JP6444490B2 - Speech segment detection apparatus and speech segment detection method - Google Patents

Description

  The present invention relates to a technique for detecting a speech section from an input signal using a plurality of feature amounts.

  The voice section detection process for extracting a section where voice is present from the input signal is a very important process as a pre-process for voice recognition. In general, since the speech recognition process performs pattern recognition on the section detected by the speech section detection process to obtain a recognition result, the recognition accuracy of the speech recognition process increases if there is an error in the speech section detection. descend. As a basic method of speech section detection, there is a method of calculating the power of an input signal and detecting a section where the calculated power is equal to or greater than a set threshold as a speech section. The detection method operates relatively well when the background noise is small and in the detection process of a stationary speech section.

  On the other hand, speech recognition that can be used by the user in a hands-free manner is an extremely effective user interface for inputting inspection results in maintenance work of plant facilities and the like, and for supporting operation of various FA (Factory Automation) devices. However, in many cases, the maintenance work environment of the plant equipment and the operating environment of the FA equipment are environments in which unsteady noises such as turbine noise and hammering noise are generated. Therefore, in the method of detecting a speech section using only the power calculated from the input signal described above, since non-stationary noise is erroneously detected as speech, the detection accuracy of the speech section decreases, and in subsequent speech recognition processing There is a problem that sufficient recognition performance cannot be obtained.

  In response to the above-described problem, for example, in Patent Document 1, a cepstrum that represents a spectral feature of an input signal is used instead of the power of the input signal as a feature amount used for speech segment detection, and the HMM ( A speech segment detection method using Hidden Markov Model) is disclosed. Specifically, several HMMs are learned for each of speech and noise, and the likelihood of each HMM is calculated when detecting the start point that is the start point of the speech section. In 12 frames (120 msec) When there are four or more frames with the highest likelihood of the calculated HMM, the first frame of the 12 frames is detected as the start end of the speech section.

JP 2001-343983 A

  However, in the technique disclosed in Patent Document 1 described above, since voice section detection is performed using a feature amount that represents a spectral feature of an input signal, noise having a spectral feature different from that of speech is erroneously detected as speech. However, unvoiced consonants (p, t, k, s, sh, h, f), etc. are similar in noise and spectrum characteristics, so the unvoiced consonants, etc. and noise can be accurately There is a problem in that it cannot be identified and detected.

  The present invention has been made to solve the above-described problems, and suppresses erroneous detection of unsteady noise as speech, and improves the detection accuracy of unvoiced consonants at the beginning and end of speech. Objective.

  The speech section detection apparatus according to the present invention includes a first feature amount calculation unit that calculates a first feature amount indicating a spectral feature from an input signal, and a feature amount of speech that is different from the first feature amount from the input signal. The first feature amount calculation unit calculates the first feature amount calculation unit using a second feature amount calculation unit that calculates the second feature amount to be shown and a recognition model for identifying speech and noise included in the input signal. On the basis of the feature amount, a speech section detection unit that detects a start time indicating a start point of a speech section and an end time indicating an end point included in the input signal, and a second feature amount calculated by the second feature amount calculation unit A start / end correction unit that corrects the start time and the end time detected by the speech section detection unit based on the comparison between the feature amount and the threshold value is provided.

  According to the present invention, it is possible to suppress erroneous detection of unsteady noise as a speech section, and it is possible to further improve the accuracy of detecting unvoiced consonants at the beginning and end of speech.

1 is a block diagram illustrating a configuration of a speech segment detection device according to Embodiment 1. FIG. 2 is a diagram illustrating a hardware configuration of the speech segment detection device according to Embodiment 1. FIG. 3 is a flowchart showing an operation of the speech segment detection device according to the first embodiment. 3 is a flowchart showing an operation of the speech segment detection device according to the first embodiment. It is a figure which shows the search area by the start / end correction | amendment part of the audio | voice area detection apparatus which concerns on Embodiment 1. FIG. 6 is a block diagram illustrating a configuration of a speech segment detection device according to Embodiment 2. FIG. It is a figure which shows the search area by the start / end correction | amendment part of the audio | voice area detection apparatus which concerns on Embodiment 2, and the threshold value calculation area by a threshold value calculation part. 6 is a flowchart illustrating an operation of the speech segment detection device according to the second embodiment. 6 is a flowchart illustrating an operation of the speech segment detection device according to the second embodiment. FIG. 10 is a block diagram illustrating a configuration of a speech segment detection device according to Embodiment 3. 10 is a flowchart showing the operation of the speech segment detection device according to the third embodiment. 10 is a flowchart showing the operation of the speech segment detection device according to the third embodiment.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a speech segment detection apparatus 10 according to the first embodiment.
The speech section detection device 10 includes a first feature quantity calculation unit 1, a second feature quantity calculation unit 2, a pattern recognition model storage unit 3, a speech segment detection unit 4, and a start / end correction unit 5.

