outside to generate the output voice signal.

There is provided a voice output program for causing a computer to execute a method, comprising:

outputting a voice to an ear canal of a user based on an output voice signal;

arranging to face outward from a body of the user and capturing a mixed voice including external noise arriving from an outside of the user to output a mixed voice signal;

canceling an influence, on the external noise, of a leaked voice output in the outputting and leaking to the outside of the user; and

generating an external noise signal corresponding to the external noise, and processing, using the external noise signal, an input voice signal input from the outside to generate the output voice signal.