JP2008292684A - Sound recording and reproduction device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound recording and reproduction device which has better recording quality than a conventional device. <P>SOLUTION: The sound recording and reproduction device comprises: a sound taking means for taking sound; a level detecting means in which sound is quantized as a sound signal, and which detects the output frequency of the sound signal having a larger level than a predetermined level, in the sound signal taken during a predetermined period; a storage means in which the output frequency of the sound signal having the larger level than the predetermined level is stored during the predetermined period, as a predetermined threshold based on a classification on a recording object or a distance to the recording object; and a sound volume determination means for recording the sound by performing comparison based on the frequency detected by the level detection means and the predetermined threshold stored in the storage means, while determining whether or not, a sound volume of the sound generated in an actual recording object is larger than the predetermined sound volume which is set beforehand according to the predetermined threshold. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an audio recording / reproducing apparatus, and more particularly to an audio recording / reproducing apparatus having a function capable of determining a distance to a recording target.

  As is well known, portable audio recording / reproduction in which an audio signal is converted into digital data, then stored in a flash memory as a rewritable recording medium, and the audio data recorded in the flash memory is converted into analog data and reproduced. An apparatus (hereinafter referred to as an IC recorder) has been put into practical use since the late 1990s. More recently, IC recorders as music players capable of reproducing music files such as WMA and MP3 with high sound quality have been commercialized. And as a technique applicable in these IC recorders, there exists a technique described in patent document 1, for example.

Specifically, Patent Document 1 describes a technique for correcting a gain in accordance with a distance to a recording target in an input device of a voice recognition device.
JP 59-65900 A

  However, Patent Document 1 only describes the use of the distance to the recording target as a parameter for gain correction, and does not take into account the magnitude of the volume emitted from the recording target. There is a problem that the volume of the sound is not constant.

  Specifically, for example, when the sound volume generated at the recording object is small even though the distance to the recording object is short, the sound volume in the recorded sound becomes small. As a result, when the recorded sound is reproduced, it is necessary to increase the volume to a level sufficient for listening, and sound cracking may occur as the volume increases.

  The present invention has been made in view of the above circumstances, and in addition to the type of recording target or the distance to the recording target, in addition to performing the operation in consideration of the sound volume generated in the recording target, An object of the present invention is to provide an audio recording / reproducing apparatus capable of improving recording quality.

  In order to achieve the above-described object, the audio recording / reproducing apparatus of the present invention uses an audio acquisition means for acquiring audio and a sampling frequency corresponding to the sensitivity at the time of acquiring the audio as a quantum signal as the audio signal. And level detection means for detecting the number of times that an audio signal having a level greater than a predetermined level is output among the audio signals acquired within a predetermined time, and the type of recording target or the recording target As a predetermined threshold value determined in advance based on the distance, the number of times that an audio signal having a level larger than the predetermined level is output within the predetermined time is stored, and the level detecting unit detects the sound signal. In addition, a comparison is made based on the number of times and the predetermined threshold value stored in the storage means, so that Volume of the sound, characterized in that anda volume determination means for performing recording while determining whether greater than a predetermined volume which is set in advance according to the predetermined threshold value.

  According to the audio recording / reproducing apparatus of the present invention, the recording quality is improved as compared with the prior art by performing the operation in consideration of the type of the recording target or the distance to the recording target and the volume emitted from the recording target. It is possible to make it.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 8B relate to an embodiment of the present invention. FIG. 1 is a block diagram showing a configuration of a main part of an audio recording / reproducing apparatus as an embodiment of the present invention. FIG. 2 is a diagram showing a block configuration of a main part of an IC recorder configured with the audio recording / reproducing apparatus of FIG. FIG. 3 is a flowchart showing the main operation of the IC recorder of the present embodiment. FIG. 4 is a diagram showing a block configuration of functions related to a recording operation in the IC recorder of FIG. FIG. 5A is a diagram illustrating a correlation among an input audio signal, a dynamic range of an A / D converter, and a threshold value used in a comparison process performed by a magnitude comparator. FIG. 5B is a diagram illustrating a correlation between the distance from the speaker to the microphone and the voltage value output from the distance detection circuit. FIG. 6 is a flowchart showing a recording process performed in the IC recorder of the present embodiment. FIG. 7 is a flowchart showing a subroutine of the speaker distance detection process in FIG. FIG. 8A is a diagram illustrating an appearance of an upper surface portion in the IC recorder of the present embodiment. FIG. 8B is a diagram showing an appearance of the front surface portion of the IC recorder of the present embodiment.