  The first feature amount calculation unit 1 performs acoustic analysis of an input signal input from the outside, and calculates a time series of feature amounts (hereinafter referred to as first feature amounts) expressing spectral features. The first feature amount is, for example, data of 1 to 12 dimensions of MFCC (Mel Frequency Cepstral Coefficient). In the following, for simplification of description, data of 1 to 12 dimensions of MFCC is simply referred to as MFCC.

  The second feature quantity calculation unit 2 is a feature quantity that is different from the first feature quantity converted by the first feature quantity calculation unit 1, and is suitable for detection of speech that is difficult to identify with the first feature quantity. A time series of feature quantities (hereinafter referred to as second feature quantities) is calculated. For example, a time series of feature quantities suitable for detecting unvoiced consonants of speech that is difficult to distinguish from noise with the first feature quantities is calculated. Here, unvoiced consonants are p, t, k, s, sh, h, f, and the like. In general, since the power of the unvoiced consonant is concentrated in the high frequency range of the voice, for example, the power that emphasizes the high frequency range is calculated as the second feature amount.

  The pattern recognition model storage unit 3 stores a pattern recognition model for identifying speech and noise in the input signal. In the first embodiment, a case where a GMM (Gaussian Mixture Model) is used as a model will be described as an example. Specifically, a pattern recognition model is composed of one GMM that models speech (hereinafter referred to as speech GMM) and one GMM that models noise (hereinafter referred to as noise GMM). The parameters of the speech GMM and noise GMM are obtained in advance by learning using, for example, the maximum likelihood estimation method. Speech GMM parameter learning is performed using various speech MFCCs, and noise GMM parameter learning is performed using various noise MFCCs.

  The speech section detection unit 4 refers to the pattern recognition model stored in the pattern recognition model storage unit 3, performs pattern matching of the first feature amount calculated by the first feature amount calculation unit 1, and A provisional start end time (hereinafter referred to as a provisional start end time) indicating the start point of the voice section and a termination time (hereinafter referred to as a provisional end time) indicating a provisional end point are detected. The start / end correction unit 5 corrects the temporary start time and the temporary end time detected by the speech section detection unit 4 based on the second feature amount, and determines the start time and the end time. The start / end correction unit 5 outputs the obtained start end time and end time as time information of a voice section in the input signal.

FIG. 2 is a diagram illustrating a hardware configuration of the speech segment detection device 10 according to the first embodiment.
The first feature amount calculation unit 1, the second feature amount calculation unit 2, the speech segment detection unit 4, and the start / end correction unit 5 of the speech segment detection device 10 execute a program stored in the memory 30. This is realized. The pattern recognition model accumulation unit 3 constitutes a memory 30. Further, a plurality of processors 20 and a plurality of memories 30 may be configured to cooperate to execute the above-described functions.

Next, the operation of the speech segment detection device 10 will be described.
3A and 3B are flowcharts showing the operation of the speech segment detection apparatus 10 according to Embodiment 1.
When a signal is input (step ST1), the first feature quantity calculation unit 1 divides the input signal into set time intervals (hereinafter referred to as frames), and converts the input signal for each divided frame. A first feature amount is calculated (step ST2). In the frame division, adjacent time frames may overlap with each other. For example, the time interval length of the frame is set to 30 milliseconds, and the first feature value is calculated by converting the input signal while shifting the frame by 10 milliseconds. The first feature amount is MFCC as described above. That is, in the process of step ST2, the first feature quantity calculation unit 1 calculates and outputs the MFCC time series at intervals of 10 milliseconds.

