Patent Publication Number: US-10783903-B2

Title: Sound collection apparatus, sound collection method, recording medium recording sound collection program, and dictation method

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Japanese Application No. 2017-092209 filed in Japan on May 8, 2017, the contents of which are incorporated herein by this reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a sound collection apparatus, a sound collection method, a recording medium recording a sound collection program, and a dictation method, which are effective for dictation. 
     Description of Related Art 
     Conventionally, various kinds of microphones employed in sound collection apparatuses have been developed in accordance with usage purposes. For example, some developed sound collection apparatuses include a plurality of microphones and have a directionality switching function capable of switching a direction in which high sensitivity can be obtained. For example, a user switches directionality to specify which direction to increase the sensitivity in. In this manner, the sensitivity can be increased in a desired direction without changing directions of the microphones by a user. 
     Sound collection apparatuses are used for various purposes such as voice amplification, conversation between persons, and conversation between a person and a machine. Japanese Patent Application Laid-Open Publication No. 2000-244609 discloses such a technology that a noise level around a speaker is detected by fuzzy control and a volume of output sound is controlled based on the noise level. 
     Japanese Patent Application Laid-Open Publication No. 2000-106592 discloses a telephone apparatus having a voice response function and capable of excellently preventing false operation of the voice response function due to surrounding noise at handsfree call. 
     Such a sound collection apparatus is also used in a dictation system. Recent products as devices developed along with progress in voice recognition technologies include a dictation system configured to generate text through voice input. The dictation system talks in text with voice input, which has been conventionally performed by using a keyboard or the like. 
     The dictation system is used in various fields such as automation of dictation on a personal computer and inputting of mail sentences on a portable terminal. For example, in a medical field, the dictation system can be used to produce a medical record. Doctors need to have time necessary for use of various medical instruments and information terminals and contact with patients. The dictation system, which allows preparation of a medical record in a short time period, is extremely useful to the doctors. 
     In voice recognition processing, voice input is acquired through a microphone, an acoustic feature value is extracted from the acquired voice input, and text is determined based on a result of matching of the extracted feature value with an acoustic model. Thus, relatively high voice recognition performance can be obtained when only human voice is inputted through a microphone, but the voice recognition performance significantly decreases when the voice input includes a noise component other than dictation target voice. 
     However, for example, in clinical situations, a large number of medical professionals including doctors are present in the same space, and various kinds of environmental noise such as conversation among the medical professionals and operation sound of air conditioning facilities and various medical devices are generated. In particular, when any other person&#39;s voice is generated as environmental noise to dictation target voice, performance of voice recognition of the target voice degrades so that dictation cannot reliably performed in some cases. 
     SUMMARY OF THE INVENTION 
     A sound collection apparatus according to an aspect of the present invention includes: a sound collection unit including a microphone configured to collect sound; a noise determination unit configured to determine noise in dictation based on voice collected by the sound collection unit; and a presentation unit configured to perform presentation based on a determination result by the noise determination unit. 
     A sound collection method according to another aspect of the present invention includes: a procedure of collecting sound by a sound collection unit including a microphone; a procedure of determining noise in dictation based on voice collected by the sound collection unit; and a presentation procedure of performing presentation based on a determination result of the noise. 
     A recording medium according to another aspect of the present invention records a sound collection program configured to cause a computer to execute: a procedure of collecting sound by a sound collection unit including a microphone; a procedure of determining noise in dictation based on voice collected by the sound collection unit; and a presentation procedure of performing presentation based on a determination result of the noise. 
     A dictation method according to another aspect of the present invention includes: a procedure of reading, from a recording unit recording first sound collected by a sound collection unit, second sound acquired by performing noise reduction processing on the collected first sound, and information of noise in a duration of sound collection by the sound collection unit, the second sound and generating a document by performing first dictation processing through voice recognition of the read second sound; a procedure of generating, when the document cannot be generated by the first dictation processing, a document by reading the second sound and the noise information and performing second dictation processing through voice recognition of third sound acquired by adding noise based on the noise information to the read second sound; and a procedure of generating, when the document cannot be generated by the second dictation processing, a document by performing third dictation processing through voice recognition of fourth sound acquired by performing noise reduction processing on the read first sound. 
     The above and other objects, features and advantages of the invention will become more clearly understood from the following description referring to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating a sound collection apparatus according to a first embodiment of the present invention; 
         FIG. 2  is a block diagram illustrating a dictation apparatus configured to receive a voice file from the sound collection apparatus illustrated in  FIG. 1  and perform dictation; 
         FIG. 3  is an explanatory diagram illustrating a reproduction-recording device configured to receive a voice file from the sound collection apparatus illustrated in  FIG. 1  and perform dictation by manual input; 
         FIG. 4  is an explanatory diagram illustrating exemplary appearance of a sound collection apparatus (microphone apparatus) having a dictation function and including components illustrated in  FIGS. 1 and 2 ; 
         FIG. 5  is an explanatory diagram for description of a configuration of a microphone unit  2   a  including microphones  2   al  and  2   a   2  in the sound collection apparatus; 
         FIG. 6  is a circuit diagram illustrating an exemplary specific configuration of a directionality control unit  2   b  in  FIG. 1 ; 
         FIG. 7  is a circuit diagram illustrating an exemplary specific configuration of an NR unit  2   c  in  FIG. 1 ; 
         FIG. 8  is an explanatory diagram for description of an exemplary document generated by a document generation unit  21   c;    
         FIG. 9  is a flowchart for description of operation of the sound collection apparatus; 
         FIG. 10  is a flowchart illustrating an exemplary specific procedure of environmental noise determination processing; 
         FIG. 11A  is an explanatory diagram for description of LED lighting control by a presentation control unit  1   a;    
         FIG. 11B  is an explanatory diagram for description of LED lighting control by the presentation control unit  1   a;    
         FIG. 12A  is an explanatory diagram for description of operation of the embodiment; 
         FIG. 12B  is an explanatory diagram for description of operation of the embodiment; 
         FIG. 12C  is an explanatory diagram for description of operation of the embodiment; 
         FIG. 12D  is an explanatory diagram for description of operation of the embodiment; 
         FIG. 12E  is an explanatory diagram for description of operation of the embodiment; 
         FIG. 13  is an explanatory diagram illustrating an exemplary configuration of a voice file; and 
         FIG. 14  is a flowchart for description of operation of a dictation apparatus. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 
     First Embodiment 
       FIG. 1  is a block diagram illustrating a sound collection apparatus according to a first embodiment of the present invention.  FIG. 2  is a block diagram illustrating a dictation apparatus configured to receive a voice file from the sound collection apparatus illustrated in  FIG. 1  and perform dictation.  FIG. 3  is an explanatory diagram illustrating a reproduction-recording device configured to receive a voice file from the sound collection apparatus illustrated in  FIG. 1  and perform dictation by manual input. 
     Note that the present embodiment describes an example in which the sound collection apparatus and the dictation apparatus are separately provided, but the apparatuses illustrated in  FIGS. 1 and 2  may be integrated to obtain, for example, an IC recorder having functions illustrated in  FIGS. 1 and 2 . Alternatively, the dictation function illustrated in  FIG. 2  may be included in the sound collection apparatus illustrated in  FIG. 1  to obtain, for example, a microphone apparatus having a dictation function. 
