JPH0950293A - Sound signal conversion device and ultrasonic diagnostic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply perform voice conversion with high quality without being affected by noise by changing the phase of a complex signal so that the angular velocity of the inputted complex signal is increased/decreased by a prescribed magnification. SOLUTION: This sound signal conversion device consists of a complex signal conversion part 10 and a phase variable adjustment part 20. Then, the complex signal conversion part 10 inputs a sound signal, and converts the inputted sound signal into the complex signal consisting of a real number part and an imaginary number part. The phase variable adjustment part 20 inputs the complex signal obtained by the complex signal conversion part 10, and changes the phase of the inputted complex signal so that the angular velocity of the complex signal is increased/decreased by a prescribed first magnification. Thus, the voice pitch is changed while maintaining an original voice speed, to be applied for the conversion of a key of accompaniment in 'KARAOKE' (orchestration without lyrics), and a device unspecified in speaker for example. Further, the device is used for a special effect sound adding function of an electronic instrument.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio signal converting apparatus and an ultrasonic diagnostic apparatus for inputting an audio signal and converting the pitch of a sound or the like.

[0002]

2. Description of the Related Art Conventionally, there has been known a voice signal converter for changing a voice speed of a voice signal (for example, a conversation speed in conversation) or a pitch of a voice. This type of device, for example, for learning a foreign language, makes it easy for an inexperienced foreign language beginner to distinguish a foreign language by slowly playing back a voice while keeping the pitch high, and a foreign language advanced The purpose of this training is to strengthen the training of the person by increasing the voice speed from the original speed while keeping the pitch. Also, this kind of device is not only for foreign language training,
It can be used in the same way for musical instrument training. Furthermore, by applying this type of device to a video playback device and increasing the voice speed to N times the original voice speed while maintaining the pitch of the sound, it is possible to hear the voice even in N-times speed playback. Becomes Further, in the karaoke device, it is possible to match the accompaniment key with the singer's key by changing the pitch of the sound while maintaining the voice speed. In the ultrasonic diagnostic apparatus, the Doppler shift of the reflected ultrasonic wave from the bloodstream is reproduced as a sound, and this sound is used as important diagnostic information for the doctor. When a high frequency of, for example, 5 MHz or more is selected as the center frequency of the ultrasonic wave with the aim of improving the spatial resolution of the ultrasonic image and a high flow velocity is detected,
There is a problem that Doppler sound becomes inaudible beyond the audible range, but this problem can be solved by applying a device of this kind and reducing the pitch of the sound while maintaining the voice speed.

This type of conventional audio signal converter is disclosed in "Nikkei Electronics" 1994, 11, 21 (no. 6).
22) Details on pages 93-98. In addition, the example applied to the Doppler sound of the ultrasonic diagnostic apparatus is Japanese Patent Publication No. 6-5.
This is described in detail in Japanese Patent No. 5211.

[0004]

However, in the conventional method, the pitch of the voice waveform is detected and the insertion / deletion of the waveform for each pitch and the expansion / compression in the time axis direction are combined, or the voice waveform is set at regular intervals. Since the audio processing that is performed after deleting the audio is performed, the amount of calculation for the processing is enormous, and the sound quality is impaired because the waveform is cut and pasted, and the sound is reproduced. The problem is that the sound is a little unnatural and it is easily affected by background noise.

The present invention has been made in consideration of the above problems, and provides an audio signal conversion apparatus and an ultrasonic diagnostic apparatus capable of easily performing high-quality audio conversion with less influence of noise. The purpose is to do.

[0006]

Means for Solving the Problems An audio signal conversion apparatus of the present invention that achieves the above object is: (1) Complex signal conversion means for inputting an audio signal and converting the input audio signal into a complex signal ( 2) A complex signal obtained by the complex signal converting means or a complex signal generated based on the complex signal is inputted, and the angular velocity of the inputted complex signal is increased or decreased by a predetermined first magnification. It is characterized in that it comprises phase change amount adjusting means for changing the phase of the input complex signal.