  The second feature quantity calculation unit 2 divides the input signal at the same frame interval as the first feature quantity calculation unit 1, and calculates the second feature quantity by converting the input signal for each divided frame ( Step ST3). In step ST3, the following description will be given on the assumption that the power that emphasizes the high frequency is calculated as the second feature amount. The second feature amount calculation unit 2 regards the first K frame (for example, K = 10) of the input signal as a noise section in which no speech exists, calculates an average of the power of the voice in the section of the K frame, and generates noise. Level (step ST4). Further, the second feature amount calculation unit 2 calculates the high frequency emphasis difference power by subtracting the noise level calculated in step ST4 from the power emphasizing the high frequency calculated in step ST3 for each frame (step ST5). ). In the process of step ST5, the second feature quantity calculation unit 2 calculates and outputs a time series of high-frequency emphasis difference power at intervals of 10 milliseconds.

The speech section detection unit 4 receives the first feature amount calculated in step ST2, that is, the MFCC time series, and refers to the pattern recognition model stored in the pattern recognition model storage unit 3, and performs speech for each frame. The likelihood Ls of GMM and the log likelihood Ln of noise GMM are calculated (step ST6). The speech section detection unit 4 calculates the log likelihood difference S based on the following equation (1) using the speech LMM likelihood Ls and the noise GMM log likelihood Ln calculated in step ST6 (step ST7). ).
S = Ls−Ln (1)

  The speech section detection unit 4 searches in the forward direction of the time axis for a section in which the frames having the log likelihood difference S calculated in step ST7 equal to or greater than the set threshold Th_S continue for the set frame count threshold Th_T1. (Step ST8). The speech section detection unit 4 obtains the time of the frame in which the log likelihood difference S first becomes equal to or greater than the threshold Th_S in the forward direction of the time axis for the section searched in step ST8, and the temporary start time Tb ′ of the speech section (Step ST9).

  Next, the speech section detection unit 4 forwards a section in which a frame in which the log likelihood difference S calculated in step ST7 is less than the set threshold value Th_S continues for the set frame number threshold Th_T2 or more in the forward direction of the time axis. (Step ST10). The speech section detection unit 4 obtains the time of the frame in which the log likelihood difference S first becomes less than the threshold Th_S in the forward direction of the time axis for the section searched in step ST10, and the temporary termination time Te ′ of the speech section (Step ST11). Note that the above-described search processing in step ST8 and step ST10 is continued until the target frame is searched.

  The start / end correction unit 5 refers to the time series of the high frequency emphasis difference power calculated in step ST5, and the time Tb1 of the frame b1 positioned in front of the time series of the temporary start time Tb ′ of the speech section detected in step ST9. Until the time Tb2 of the frame b2 located behind the time series of the voice temporary start time Tb ′, the frames whose high-frequency emphasis difference power is equal to or greater than the threshold Th_P1 are continuously equal to or greater than the threshold Th_T1 of the set number of frames. A section to be searched is searched in the forward direction of the time axis (step ST12). The start / end correction unit 5 determines whether or not a section is searched in the process of step ST12 (step ST13). When the section is searched (step ST13; YES), the start / end correction unit 5 first acquires the time of the frame in which the high frequency emphasis difference power is equal to or higher than the threshold Th_P1 in the forward direction of the time axis in the searched section. The start time Tb is set (step ST14). On the other hand, when the section is not searched (step ST13; NO), the start / end correction unit 5 sets the temporary start end time Tb ′ detected in step ST9 as the start end time Tb (step ST15).

  Next, the start / end correction unit 5 refers to the time series of the high frequency emphasis difference power calculated in step ST5, and the frame e2 located behind the time series of the temporary end time Te ′ of the speech section detected in step ST11. In a section from time Te2 to time Te1 of the frame e1 located in time series front of the speech temporary termination time Te ′, a frame in which the high frequency emphasis differential power is equal to or higher than the threshold Th_P1 is a threshold Th_T1 of the set number of frames. The continuous section is searched in the reverse direction of the time axis (step ST16). The start / end correction unit 5 determines whether or not a section is searched in the process of step ST16 (step ST17). When the section is searched (step ST17; YES), the start / end correction unit 5 first acquires the time of the frame in which the high frequency emphasis difference power is equal to or higher than the threshold Th_P1 in the reverse direction of the time axis in the searched section. The termination time Te is set (step ST18). On the other hand, when the section is not searched (step ST17; NO), the start / end correction unit 5 sets the temporary end time Te ′ detected in step ST11 as the end time Te (step ST19).

The start / end correction unit 5 outputs the start time Tb acquired in step ST14 or step ST15 and the end time Te acquired in step ST18 or step ST19 as time information of the voice section (step ST20), and ends the process. To do.
Note that the threshold value Th_S, threshold value Th_P1, threshold value Th_T1, and threshold value Th_T2 described above are preset constants of 0 or more.