       FIG. 4  is an explanatory diagram illustrating exemplary appearance of a sound collection apparatus (microphone apparatus) having a dictation function and including components illustrated in  FIGS. 1 and 2 .  FIG. 5  is an explanatory diagram for description of a configuration of a microphone unit  2   a  including microphones  2   al  and  2   a   2  in the sound collection apparatus. 
     According to the present embodiment, for example, at dictation work, it is possible to detect environmental noise, which hinders voice recognition performance, before voice production and allow a dictation operator to recognize dictation environment by presenting a result of the detection. For example, the dictation operator can determine, before voice production, whether the dictation operator is in environment in which dictation is possible. According to the present embodiment, voice recognition performance can be improved by changing a sound collection characteristic based on a result of detection of environmental noise. 
     The following first describes the configuration of the microphone unit  2   a  with reference to  FIGS. 4 and 5 .  FIG. 4  illustrates a state in which a user operates a sound collection apparatus  10  with a right hand  51 R while grasping a housing  10   a  of the sound collection apparatus  10  with a left hand  51 L, when viewed from a front side of the sound collection apparatus  10 .  FIG. 5  schematically illustrates disposition of internal components of the sound collection apparatus  10  at a section taken along line A in  FIG. 4  when viewed from a left side.  FIG. 5  illustrates a state in which the user grasps front and back surfaces of the housing  10   a  with a thumb  53 R and an index finger  54 R of the right hand. 
     A filter unit  42  is disposed at an upper end of the front surface of the housing  10   a  and positioned obliquely tilted relative to a longitudinal direction of the housing  10   a . The filter unit  42  blocks an opening provided at the upper end of the front surface side of the housing  10   a . The filter unit  42  has a three-layer structure in which a relatively coarse mesh metal unit  42   a , a non-woven fabric  42   b , and a relatively fine mesh metal unit  42   c  are provided in this order from the external side of the housing  10   a  to the internal side thereof. The filter unit  42  removes pop noise in voice emitted from a mouth  52 . 
     The front microphone  2   al  is disposed at a position facing to the filter unit  42  on the back surface side inside the housing  10   a . A housing part  44  in which the back microphone  2   a   2  is disposed is provided below the front microphone  2   al  on the back surface side inside the housing  10   a . An elastic member  43   b  such as rubber is disposed between an upper surface of the housing part  44  and a bottom surface of the front microphone  2   al . An elastic member  43   a  such as rubber is disposed between an upper surface of the front microphone  2   al  and an upper surface of the housing  10   a . The elastic members  43   a  and  43   b  allow the front microphone  2   al  to be held in the housing  10   a  and reduction of influence of vibration occurring to the housing  10   a  on the microphone  2   al . In particular, the elastic members  43   a  and  43   b  can reduce influence of vibration from the fingers  53 R and  54 R. 
     The housing part  44  is configured as a recess provided on the back surface of the housing  10   a  and blocked by a blockage member  46  provided with a large number of small holes. The back microphone  2   a   2  is disposed in the recess of the housing part  44 . An elastic member  45   a  such as urethane is disposed between an upper surface of the microphone  2   a   2  and an upper surface of the recess. An elastic member  45   b  such as urethane is disposed between a bottom surface of the microphone  2   a   2  and a bottom surface of the recess. The elastic members  45   a  and  45   b  hold the microphone  2   a   2  in the recess. 
     A substrate  47  on which, for example, a component for each circuit illustrated in  FIGS. 1 and 2  is mounted is disposed on a lower side inside the housing  10   a.    
     The front microphone  2   al  has such a directional characteristic that sound can be collected in a sound collection range D 1  illustrated with dashed lines in  FIG. 5 . The back microphone  2   a   2  has such a directional characteristic that sound can be collected in a sound collection range D 2  illustrated with dashed lines in  FIG. 5 . In the present embodiment, an overall directional characteristic of the microphone unit  2   a  including the front microphone  2   al  and the back microphone  2   a   2  can be electrically controlled as described later. 
     Note that a thickness of the housing  10   a  is denoted by Zm, and a distance (microphone depth) between the front microphone  2   al  and the filter unit  42  in a horizontal direction is denoted by Zd. The thickness Zm is desirably as small as possible to reduce a thickness of the apparatus. The microphone depth Zd is set to be a distance sufficient to avoid generation of distortion in voice due to influence of airflow at sound collection. Since material of cushion members used as the elastic members  45   a  and  45   b  is different from material of cushion members used as the elastic members  43   a  and  43   b , a too large height Ym between the upper surface of the housing  10   a  and the bottom surface of the housing part  44  is avoided. 
     As illustrated in  FIG. 1 , a control unit  1  is provided to a sound collection apparatus  10 . The control unit  1  includes a processor such as a CPU and may be configured to operate in accordance with a computer program stored in a memory (not illustrated) to control each component. The computer program may be partially replaced with a hardware electronic circuit. 
     A sound collection unit  2  includes the microphone unit  2   a  including a plurality of microphones. In the example illustrated in  FIG. 5 , the microphone unit  2   a  includes two microphones of the front microphone  2   al  and the back microphone  2   a   2 . The microphone unit  2   a  collects surrounding sound, converts the collected sound into a voice signal, and outputs the voice signal. The sound collection unit  2  includes a directionality control unit  2   b  configured to control directionality of sound collection by the microphone unit  2   a  under control of the control unit  1 . That is, the directionality control unit  2   b  can control a direction (hereinafter referred to as a beam direction) in which highest sensitivity is obtained at sound collection by the microphone unit  2   a , and a range of sound collection. 
       FIG. 6  is a circuit diagram illustrating an exemplary specific configuration of the directionality control unit  2   b  in  FIG. 1 . 
     The directionality control unit  2   b  includes AD converters (ADC)  61   a  and  61   b  configured to convert outputs from the two microphones  2   al  and  2   a   2 , respectively, into digital signals. The ADC  61   a  converts a voice signal from the microphone  2   al  into a digital signal and outputs the digital signal to adders  62   a  and  63   a . The ADC  61   b  converts a voice signal from the microphone  2   a   2  into a digital signal and outputs the digital signal to adders  62   b  and  63   b.    
     The adder  63   a  subtracts the output of the ADC  61   a  from the output of the ADC  61   b , and outputs a result of the subtraction to a multiplier  64   a . The adder  63   b  subtracts the output of the ADC  61   b  from the output of the ADC  61   a , and outputs a result of the subtraction to a multiplier  64   b.    
     First and second multiplication coefficients are supplied to control ends of the multiplier  64   a  and the multiplier  64   b , respectively, from the control unit  1 . The multiplier  64   a  multiplies the output of the adder  63   a  by the first multiplication coefficient, and outputs a result of the multiplication to the adder  62   a . The multiplier  64   b  multiplies the output of the adder  63   b  by the second multiplication coefficient and outputs a result of the multiplication to the adder  62   b . The adder  62   a  adds the output of the ADC  61   a  and the output of the multiplier  64   a , and outputs a result of the addition. The adder  62   b  adds the output of the ADC  61   b  and the output of the multiplier  64   b , and outputs a result of the addition. 