Here, in the audio signal conversion device of the present invention, (3) the audio signal before being input to the complex signal converting means, after being output from the complex signal converting means, being input to the phase change amount adjusting means. Any one of the previous complex signal, the complex signal whose phase has been changed by the phase change amount adjusting means, and the signal generated based on the complex signal is used as a second predetermined signal in the time axis direction. It is preferable to provide a time-expansion / contraction means that expands / contracts by a factor of.

When the time expanding / contracting means (3) is provided, the phase change amount adjusting means and the time expanding / contracting means are adjusted so that the first magnification and the second magnification are the same. May be. In the audio signal conversion device of the present invention, the complex signal conversion means of the above (1) performs the Hilbert conversion on the input audio signal, and performs the Hilbert conversion on the input audio signal and the input audio signal. It is also possible to obtain a complex signal composed of the signal obtained by the above, or the complex signal converting means of the above (1) performs a Fourier transform on the input audio signal to remove the negative frequency component, and then the inverse signal A complex signal may be obtained by performing a Fourier transform. Alternatively, the complex signal conversion means of the above (1) performs a Fourier transform on the input audio signal to remove a negative frequency component and further a positive frequency component. May be obtained by performing an inverse Fourier transform after shifting to a low frequency direction. Furthermore, the complex signal conversion means of the above (1) may be one that obtains a complex signal by performing quadrature detection of the input audio signal.

In the present invention, the "voice signal" is not limited to a specific signal, but may be any signal that is intended to be finally perceived by human hearing,
For example, an ultrasonic signal in the ultrasonic diagnostic apparatus of the present invention described below is also recognized as an example of an audio signal. A first ultrasonic diagnostic apparatus of the present invention obtains an ultrasonic signal by transmitting an ultrasonic wave into a subject and receiving an ultrasonic wave reflected in the subject, and based on the ultrasonic signal, the inside of the subject In the ultrasonic diagnostic apparatus for obtaining the information of (4) complex signal converting means for inputting an ultrasonic signal and converting the input ultrasonic signal into a complex signal (5) complex signal obtained by the complex signal converting means Out of
Sample-hold means for repeatedly sample-holding a complex signal corresponding to an ultrasonic signal obtained by an ultrasonic wave reflected at a predetermined point in the subject (6) The sample-hold complex signal is input to the sample-hold means and input. Phase change amount adjusting means for changing the phase of the input complex signal so that the angular velocity of the complex signal increases or decreases by a predetermined magnification. (7) The phase change amount adjusting means changes the phase of the complex signal. The present invention is characterized by comprising an adding / subtracting means for adding and subtracting the real number component and the imaginary number component in phase with each other.

The second ultrasonic diagnostic apparatus of the present invention is
In an ultrasonic diagnostic apparatus that obtains an ultrasonic signal by transmitting an ultrasonic wave into the subject and receiving an ultrasonic wave reflected in the subject, and obtaining information in the subject based on the ultrasonic signal, ) Complex signal converting means for inputting the ultrasonic signal and converting the input ultrasonic signal into a complex signal (9) Inputting the complex signal obtained by the complex signal converting means,
Phase change amount adjusting means for changing the phase of the input complex signal so that the angular velocity of the input complex signal increases or decreases by a predetermined magnification (10) Complex signal after the phase is changed by the phase changing amount adjusting means Sample hold means for repeatedly sample-holding a complex signal corresponding to an ultrasonic signal obtained by an ultrasonic wave reflected at a predetermined point in the subject (11) Real number of the complex signal sample-held by the sample-hold means It is characterized in that it is provided with an adder / subtractor for adding and subtracting the components and the imaginary number component in phase with each other.