FIG. 4 is a diagram illustrating a search section by the start / end correction unit 5 of the speech section detection apparatus 10 according to the first embodiment.
In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates the strength of the log likelihood difference S between the speech GMM and the noise GMM. In FIG. 4, time Tb ′ is the temporary start time Tb ′ calculated in step ST9, and time Te ′ is the temporary end time Te ′ calculated in step ST11. A section A shows a section from the time Tb1 of the frame b1 located in front of the time series of the temporary start time Tb ′ to the time Tb2 of the frame b2 located behind, so that the start / end correction unit 5 corrects the start time. The search section where the search is performed is shown. An arrow B indicates a search direction when the start / end correction unit 5 searches for the section A, and indicates that the search is performed in the forward direction of the time axis.

Further, the section C shows a section from the time Te2 of the frame e2 located behind the temporary end time Te ′ in time series to the time Te1 of the frame e1 located ahead, and the start / end correction unit 5 performs the end time correction. The search section which performs the search for is shown. An arrow D indicates a search direction when the start / end correction unit 5 searches for the section C, and indicates that the search is performed in the reverse direction of the time axis.
Specifically, for example, time Tb1 is set 25 frames ahead of the temporary start time Tb ′, time Tb2 is set 10 frames behind the temporary start time Tb ′, and 10 frames ahead of the temporary end time Te ′. Time Te1 is set, and time Te2 is set 30 frames behind the provisional start time Te ′. Note that Tb2 is set to 0 frame from the temporary start time Tb ′, and Te1 is set to 0 frame from the temporary end time Te ′, so that the speech section detected by the first feature amount is not corrected forward. It is also possible to configure as described above.

  As described above, according to the first embodiment, the first feature amount calculation unit 1 that calculates the first feature amount of the input signal, and the voice that is difficult to distinguish from noise by the first feature amount. A second feature quantity calculation unit 2 that computes a second feature quantity suitable for detection from the input signal, and a first feature quantity using a pattern recognition method to discriminate between speech and noise, and the provisional start time and provisional time A speech section detection unit 4 that calculates the end time, and a start / end correction unit 5 that corrects the temporary start time and the temporary end time using the second feature amount and obtains time information of the speech section. Therefore, it is possible to suppress the detection of non-stationary noise having different spectral feature amounts as speech intervals by the processing of the speech section detection unit 4, and further, the processing of the start / end correction unit 5 distinguishes noise from the noise. Suppresses voice detection omissions that are difficult to It is possible to improve the detection accuracy between.

  Further, according to the first embodiment, the second feature quantity calculation unit 2 uses, as the second feature quantity, the high-frequency emphasis difference power suitable for detecting unvoiced consonants that are difficult to identify noise from the spectrum feature quantity. Since the start / end correction unit 5 is configured to correct the temporary start time and the temporary end time using the time series of the high-frequency emphasis difference power and acquire time information of the voice section, detection of unvoiced consonants Leakage can be suppressed and the detection accuracy of the voice section can be improved.

  In the first embodiment described above, the maximum likelihood estimation method is used as an example for parameter learning of the speech GMM and noise GMM constituting the pattern recognition model stored in the pattern recognition model storage unit 3. Further, parameter learning for positively identifying speech and noise, for example, a mutual information maximization estimation method may be applied.

  In the first embodiment described above, a configuration in which one voice GMM and one noise GMM are used as GMMs constituting the pattern recognition model stored in the pattern recognition model storage unit 3 is shown. It may be used. In this case, the log likelihood of the speech GMM may be a maximum value or a weighted average value of log likelihoods of a plurality of speech GMMs. Similarly, the log likelihood of the noise GMM is a maximum value or a weighted average value of log likelihoods of a plurality of noise GMMs.

  In the first embodiment described above, the GMM is used as the pattern recognition model accumulated by the pattern recognition model accumulation unit 3. However, an HMM may be used. Alternatively, pattern recognition methods such as a logistic regression model, a support vector machine, and a neural network may be used.

  Moreover, in Embodiment 1 mentioned above, although the 2nd feature-value calculation part 2 showed the structure which calculates a high region emphasis difference power as a feature-value suitable for the detection of an unvoiced consonant, it was suitable for the detection of an unvoiced consonant. Any feature amount can be applied as long as it is a feature amount, that is, a feature amount characteristic of an unvoiced consonant. For example, the power of the input signal can be calculated for each frequency band, the power whose frequency band is less than 2 KHz and the power of 2 KHz or more can be calculated, and the ratio of both powers can be applied as the feature amount.