     The microphone  2   al  has such a directional characteristic that highest sensitivity is obtained for voice obliquely from above the front surface of the housing  10   a . Hereinafter, voice collected by the microphone  2   al  is referred to as primary voice. The microphone  2   a   2  has such a directional characteristic that highest sensitivity is obtained for voice in the horizontal direction from the back surface of the housing  10   a . Hereinafter, voice collected by the microphone  2   a   2  is referred to as secondary voice. 
     The result of the addition by the adder  62   a  corresponds to a result of addition of the primary voice and the secondary voice at distribution in accordance with the first multiplication coefficient. The addition corresponds to increase of the sound collection range of the microphone  2   al  toward the sound collection range side of the microphone  2   a   2  in accordance with the first multiplication coefficient. Similarly, the result of the addition by the adder  62   b  corresponds to a result of addition of the secondary voice and the primary voice at distribution in accordance with the second multiplication coefficient. The addition corresponds to increase of the sound collection range of the microphone  2   a   2  toward the sound collection range side of the microphone  2   al  in accordance with the second multiplication coefficient. 
     The output of each of the adders  62   a  and  62   b  may be outputted as individual voice data. For example, the output of the adder  62   a  may be outputted as primary voice data, and the output of the adder  62   b  may be outputted as secondary voice data. Alternatively, the outputs of the adders  62   a  and  62   b  may be synthesized and outputted as one piece of voice data. 
     In this manner, the sound collection unit  2  can narrow, widen, and change sound directionality by controlling balance between the primary voice and the secondary voice from the microphones  2   al  and  2   a   2 . That is, the voice data outputted from the adders  62   a  and  62   b  corresponds to voice output with controlled spread of a sound collection range extending over the front and back sides. The spread can be reduced by increasing the first and second multiplication coefficients at the multipliers  64   a  and  64   b . The spread can be increased by decreasing the multiplication coefficients. In addition, a direction (beam direction) of the sound collection range can be adjusted by setting the first and second multiplication coefficients as appropriate. Note that, hereinafter, the sound collection range of the microphone unit  2   a  refers to an overall sound collection range configured of the microphones  2   al  and  2   a   2  after controlling directionality. 
     In the present embodiment, the voice signals from the ADCs  61   a  and  61   b  can be directly output. The voice signals from the ADCs  61   a  and  61   b  can be used by an external circuit to perform directionality control. 
     The sound collection unit  2  includes a noise reduction (NR) unit  2   c . The NR unit  2   c  removes, under control of the control unit  1 , noise from a voice signal acquired by the microphone unit  2   a.    
       FIG. 7  is a circuit diagram illustrating an exemplary specific configuration of the NR unit  2   c  illustrated in  FIG. 1 . Note that  FIG. 7  illustrates a circuit configured to process voice data of a single system. Two systems of circuits each having a configuration same as the configuration of the circuit illustrated in  FIG. 7  are used to process two voice signals from the microphones  2   al  and  2   a   2 . 
     As illustrated in  FIG. 7 , each voice signal from the directionality control unit  2   b  is supplied to an input unit  71 . The input unit  71  receives the voice signal thus inputted, and outputs the voice signal to a subtraction unit  72  and a specific frequency voice determination unit  73 . The specific frequency voice determination unit  73  performs frequency analysis of the inputted voice signal to calculate a frequency of a noise component. 
     Unlike surrounding noise, voice has a sound pattern, a frequency characteristic of which largely changes in accordance with emotional expression of words and syllables and wording. However, noise has a largely changing sound magnitude (amplitude) rather than a difference in a frequency characteristic, and is clearly different from human voice, which has a slightly changing sound magnitude. Thus, the specific frequency voice determination unit  73  determines a noise frequency to be a specific frequency having a hardly changing frequency characteristic, and determines a voice component to be a component having a changing frequency characteristic. The specific frequency voice determination unit  73  outputs a result of the determination to an amplitude variation prediction unit  74 . 
     The amplitude variation prediction unit  74  determines amplitude variation at the specific frequency to be noise-level variation based on the determination result from the specific frequency voice determination unit  73 , and predicts the variation. The amplitude variation prediction unit  74  directly outputs a result of the prediction as prediction of the noise-level variation and also provides the result to the subtraction unit  72 . The subtraction unit  72  removes a noise component from an inputted voice signal by subtracting the result of the prediction by the amplitude variation prediction unit  74  from the voice signal, and outputs the voice signal. 
     In this manner, the sound collection unit  2  digitalizes voice collected by the microphone unit  2   a  and outputs, to the control unit  1 , voice signals before and after directionality control and a voice signal provided with noise reduction processing by the NR unit  2   c.    
     In the present embodiment, the sound collection unit  2  includes a noise determination unit  2   d . The noise determination unit  2   d  determines any environmental noise in collected voice. For example, the noise determination unit  2   d  may determine the environmental noise based on a synthesis signal of voice signals obtained by the microphones  2   al  and  2   a   2 , or may determine the environmental noise based on a voice signal obtained by any one of the microphones  2   al  and  2   a   2 , for example, the back microphone  2   a   2 . For example, the noise determination unit  2   d  may calculate a mean square of a synthesis signal of voice signals obtained by the microphones  2   al  and  2   a   2  and may output the calculated value of the mean square as environmental noise. Alternatively, for example, the noise determination unit  2   d  may calculate a mean square of a voice signal obtained by the back microphone  2   a   2  and may output the calculated value of the mean square as environmental noise. 
     Note that the noise determination unit  2   d  may determine environmental noise by using the outputs of the ADCs  61   a  and  61   b  of the directionality control unit  2   b  illustrated in  FIG. 6 . Alternatively, the noise determination unit  2   d  may determine environmental noise based on a voice signal provided with a predetermined directional characteristic through directionality control by the directionality control unit  2   b.    
     Alternatively, the noise determination unit  2   d  may determine environmental noise based on a voice signal in a predetermined frequency band among voice obtained by the microphone unit  2   a . Alternatively, for example, the noise determination unit  2   d  may determine environmental noise based on a voice signal having a predetermined voice characteristic among voice obtained by the microphone unit  2   a . For example, the noise determination unit  2   d  may extract, based on a voice characteristic, a voice signal attributable to speech by a person among voice obtained by the microphone unit  2   a , and determine environmental noise based on the extracted voice signal. 
     For example, a voice of any person other than a voice recognition target may adversely affect voice recognition. Whether voice recognition performance is affected can be easily determined in some cases by determining environmental noise based on an output of voice component. Thus, for example, the noise determination unit  2   d  may determine environmental noise based on a voice component output from the subtraction unit  72  of the NR unit  2   c  illustrated in  FIG. 7 . Alternatively, the noise determination unit  2   d  may determine environmental noise based on a noise component output from the amplitude variation prediction unit  74 . The noise determination unit  2   d  outputs a result of the environmental noise determination to the control unit  1 . 
