Patent Description:
Conventionally disclosed is a technology that enables a sound collecting device, which collects voices of a speaker, to collect sound while reducing noise influence (see, for example, Patent Literature (PTL) <NUM> and <NUM>).

Nowadays, a person gets a message across to another person in a city, for instance, by translating their utterances collected by a sound collecting device (referred to herein as "speech input device") and displaying or outputting the result of the translation on the display or from the microphone(s) of the speech input device. However, speech recognition is not properly performed due to surrounding noise etc., in some cases, and a user of the speech input device has to bring the device closer to their face (mouth to be specific) to utter a voice again so that speech recognition is performed again. A problem here is that since the user's face is in proximity to the speech input device, speech recognition performance decreases.

In view of this, one non-limiting and exemplary embodiment provides, for instance, a speech input method capable of inhibiting a decrease in speech recognition performance caused by proximity between a user's face and a speech input device.

In one general aspect, the techniques disclosed here feature a speech input method including: detecting whether a user's face is in proximity to a speech input device including at least two microphones; and performing correction processing on an audio signal obtained through sound collection by the at least two microphones when it is detected that the user's face is in proximity to the speech input device.

General and specific aspects disclosed above may be implemented using a computer program or a speech input device.

The speech input method and so on according to one or more exemplary embodiments or features disclosed herein enable inhibiting a decrease in speech recognition performance caused by proximity between a user's face and a speech input device.

First, a background to the conception of one aspect of the present disclosure will be described with reference to <FIG>.

<FIG> is a diagram for explaining that proximity between the face of user <NUM> and speech input device <NUM> decreases speech recognition performance.

Speech input device <NUM> is used, for example, when user <NUM> gets a message across to a person who does not understand the language that user <NUM> speaks. Normally, user <NUM> holds speech input device <NUM> in front of their chest or thereabouts and makes an utterance that they desire to be translated. With this, speech input device <NUM> collects the utterance, speech recognition is performed on the utterance by, for example, a server device, and the utterance is translated into a desired language.

However, in some cases, speech recognition is not properly performed, for instance, in a city due to surrounding noise etc. and user <NUM> has to bring speech input device <NUM> closer to their face to make an utterance again so that speech recognition is performed again, as illustrated in <FIG>. When the face of user <NUM> is in proximity to speech input device <NUM>, the following problems occur. It is to be noted that there is also a case where the face of user <NUM> comes in proximity to speech input device <NUM> by user <NUM> bringing their face closer to speech input device <NUM>.

Speech input device <NUM> includes two microphones at least, and an audio signal obtained through sound collection by the two microphones has single directivity.

In other words, speech input device <NUM> may have higher sound collection sensitivity in a specific direction. Stated differently, speech input device <NUM> may have lower sound collection sensitivity in a direction other than the specific direction. When speech input device <NUM> is held in front of the chest of user <NUM> or thereabouts, for example, speech input device <NUM> has higher sound collection sensitivity in a direction toward the face of user <NUM>. Accordingly, when the audio signal has single directivity, speech recognition may not be properly performed because due to proximity between the face of user <NUM> and speech input device <NUM>, the mouth of user <NUM> is positioned away from a direction to which speech input device <NUM> has higher sound collection sensitivity.

Another problem that occurs when the face of user <NUM> is in proximity to speech input device <NUM> is that the input signal level of a voice collected by the microphones in speech input device <NUM> increases and is even saturated depending on a case, and speech recognition is not properly performed in some cases.

Yet another problem that occurs when the face of user <NUM> is in proximity to speech input device <NUM> is that the low frequencies of a voice collected by the microphones in speech input device <NUM> are emphasized due to proximity effect and speech recognition is not properly performed in some cases.

In view of this, according to an exemplary embodiment disclosed herein, a speech input method includes: detecting whether a user's face is in proximity to a speech input device including at least two microphones; and performing correction processing on an audio signal obtained through sound collection by the at least two microphones when it is detected that the user's face is in proximity to the speech input device.