Embodiment 2. FIG.
In the first embodiment described above, the start / end correction unit 5 uses the preset threshold Th_P1 when comparing the high frequency emphasis difference power and the threshold. However, in the second embodiment, the high frequency The structure which calculates the threshold value used as the comparison object of emphasis difference power using the standard deviation of high region emphasis difference power is shown.
FIG. 5 is a block diagram illustrating a configuration of the speech segment detection device 10a according to the second embodiment.
The speech segment detection device 10a according to the second embodiment is provided by adding a threshold value calculation unit 6 to the speech segment detection device 10 described in the first embodiment.
FIG. 6 is a diagram illustrating a search section by the start / end correction unit 5a and a threshold calculation section by the threshold calculation unit 6 of the speech section detection device 10a according to the second embodiment.
In the following, the same or corresponding parts as those of the speech section detection apparatus 10 according to the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and the description thereof is omitted or simplified. To do.

式（２）において、ｍｐは時刻Ｔｂ０から時刻Ｔｂ１の区間Ｅの高域差分パワーの平均値、ｐｉは時刻ｉにおける高域差分パワー、ｓｑｒｔ（）は平方根をとる関数を示している。なお、フレーム数Ｔｖは予め設定した定数であり、例えば５０フレームとする。The threshold value calculation unit 6 is based on the second feature value calculated by the second feature value calculation unit 2, that is, the time series of the high frequency emphasis difference power and the temporary start time Tb ′ detected by the speech section detection unit 4. Thus, the threshold value referred to by the start / end correction unit 5a is calculated. Referring to FIG. 6, the threshold value calculation unit 6 sets Tb0 as a time further Tv0 from the time Tb1 of the frame b1 located ahead of the temporary start time Tb ′ in time series, and from the time Tb0 to the time Tb1. In the section E, the standard deviation sd of the high frequency emphasis difference power is calculated based on the following formula (2).

In Expression (2), mp represents an average value of the high-frequency difference power in the section E from time Tb0 to time Tb1, pi represents the high-frequency difference power at time i, and sqrt () represents a function that takes a square root. The number of frames Tv is a preset constant, for example, 50 frames.

The threshold calculation unit 6 calculates the start / end correction threshold Th_P2 based on the following equation (3) using the standard deviation sd of the high frequency emphasis difference power calculated based on the equation (2).
Th_P2 = α * sd + β (3)
In Expression (3), α and β are constants equal to or greater than 0. The start / end correction threshold Th_P2 calculated by the threshold calculation unit 6 is output to the start / end correction unit 5a.

Next, the operation of the speech segment detection device 10a will be described.
7A and 7B are flowcharts illustrating the operation of the speech segment detection device 10a according to Embodiment 2.
In the following, the same steps as those in speech section detection apparatus 10 according to Embodiment 1 are denoted by the same reference numerals as those used in FIGS. 3A and 3B, and description thereof will be omitted or simplified.

  When the speech section detection unit 4 detects the temporary termination time Te ′ of the speech in step ST11, the threshold calculation unit 6 performs the time Tb1 of the frame b1 that is located in front of the temporal sequence of the speech temporary start time Tb ′ detected in step ST9. Then, a time Tb0 that is further back by the number of frames Tv is calculated (step ST31). The threshold calculation unit 6 calculates the standard deviation sd of the high frequency emphasis difference power for the section from time Tb0 to time Tb1 calculated in step ST31 based on the above-described equation (2) (step ST32). Further, the threshold calculation unit 6 calculates the start / end correction threshold Th_P2 based on the above-described equation (3) using the standard deviation sd of the high frequency emphasis difference power calculated in step ST32 (step ST33).

  The start / end correction unit 5a refers to the time series of the high frequency emphasis difference power calculated in step ST5, and starts from the time Tb1 of the frame b1 positioned in front of the time series of the temporary start time Tb ′ of the speech detected in step ST9. A frame in which the high-frequency emphasis differential power is equal to or higher than the start / end correction threshold Th_P2 calculated in step ST33 is set in a section up to the time Tb2 of the frame b2 located behind the time series of the audio temporary start time Tb ′. A section that is equal to or greater than the threshold Th_T1 of the number of frames is searched in the forward direction of the time axis (step ST34).