     The control unit  1  includes a presentation control unit  1   a . The presentation control unit  1   a  executes various kinds of processing related to display and sound output. The sound collection apparatus  10  includes a presentation unit  6 . The presentation unit  6  may be configured of a display apparatus or speaker (not illustrated) or the like. The presentation unit  6  may be configured of, for example, a LED  48  (refer to  FIG. 4 ) provided on the front surface of the housing  10   a . The presentation control unit  1   a  can cause the presentation unit  6  to display a result of the determination by the noise determination unit  2   d . For example, when it is determined based on a result of the environmental noise determination that environmental noise has a noise level higher than a predetermined threshold, the presentation control unit  1   a  may cause the presentation unit  6  to perform a display indicating that sufficient voice recognition performance cannot be obtained and dictation is impossible with the environmental noise at the acquired level. For example, when the LED  48  is employed as the presentation unit  6 , the presentation control unit  1   a  may flash the LED  48  in red to present that dictation is impossible. 
     When the presentation unit  6  is configured of the LED  48 , the presentation control unit  1   a  may flash the LED  48  in blue to indicate that the environmental noise determination is being performed, or may light the LED  48  in blue to indicate that the level of environmental noise is relatively low and dictation is possible. 
     When an LCD (not illustrated) is employed as the presentation unit  6 , the presentation control unit  1   a  may display a result of the environmental noise determination on a display screen of the presentation unit  6 . For example, the presentation control unit  1   a  may display, on the display screen of the presentation unit  6 , an error message such as “dictation is impossible with current environmental noise”. When the presentation unit  6  is configured of a speaker, the error message may be outputted from the speaker in sound. 
     The sound collection apparatus  10  includes an operation unit  3 . The operation unit  3  includes various keys and buttons and outputs an operation signal based on a user operation to the control unit  1 . For example, in the example illustrated in  FIG. 4 , a recording start button  49   a , a stop button  49   b , a reproduction start and temporary stop button  49   c , a rewind button  49   d , and a fast-forward button  49   e  are disposed as the operation unit  3  on the front surface of the housing  10   a . In addition, for example, mode buttons  50   a  and  50   b  for transition to an environmental noise determination mode, and a button  50   c  for instructing dictation start are provided as the operation unit  3  on the front surface of the housing  10   a.    
     The control unit  1  receives an operation signal based on a user operation through the operation unit  3  and controls each component based on the operation signal. For example, the user can perform, through the operation unit  3 , an operation to control the directional characteristic of the microphone unit  2   a , and the control unit  1  can set, to the microphone unit  2   a , a directional characteristic in accordance with a user operation. 
     The sound collection apparatus  10  also includes a posture determination unit  4 . The posture determination unit  4  is configured of, for example, an acceleration sensor or a gyro sensor. The posture determination unit  4  determines a posture of the housing  10   a  of the sound collection apparatus  10  and outputs a result of the determination to the control unit  1 . A sound quality adjustment unit  7  can adjust, under control of the control unit  1 , a frequency characteristic of voice collected by the sound collection unit  2 . The sound collection apparatus  10  also includes a clock unit  8 . The clock unit  8  generates time information and outputs the time information to the control unit  1 . 
     The sound collection apparatus  10  includes a communication unit  5 . The communication unit  5  can perform, under control of the control unit  1 , data transmission and reception with an external device in a wired or wireless manner. For example, the communication unit  5  is configured to be able to perform wired communication of a USB standard, wireless LAN communication of Wifi or the like, or wireless communication of Bluetooth (registered trademark). The control unit  1  can transmit, for example, an intact voice signal collected by the microphone unit  2   a , a voice signal after being subjected to directional characteristic control, a voice signal after being subjected to noise reduction processing, or a voice signal after being subjected to sound adjustment to an external device through the communication unit  5 . 
     The sound collection apparatus  10  includes a filter information recording unit  9 . The filter information recording unit  9  records information on a filter characteristic of the filter unit  42 . The control unit  1  can correct the frequency characteristic of the filter unit  42  by setting the sound quality adjustment unit  7  based on the filter characteristic information from the filter information recording unit  9 . The control unit  1  can also output a voice signal subjected to the correction through the communication unit  5 . The control unit  1  may directly output the filter characteristic information to an external device through the communication unit  5 . 
     Note that the control unit  1  includes a track input unit  1   b . The track input unit  1   b  performs processing of determining a phrase and providing an index to each determined phrase. The sound collection apparatus  10  includes a noise information recording unit  11 . The noise information recording unit  11  may be configured of, for example, an IC memory, and records noise information or the like under control of the control unit  1 . 
     The following describes a configuration of the dictation apparatus with reference to  FIG. 2 . As illustrated in  FIG. 2 , this dictation apparatus  20  includes a control unit  21 . The control unit  21  includes a processor such as a CPU and may be configured to operate in accordance with a computer program stored in a memory (not illustrated) to control each component. The processor may be partially replaced with a hardware electronic circuit. 
     The dictation apparatus  20  includes a communication unit  22 . The communication unit  22  can perform, under control of the control unit  21 , communication with the communication unit  5  of the sound collection apparatus  10  through a predetermined transmission path. The communication unit  22  can output, to the control unit  21 , various voice signals transmitted from the sound collection apparatus  10 . 
     The dictation apparatus  20  includes a text generation unit  23 . The text generation unit  23  generates, under control of the control unit  21 , a text based on an inputted voice signal by well-known voice recognition processing. A recording unit  24  includes a voice-text generation dictionary unit  24   a  used for the text generation. The text generation unit  23  calculates a feature value of a voice signal, performs matching calculation of the calculated feature value and an acoustic model, and generates text from information of human voice included in the voice signal by referring to voice text in the voice-text generation dictionary unit  24   a.    
     The recording unit  24  also includes a format information unit  24   b . The format information unit  24   b  records format information describing a format for generating a predetermined document from voice information generated in text. A document generation unit  21   c  of the control unit  21  refers to the format information in the format information unit  24   b  and generates a document from the voice information generated in text. 
       FIG. 8  is an explanatory diagram for description of an exemplary document generated by the document generation unit  21   c .  FIG. 8  illustrates an example in which a medical record is generated as a document. The document generation unit  21   c  acquires a format of a medical record from the format information and generates a document of the medical record. The medical record illustrated in  FIG. 8  includes items of “patient”, “age”, “sex”, “site”, “comment”, and “date”. 
     For example, a doctor speaks in an order of the items of the medical record in  FIG. 8 . In such a case, the text generation unit  23  sequentially generates text to be set to each item by generating text from voice spoken in the order of the items. The document generation unit  21   c  generates a medical record by disposing the sequentially acquired text in a column of each item. 
     The document generation unit  21   c  may determine content of information generated in text and dispose the information generated in text in each column in the medical record. For example, when a person name is generated in text, the document generation unit  21   c  may dispose the name generated in text in the column of “patient”. For example, when voice spoken as “x years old” is generated in text, the document generation unit  21   c  may dispose the age generated in text in the column of “age”. For example, the document generation unit  21   c  may determine an input operation to each item when a string generated in text matches with a string in the item. For example, text of voice that is inputted following sound of “patient” may be disposed in the column of “patient”. In this manner, the medical record is automatically generated by the document generation unit  21   c.    