  As shown in FIG. 1, the audio recording / reproducing apparatus 101 of this embodiment compares the size of an dictation audio signal amplified by a microphone amplifier (not shown in FIG. 1) with a predetermined criterion value. Audio signal level detection means 1 and recording target determination means 2 for discriminating and specifying a recording target based on the number of times that an audio signal equal to or higher than the determination reference value detected by the audio signal level detection means 1 is input within a predetermined time. And a speaker distance ranging means 3 for measuring the distance from the microphone provided on one end surface of the voice recording / reproducing apparatus 101 to the speaker, and a distance signal output from the speaker distance ranging means 3 are determined in advance. The distance to the recording target is determined based on the correlation between the speaker distance detection means 4 for comparing the predetermined determination reference value and the distance signal detected by the speaker distance detection means 4 and the determination reference value. And specific Recording control for optimizing the level of the voice signal based on the determination result of the speaker distance determination means 5 and the determination result of the recording target determination means 2 and the determination result of the speaker distance determination means 5. The main part is composed of means 6 and encoding means 7 for encoding the audio signal into audio data of a bit rate corresponding to a predetermined sampling frequency based on the control of the recording control means 6. Yes.

  FIG. 2 shows a block configuration of a main part of an IC recorder configured with the audio recording / reproducing apparatus of FIG.

  The IC recorder 102 of the present embodiment configured to include the above-described audio recording / reproducing apparatus 101 includes a microphone (MIC) 11 that converts audio into an electric signal. The sound output from the microphone (MIC) 11 is amplified by a subsequent microphone amplifier (AMP) 12.

  An analog audio signal amplified by the microphone amplifier (AMP) 12 is input to an A / D converter (ADC) 14 after an unnecessary frequency band is cut by a low-pass filter (LPF) 13.

  The audio signal converted into a digital signal by the A / D converter (ADC) 14 is input to a digital signal processing unit (DSP) 24. The digital signal processing unit (DSP) 24 is controlled by the system control unit 21, and at the time of recording, the audio signal converted into a digital signal by the A / D converter (ADC) 14 is encoded in a predetermined encoding unit for each frame. Are encoded (compressed). The audio data is temporarily stored in a buffer memory (not shown) of the system control unit 21.

  On the other hand, the digital signal processing unit (DSP) 24 is controlled by the system control unit 21. During reproduction, the digital signal processing unit (DSP) 24 reads audio data from a buffer memory (not shown) of the system control unit 21 and reads the audio data in units of frames. Decrypt (decompress). The decoded digital audio signal is converted to an analog signal by a D / A converter (DAC) 15, an unnecessary frequency band is cut by a low-pass filter (LPF) 16, and a power amplifier (AMP) 17 is used. After being amplified, it is output from the speaker (SP) 18 as sound.

  In addition to the digital signal processing unit (DSP) 24, the system control unit 21 configured with a CPU 46 and the like described later includes a storage unit (memory) 23, an operation unit 22, a display unit 20, and a distance. A detection unit 19 is connected.

  The storage unit (memory) 23 is configured by a nonvolatile semiconductor memory such as a flash memory, for example. The storage unit (memory) 23 stores the audio data encoded by the digital signal processing unit (DSP) 24 through a buffer memory (not shown) of the system control unit 21 during recording. At this time, the storage unit (memory) 23 also stores index information related to the audio data in addition to the audio data.

  The operation unit 22 includes a recording switch (REC), a playback switch (PLAY), a stop switch (STOP), a fast forward switch (FF), a fast reverse switch (REW), a menu switch (MENU), a hold switch (HOLD), and the like. Various switches are arranged according to function.

  The display unit 20 displays an operation mode when a predetermined sequence is started or a subsequent operation state by any switch operation of the operation unit 22. For example, when the recording switch (REC) is pressed, the display unit 20 displays an elapsed recording time, a remaining recording time, a file number, and the like. When the menu switch (MENU) is pressed, the display unit 20 selects functions such as microphone sensitivity (conference / dictation), recording mode (HQ / SP / LP), and alarm (on / off). Perform related display. Further, when the system control unit 21 has a clock function, the display unit 20 also displays a calendar of the current date and time.

  The distance detection unit 19 is composed of an active distance measuring module in which a light projecting / receiving unit is paired. The distance detector 19 outputs a distance signal such as a voltage value proportional to or inversely proportional to the distance from the speaker to the microphone, for example, by a series of distance measuring sequences described later. Of course, the distance measuring module may be formed of a passive distance measuring module that is easy to handle and has excellent distance measuring performance as long as cost and the like are acceptable.