  The start / end correction unit 5a determines whether or not a section is searched in the process of step ST34 (step ST35). When the section is searched (step ST35; YES), the start / end correction unit 5a first acquires the time of the frame in which the high frequency emphasis difference power is equal to or higher than the start / end correction threshold Th_P2 in the searched section. Time Tb is set (step ST36). On the other hand, when the section is not searched (step ST35; NO), the start / end correction unit 5a sets the temporary start end time Tb ′ detected in step ST9 as the start end time Tb (step ST15).

  Next, the start / end correction unit 5a refers to the time series of the high-frequency emphasis difference power calculated in step ST5, and the time of the frame e2 located behind the temporary end time Te ′ of the speech detected in step ST11. The number of frames in which the high frequency emphasis differential power is equal to or greater than the start / end correction threshold Th_P2 in the range from Te2 to the time Te1 of the frame e1 located in front of the time series of the speech temporary end time Te ′ Are searched for in the reverse direction of the time axis (step ST37). The start / end correction unit 5a determines whether or not a section is detected in the process of step ST37 (step ST38). When the section is searched (step ST38; YES), the start / end correction unit 5a first acquires the time of the frame in which the high frequency emphasis difference power is equal to or higher than the start / end correction threshold Th_P2 in the searched section. Time Te is set (step ST39). On the other hand, when the section is not searched (step ST38; NO), the start / end correction unit 5a sets the end time Te ′ detected in step ST11 as the end time Te (step ST19).

  The start / end correction unit 5a outputs the start end time Tb acquired in step ST36 or step ST15 and the end time Te acquired in step ST39 or step ST19 as time information of the speech section (step ST20), and ends the process. To do.

  As described above, according to the second embodiment, the time Tb0 further from the time Tb1 of the frame b1 located in front of the temporary start time Tb ′ in time series is defined as Tb0, and from the time Tb0 to the time Tb1. The threshold calculation unit 6 that calculates the start / end correction threshold Th_P2 using the standard deviation sd of the high frequency emphasis difference power calculated in the section of FIG. 5, the calculated start / end correction threshold Th_P2, and the high frequency emphasis difference power Based on the series, the temporary start time and the temporary end time are corrected, and the start / end correction unit 5a that acquires the time information of the speech section is provided. Therefore, the standard deviation value of the high frequency emphasis difference power is small. For a stationary noise environment, it is possible to set a low threshold value for starting and terminating correction, and it is possible to improve the detection performance of weak unvoiced consonants. On the other hand, the standard deviation value of the high-frequency emphasis differential power is large, and it is possible to set a high threshold value for starting and ending correction for non-stationary noise environments, which suppresses false detection of noise as speech. can do.

Embodiment 3 FIG.
In the third embodiment, in addition to the time series of the high frequency emphasis difference power calculated by the second feature quantity calculation unit 2, the time series of the log likelihood difference S detected by the speech section detection unit 4 is also taken into consideration. The structure which correct | amends start / end time is shown.
FIG. 8 is a block diagram illustrating a configuration of the speech segment detection device 10b according to the third embodiment.
The speech segment detection device 10b of the third embodiment has the same configuration as the speech segment detection device 10a shown in the second embodiment. In the following, the same or corresponding parts as the components of the speech section detection device 10a according to the second embodiment are denoted by the same reference numerals as those used in the second embodiment, and the description thereof is omitted or simplified.

  Similar to the first and second embodiments, the voice section detection unit 4 outputs the temporary start time Tb ′ and the temporary end time Te ′ to the start / end correction unit 5b. Furthermore, the speech section detection unit 4 calculates the log likelihood difference S between the speech GMM and the noise GMM calculated based on the above-described equation (1) for each frame, that is, the time series of the log likelihood difference S is a start / end correction unit. Output to 5b. Similarly to the second embodiment, the threshold calculation unit 6 is configured to input the time series of the high frequency emphasis difference power input from the second feature amount calculation unit 2 and the temporary start time Tb ′ detected by the speech section detection unit 4. Based on the above, a start / end correction threshold Th_P2, which is a threshold referred to by the start / end correction unit 5b, is calculated.

  The start / end correction unit 5b uses the temporary start time Tb ′ and the temporary end time Te ′ detected by the speech section detection unit 4 as a time series of the high frequency emphasis difference power input from the second feature amount calculation unit 2, and Correction is performed based on the time series of the log likelihood difference S input from the speech section detection unit 4 and the start / end correction threshold Th_P2 input from the threshold calculation unit 6, and the start end time Tb and the end time Te are obtained.