     The control unit  21  includes a recording-reproduction control unit  21   a . The recording-reproduction control unit  21   a  can provide the recording unit  24  with various voice signals inputted through the communication unit  22  and record the voice signals in the recording unit  24 . The recording-reproduction control unit  21   a  can read voice recorded in the recording unit  24  and reproduce the voice. The text generation unit  23  and the document generation unit  21   c  can perform text generation processing and document generation processing based on a reproduced voice signal. 
     The control unit  21  also includes a voice processing unit  21   b . The voice processing unit  21   b  can perform various kinds of voice processing on a voice signal received through the communication unit  22  or a voice signal reproduced by the recording-reproduction control unit  21   a . The voice processing unit  21   b  can perform, for example, directionality control, noise reduction processing, and sound quality adjustment processing same as the directionality control, the noise reduction processing, and the sound quality adjustment processing performed by the directionality control unit  2   b  of the sound collection apparatus  10 . Accordingly, when a voice signal acquired by the microphone unit  2   a  is directly provided from the sound collection apparatus  10 , the text generation unit  23  and the document generation unit  21   c  can effectively perform the text generation processing and the document generation processing through the voice processing by the voice processing unit  21   b.    
     The following describes a reproduction-recording device  30  with reference to  FIG. 3 .  FIG. 3  indicates that, for example, a personal computer  30   a  can be employed as the reproduction-recording device  30 , and the reproduction-recording device  30  can be configured of the personal computer  30   a . In this case, a keyboard  34   a  for operating the personal computer  30   a  corresponds to an input unit  34  of the reproduction-recording device  30 , and a hard disk (not illustrated) included in the personal computer  30   a  corresponds to a recording unit  33  of the reproduction-recording device  30 . 
     The reproduction-recording device  30  includes a communication unit  31 . The communication unit  31  can perform communication with the communication unit  5  of the sound collection apparatus  10  through a predetermined transmission path. The communication unit  31  can output, to a voice reproduction unit  32 , various voice signals transmitted from the sound collection apparatus  10 . 
     The voice reproduction unit  32  includes a speaker (not illustrated) and outputs voice based on a voice signal received through the communication unit  31 . An operator  35  of the personal computer  30   a  inputs text by operating the input unit  34  (the keyboard  34   a ) while listening to the voice outputted from the voice reproduction unit  32 . Text data is stored in the recording unit  33  by an input operation through the input unit  34 . 
     The following describes operation of the embodiment thus configured with reference to  FIGS. 9 to 14 .  FIG. 9  is a flowchart for description of operation of the sound collection apparatus.  FIG. 10  is a flowchart illustrating an exemplary specific procedure of environmental noise determination processing.  FIGS. 11A and 11B  are each an explanatory diagram for description of LED lighting control by the presentation control unit  1   a .  FIGS. 12A to 12E  are each an explanatory diagram for description of operation of the embodiment.  FIG. 13  is an explanatory diagram illustrating an exemplary configuration of a voice file.  FIG. 14  is a flowchart for description of operation of the dictation apparatus. 
     (Sound Collection) 
       FIGS. 12A to 12E  each illustrate a situation in which the sound collection apparatus in the present embodiment is used.  FIG. 12A  illustrates a situation in which a user  81  grasps the housing  10   a  with a right hand  82 R. For example, at dictation in the present embodiment, the user  81  speaks while a mouth is positioned close to the microphone unit  2   a  included in the sound collection unit  2  to improve voice recognition accuracy. For example, as illustrated in  FIGS. 12A and 5 , the user  81  grasps the housing  10   a  with the right hand  82 R and speaks while a mouth  83  (in  FIG. 5 , the mouth  52 ) is positioned close to the filter unit  42  so that voice can be easily acquired by the front microphone  2   al . Note that a sound collection range Dw illustrated in  FIG. 12A  is the sound collection range of the microphone unit  2   a  including the front microphone  2   al  and the back microphone  2   a   2 .  FIG. 12A  illustrates a state in which the sound collection range is set to be a relatively wide sound collection range by directionality control. 
     At step S 1  in  FIG. 9 , the control unit  1  determines whether a sound recording mode is set. For example, transition to the sound recording mode is made when the recording start button  49   a  illustrated in  FIG. 4  is operated. Note that, since the sound collection apparatus  10  illustrated in  FIG. 1  includes no recording unit for sound recording, processing of transmitting, from the communication unit  5 , various voice signals obtained through sound collection is performed in the sound recording mode, and the voice signals are recorded in the recording unit  24  at the dictation apparatus  20  illustrated in  FIG. 2 . Thus, sound recording in  FIG. 9  means sound collection for the sound collection apparatus  10 . Thus,  FIG. 9  illustrates operation of an apparatus such as an IC recorder including the sound collection apparatus  10  and the dictation apparatus  20 . Note that the sound collection apparatus  10  illustrated in  FIG. 1  may include a recording unit for sound recording so that sound recording can be performed by the sound collection apparatus  10  alone. Note that sound recording does not necessarily need to be performed at dictation, but is preferably performed when dictation processing is performed at an external device or a computer on a cloud (not illustrated). 
     In the present embodiment, an environmental noise determination mode is executed before dictation work. The control unit  1  may automatically transition to the environmental noise determination mode when turned on, or may transition to the environmental noise determination mode based on a user operation. For example, the transition to the environmental noise determination mode may be performed when a user simultaneously presses the mode buttons  50   a  and  50   b  as illustrated in  FIG. 4  for a predetermined number of seconds (for example, five seconds). 
     When having determined that the sound recording mode is not specified at step S 1 , the control unit  1  determines whether the environmental noise determination mode is specified at step S 2 . When having determined that the environmental noise determination mode is not specified at step S 2 , the control unit  1  transitions to step S 21 . Steps S 21  to S 24  indicate control by the control unit  21  of the dictation apparatus  20 . The control unit  21  selects a voice file from the recording unit  24  based on a user operation (step S 21 ), and reproduces voice (step S 22 ). The control unit  21  determines whether transmission is requested by the user (step S 23 ). When transmission is requested, the control unit  21  performs the transmission (step S 24 ). 
     Steps S 2  to S 8  in  FIG. 9  indicate the environmental noise determination processing. Steps in  FIG. 10  indicate specific examples of procedures at steps S 2  to S 5  in  FIG. 9 . At step S 31  in  FIG. 10 , the control unit  1  transitions to the environmental noise determination mode when the buttons  50   a  and  50   b  are simultaneously pressed for five seconds or longer. 
     When the environmental noise determination mode is specified, the control unit  1  transitions from step S 2  to step S 3  in  FIG. 9 , and generates guide. The guide notifies the user of the transition to the environmental noise determination mode. For example, the control unit  1  instructs, by sound or screen display, no voice production while the housing  10   a  of the sound collection apparatus  10  is held close to the mouth. In the example illustrated in  FIG. 10 , the control unit  1  presents the transition to the environmental noise determination mode by flashing the LED  48  in blue at step S 32 . 