  Next, the operation of the IC recorder 102 of this embodiment will be described with reference to the flowchart of FIG.

  When the IC recorder 102 is powered on, the system control unit 21 performs predetermined initial settings (step S1) and timer start (step S2). The timer measures the time for the IC recorder to shift from the normal operation mode to the standby mode (low current consumption mode) after a predetermined time has elapsed.

  When the IC recorder 102 shifts to the operation mode, the system control unit 21 performs a recording switch (REC), a playback switch (PLAY), a fast-forward switch (FF), a switch detection operation shown in steps S3 to S8 and S18. It is detected whether there is a switch that is turned on in the order of the fast reverse switch (REW), the stop switch (STOP), the menu switch (MENU), and the erase switch (ERASE).

  When the turned-on switch is the recording switch (step S3), the system control unit 21 executes a recording processing subroutine (step S11). Further, the system control unit 21 executes a subroutine (step S12) of the reproduction process when the turned-on switch is the reproduction switch (step S4), and when the turned-on switch is the fast-forward switch (S5). Executes a fast-forward process subroutine (step S13), and if the turned-on switch is a rewind switch (step S6), executes a fast-rewind process subroutine (step S14), and the turned-on switch is a stop switch. If it is (step S7), a stop processing subroutine (step S15) is executed, and if the turned-on switch is a menu switch (step S8), a menu change processing subroutine (step S16) is executed. When the turned on switch is an erase switch (step S18) Executing the processed subroutine (step S19). When any one of the subroutines is executed, the system control unit 21 returns to the main loop while restarting the timer (step S17).

  The fast-forward process, the fast-rewind process, the stop process, the menu change process, and the erase process are performed by using well-known technical means, and thus detailed description thereof will be omitted.

  On the other hand, if all the switches are off, the process proceeds to the standby mode subroutine (step S10) at the timing when the time measured by the timer exceeds the predetermined time (step S9).

  The IC recorder 102 performs an operation corresponding to the low current consumption operation in the standby mode. Specifically, the system control unit 21 includes a microphone (MIC) 11, a microphone amplifier (AMP) 12, a low-pass filter (LPF) 13, an A / D converter (ADC) 14, and a D / A converter (DAC) 15. , Low-pass filter (LPF) 16, power amplifier (AMP) 17, digital signal processing unit (DSP) 24, display unit 20, and storage unit (memory) 23 are turned off, or each block is not shown. By outputting a non-selection signal to a chip enable terminal provided in the IC, each block is caused to perform an operation corresponding to a low current consumption state.

  At this time, the system control unit 21 performs an operation for switching its own operation clock to a low-speed clock with a small current consumption as an operation corresponding to the low current consumption state. The system control unit 21 switches the operation clock from the main clock (for example, 16.384 MHz) to the sub clock (for example, 32.768 kHz) as an operation corresponding to the low current consumption state, and thereafter, until a switch input is detected. May perform an operation that completely stops the main clock.

  As shown in FIG. 4, the audio signal VIN input from the microphone (MIC) 11 in FIG. 2 is approximately R2 / R1 times by an amplifier circuit including an operational amplifier 40, a capacitor C1, a capacitor C2, a resistor R1, and a resistor R2. Are then output to a low-pass filter (LPF) 41. The resistor R1 is composed of a variable resistor such as an electronic volume that can increase or decrease its own resistance value in accordance with a control signal GCNT output from the CPU 46.

  At this time, an auto gain control (AGC) constituted by a negative feedback circuit is provided between the input and output of the amplifier circuit so that the amplitude of the audio signal VLO does not exceed the input dynamic range of the A / D converter 43 described later. 42 is added. The excessive input of the audio signal VIN is automatically suppressed by the action of the auto gain control (AGC) 42.

  The audio signal VLO passes through an anti-aliasing low-pass filter (LPF) 41 that operates at a cutoff frequency approximately 0.45 times the sampling frequency, so that an audio signal in a high frequency band unnecessary for quantization is attenuated. And removed. The audio signal in the frequency band lower than the cut-off frequency that has passed through the low-pass filter (LPF) 41 is quantized (A / D) at each sampling period by the A / D converter (ADC) 43 in the subsequent stage. Conversion) and at the same time being converted into a digital audio signal of at least 14 bits and output to a digital signal processing unit (DSP) 44.

  A sampling frequency fs is supplied to the low-pass filter (LPF) 41, the A / D converter (ADC) 43, and the digital signal processing unit (DSP) 44.