In this way, whether a user's face is in proximity to the speech input device is detected. Therefore, when it is detected that the user's face is in proximity to the speech input device, it is possible to perform correction processing so that a decrease in speech recognition performance caused by proximity between the user's face and the speech input device is inhibited. Accordingly, it is possible to inhibit such a decrease, and this in turn makes it possible, for example, to correctly translate utterances obtained through sound collection.

The audio signal is obtained through sound collection by the at least two microphones and has single directivity.

The correction processing includes a process of converting single directivity into omni-directional directivity.

When the user's face is in proximity to the speech input device, it is easy to achieve a sufficient level of sound collection sensitivity even though an audio signal obtained through sound collection has omni-directional directivity. Accordingly, it is possible to inhibit a decrease in speech recognition performance irrespective of a direction from each of the microphones to the user's face by performing the process of converting single directivity into omni-directional directivity when the user's face is in proximity to the speech input device.

The correction processing may include a process of decreasing gain.

With this, when the user's face is in proximity to the speech input device, the saturation of the input signal level of a voice collected by the microphone(s) in speech input device <NUM> is inhibited by performing the process of decreasing gain. Accordingly, it is possible to inhibit a decrease in speech recognition performance.

The correction processing may include a process of decreasing gain of a component at a predetermined frequency or lower.

With this, when the user's face is in proximity to the speech input device, an emphasis on low frequencies due to proximity effect is inhibited by performing the process of decreasing the gain of a component at a predetermined frequency or lower (e.g., low frequency component). Accordingly, it is possible to inhibit a decrease in speech recognition performance.

The speech input device may include a triaxial accelerometer. In the detecting, whether the user's face is in proximity to the speech input device may be detected based on a result obtained by comparing a pattern that indicates a temporal change in an output from the triaxial accelerometer with a premeasured pattern.

With this, it is possible to recognize the motion of the speech input device by the triaxial accelerometer included in the speech input device. Previously measuring a pattern indicating a temporal change in an output from the triaxial accelerometer when the speech input device is brought closer to the user's face, in particular, makes it possible to detect that the user's face is in proximity to the speech input device when a pattern similar to the previously measured pattern is output from the triaxial accelerometer.

The speech input device may include a camera. In the detecting, whether the user's face is in proximity to the speech input device may be detected according to a change in a size of the user's face in an image captured by the camera.

The size of the user's face in an image captured by the camera increases when the user's face is in proximity to the speech input device compared to the case where the user's face is not in proximity to the speech input device. Accordingly, it is possible to detect that the user's face is in proximity to the speech input device when the size of the user's face in an image increases.

In the detecting, whether the user's face is in proximity to the speech input device may be detected according to a change in gain of the audio signal obtained through the sound collection.

When the user's face is in proximity to the speech input device, the gain of an audio signal obtained through sound collection may increase. Accordingly, it is possible to detect that the user's face is in proximity to the speech input device when the gain of an audio signal obtained through sound collection increases.

In the detecting, whether the user's face is in proximity to the speech input device may be detected according to a change observed between an average value of gains of the audio signal obtained through the sound collection in a first period, and an average value of gains of the audio signal obtained through the sound collection in a second period following the first period.

Even when the user's face is not in proximity to the speech input device, the gain of an audio signal obtained through sound collection may instantaneously increase in some cases. In view of this, detecting whether the user's face is in proximity to the speech input device according to a change in an average value of the gains of an audio signal obtained through sound collection in a specified period of time enables correct detection.

In the detecting, whether the user's face is in proximity to the speech input device may be detected according to a change in gain of a component at a predetermined frequency or lower of the audio signal obtained through the sound collection.

When the user's face is in proximity to the speech input device, the gain of a component at a predetermined frequency or lower (e.g., low frequency component) of an audio signal obtained through sound collection may increase due to proximity effect. Accordingly, it is possible to detect that the user's face is in proximity to the speech input device when the gain of a component at a predetermined frequency or lower of the audio signal increases.