Here, in the first and second ultrasonic diagnostic apparatuses of the present invention, the sample hold means samples an analog signal and holds the signal obtained by the sampling until the next sampling timing, that is, so-called. The sample and hold circuit may be a sample and hold circuit, but the sample and hold means according to the present invention is not limited to a sample and hold circuit that handles analog signals, and a digital signal obtained by A / D converting an ultrasonic signal or a complex signal. The concept includes a register in which digital signals corresponding to the ultrasonic waves reflected at the above-mentioned predetermined points among the signals are sequentially input and the input digital signals are held until the next input.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing a first embodiment of an audio signal converter of the present invention. As shown in FIG. 1A, the audio signal conversion device in this embodiment has
It comprises a complex signal converter 10 and a phase change amount adjuster 20. The complex signal converter 10 inputs a voice signal and converts the input voice signal into a complex signal composed of a real number component and an imaginary number component. The phase change amount adjustment unit 20 inputs the complex signal obtained by the complex signal conversion unit 10, and changes the phase of the input complex signal so that the angular velocity of the complex signal increases or decreases by a predetermined first magnification. Change. A specific configuration example of the complex signal conversion unit 10 will be described later, and in the following, first, a specific configuration example of the phase change amount adjustment unit 20 will be described.

FIG. 1B shows an example of the configuration of the phase change amount adjusting section 20 in FIG. Complex signal converter 10
When the complex signal generated in (1) is input to the phase change amount adjusting unit 20, the complex signal is obtained by an absolute value calculation circuit 21 for obtaining the absolute value of the complex number represented by the complex signal, and a complex conjugate for obtaining the complex conjugate of the complex number. It is input to the arithmetic circuit 22 and the delay circuit 23 that delays the complex signal by one sampling clock.

Here, it is assumed that the complex number (complex signal) at the i-th sampling is R _i + jI _i . Absolute value calculation circuit 2
1, the absolute value | R _i + jI _i | = √ {R _i ² +
I _i ² } is obtained, and its absolute value is input to the polar coordinate-rectangular coordinate conversion circuit 24. Further, the complex conjugate operation circuit 22 obtains the complex conjugate R _i −jI _i of the complex number R _i + jI _i and inputs it to the multiplication circuit 25. The complex signal R _i-1 + jI _i-1 delayed by one sampling clock by the delay circuit 23 is also input to the multiplication circuit 25, and their product (R _i −jI _i ) · (R _i-1 + jI _i ) is input. _-1 ) = R _i · R
_i-1 + I _i · I _i-1 + j (R _i · I _i-1 −R _i-1 · I
_i ) is required. This product is input to the arctangent calculation circuit 26, and the phase angle θ _i is calculated by the equation θ _i = tan ⁻¹ {(R _i I _i-1 −R _{i -1} · I _i ) / (R _i R _{i- 1} + I _i I _i-1 )} (1) This phase angle θ _i is the phase angle between the complex number R _i + jI _i represented by the complex signal input this time and the complex number R _i-1 + jI _i-1 represented by the complex signal input one sampling clock earlier. Is. The phase angle θ _i is input to the next multiplication circuit 27, multiplied by a predetermined constant k, and further input to the integration circuit 28 to calculate the integration (cumulative) angle Θ.

[0015]

[Equation 1]

[0016] This constant k corresponds to the first magnification in the present invention. This integration (cumulative) angle Θ is input to the polar coordinate-rectangular coordinate conversion circuit 24. In the polar coordinate-rectangular coordinate conversion circuit 24, the integration (cumulative) angle Θ input from the integration circuit 28 and the absolute value calculation circuit 21 are input. Based on the input absolute value √ {R _i ² + I _i ² } and the absolute value √ {R _i ² + I _i ² } and the angle Θ, a complex number expressed in polar coordinates is expressed in Cartesian coordinates. Complex numbers,
That is, it is converted into √ {R _i ² + I _i ² } {cos Θ + jsin Θ} (2). In this way, the input complex signal R
_{From i} + jI _i , the angular velocity of the complex signal is constant k (first
A complex signal (formula (2) above) in which the phase of the complex signal is changed so as to increase or decrease by the factor (1) is obtained.