The digital signal processing unit (DSP) 44 converts the digital audio signal output from the A / D converter (ADC) 43 into audio of a predetermined bit rate according to the combination of the compression rate designated in advance by the CPU 46 and the sampling frequency fs. Encode to data.
The magnitude comparator 45 compares the magnitude of the digital audio signal output from the A / D converter (ADC) 43 with respect to the upper threshold value + VTH and the lower threshold value −VTH for each sampling period. The comparison result is output to the CPU 46 as an audio signal level detection signal. Specifically, as shown in FIG. 5A, the magnitude comparator 45 generates an audio signal VLO that amplitudes approximately symmetrically with respect to the operation reference voltage AVREF of the operational amplifier 40 within the dynamic range of the A / D converter (ADC) 43. Compares the magnitudes of how large or small the upper threshold + VTH and the lower threshold −VTH are. It is assumed that the dynamic range of the A / D converter (ADC) 43 is shown as a range from ADIN (MIN) to ADIN (MAX) in FIG. 5A. Furthermore, in the dynamic range, it is assumed that VCC> ADIN (MAX) and ADIN (MIN)> GND.

  When the sound input to the microphone (MIC) 11 is relatively loud, the sound signal VLO amplifies beyond the upper threshold value + VTH and the lower threshold value −VTH (ADIN (MAX)> VLO ≧ + VTH, and − VTH ≧ VLO> ADIN (MIN)). When the sound input to the microphone (MIC) 11 is relatively small, the amplitude of the sound signal VLO converges within the range of the upper threshold value + VTH and the lower threshold value −VTH (+ VTH> VLO> −VTH). ).

  On the other hand, the threshold value comparison unit 54 compares the magnitude of the distance signal such as the voltage value output from the active distance measuring module 47 with respect to the threshold value VTH at regular intervals. The comparison result is output to the CPU 46 as a speaker distance detection signal. Specifically, as shown in FIG. 5B, the threshold comparison unit 54 preliminarily outputs a voltage value VDS inversely proportional to the distance from the speaker to the microphone, which is output from the distance detection circuit 48 in the active distance measuring module 47, and A magnitude comparison with a threshold value VTH corresponding to the determined microphone sensitivity optimum adjustment distance limit is performed.

  The CPU 46 determines the distance from the speaker to the microphone based on the comparison result output from the threshold comparison unit 54. That is, based on the correlation between the predetermined voltage value VDS and the distance, the CPU 46 determines that the distance from the speaker to the microphone is close when VDS ≧ VTH, and from the speaker when VDS <VTH. It is determined that the distance to the microphone is long.

  At this time, the active distance measuring module 47 projects the infrared light generated in the light projecting unit including the infrared LED 50 and the light projecting lens 51 to the speaker 53 at regular intervals, and also receives the light receiving element 49 and the light receiving unit. The reflected light of the infrared light is received by the light receiving unit including the lens 52. Then, the distance detection circuit 48 outputs the voltage value VDS by amplifying the incident angle and light quantity of the reflected light received by the light receiving unit.

  Note that the active type distance measurement and the distance measurement algorithm in the distance measurement are performed using a technique well known in autofocus control of a camera or the like, and thus detailed description thereof will be omitted.

  Next, the recording process in this embodiment will be described mainly with reference to the flowchart of FIG.

  When the recording process is started, various information such as microphone sensitivity (conference / dictation), recording mode (HQ / SP / LP), file number, and voice data storage area start address for storing the voice data are first stored. It is stored in the index information area of the section (memory) 23 (step S30). Next, microphone sensitivity is selected by speaker distance detection processing (step S31) described later, and the distance from the speaker to the microphone is determined by the active distance measuring module 47.

  When the microphone sensitivity is “conference”, or when the microphone sensitivity is “dictation” and VDS ≧ VTH, the process proceeds to step S34 described later. When the stop switch (STOP) is turned on (step S32), the recording is ended by the recording end process (step S44).

  Note that the microphone sensitivity of the present embodiment is such that “conference” corresponds to high sensitivity and “dictation” corresponds to low sensitivity. In the recording mode of this embodiment, “HQ” corresponds to the sampling frequency for the high bit rate, “SP” corresponds to the sampling frequency for the medium bit rate, and “LP” corresponds to the sampling frequency for the low bit rate. Suppose you are.