Next, the operation of the speech segment detection device 10b will be described.
9A and 9B are flowcharts showing the operation of the speech segment detection device 10b according to Embodiment 3.
In the following, the same steps as those in speech section detection apparatus 10a according to Embodiment 2 are denoted by the same reference numerals as those used in FIGS. 7A and 7B, and description thereof is omitted or simplified.

When the threshold calculation unit 6 calculates the start / end correction threshold Th_P2 in step ST33, the start / end correction unit 5b calculates the time series of the high frequency emphasis difference power calculated in step ST5 and the log likelihood calculated in step ST7. A frame positioned behind the time series of the voice temporary start time Tb ′ from the time Tb1 of the frame b1 positioned in front of the time series of the voice temporary start time Tb ′ detected in step ST9 with reference to the time series of the difference S Frames in which the high-frequency emphasis difference power is equal to or higher than the threshold value Th_P2 for start / end correction calculated in step ST33 and is equal to or higher than the threshold value Th_S2 in which the log likelihood difference S is set in the interval up to time Tb2 of b2 A section that continues for a number of threshold values Th_T1 or more is searched in the forward direction of the time axis (step ST41).
Here, it is assumed that the above-described threshold Th_S2 is a predetermined constant equal to or larger than 0 and smaller than the threshold Th_S.

  The start / end correction unit 5b determines whether or not a section has been searched in the process of step ST41 (step ST42). When the section is searched (step ST42; YES), the start / end correction unit 5b first has the high frequency emphasis difference power equal to or higher than the start / end correction threshold Th_P2 and the log likelihood difference S is equal to or higher than the threshold Th_S2 in the searched section. The time of the frame that has become is acquired and set as the start time Tb (step ST43). On the other hand, when the section is not searched (step ST42; NO), the start / end correction unit 5b sets the temporary start time Tb ′ detected in step ST9 as the start time Tb (step ST15).

  Next, the start / end correction unit 5b refers to the time series of the high-frequency emphasis difference power calculated in step ST5 and the time series of the log likelihood difference S calculated in step ST7, and the speech detected in step ST11. The high-frequency emphasis differential power starts and ends in a section from the time Te2 of the frame e2 positioned behind the temporary end time Te ′ to the time Te1 of the frame e1 positioned ahead of the time series of the audio temporary end time Te ′. A search is performed in the reverse direction of the time axis for a frame in which frames equal to or larger than the threshold Th_S2 for which the logarithmic likelihood difference S is set and the threshold Th_S2 for which the threshold value for edge correction is equal to or greater than the threshold Th_T1 for the set number of frames.

  The start / end correction unit 5b determines whether or not a section is detected in the process of step ST44 (step ST45). When the section is searched (step ST45; YES), the start / end correction unit 5b first has a high-frequency emphasis difference power equal to or higher than the start / end correction threshold Th_P2 and the log likelihood difference S is equal to or higher than the threshold Th_S2 in the searched section. The time of the frame that has become is acquired and set as the end time Te (step ST46). On the other hand, when the section is not searched (step ST45; NO), the start / end correction unit 5b sets the temporary end time Te ′ detected in step ST11 as the end time Te (step ST19).

The start / end correction unit 5b outputs the start end time Tb acquired in step ST43 or step ST15 and the end time Te acquired in step ST46 or step ST19 as time information of the voice section (step ST20), and ends the process. To do.
As described above, by setting the threshold value Th_S2 to a value smaller than the threshold value Th_S, it is easy to detect weak unvoiced consonants that could not be detected at the time of detecting the temporary start time Tb ′ and the temporary end time Te ′. It becomes. Note that noise is detected when the threshold value Th_S2 is set to a value smaller than the threshold value Th_S using only the time series of the log likelihood difference S without using the time series of the high frequency emphasis difference power. However, only when both of the feature quantities are equal to or greater than the threshold using the time series of the high frequency emphasis difference power and the time series of the log likelihood difference S, the temporary start time Tb ′ and Correction accuracy can be improved by correcting the provisional termination time Te ′.

  In the start / end correction unit 5b, by correcting the start / end time based on the log likelihood difference in addition to the high frequency emphasis difference power, it is possible to easily detect a weak unvoiced consonant that could not be detected at the time of detecting the temporary start time. can do. However, if the threshold is set low using only the log likelihood difference and the start / end time is corrected, the possibility of erroneous detection of noise as speech increases. Therefore, the correction accuracy is improved by adopting a configuration in which the start and end times are corrected only when the log likelihood difference and other feature quantities are used together and both feature quantities are equal to or greater than the threshold value.