FIG. 2 is an explanatory diagram of the audio signal converter shown in FIG. FIG. 2A is a schematic diagram showing a complex signal obtained by the complex signal conversion unit 10 shown in FIG. 1, in which a thick line shows a real number component of the complex signal and a thin line shows an imaginary number component of the complex signal. FIG. 2B is an enlarged view of a part of the complex signal shown in FIG. 2A, and FIG. 2C shows polar numbers of the complex numbers of the sampling points 1 to 7 shown in FIG. FIG. 3 is a diagram showing the absolute value and the phase in the vector direction.

Assuming that the constant k by which the phase angle θ _i is multiplied by the multiplication circuit 27 shown in FIG.
As shown in (d), the angular velocity of this complex signal becomes 1/2. That is, as compared with FIG. 2C, the angle between the vector of each sampling point i and the vector of the immediately preceding sampling point i−1 is compressed to ½. However, the absolute value of each vector remains unchanged.

FIG. 2 (e) is a diagram in which the complex number displayed in polar coordinates in FIG. 2 (d) is displayed as a waveform without changing the sampling time interval. 2 (c) to FIG. 2 described above
As shown in FIG. 2E, the complex signal after the phase adjustment to FIG.
It is the same as the envelope shown in (a)), and the frequency of the waveform is reduced to 1/2. This decrease (or increase) of the frequency is determined by the constant k (see FIG. 1B).

When either the real number component or the imaginary number component of the complex signal shown in FIG. 2 (e) is heard as a voice, the voice speed (conversation speed) is higher than that when the original voice signal is heard as it is. The pitch of the voice is 1/2 as it is
You can hear the voice changed to the height of. As described above, according to the embodiment shown in FIG. 1, it is possible to change only the voice pitch to the pitch according to the constant k while keeping the voice speed unchanged.

Although it has been described here that either the real number component or the imaginary number component of the complex signal which is variable as shown in FIG. 2 (e) is reproduced as the voice, the voice is reproduced even if it is the real number component. It may be either an imaginary component or either. Alternatively, both the real number component and the imaginary number component may be used for stereo output, for example. In the embodiment shown in FIG. 1, the complex signal generated by the complex signal conversion unit 10 is directly input to the phase change amount adjustment unit 20.
On the other hand, since the phase change amount adjusting unit 20 adjusts the voice pitch by changing the phase of the complex signal input to the phase change amount adjusting unit 20, the phase change amount adjusting unit 20 does not , It suffices to input a complex signal whose voice pitch is to be adjusted. That is, if the complex signal generated by the complex signal converter 10 is a signal to be directly reproduced by changing the pitch of the voice, the complex signal converter 10 as in the embodiment shown in FIG. And phase change amount adjusting unit 20
May be directly connected, but this need not be the case. By performing signal processing on the complex signal generated by the complex signal converter 10, it is possible to change the pitch of the voice and reproduce it as voice. A signal may be newly generated, and the newly generated complex signal may be input to the phase change amount adjusting unit 20. The specific embodiment will be described later as an embodiment of the ultrasonic diagnostic apparatus of the present invention.

FIG. 3 shows a second example of the audio signal conversion apparatus of the present invention.
3 is a block diagram showing an embodiment of FIG. 1 corresponds to the components of the first embodiment shown in FIG.
The same reference numerals as those given to the above are given to indicate, and the differences will be described. In the audio signal conversion device shown in FIG. 3, in addition to the complex signal conversion unit 10 and the phase change amount adjustment unit 20 which are components in the audio signal conversion device shown in FIG. A time expansion / contraction unit 3 for expanding / compressing the time of the real number component and the time of the imaginary number component of the adjusted complex signal, respectively.
0A and 30B are provided. These time stretcher 3
At 0A and 30B, the complex signal after the phase adjustment is compressed to, for example, 1/2 in the time axis direction.

FIG. 4 is an explanatory diagram of the audio signal converter shown in FIG. 4A to 4D are explanatory views of the audio signal conversion device shown in FIG. 1 described above, and FIGS.
Since each is the same as (d), duplicate description is omitted here. Here, the phase-adjusted complex signal as shown in FIG. 4D is compressed to 1/2 in the time axis direction. The waveform is shown in FIG.