  The audio signal is quantized (A / D converted) at each sampling period of the sampling frequency fs in the selected recording mode (step S33), and then encoded by the digital signal processing unit (DSP) 44 (step S34). ). Note that the encoding by the digital signal processing unit (DSP) 44 is performed in units of frames and continuously performed until the audio data reaches a predetermined number of frames.

  Then, when the audio data stored in the buffer memory (not shown) included in the CPU 46 reaches a predetermined number of frames (step S35), the CPU 46 stores the audio data of the predetermined number of frames in the audio of the storage unit (memory) 23. The data is written and stored in the data storage area (step S36). Specifically, for example, when audio data obtained by encoding an audio signal of 14 bits / frame up to 4 bits / frame is written to the storage unit (memory) 23 in units of 512 bytes, the predetermined number of frames is 1024.

  If audio data of a predetermined number of frames is not accumulated in the storage unit (memory) 23, whether or not a predetermined time has elapsed after the audio signal level detection necessary for recording target determination is performed (step S37). Is detected (step S38). If the CPU 46 detects that the predetermined time has not elapsed in the process of step S38, the process proceeds to step S33 and the processes from step S33 to step S38 are performed until the predetermined time elapses. Repeatedly.

  On the other hand, in the magnitude comparator 45, the level detection of the quantized audio signal is performed every sampling period. Then, when detecting the elapse of a predetermined time (step S38), the CPU 46 determines a recording target based on a plurality of audio signal level detection signals collected by the magnitude comparator 45 within the predetermined time.

  Specifically, the CPU 46 determines the recording target by comparing and referring to the number of detections of the audio signal level detection signal described above within the predetermined time and the average number of detections for each recording target (step S39). It is assumed that the average number of detection times for each recording target is stored as a default value in a program memory (not shown) of the CPU 46 as a value obtained by actual measurement such as a field test.

  Specifically, for example, the maximum number of audio signal level detection signals detected for 10 seconds from the start of recording of an audio signal quantized with a sampling frequency of fs = 16 kHz is 160000 times. At this time, the CPU 46 determines, as a recording target, a plurality of recording targets in which a detection frequency average value closest to the number of detections of the audio signal level detection signal is detected.

  That is, since the number of detections of the audio signal level detection signal within a predetermined time increases or decreases in proportion to the level of the sound input to the microphone (MIC) 11, the average number of detections for each preset recording target and the sound By comparing and referring to the number of detections of the signal level detection signal, an approximate recording environment can be inferred.

  In the process of step S39 described above, in order to improve the determination accuracy of the recording target, for example, a process using a plurality of detection levels of the audio signal may be performed, or the acquired audio signal The detection interval and the number of detections may be statistically arithmetically processed, and an actual recording target analogy may be performed based on the correlation with the model recording target.

  Furthermore, the recording target for each recording mode may be broadly classified into at least “far dictation recording” and “close dictation recording”. Therefore, the CPU 46 determines “close dictation recording” when the number of detections of the audio signal level detection signal is greater than the above-described average number of detections, and “distant dictation recording” when the number is small. Specifically, for example, in the recording at the sampling frequency of fs = 16 kHz described above, the CPU 46 determines that the voice signal level detection signal detected in 10 seconds is equal to or greater than 10000 [times] “near dictation recording”, 10000 [ When it is less than [times], it is determined as “distant dictation recording”.

  At this time, the distance from the speaker to the microphone can be expressed by a relational expression of VDS = −aD + Vb. Note that “a” in the above relational expression is an arbitrary coefficient related to the distance variable “D”. Further, “Vb” in the above relational expression is an output value when the distance from the speaker to the microphone is closest.

  When the CPU 46 determines that the recording target is “close dictation recording”, the distance from the speaker to the microphone is kept within the microphone sensitivity optimum adjustment distance limit (VDS ≧ VTH), that is, a microphone (MIC). 11 is strong and loud, so even if recording is continued as it is, high quality recording can be obtained.

  On the other hand, when the CPU 46 determines that the recording target is “far dictation recording”, the distance from the speaker to the microphone is not kept within the microphone sensitivity optimum adjustment distance limit (VDS <VTH), that is, Since the sound perceived by the microphone (MIC) 11 may become weak and small, the distance from the speaker to the microphone is determined again by the speaker distance detection process (step S40) described later.

  Here, the speaker distance detection processing will be described mainly with reference to the flowchart of FIG.

  First, when the microphone sensitivity is “conference”, the process immediately returns to the recording process loop from this subroutine (step S50), and the recording is continued. If the microphone sensitivity is “dictation”, whether or not the distance from the speaker to the microphone is kept within the microphone sensitivity optimum adjustment distance limit after the speaker distance detection is executed (step S51). Determination is made (step S52).