       FIG. 11A  illustrates flashing control of the LED  48  in such a case. In the example illustrated in  FIG. 11A , a high level (H) indicates a turned-on state, and a low level (L) indicates a turned-off state.  FIG. 11A  illustrates that flashing is performed at intervals of 300 ms (milliseconds). 
     The user  81  can recognize the transition to the environmental noise determination mode based on guide display or a flashing state of the LED  48 . Accordingly, the user can be prevented from changing the posture of the housing  10   a  or from performing unnecessary speech while the environmental noise determination mode is executed. 
     Subsequently, the control unit  1  performs noise determination at step S 4  in  FIG. 9  (step S 33  in  FIG. 10 ). In this case, the control unit  1  controls the directionality control unit  2   b  to set the sound collection range of the microphone unit  2   a  to be a widest sound collection range. The noise determination unit  2   d  of the sound collection unit  2  performs environmental noise level determination and outputs a result of the determination to the control unit  1 . The control unit  1  displays the determination result on the presentation unit  6  (step S 5 ). Note that, when the directional characteristic of the microphone unit  2   a  is set by the user  81 , environmental noise may be determined in a state with the directional characteristic set by the user. 
     For example, the control unit  1  determines, based on the determination result, whether voice recognition performance necessary for dictation can be obtained. For example, at step S 34  in  FIG. 10 , the control unit  1  determines whether the level of environmental noise is higher than a predetermined threshold. The control unit  1  may determine that voice recognition performance necessary for dictation cannot be obtained when the level of environmental noise is higher than the predetermined threshold, or may determine that voice recognition performance necessary for dictation can be obtained when the level of environmental noise is equal to or lower than the predetermined threshold. 
     When having determined that the level of environmental noise is relatively low and voice recognition performance necessary for dictation can be obtained, the control unit  1  causes the presentation control unit  1   a  to light the LED  48  in blue (step S 35 ). Subsequently, the control unit  1  determines whether the lighting has continued for a predetermined time period (for example, 30 seconds) (step S 36 ). When the lighting in blue has continued for the predetermined time period, the control unit  1  transitions to step S 37  to turn off the LED  48 , and ends the processing. Note that the processing is returned to step S 33  until the blue lighting time period becomes equal to the predetermined duration. 
     Consider a situation, as illustrated in  FIG. 12B , in which an air conditioning apparatus  85  exists in a direction in the sound collection range Dw and generates noise  86  at relatively high level. In such a case, the level of environmental noise potentially becomes higher than the predetermined threshold. When having determined that the level of environmental noise is relatively high and voice recognition performance necessary for dictation cannot be obtained, the control unit  1  causes the presentation control unit  1   a  to flash the LED  48  in red (step S 41 ).  FIG. 11B  illustrates flashing control of the LED  48  in such a case. In the example illustrated in  FIG. 11B , relatively fast flashing is performed at intervals of 100 ms (milliseconds). 
     Based on the relatively fast flashing of the LED  48  in red, the user  81  can recognize, before dictation work, that the level of environmental noise is high and sufficient voice recognition performance cannot be obtained. The control unit  1  determines whether the fast flashing has continued for a predetermined time period (for example, 30 seconds) (step S 42 ). When the fast flashing in red has continued for the predetermined time period, the control unit  1  transitions to step S 43  to turn off the LED  48 , and ends the processing. Note that the processing is returned to step S 33  until the red flashing time period becomes equal to the predetermined duration. 
     In the present embodiment as described above, the level of environmental noise is determined and the result of the determination is presented to the user before start of dictation work. Accordingly, the user can check in advance of the dictation work, for example, whether voice recognition performance necessary for dictation can be obtained. 
     In addition, in the present embodiment, scanning for specifying a direction to an environmental noise source can be performed to improve voice recognition performance. At step S 6 , the control unit  1  narrows the sound collection range of the microphone unit  2   a  and changes the sound collection range to determine environmental noise. The control unit  1  determines the posture of the housing  10   a  based on an output from the posture determination unit  4 . For example, the control unit  1  determines a state of a predetermined posture of the housing  10   a , which is determined by the posture determination unit  4 , to be a reference posture in, for example, an orthogonal coordinate system. Then, the control unit  1  determines each beam direction of the microphone unit  2   a  with respect to the reference posture, calculates environmental noise for each beam direction, and records the calculated environmental noise as noise distribution information in the noise information recording unit  11 . That is, the noise distribution information is obtained by calculating noise direction and intensity as noise distribution in a duration in which environmental noise is determined. 
       FIG. 12C  illustrates scanning for specification of the direction of a noise source, in which the microphone unit  2   a  has a sufficiently narrow sound collection range Dnm. In the example illustrated in  FIG. 12C , the air conditioning apparatus  85  is positioned in a direction of the sound collection range Dnm, and thus the level of environmental noise is relatively high in the sound collection range Dnm due to the noise  86 . The control unit  1  obtains, as noise distribution information, distribution in the direction of each noise source and the level of noise due to the noise source with respect to the reference posture by changing the beam direction while the sound collection range of the microphone unit  2   a  is narrowed down. 
     At step S 7 , the control unit  1  determines whether the scanning is performed in every direction in which the scanning can be performed. The control unit  1  repeats the processing at steps S 6  and S 7  until the scanning is performed in all directions. When the scanning ends in all directions, at step S 8 , the control unit  1  records, in the noise information recording unit  11 , the noise distribution information obtained for each direction and emits warning depending on a result of the scanning. For example, when it is determined, for all scanning directions, that the level of an environmental noise source is higher than a predetermined threshold and voice recognition performance necessary for dictation cannot be obtained, the control unit  1  causes the presentation unit  6  to perform display or output sound indicating the determination. Alternatively, the presentation unit  6  may present a direction in which an environmental noise source at a level equal to or higher than a predetermined level exists. 
     Next, consider a case in which the user  81  specifies the sound recording mode to start dictation work. When having determined that the sound recording mode is specified at step S 1 , the control unit  1  determines whether the level of environmental noise is lower than a predetermined threshold at step S 11 . When the level of environmental noise is lower than the predetermined threshold, for example, when it is determined that the level of environmental noise is relatively low at step S 4 , the control unit  1  transitions to step S 20  where the control unit  1  performs sound collection while a wide sound collection range is set, transmits collected voice or the like through the communication unit  5 , and records the collected voice or the like in the dictation apparatus  20 . Since the level of environmental noise is relatively low in this case, sufficient voice recognition performance is expected to be obtained. 
     For example, as illustrated in  FIG. 12A , the user  81  grasps the housing  10   a  with the right hand  82 R and speaks while the mouth  83  is positioned close to the microphone unit  2   a . The sound collection unit  2  acquires voice of the user  81  and outputs, to the control unit  1 , intact voice data acquired by the microphones  2   al  and  2   a   2 , voice data after being subjected to directionality control by the directionality control unit  2   b , and voice data after being subjected to noise removal by the NR unit  2   c . Note that the sound collection unit  2  also outputs directionality information related to directionality and NR information related to noise reduction processing to the control unit  1 . The control unit  1  externally transmits various kinds of voice data from the sound collection unit  2  through the communication unit  5  directly or after being subjected to sound quality adjustment by the sound quality adjustment unit  7 . Note that the control unit  1  may also externally transmit directionality information, NR information, and filter information recorded in the filter information recording unit  9  through the communication unit  5 . 