If the waveform shown in FIG. 4A is compressed (or expanded) in the time axis direction, both the envelope and the frequency change by the compression (or expansion) magnification, but here. , The angular velocity is converted to ½ in the phase adjustment process from FIG. 4 (c) to FIG. 4 (d), and the expansion / contraction in the time axis direction from FIG. 4 (d) to FIG. 4 (e). At this time, since it is halved in the time axis direction, only the envelope is halved, and the frequency remains as in FIG. By doing so, only the voice speed (speaking speed) can be changed without changing the pitch of the voice.
Note that, here, the magnification of the angular velocity (1/2 times in the above example) and the magnification of the expansion / contraction in the time axis direction (1/2 times in the above example) are the same, so the pitch of the voice does not change and the voice speed does not change. Although only the (speech speed) changes, the pitch of the voice can be arbitrarily changed and the voice speed can also be arbitrarily changed by combining the magnification of the angular velocity and the magnification of the temporal direction.

In the second embodiment shown in FIG. 3, the real-time component and the imaginary-number component of the phase-adjusted complex signal output from the phase change amount adjusting unit 20 are respectively processed by the time expanding and contracting units 30A and 30B. , Same magnification (1 in the above example)
However, if the time expansion / contraction rates of the two time expansion / contraction units 30A and 30B are slightly shifted from each other, a special effect as an electronic musical instrument or a device for karaoke can be obtained. Alternatively, time adjustment may be performed on only one of the real number component and the imaginary number component as long as the voice speed and the voice pitch are simply adjusted.

FIG. 5 shows a third example of the audio signal converter of the present invention.
It is a block diagram showing an embodiment. Compared to the second embodiment shown in FIG. 3, in the third embodiment shown in FIG.
The order of the phase change adjusting unit 20 and the time stretching units 30A and 30B is reversed. As is already clear from the above description, the adjustment of the phase amount and the expansion / contraction in the time axis direction are performed separately, whichever comes first. Therefore, the time stretch unit may be on the rear end side of the phase change amount adjusting unit 20 as shown in FIG. 3 or on the front stage side as shown in FIG. 5. Furthermore, the time stretch unit may perform complex signal conversion. It may be provided on the front side of the section 10. Alternatively, if further signal processing (for example, bass enhancement, special filtering processing, etc.) is performed before the signal output from the phase change amount adjustment unit 20 is heard as a voice, a time expansion / contraction unit is provided on the subsequent stage of the signal processing. You may prepare.

FIG. 6 is a block diagram showing an example of the configuration of the complex signal converter 10 shown in FIGS. 1, 3 and 5. Figure 6
The complex signal converter shown in FIG. 6A includes a Hilbert transform filter 11 having the impulse response characteristic shown in FIG.
Is provided. The input voice signal itself can be adopted as the real number component of the complex signal, and the signal passed through the Hilbert transform filter 11 can be adopted as the imaginary number component of the complex signal.

FIG. 7 is a block diagram showing another example of the structure of the complex signal converter. The complex signal converter shown in FIG. 7A has a fast Fourier transform (FFT).
FFT circuit 1 for performing tier transform
2, a circuit 13 for suppressing the negative frequency of the Fourier transform signal obtained by the FFT circuit 12 to zero, and an inverse Fourier transform (IFFT; Inv) at the output of the circuit 13.
erse Fast Fourier Transform
rm) is applied to the IFFT circuit 14.

The circuit 13 for suppressing negative frequencies to zero is
The negative frequency components of the real number component (see FIG. 7B) and the imaginary number component (see FIG. 7C) of the Fourier transform signal obtained by the FFT circuit 12 are suppressed to zero, and each of the components shown in FIG.
It is a circuit for generating a signal having only positive frequency components shown in (d) and (e). In this way, a negative frequency component is suppressed to zero, and then inverse Fourier transform is performed to generate a complex signal.