  If there is a speaker within the microphone sensitivity optimum adjustment distance limit range based on the determination result of step S52, it is continuously determined whether or not the sound perceived by the microphone (MIC) 11 is sufficiently high ( Step S53). If the sound perceived by the microphone (MIC) 11 is sufficiently loud based on the determination result in step S53, the auto gain control (AGC) 42 performs an operation for suppressing excessive sound input. (Step S54). On the basis of the determination result in step S53, if the sound perceived by the microphone (MIC) 11 is not sufficiently loud, the microphone sensitivity is increased to the optimum sensitivity (step S55), and then this subroutine. To return to the recording processing loop and recording continues.

  Also, based on the determination result of step S52, even when the speaker is within the microphone sensitivity optimum adjustment distance limit range, is the sound perceived by the microphone (MIC) 11 sufficiently loud as in step S53? A determination of whether or not is made (step S56). If the sound perceived by the microphone (MIC) 11 is sufficiently high based on the determination result in step S56, the microphone sensitivity is increased to the optimum sensitivity (step S55), and then the recording process is started from this subroutine. Return to the loop. If the sound perceived by the microphone (MIC) 11 is not sufficiently loud based on the determination result in step S56, a recording impossible warning display is output to the display unit 20 (step S57).

  Then, speaker distance detection is continuously performed (step S58) until the distance from the speaker to the microphone is kept within the microphone sensitivity optimum adjustment distance limit (step S59). Then, in the loop of step S58 and step S59, when the stop switch (STOP) is turned on by the operator (step S60), or the operator notices the recording impossible warning display, and determines the distance from the speaker to the microphone. When the microphone sensitivity is kept within the optimum adjustment distance limit again, the recording impossible warning display is stopped (step S61), the process returns to the recording process loop from this subroutine, and the recording is continued.

  After the speaker distance detection process (step S40) is completed, it is determined whether or not the stop switch (STOP) is turned on (step S41). When the stop switch (STOP) is turned on based on the determination result in step S41, the recording is terminated by executing the recording end process (step S44). Further, if the stop switch (STOP) is not turned on based on the determination result in step S41, there is a high possibility that the distance from the speaker to the microphone has changed, so that the microphone sensitivity is optimized. Adjustment is performed (step S42). Specifically, the CPU 46 outputs the control signal GCNT to the resistor R1, thereby reducing the resistance value of the resistor R1 so that the amplification factor of the audio signal VLO is maximized. Thereby, for example, even when an excessive audio signal VIN is input, the auto gain control (AGC) 42 automatically suppresses the excessive input of the audio signal, so that the amplitude of the audio signal VLO is A / D. The input dynamic range of the converter (ADC) 43 is not exceeded.

  In this manner, until the stop switch (STOP) is turned on (step S43), the processing from step S33 to step S42 is repeatedly performed, whereby the resistance value of the resistor R1 is gradually reduced, and finally The resistance value of R2 / R1 times is determined so that the amplification factor of the audio signal VLO is optimized within the microphone sensitivity optimum adjustment distance limit.

  Here, referring to FIGS. 8A and 8B, a description will be given of a case where oral recording is performed in a situation similar to an interview while actually using the IC recorder 102. FIG.

  As shown in FIG. 8A, on the outer surface of the IC recorder 102, a microphone jack 201, a microphone hole 202, an earphone jack 203, and a light projecting lens 51 and a light receiving lens 52 of the active distance measuring module 47 in FIG. A light projecting / receiving lens unit 204 is provided. Further, the microphone (MIC) 11 of FIG. 2 is disposed directly below the microphone hole 202.

  As shown in FIG. 8B, a recording switch (REC) 207 and one or a plurality of switches (not shown) other than the recording switch (REC) 207 are arranged on the front surface of the IC recorder 102. Yes. The one or more switches (not shown) are not limited to those provided on the front surface of the exterior of the IC recorder 102, and some or all of them are provided on the side surface of the exterior of the IC recorder 102. May be.

  When the recording switch (REC) 207 of the IC recorder 102 is turned on, recording is started. At this time, a display at the beginning of recording is output to the display unit 208 provided on the front surface of the exterior of the IC recorder 102 to notify the operator that the recording operation is in progress. Specifically, the display unit 208 includes, for example, “REC” indicating that recording is in progress, “DICT” indicating that the microphone sensitivity is “dictation”, “00 00 00” indicating the elapsed recording time, and time “H M S” or the like representing the unit is displayed.