     When having determined that the level of environmental noise is equal to or higher than the predetermined threshold at step S 11 , the control unit  1  sets a predetermined beam direction with a narrow sound collection range and starts voice recording at step S 12 . For example, the beam direction may be a direction at an angle θ illustrated in  FIG. 4 . 
       FIG. 12D  illustrates a state in which sound collection is performed in a narrow sound collection range. A sound collection range Dn 1  is sufficiently narrow to allow sound recording with reduced influence of a noise source existing in any direction other than the sound collection range Dn 1 . In this case, too, the sound collection unit  2  acquires voice of the user  81 , and obtains intact voice data acquired by the microphones  2   al  and  2   a   2  and voice data after being subjected to directionality control by the directionality control unit  2   b . At step S 13 , the NR unit  2   c  predicts noise and obtains a result of noise determination. The control unit  1  records the result of the noise determination at the NR unit  2   c  as the noise information in the noise information recording unit  11 . 
     Note that the noise information is recorded at each directionality change. Alternatively, the control unit  1  sequentially calculates the noise information in the duration of sound collection, in other words, as the noise information, the result of the noise determination by the NR unit  2   c  in each time period since start of sound collection. 
     The NR unit  2   c  removes noise in a voice signal by using the noise determination result (step S 14 ), and outputs voice data after being subjected to the noise removal to the control unit  1 . Note that the control unit  1  also records, in the noise information recording unit  11 , NR information related to the noise reduction processing by the NR unit  2   c.    
     The control unit  1  externally transmits various kinds of voice data from the sound collection unit  2  through the communication unit  5  directly or after being subjected to sound quality adjustment by the sound quality adjustment unit  7 , and records the voice data in the dictation apparatus  20  (step S 15 ). The control unit  1  may also externally transmit directionality information, NR information, and filter information recorded in the filter information recording unit  9  through the communication unit  5 . 
     At step S 16 , the control unit  1  determines whether the level of environmental noise becomes higher than the level of environmental noise at start of sound recording. Note that, at step S 16 , the control unit  1  may determine whether a level of a voice component in voice data becomes lower than the level of the voice component at start of sound recording. At sound recording, the user  81  speaks while grasping the housing  10   a  of the sound collection apparatus  10  with a hand, and thus, the sound collection range potentially changes when the posture of the housing  10   a  changes halfway through the sound recording. For example, as illustrated in  FIG. 12E , the sound collection range of the microphone unit  2   a  changes from the sound collection range Dn 1  to a sound collection range Dn 2  as the posture of the housing  10   a  changes, and as a result, the air conditioning apparatus  85  as a noise source is positioned in a direction of the sound collection range Dn 2 . Accordingly, the level of environmental noise becomes higher due to influence of the air conditioning apparatus  85 , which can lead to degraded voice recognition performance. 
     When having determined that the level of environmental noise has become higher, the control unit  1  transitions to step S 17  to adjust directionality. That is, the control unit  1  performs directionality control through the directionality control unit  2   b  based on a position of any noise source indicated by noise distribution information recorded in the noise information recording unit  11  and posture information from the posture determination unit  4  so that the sound collection range does not include a direction of the noise source. Accordingly, the level of environmental noise becomes lower, which leads to improved voice recognition performance. Note that the control unit  1  may perform directionality control to align the sound collection range of the microphone unit  2   a  at start of sound recording only based on the posture information from the posture determination unit  4 . After having adjusted directionality at step S 17 , the control unit  1  returns to step S 13  to continue sound recording. 
     That is, with the above-described configuration, noise in dictation is determined by changing directionality by a directionality control unit configured to control directionality of a sound collection unit including a plurality of microphones. When the noise is larger than a predetermined level (predetermined reference value), a sound collection direction can be changed while a sound collection range of the sound collection unit is set to be a second range smaller than a first range by the directionality control unit, thereby obtaining favorable dictation voice. That is, an S/N ratio of dictation voice and environmental noise can be improved by restricting an effective range at sound collection. A noise level, which is a generalized term used in the present specification, is obtained through digitalization of a value using an index based on experiment of noise in an office, such as noise criteria (NC) value proposed by acousticians, or a value used for determination of, for example, air conditioning with steady noise having a wide band spectrum. For example, noise may be determined based on a sound pressure level by using NC-40, which is a level at which telephone voice can be recognized, as a reference value. Such a setting is applicable when a level of recognition on microphone is designed to be equivalent to a level of recognition on telephone. Not only the NC-40 needs to be used as a reference value, but analog determination may be employed in accordance with a sound pressure and a frequency. These methods may be switched in accordance with directionality. Alternatively, a fraction of a dynamic range of a microphone may be set as a reference value, or, for example, a maximum sound pressure of voice of a person using a device may be determined, and the maximum measured sound pressure thus determined and an S/N ratio of environmental noise determined at the pressure may be set as a noise level. That is, a reference value may be determined based on a noise level that allows dictation when such a microphone sensitivity or circuit gain is set that voice does not exceed the dynamic range at dictation with maximum voice. In this manner, distribution of noise at dictation can be determined. Thus, when means or procedure for determining the distribution, and means or procedure for recording information of the noise distribution are provided, directionality and the like can be controlled based on the noise distribution to achieve extremely highly reliable dictation voice collection by providing a procedure of performing sound collection while causing the directionality control unit to control a sound collection direction of the sound collection unit so that a noise level at the sound collection unit is lower than a predetermined level (which may be, as described above, set with reference to, for example, the dynamic range of a microphone or the NC value, and may be changed in accordance with directionality, performance of the microphone, or a frequency range for determining voice of a speaker) based on a result of determination of a posture of the sound collection unit and the information of the noise distribution. That is, the directionality can be changed by switching the directionality to improve a ratio (S/N ratio) of dictation voice and environmental noise in sound pressure or the like and decrease an observed value of environmental noise. 
     At step S 18 , the control unit  1  determines whether a sound recording end operation has been performed. When the sound recording end operation has not been performed, the control unit  1  returns to step S 11 . When having detected that the sound recording end operation has been performed, the control unit  1  instructs generation of a voice file at step S 19 . That is, end of sound recording is notified to the dictation apparatus  20  through the communication unit  5 , and the dictation apparatus  20  generates a file of received voice data. The dictation apparatus may record, for example, a microphone characteristic and noise information. 
       FIG. 13  is an explanatory diagram illustrating an exemplary configuration of a voice file that can be generated from data transmitted from the sound collection apparatus  10 . 
     In the example illustrated in  FIG. 13 , the voice file includes a file name, primary voice data, secondary voice data, and voice data after being subjected to noise reduction (NR). In addition, the voice file includes auxiliary data such as date and time information, correction information, microphone characteristic information, NR information, directionality information, and noise information for each directionality. Note that the primary voice data and the secondary voice data are voice data after being subjected to directionality control. The voice file may include two pieces of voice data from the microphones  2   al  and  2   a   2  not subjected to directionality control. 