FIG. 8 is a block diagram showing another configuration example of the complex signal conversion section. The complex signal converter shown in FIG. 8 is provided with a shift circuit 15 that shifts the output of the circuit 13 that suppresses negative frequencies to zero as compared with the complex signal converter shown in FIG. . The provision of such a shift circuit 15 is convenient because it is not necessary to handle high frequency components.

FIG. 9 shows another example of the complex signal converter.
It is a block diagram which shows one structural example. The complex signal conversion unit shown in FIG. 9 obtains a complex signal by quadrature detection.
The sine wave signal generated by the sine wave signal generation circuit 18 is multiplied, and the input voice signal is generated by the sine wave signal generation circuit 18 in the multiplication circuit 16B, and is further converted into π / 2 by the phase conversion circuit 19. The sine wave signal whose phase is delayed by is multiplied. The outputs of the multiplying circuits 16A and 16B are passed through the low-pass filters 17A and 17B, whereby a complex signal including a real number component and an imaginary number component is generated. Each of the low-pass filters 17A and 17B outputs a signal corresponding to the sum and difference between the audio signal and the sine wave signal from each of the multiplication circuits 16A and 16B, and the only necessary signal among these signals is the signal corresponding to the difference. Therefore, it plays a role of cutting high-frequency signals corresponding to the sum.

Next, an embodiment of the ultrasonic diagnostic apparatus of the present invention will be described. Here, first, the overall configuration of the ultrasonic diagnostic apparatus will be described. However, since the basic configuration itself of the ultrasonic diagnostic apparatus is already widely known, only the outline description will be given here. FIG. 10 is a schematic configuration diagram of the ultrasonic diagnostic apparatus. A pulse signal Tp is transmitted from the transmission control unit 120 to a large number of transducers (not shown) included in the ultrasonic probe 110 at predetermined timings, respectively, so that an ultrasonic pulse beam is transmitted into the subject 100. The ultrasonic pulse beam is reflected by blood cells and other tissues flowing in the subject and received by a large number of transducers in the ultrasonic probe 110. The ultrasonic signal Ap obtained by the reception by each transducer is input to the delay adder 130, and delayed and added in the delay adder 130 so as to satisfy the reception dynamic focus. The ultrasonic signal S after the delay addition is processed by the B mode detection unit 140 and the blood flow information detection unit 15.
Input to 0.

In the B-mode detector 140, a signal S _A for B-mode (tomographic image) display is generated based on the input received signal S, and this signal S _A is displayed on the display unit 160 such as a CRT display device. The display 16
At 0, a tomographic image is displayed and used for diagnosis. Further, in the blood flow information detection unit 150, blood flow information is detected based on the input received signal S using the Doppler effect as described below.

That is, the reflected ultrasonic waves reflected by the blood cells in the blood flow undergo a frequency shift due to the movement of the blood cells, and this displacement amount (Doppler displacement frequency) f _d is the velocity of the blood flow flowing in the body. V _B , the angle between the direction of this blood flow and the direction of the transmitted ultrasonic beam is α, and the center frequency of the transmitted ultrasonic wave is f
_c , where C is the velocity of the ultrasonic wave propagating in the body, it is expressed by f _d = (2V _B cos α / C) · f _c (3), and the central frequency f of the received signal that receives the reflected ultrasonic wave becomes _{f = f c + f d ...} (4). Therefore, by detecting the Doppler shift frequency f _d , and also by detecting the direction in which the blood vessel extends based on, for example, the signal S _A carrying the tomographic image, the blood flow velocity V
_B can be detected. This Doppler shift frequency f _d
Are, for example, the widely used autocorrelation method, FFT method, and other small displacement measurement methods (eg, cross-correlation method (for example, the 54th Research Conference of the Japanese Society of Ultrasonics, Proc.
Pp.-360 "Measurement of minute displacement of inhomogeneous tissue using spatial correlation of analytic signal" Yagi et al.), Phase tracking method (for example, Proceedings of the 57th Research Meeting of the Japanese Society of Ultrasonics, p.445) Pp. 446, "Measurement of In-vivo Tissue Displacement by Phase Tracking Process" Shinki et al., Patent Application "Ultrasonic Diagnostic Device" Japanese Patent Application No. 2-273910 on Oct. 12, 1990), observation data oriented Method (Japan Society for Ultrasonic Medicine 5th
Proceedings of the 6th Research Presentation, pp. 233-234 "Estimation method of small fluctuation in reflection type that does not depend on random structure of scatterer" Yamakoshi et al., Patent application "Ultrasonic wave" on April 3, 1990 Diagnostic device "(see Japanese Patent Application No. 2-088553))).