In the detecting, whether the user's face is in proximity to the speech input device may be detected according to a change observed between an average value of gains of components at the predetermined frequency or lower of the audio signal obtained through the sound collection in a third period and an average value of gains of components at the predetermined frequency or lower of the audio signal obtained through the sound collection in a fourth period following the third period.

Even when the user's face is not in proximity to the speech input device, the gain of an audio signal obtained through sound collection may instantaneously increase in some cases. In view of this, detecting whether the user's face is in proximity to the speech input device according to a change in the average value of the gains of components at a predetermined frequency or lower of an audio signal obtained through sound collection in a specified period of time enables correct detection.

A program according to an exemplary embodiment disclosed herein is a program for causing a computer to execute the speech input method described above.

A speech input device according to an exemplary embodiment disclosed herein is a speech input device including at least two microphones and includes: a detector that detects whether a user's face is in proximity to the speech input device; and a corrector that performs correction processing on an audio signal obtained through sound collection by the at least two microphones when it is detected that the user's face is in proximity to the speech input device.

With such elements, it is possible to provide a speech input device capable of inhibiting a decrease in speech recognition performance caused by proximity between a user's face and the speech input device.

Hereinafter, certain exemplary embodiments will be described in greater detail with reference to the accompanying Drawings.

The exemplary embodiment described below shows a general or specific example. The numerical values, shapes, materials, elements, the arrangement and connection of the elements, steps, the processing order of the steps etc. shown in the following exemplary embodiment are mere examples, and therefore do not limit the scope of the appended claims.

Hereinafter, an embodiment will be described with reference to <FIG>.

<FIG> is a block diagram illustrating an example of a configuration of speech input device <NUM> according to the embodiment.

Speech input device <NUM> is a device which receives a voice uttered by a user of speech input device <NUM>, to perform speech recognition on the voice and, for example, translate the voice. An audio signal indicating the received voice is transmitted, for example, to a server device capable of communicating with speech input device <NUM>, speech recognition and translation are performed on the voice by the server device, and information indicating the translation of the voice is transmitted to speech input device <NUM>. Speech input device <NUM> outputs the translation of the voice from a loudspeaker of speech input device <NUM> or display a text presenting the translation on the display of speech input device <NUM>. Speech input device <NUM> is, for example, a smartphone, a tablet terminal, or a translator exclusively intended for making a translation.

Speech input device <NUM> includes: at least two microphones; detector <NUM>; triaxial accelerometer <NUM>; comparer <NUM>; pattern data <NUM>; camera <NUM>; face detector <NUM>; face-size measurer <NUM>; analog-to-digital converter (ADC) <NUM>; and corrector <NUM>.

Speech input device <NUM> includes two microphones <NUM>. A voice uttered by the user reaches each of microphones <NUM> with a time difference. Therefore, by utilizing a positional relationship between microphones <NUM> and the time difference generated when the voice reaches each of microphones <NUM>, it is possible to obtain, through sound collection, an audio signal having single directivity.

Detector <NUM> detects whether the face of the user is in proximity to speech input device <NUM>. The details of detector <NUM> will be described later.

Triaxial accelerometer <NUM> is a sensor that detects acceleration with respect to orthogonally intersecting three directions. When speech input device <NUM> has a tabular shape like a smartphone, as illustrated in <FIG> which will be mentioned later, triaxial accelerometer <NUM> detects acceleration in a lateral direction (x-axis direction) of a tabular-shaped plane, acceleration in a longitudinal direction (y-axis direction) of the tabular-shaped plane, and also acceleration in a direction perpendicular to the tabular-shaped plane (y-axis direction).

Pattern data <NUM> has previously been measured and indicates a temporal change in an output from triaxial accelerometer <NUM> when speech input device <NUM> is brought closer to the user's face. The details of pattern data <NUM> will be described later.

Comparer <NUM> compares a pattern indicating a temporal change in an output from triaxial accelerometer <NUM> with a premeasured pattern. Specifically, triaxial accelerometer <NUM> detects whether the pattern is similar to the premeasured pattern.