  Further, when the microphone sensitivity is “dictation”, notification of the availability of recording is performed based on the above-described reader distance detection determination result. Specifically, for example, when a speaker is outside the microphone sensitivity optimum adjustment distance limit range in which the sound perceived by the microphone (MIC) 11 in FIG. As such, a character string “SPL LOW” is displayed on the display unit 208. The warning display continues to be displayed until the distance from the speaker 53 to the microphone hole 202 is kept within the microphone sensitivity optimum adjustment distance limit.

  The warning display may be displayed, for example, while a character string “SPL LOW” is blinking so that the operator can be notified more clearly that recording is impossible. Moreover, as a warning display method for indicating that recording is impossible, for example, a light emitting display such as an LED may be turned on or blinked.

  As described above, according to the audio recording / playback apparatus of the present embodiment, in addition to the type of the recording target or the distance to the recording target, the operation is performed in consideration of the volume emitted from the recording target. It is possible to improve the recording quality compared to the conventional case.

  Further, according to the audio recording / reproducing apparatus of the present embodiment, it is possible to reliably record the audio to be recorded such as dictation while reducing the portion depending on the experience and knowledge of the operator himself.

  Further, the IC recorder 102 according to the present embodiment can suppress the consumption of the battery energy during recording stop by performing the operation according to the low current consumption state as described above in the standby mode.

  In addition, this invention is not limited to embodiment mentioned above, Of course, a various change and application are possible in the range which does not deviate from the meaning of invention.

(Appendix)
(Additional item 1)
In the recording operation, an audio signal level detecting means for comparing the size of an audio signal to be recorded such as dictation with a predetermined level value determined in advance;
A recording target determining means for determining the recording target based on the number of times of input of a sound signal equal to or higher than the predetermined level value detected by the sound signal level detecting means within a predetermined time;
Speaker distance ranging means for measuring the distance from the sound pickup position of the voice recording / reproducing device to the recording target,
Speaker distance detecting means for comparing the magnitude of the distance signal output from the speaker distance measuring means with a predetermined determination criterion value;
Whether the distance from the sound pickup position of the voice recording / reproducing apparatus to the recording target is within a predetermined distance based on the correlation between the distance signal detected by the speaker distance detecting means and the predetermined determination reference value Speaker distance determining means for determining whether or not
Recording control means for optimizing the audio signal level detected by the audio signal level detection means and controlling recording start / stop based on the determination result of the recording object determination means and the determination result of the speaker distance determination means;
An encoding means for encoding the audio signal into audio data of a bit rate corresponding to a predetermined sampling frequency based on the control of the recording control means;
An audio recording / reproducing apparatus comprising:

(Appendix 2)
The sound recording control means is the sound signal level detecting means when the speaker distance determining means determines that the distance from the sound pickup position of the sound recording / reproducing apparatus to the recording target is within the predetermined distance. 2. The audio recording / reproducing apparatus according to appendix 1, wherein control is performed so that the audio signal level detected by the above becomes equal to or higher than the predetermined level value.

(Appendix 3)
The apparatus further comprises warning means for displaying a warning when it is determined by the speaker distance determining means that the distance from the sound pickup position of the voice recording / reproducing device to the recording target is outside the predetermined distance. The audio recording / reproducing apparatus according to Item 1.

(Appendix 4)
When it is determined by the speaker distance determination means that the distance from the sound pickup position of the voice recording / reproducing device to the recording target is outside the predetermined distance, the operation mode set before the recording operation is started. In response, the audio recording / reproducing apparatus according to item 1, wherein control by the recording control means is temporarily stopped.

The block diagram which showed the structure of the principal part of the audio | voice recording / reproducing apparatus as one Embodiment of this invention. The figure which shows the block structure of the principal part of an IC recorder comprised with the audio | voice recording / reproducing apparatus of FIG. The flowchart which shows the main operation | movement of the IC recorder of this embodiment. The figure which shows the block structure of the function in connection with recording operation in the IC recorder of FIG. The figure which shows the correlation with the audio | voice signal input, the dynamic range of an A / D converter, and the threshold value used in the comparison process which a magnitude comparator performs. The figure which shows the correlation with the distance from a speaker to a microphone, and the voltage value output from a distance detection circuit. The flowchart which shows the recording process performed in the IC recorder of this embodiment. The flowchart which shows the subroutine of the speaker distance detection process in FIG. The figure which shows the external appearance of the upper surface part in the IC recorder of this embodiment. The figure which shows the external appearance of the front part in the IC recorder of this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Audio | voice signal level detection means, 2 ... Recording object determination means, 3 ... Speaker distance ranging means, 4 ... Speaker distance detection means, 5 ... Speaker distance determination means, 6 ... Recording control means, 7 ... Encoding means, 101 ... Audio recording / playback apparatus, 102 ... IC recorder