  As described above, according to the third embodiment, the time series of the high frequency emphasis difference power calculated by the second feature quantity calculation unit 2 and the time series of the log likelihood difference detected by the speech section detection unit 4 And the start / end correction unit 5b that corrects the temporary start time and the temporary end time detected by the speech section detection unit 4 based on the start / end correction threshold value input from the threshold calculation unit 6. It is possible to suppress erroneous detection and correction of noise as speech, and to improve the accuracy of correcting the start point and end point of speech.

  Further, according to the third embodiment, since the threshold value Th_S2 is set to a value smaller than the threshold value Th_S, it cannot be detected at the time of detecting the temporary start time Tb ′ and the temporary end time Te ′. A weak unvoiced consonant can be easily detected.

  In the above-described third embodiment, the configuration in which the start / end correction unit 5b is applied to the speech segment detection device 10a illustrated in the second embodiment has been described. However, the speech segment detection device 10 illustrated in the first embodiment has the configuration shown in FIG. The start / end correction unit 5b may be adapted and configured.

  In Embodiment 1 to Embodiment 3 described above, detection of unvoiced consonants has been described as an example of detection of speech that is difficult to distinguish from noise with the first feature amount, but in addition to unvoiced consonants, It can also be configured to detect unvoiced vowels. Furthermore, when the utterance is unclear, such as the detection of voiced consonants such as the consonant part of muddy sounds, or the detection of vowels, detection of speech that is predicted to be difficult to distinguish from noise with the first feature amount is performed. It is also possible to configure.

  In addition to the above, within the scope of the present invention, the present invention can be freely combined with each embodiment, modified any component of each embodiment, or omitted any component in each embodiment. Is possible.

  The speech segment detection device according to the present invention is applicable to a device that requires speech segment detection, for example, a speech recognition device, prevents erroneous detection of unsteady noise as speech, and voiceless consonants at the beginning or end of a word. Detection accuracy can be improved.

  DESCRIPTION OF SYMBOLS 1 1st feature-value calculation part, 2nd feature-value calculation part, 3 pattern recognition model storage part, 4 audio | voice area detection part, 5, 5a, 5b start / end correction | amendment part, 6 threshold value calculation part 10, 10a, 10b Voice segment detection device.

Claims (5)

A first feature amount calculation unit for calculating a first feature amount indicating a spectral feature from an input signal;
A second feature quantity calculation unit for calculating a second feature quantity indicating a feature quantity of speech different from the first feature quantity from the input signal;
Based on the first feature amount calculated by the first feature amount calculation unit using a recognition model for identifying speech and noise included in the input signal, the speech section included in the input signal A voice interval detection unit that detects a start time indicating a start point and an end time indicating an end point;
A voice including a start / end correction unit that corrects the start time and the end time detected by the voice section detection unit based on a comparison between the second feature value calculated by the second feature value calculation unit and a threshold value. Section detection device.   A threshold for calculating a standard deviation of the second feature quantity in a section that is back for a certain time from the start time detected by the speech section detection unit, and calculating the threshold based on the standard deviation of the second feature quantity The speech section detection apparatus according to claim 1, further comprising a calculation unit. The speech section detection unit refers to the recognition model, calculates a likelihood difference between a speech model that models the speech and a noise model that models the noise,
The start / end correction unit is detected by the speech segment detection unit based on the comparison between the likelihood difference calculated by the speech segment detection unit and the threshold value in addition to the comparison between the second feature amount and the threshold value. The speech section detection device according to claim 1, wherein the start time and end time are corrected.   The speech section detection device according to claim 1, wherein the second feature amount calculation unit calculates the second feature amount indicating a feature of an unvoiced consonant among speech included in the input signal. A first feature amount calculating unit that calculates a first feature amount indicating a spectral feature from the input signal;
A second feature amount calculation unit calculates a second feature amount indicating a feature amount of speech different from the first feature amount from the input signal;
The speech section detection unit indicates a start point of the speech section included in the input signal based on the first feature amount using a recognition model for identifying speech and noise included in the input signal. Detect end time indicating start time and end point,
A speech section detection method in which a start / end correction unit corrects the start time and end time based on a comparison between the second feature amount and a threshold value.

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