Camera <NUM> is a device that captures images. Camera <NUM> is provided, for example, in a position such that the face of the user appears in an image captured by camera <NUM> when the user holds speech input device <NUM> in the hand and looks at speech input device <NUM>. In the case where input speech device <NUM> is a smartphone, for example, camera <NUM> is provided next to the display of speech input device <NUM> for capturing the user holding speech input device <NUM> in the hand.

Face detector <NUM> detects a user's face in an image captured by camera <NUM>. A method for detecting a user's face in an image is not specifically limited, and a general face detection technique may be used.

Face-size measurer <NUM> measures the size of a user's face in an image captured by camera <NUM>.

ADC <NUM> is a circuit that converts an analog signal into a digital signal, and speech input device <NUM> has two ADCs <NUM> corresponding to two microphones <NUM>. ADC <NUM> converts an analog audio signal obtained through sound collection by microphone <NUM> into a digital audio signal. Note that ADC <NUM> converts an analog audio signal amplified by amplifier circuit <NUM> into a digital audio signal, as will be described later.

Corrector <NUM> includes amplifier circuit <NUM>, directivity merger <NUM>, and proximity effect corrector <NUM>. The details of corrector <NUM> (amplifier circuit <NUM>, directivity merger <NUM>, and proximity effect corrector <NUM>) will be described later.

Speech input device <NUM> is a computer that includes a processor (microprocessor), a user interface, a communication interface (e.g., communication circuit not shown in the diagram), a memory, etc. The user interface includes, for example, a display such as a liquid crystal display (LCD) or an input device such as a keyboard or a touch panel. The memory is, for instance, a read only memory (ROM) or a random access memory (RAM), and is cable of storing a program to be executed by a processor. Input speech device <NUM> may include one memory or plural memories. With the processor operating in accordance with a program, the operations of detector <NUM>, comparer <NUM>, face detector <NUM>, face-size measurer <NUM>, and corrector <NUM> are realized.

The details of the operations performed by detector <NUM> and corrector <NUM> will be described with reference to <FIG>.

<FIG> is a flowchart showing an example of a speech input method according to the embodiment.

The speech input method includes a detection step (step S11) of detecting whether a user's face is in proximity to speech input device <NUM> and a correction step (step S12) of performing correction processing on an audio signal obtained through sound collection by at least two microphones when it is detected that the user's face is in proximity to speech input device <NUM>.

The speech input method according to the embodiment is, for example, a method to be executed by speech input device <NUM>. In other words, <FIG> is also a flowchart illustrating the operations performed by detector <NUM> and corrector <NUM>. The detection step corresponds to the operation performed by detector <NUM>, and the correction step corresponds to the operation performed by corrector <NUM>.

Detector <NUM> determines whether a user's face is in proximity to speech input device <NUM> (step S11).

Detector <NUM> detects whether the user's face is in proximity to speech input device <NUM> according to, for example, a result obtained by comparing a pattern that indicates a temporal change in an output from triaxial accelerometer <NUM> with a premeasured pattern. This will be described with reference to <FIG> and <FIG>.

<FIG> is a diagram for explaining a force imposed on speech input device <NUM> according to the embodiment when speech input device <NUM> is brought closer to the user's face. <FIG> is a diagram illustrating an example of an output signal of triaxial accelerometer <NUM> in speech input device <NUM> according to the embodiment when speech input device <NUM> is brought closer to the user's face.

As illustrated in <FIG>, a user's movement of bringing speech input device <NUM> closer to the user's face is, for example, a movement of moving speech input device <NUM> held in a hand of the user in front of the user's chest or thereabouts to the mouth of the user. The movement of bringing speech input device <NUM> closer to the user's face is, if stated differently, a movement of lifting speech input device <NUM> that lies along an approximately horizontal direction up so that the display of speech input device <NUM> faces the user's face. A state in which speech input device <NUM> lies along the approximately horizontal direction in front of the user's chest or thereabouts is referred to as state <NUM>, and a state in which speech input device <NUM> is up from the horizontal to about <NUM> degrees to <NUM> degrees near the user's face (mouth to be specific) is referred to as state <NUM>.