     Note that, in  FIG. 9 , the directional characteristic is adjusted in accordance with environmental noise at sound recording for dictation. However, the sound recording may be performed in a state with a directional characteristic set by the user. 
     (Dictation) 
       FIG. 14  illustrates dictation processing executed by the dictation apparatus  20  illustrated in  FIG. 2 . Note that the processing illustrated in  FIG. 14  may be executed by, for example, a computer on a cloud (not illustrated). For example, the recording unit  24  of the dictation apparatus  20  records, in addition to each data illustrated in  FIG. 13 , a voice file including two pieces of voice data from the microphones  2   a   1  and  2   a   2  not subjected to directionality control. 
     At step S 31 , the control unit  21  determines whether a voice file as a dictation target is acquired in the recording unit  24 . When no voice file is acquired, the control unit  21  waits for the acquisition at step S 32 . When a voice file as a dictation target is acquired, the control unit  21  reproduces voice data (NR sound) from the recording unit  24 , which is subjected to noise reduction (step S 33 ). At step S 34 , the control unit  21  controls the text generation unit  23  to generate characters from the voice data. Subsequently at step S 35 , the document generation unit  21   c  determines whether the generated character text can be determined as an item of a document to be generated and a content of the item. When the determination is possible, the document generation unit  21   c  generates a document from voice generated in text at step S 36 . At step S 37 , the control unit  21  determines whether the document generation has ended. When the document generation has not ended, the control unit  21  returns to step S 33 . When the document generation has ended, the control unit  21  records the generated document in the recording unit  24  at step S 38 . 
     When, at step S 35 , the document generation unit  21   c  determines that the generated character text cannot be used to generate a document, the control unit  21  performs noise reduction processing again at steps S 41  to S 47  and tries document generation. The noise reduction processing potentially removes not only the noise component but also the voice component. Thus, the control unit  21  determines whether noise information is recorded to generate information before being subjected to the noise reduction processing (step S 41 ). When the noise information acquired at step S 13  in  FIG. 9  is transferred to the dictation apparatus  20  and recorded in the recording unit  24 , at step S 42 , the voice processing unit  21   b  sequentially adds noise obtained from the noise information to a voice signal in each time period to produce a voice signal before being subjected to the noise reduction processing, and then executes voice recognition again. Subsequently, the text generation unit  23  and the document generation unit  21   c  try document generation at steps S 45  to S 47 , and then transition to step S 37 . Note that the processing at steps S 45  to S 47  is identical to the processing at steps S 34  to S 36 , respectively. 
     When having determined that no noise information is recorded at step S 41 , the control unit  21  determines whether the primary voice data and the secondary voice data before being subjected to the noise reduction processing are recorded in the recording unit  24  at step S 43 . When the data is recorded, the voice processing unit  21   b  executes the noise reduction processing using the primary voice data and the secondary voice data to remove noise. Subsequently, the text generation unit  23  and the document generation unit  21   c  try document generation at steps S 45  to S 47 , and then transition to step S 37 . 
     Note that, when having determined that the generated character text cannot be used for document generation at steps S 41  and S 46 , the control unit  21  transitions to step S 37  without generating a document. 
     In the present embodiment as described above, when sound collection for dictation is performed by the sound collection apparatus, the level of environmental noise is determined, and a result of the determination is presented to the user. Accordingly, the user can check in advance of dictation work, for example, whether voice recognition performance necessary for dictation can be obtained, thereby preventing unnecessary speech. Since the direction of any noise source can be specified and presented, it is possible to obtain knowledge for improving environment necessary for dictation. Information on distribution of noise sources can be held to control the sound collection range so that noise is reduced or a level of target voice becomes higher, thereby achieving improved voice recognition performance. In addition, the sound collection apparatus in the present embodiment can perform the noise reduction processing on acquired voice and then output resulting voice data, and can also output not only a voice signal after being subjected to noise reduction but also a voice signal before being subjected to noise reduction and noise information. Accordingly, in an apparatus that executes dictation processing, when voice recognition processing on voice after being subjected to the noise reduction processing has low recognition accuracy, the recognition accuracy can be improved by newly performing noise reduction processing and voice recognition processing by using a voice signal before being subjected to the noise reduction processing and noise information. 
     A noise level, which is a generalized term used in the present specification, may be a value using an index based on experiment of noise in an office, such as NC (noise criteria) value proposed by acousticians. That is, noise may be determined based on a sound pressure level by using the NC-40 described above or the like as a reference value. The NC-40 can be used for determination of, for example, air conditioning with steady noise having a wide band spectrum. Not only the NC-40 needs to be used as a reference value, but analog determination may be employed in accordance with a sound pressure and a frequency. These methods may be switched in accordance with directionality. Alternatively, a fraction of a dynamic range of a microphone may be set as a reference value, or, for example, a maximum sound pressure of voice of a person using a device may be determined, and the maximum measured sound pressure thus determined and an S/N ratio of environmental noise determined at the pressure may be set as a noise level. 
     The present invention is not limited to the above-described embodiments. When the present invention is performed, any component may be deformed and realized without departing from the scope of the present invention. In addition, various kinds of inventions may be achieved through appropriate combination of a plurality of components disclosed in the above-described embodiments. For example, some of all components indicated in the embodiments may be deleted. 
     Note that, when any operation processes in the claims, the specification, and the drawings are described with words such as “first” and “subsequently” for sake of convenience, it is not essential to perform the processes in the stated order. Part of each step in the operation processes, which does not affect the gist of the invention may be omitted as appropriate. 
     Note that, among technologies described above, control mainly described with a flowchart can be often set by a computer program that is recorded in a semiconductor recording medium, any other recording medium, or a recording unit in some cases. The recording to the recording medium or the recording unit may be performed at product shipment, performed by using a distributed recording medium, or performed by downloading through the Internet. External devices may cooperate as necessary to replace some functions and determination. 
     [Note 1] 
     A sound collection method includes: a procedure of collecting sound by a sound collection unit including a microphone; a procedure of determining noise in dictation while a sound collection range of the sound collection unit is set to be a first range by a directionality control unit configured to control directionality of the sound collection unit including a plurality of microphones; and a procedure of performing the sound collection for dictation while the sound collection range of the sound collection unit is set to be a second range smaller than the first range by the directionality control unit. 
     [Note 2] 
     A sound collection method including a procedure of collecting sound by a sound collection unit including a microphone; a procedure of determining noise in dictation while sound collection range of the sound collection unit is set to be a first range by a directionality control unit configured to control directionality of the sound collection unit including a plurality of microphones; and a procedure of performing, when the noise in dictation is larger than a predetermined level, the sound collection for dictation while the sound collection range of the sound collection unit is set to be a second range smaller than the first range by the directionality control unit. 
     [Note 3] 
     In Note 2, the sound collection method further including: a procedure of determining distribution of the noise in dictation by changing a sound collection direction, a procedure of recording information of the noise distribution; and a procedure of performing sound collection by causing the directionality control unit to control a sound collection direction of the sound collection unit so that a level of noise at the sound collection unit becomes smaller than a predetermined level based on a result of determination of a posture of the sound collection unit and the information of the noise distribution.