Claims (7)

Audio capturing means for capturing audio;
While using the sampling frequency corresponding to the sensitivity at the time of capturing the sound, the sound is quantized as a sound signal, and the sound having a level higher than a predetermined level among the sound signals acquired within a predetermined time Level detection means for detecting the number of times the signal is output;
Storage means for storing the number of times that an audio signal having a level larger than the predetermined level is output within the predetermined time as a predetermined threshold that is predetermined based on the type of recording target or the distance to the recording target When,
By performing a comparison based on the number of times detected by the level detection unit and the predetermined threshold value stored in the storage unit, the volume of the sound uttered in the actual recording target is determined to be the predetermined threshold value. Sound volume determination means for recording while determining whether or not the sound volume is higher than a predetermined sound volume set in advance,
An audio recording / reproducing apparatus comprising: Ranging means for outputting information on the distance from the voice capturing means to the actual recording target;
Distance determining means for determining whether or not the distance output by the distance measuring means is within the sensitivity optimum distance that can maintain the optimum sensitivity in the sound capturing means;
When the volume of the sound uttered in the actual recording target is larger than the predetermined volume and the determination result of the distance determination means is within the sensitivity optimum distance, the sound is uttered in the actual recording target. Over-input adjusting means for performing adjustment so as to suppress over-input when the received voice is input to the voice capturing means;
The audio recording / reproducing apparatus according to claim 1, further comprising: Ranging means for outputting information on the distance from the voice capturing means to the actual recording target;
Distance determining means for determining whether the distance output by the distance measuring means is within an optimum sensitivity distance that can maintain the optimum sensitivity in the sound capturing means;
When the volume of the sound uttered in the actual recording target is larger than the predetermined volume and the determination result of the distance determination means is outside the sensitivity optimum distance, the sound is uttered in the actual recording target. Input sensitivity adjusting means for adjusting input sensitivity when the received voice is input to the voice capturing means;
The audio recording / reproducing apparatus according to claim 1, further comprising: Ranging means for outputting information on the distance from the voice capturing means to the actual recording target;
Distance determining means for determining whether the distance output by the distance measuring means is within an optimum sensitivity distance that can maintain the optimum sensitivity in the sound capturing means;
When the volume of the sound uttered in the actual recording target is lower than the predetermined volume and the determination result of the distance determining means is within the sensitivity optimum distance, the sound is uttered in the actual recording target. Input sensitivity adjusting means for adjusting input sensitivity when the received voice is input to the voice capturing means;
The audio recording / reproducing apparatus according to claim 1, further comprising: Ranging means for outputting information on the distance from the voice capturing means to the actual recording target;
Distance determining means for determining whether or not the distance output by the distance measuring means is within the sensitivity optimum distance that can maintain the optimum sensitivity in the sound capturing means;
Recording is impossible when the volume of the voice uttered in the actual recording target is lower than the predetermined volume and the determination result of the distance determination means is outside the optimum sensitivity distance. A warning means for warning,
Further comprising
Based on the determination result of the distance determination means, the warning is stopped when it is determined that the distance from the voice capturing means to the actual recording target has changed from outside the optimum sensitivity distance to within the optimum sensitivity distance. The audio recording / reproducing apparatus according to claim 1. The distance measuring means is
Conversion means for converting information about the distance output from the distance measuring sensor into a signal inversely proportional to the distance from the voice capturing means to the actual recording target;
The distance determining means compares the converted signal converted by the converting means with the signal related to the optimum sensitivity distance so that the distance from the voice capturing means to the actual recording target is within the optimum sensitivity distance. 6. The audio recording / reproducing apparatus according to claim 2, wherein it is determined whether or not there is any. Ranging means for outputting information on the distance from the voice capturing means to the actual recording target;
Distance determining means for determining whether or not the distance output by the distance measuring means is within the sensitivity optimum distance that can maintain the optimum sensitivity in the sound capturing means;
Further comprising
Recording is impossible when the volume of the voice uttered in the actual recording target is lower than the predetermined volume and the determination result of the distance determination means is outside the optimum sensitivity distance. The sound recording / reproducing apparatus according to claim 1, wherein the determination by the sound volume determination means is temporarily stopped.

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