When speech input device <NUM> is made to move from state <NUM> to state <NUM>, triaxial accelerometer <NUM> outputs a signal as illustrated in <FIG>. As described above, in the case where speech input device <NUM> has a tabular shape like a smartphone, for instance, a lateral direction of a tabular-shaped plane is defined as an x-axis direction, a longitudinal direction of the tabular-shaped plane is defined as a y-axis direction, and a direction perpendicular to the tabular-shaped plane is defined as a z-axis direction, and triaxial accelerometer <NUM> detects triaxial acceleration in the x-axis, y-axis, and z-axis directions.

In state <NUM>, gravity is imposed on speech input device <NUM> in the z-axis direction, but hardly any gravity is imposed in the x-axis and y-axis directions. Accordingly, triaxial accelerometer <NUM> outputs a signal in accordance with gravitational acceleration g for the z-axis direction, and an output is approximately <NUM> for both of the x-axis direction and the y-axis direction. Nevertheless, a bias force that is strong enough to cancel the gravitational acceleration is applied in the z-axis direction so that all of outputs become <NUM> for the x-axis, y-axis, and z-axis directions, as illustrated in <FIG>.

When speech input device <NUM> is brought closer to the user's face, as illustrated in <FIG>, a force equivalent to that caused by a camera shake is imposed in the x-axis direction, gravity is imposed in the y-axis direction, a force to lift speech input device <NUM> up from the horizontal is imposed in the z-axis direction. Thus, speech input device <NUM> is placed in state <NUM>.

When speech input device <NUM> is thus brought closer to the user's face, a pattern indicating a temporal change in an output from triaxial accelerometer <NUM> shows a pattern as indicated in <FIG>. Accordingly, by storing in advance, as pattern data <NUM>, the pattern as indicated in <FIG> which is a premeasured pattern, it is possible to determine that speech input device <NUM> is brought closer to the user's face when a pattern similar to the pattern as indicated in <FIG> is measured.

Note, however, that how the user brings speech input device <NUM> closer to their face varies depending on the user. Therefore, various patterns for bringing speech input device <NUM> closer to a face may be previously measured and various pattern data <NUM> may be stored.

In this way, when a pattern indicating a temporal change in an output from triaxial accelerometer <NUM> is similar to a premeasured pattern, detector <NUM> is capable of detecting that a user's face is in proximity to speech input device <NUM>.

Moreover, detector <NUM> detects whether the user's face is in proximity to speech input device <NUM> according to, for example, a change in the size of the user's face in an image captured by camera <NUM>. This will be described with reference to <FIG>.

<FIG> is a diagram for explaining the location and orientation of camera <NUM> mounted on speech input device <NUM> according to the embodiment when speech input device <NUM> is brought closer to the user's face. <FIG> is a diagram illustrating a change in the size of the user's face in an image captured by camera <NUM> mounted on speech input device <NUM> according to the embodiment when speech input device <NUM> is brought closer to the user's face.

When speech input device <NUM> is in state <NUM>, camera <NUM> faces upward (e.g., perpendicularly upward) in front of the user's chest or thereabouts, as illustrated in <FIG>. When speech input device <NUM> is in state <NUM>, camera <NUM> faces the user near the user's mouth. In state <NUM>, the user's face in an image is small and compressed in an up-and-down direction, as indicated by a dashed line on the left in <FIG>. This is because the location of camera <NUM> from the user is more distant in state <NUM> as compared to state <NUM>, and the user's face appears at the edge of a range capturable by camera <NUM>. In contrast, the user's face in an image is large in state <NUM>, as indicated by a dashed line on the right side in <FIG>.

Thus, detector <NUM> is capable of detecting that a user's face is in proximity to speech input device <NUM> when the size of the user's face in an image captured by camera <NUM> increases.

Detector <NUM> may detect whether the user's face is in proximity to speech input device <NUM> according to a change in the gain of an audio signal obtained through sound collection. This is because the gain of the audio signal may increase when the user's face is in proximity to speech input device <NUM> as compared to the case where the user's face is not in proximity to speech input device <NUM>. Detector <NUM> detects that the user's face is in proximity to speech input device <NUM> when the gain of the audio signal obtained through sound collection is a predetermined value (e.g., <NUM> dB) or greater, for example. Note, however, that even when the user's face is not in proximity to speech input device <NUM>, the gain of the audio signal may instantaneously increase in some cases.

In view of this, detector <NUM> may detect whether the user's face is in proximity to speech input device <NUM> according to a change observed between an average value of the gains of the audio signal obtained through sound collection in a first period (e.g., three seconds) and an average value of the gains of the audio signal obtained through sound collection in a second period (e.g., three seconds) following the first period. Detector <NUM> detects that the user's face is in proximity to speech input device <NUM>, for example, when the time-averaged gain of the audio signal is a predetermined value (e.g., <NUM> dB) or greater. In this way, detecting whether the user's face is in proximity to speech input device <NUM> according to a change in the time-averaged gain, in a predetermined period of time, of an audio signal obtained through sound collection allows correct detection.

Moreover, detector <NUM> may detect whether the user's face is in proximity to speech input device <NUM> according to a change in the gain of a component at a predetermined frequency or lower of an audio signal obtained through sound collection. This is because when the user's face is in proximity to speech input device <NUM>, the gain of a component at a predetermined frequency or lower (e.g., low frequency component) may increase compared to the case where the user's face is not in proximity to speech input device <NUM>. The gain of a component at a predetermined frequency or lower is, for example, the frequency average of the gains of components at a frequency in the range of from <NUM> to a predetermined frequency. Detector <NUM> detects that the user's face is in proximity to speech input device <NUM>, for example, when the gain of a component at a predetermined frequency (e.g., <NUM>) or lower of an audio signal obtained through sound collection is a predetermined value (e.g., <NUM> dB) or greater. However, even when the user's face is not in proximity to speech input device <NUM>, the gain of a component at a predetermined frequency or lower of the audio signal may instantaneously increase depending on how the user utters their voice.

In view of this, detector <NUM> may detect whether the user's face is in proximity to speech input device <NUM> according to a change observed between an average value of the gains of the audio signal obtained through sound collection in a third period (e.g., three seconds) and an average value of the gains of the audio signal obtained through sound collection in a fourth period (e.g., three seconds) following the third period. Detector <NUM> detects that the user's face is in proximity to speech input device <NUM>, for example, when the time-averaged gain of components at a predetermined frequency or lower of an audio signal obtained through sound collection is a predetermined value (e.g., <NUM> dB) or greater. In this way, detecting whether the user's face is in proximity to speech input device <NUM> according to a change in the time-averaged gain of components at a predetermined frequency or lower of an audio signal obtained through sound collection in a specified period of time allows correct detection.

Moreover, detector <NUM> may detect whether the user's face is in proximity to speech input device <NUM> according to whether a voice obtained through sound collection is resonating. This is because when the user's face is in proximity to speech input device <NUM>, a voice obtained through sound collection hardly resonates compared to the case where the user's face is not in proximity to speech input device <NUM>. Whether the voice is resonating may be determined using, for example, autocorrelation. The primary components and the subsequent components increase with more echoes generated. Accordingly, when the user's face is not in proximity to speech input device <NUM>, the primary components and the subsequent components increase. Stated differently, when the user's face is in proximity to speech input device <NUM>, the primary components and the subsequent components decrease. In this way, whether the user's face is in proximity to speech input device <NUM> may be detected by determining whether a voice obtained through sound collection is resonating, using autocorrelation.

Referring back to the flowchart illustrated in <FIG>, when it is detected that the user's face is in proximity to speech input device <NUM> (Yes in step S11), corrector <NUM> performs correction processing on an audio signal obtained through sound collection by at the at least two microphones (step S12). As described above, corrector <NUM> includes amplifier circuit <NUM>, directivity merger <NUM>, and proximity effect corrector <NUM>, and if stated differently, corrector <NUM> is realized by these elements.

Amplifier circuit <NUM> is a circuit that amplifies an audio signal (analog audio signal here) that has been input, and has a function to adjust the gain of the audio signal. Amplifier circuit <NUM> performs a process of decreasing.

Directivity merger <NUM> adjusts a phase of each of audio signals that have been input (two digital audio signals that have been output from two ADCs <NUM> here) to adjust directivity. Directivity merger <NUM> performs a process of converting single directivity into omni-directional directivity.

Proximity effect corrector <NUM> is an equalizer that changes the frequency characteristic of an audio signal that has been input (an audio signal on which directivity adjustment has been performed by directivity merger <NUM>). Proximity effect corrector <NUM> performs a process of decreasing the gain of a component at a predetermined frequency or lower (e.g., a low frequency range that is at most <NUM>).

The correction processing performed by corrector <NUM> includes the process of converting single directivity into omni-directional directivity performed by directivity merger <NUM>, the process of decreasing gain performed by amplifier circuit <NUM>, and the process of decreasing the gain of a component at a predetermined frequency or lower performed by proximity effect corrector <NUM>.

When it is detected that the user's face is in proximity to speech input device <NUM>, corrector <NUM> may perform, on an audio signal, in addition to the process of converting single directivity into omni-directional directivity, the process of decreasing gain, or the process of decreasing the gain of a component at a predetermined frequency or lower.

Note that corrector <NUM> does not need to perform all of these processes. Corrector <NUM> may change a process to be performed as correction processing according to, for example, under what condition detector <NUM> performs detection. When it is detected that the user's face is in proximity to speech input device <NUM> since the gain of an audio signal obtained through sound collection is a predetermined value or greater, corrector <NUM> may perform, as correction processing, only the process of decreasing gain in addition to converting the single directivity of the at least two microphones into omni-directional directivity. When it is detected that the user's face is in proximity to speech input device <NUM> since the gain of a component at a predetermined frequency or lower of an audio signal obtained through sound collection is a predetermined value or greater, corrector <NUM> may perform, as correction processing, only the process of decreasing the gain of such a component in addition to converting the single directivity of the at least two microphones into omni-directional directivity.

Speech input device <NUM> then outputs, to a server device or other like device, the audio signal on which correction processing has been performed.

In contrast, when it is detected that the user's face is not in proximity to speech input device <NUM> (No in step S11), corrector <NUM> does not perform correction processing on the audio signal obtained through sound collection by at least one microphone, and speech input device <NUM> outputs, for speech recognition to the server device or other like device, the audio signal that has not been subjected to correction processing, for instance.

As has been described above, whether a user's face is in proximity to speech input device <NUM> is detected. Therefore, when it is detected that the user's face is in proximity to speech input device <NUM>, it is possible to perform correction processing such that inhibits a decrease in speech recognition performance caused by proximity between the user's face and speech input device <NUM>. Accordingly, it is possible to inhibit such a decrease, and this in turn makes it possible, for example, to correctly translate utterances obtained through sound collection.

Although the speech input method and speech input device <NUM> according to one or more exemplary embodiments disclosed herein have been described so far, the present disclosure shall not be limited to the aforementioned embodiment. Forms obtained by various modifications to the foregoing embodiment that can be conceived by a person skilled in the art as well as forms realized by arbitrarily combining structural components and functions in the embodiment within the scope of the claims are included in one or more exemplary embodiments disclosed herein.

For example, the aforementioned embodiment has described an example that speech input device <NUM> has two microphones <NUM>, but the present disclosure is not limited to this. Speech input device <NUM> may include, for example, three or more microphones. Speech input device <NUM> includes amplifier circuit <NUM> and ADC <NUM> corresponding to the number of microphones. When speech input device <NUM> includes one microphone, speech input device <NUM> does not need to include directivity merger <NUM>.

The aforementioned embodiment has described an example that corrector <NUM> includes amplifier circuit <NUM>, directivity merger <NUM>, and proximity effect corrector <NUM>, but the present disclosure is not limited to this. Corrector <NUM> needs to include, for example, at least one of amplifier circuit <NUM>, directivity merger <NUM>, and proximity effect corrector <NUM>.

The aforementioned embodiment has described an example that speech input device <NUM> includes triaxial accelerometer <NUM>, comparer <NUM>, and pattern data <NUM>, but speech input device <NUM> does not need to include these elements. In other words, detector <NUM> does not need to detect whether a user's face is in proximity to speech input device <NUM> based on a result obtained by comparing a pattern that indicates a temporal change in an output from triaxial accelerometer <NUM> with a previously measured pattern.

The aforementioned embodiment has described an example that speech input device <NUM> includes camera <NUM>, face detector <NUM>, and face-size measurer <NUM>, but speech input device <NUM> does not need to include these elements. In other words, detector <NUM> does not need to detect whether a user's face is in proximity to speech input device <NUM> according to, for example, a change in the size of the user's face in an image captured by camera <NUM>.

The present disclosure may be realized, for example, as a server device that executes the speech input method described in the aforementioned embodiment. The server device may include detector <NUM>, comparer <NUM>, pattern data <NUM>, face detector <NUM>, face-size measurer <NUM>, directivity merger <NUM>, proximity effect corrector <NUM>, etc. In other words, the server device may have functions other than those achieved by microphone <NUM>, triaxial accelerometer <NUM>, camera <NUM>, etc. included in speech input device <NUM>.

The present disclosure can be realized as a program for causing a processor to execute the steps included in the speech input method described in the aforementioned embodiment. Furthermore, the present disclosure can be realized as a non-transitory computer-readable storage medium such as a CD-ROM in which the program is recorded.

In the case where the present disclosure is realized using a program (software), for example, each of the steps is executed by the program being executed using hardware resources such as a CPU, a memory, an input/output circuit, etc. included in a computer. In other words, each of the steps is executed by the CPU obtaining data from the memory, input/output circuit, etc. and then computing, or outputting the computing result to the memory, input/output circuit, etc..

It should be noted that in the aforementioned embodiment, each element may be configured by dedicated hardware or may be realized by executing a software program suitable for each element. Each of the elements may be implemented by a program executor such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disc or a semiconductor memory.

Part or all of the functions of speech input device <NUM> according to the aforementioned embodiment are typically realized as an LSI which is an integrated circuit. These circuits may be individually realized as one chip or may be realized as one chip including part or all of the circuits. Each of the processing units to be realized as an integrated circuit is not limited to an LSI and may be realized as a dedicated circuit or a general-purpose processor. A field programmable gate array (FPGA) which can be programmed after an LSI is manufactured or a reconfigurable processor which can reconfigure connection or setting of circuit cells inside an LSI may be used.

Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of example only and is not to be taken by way of limitation, the scope of the present invention being limited only by the terms of the appended claims.

Claim 1:
A speech input method, comprising:
detecting (S11) whether a user's face is in proximity to a speech input device (<NUM>) including at least two microphones (<NUM>);
obtaining audio signals through sound collection by the at least two microphones (<NUM>) of single directivity obtained by performing a process of adjusting directivity of the at least two microphones (<NUM>) by adjusting a phase of each of the obtained signals; and
performing correction processing (S12) by the speech input device (<NUM>) on the obtained audio signal when it is detected that the user's face is in proximity to the speech input device (<NUM>), wherein
the obtained audio signals are obtained through sound collection by each of the at least two microphones (<NUM>),
characterized in that
the correction processing includes a process of converting single directivity of the at least two microphones (<NUM>) into omni-directional directivity by not performing the process of adjusting directivity of the at least two microphones (<NUM>) by adjusting a phase of each of the obtained audio signals.