The signal S _B representing the blood flow information obtained as described above is input to the display section 160 and, for example, B
The blood flow in the direction approaching the ultrasonic probe is displayed in red, for example, and the blood flow away from the ultrasonic image is displayed in blue, for example. Further, the blood flow information detection unit 150 has a mode of obtaining blood flow information for each of a large number of points in the tomographic plane as described above, and also highly accurately obtains blood flow at one point specified in the tomographic plane. There are also modes. When blood flow information is to be obtained for a large number of points on the tomographic plane, it is necessary to transmit and receive ultrasonic waves along a large number (for example, 128) of scanning lines extending from the ultrasonic probe into the subject. In the direction along the scanning line of the book, blood flow information is obtained based on signals obtained by transmitting and receiving ultrasonic waves a small number of times, such as eight times, and thus there is a large error in the blood flow velocity. However, in this mode, it is possible to know the two-dimensional blood flow distribution while including a large error. Then, one point to be noticed is found from the blood flow distribution, this time ultrasonic waves are transmitted and received many times in the direction toward the attention point, and the blood flow at the attention point is investigated with high accuracy. Detailed blood flow information of the point of interest is displayed on the display unit 16.
Although it can be sent to 0 and displayed on the display screen, the blood flow information is sent as a sound signal S _{c to} a signal-acoustic transducer such as headphones 170, and the blood flow at the point of interest is heard by the ear for diagnosis. It is also configured to be able to do. At this time, the sound of the blood flow (Doppler sound) is heard from the right ear or the left ear depending on the direction of the blood flow. Below, this principle is shown.

The amplitude of the blood flow in the direction (TOWARD) approaching the ultrasonic probe 110 (see FIG. 10) is A _t , the Doppler shift frequency is f _t , and the amplitude of the blood flow (AWAY) moving away from the ultrasonic probe 110 is A. _a , the Doppler shift frequency is f
When _a, Doppler signal (signal after converting an ultrasonic signal into a complex signal) Z (t) _{is, Z (t) = A t} cos2πf t t + jA t sin2πf t t + A a cos2πf a t-jA a sin2πf a t ... (5) When I write down separately the equation (5) to the real part R _e and an imaginary part _{I m, R e {Z (} t)} = A t cos2πf t t + A a cos2πf a t ... (6) I m {Z (t _{)} = a t sin2πf t t} -a a sin2πf a t ... a (7). Here, when the imaginary part (equation (7)) is phase-shifted by −π / 2, the imaginary part I _m ′ after the phase shift is I _m ′ {Z (t)} = − A _t cos2πf _t t + A _a cos2πf _a t (8) When the difference and sum of the real part (equation (6)) and the imaginary part after phase shift (equation (8)) are calculated, R _e {Z (t)}-I _m ′ {Z (t)} = 2A _t cos2πf _t t (9) Re _E {Z (t)} + I _m ′ {Z (t)} = 2A _a cos2πf _a t (10) When such a calculation is performed and the difference signal shown in Expression (9) is heard in the right ear and the sum signal shown in Expression (10) is heard in the left ear, the blood flow in the direction approaching the ultrasonic probe is Blood flow away from the sonic probe is heard in the left ear.

At this time, as described above, when ultrasonic waves with a high center frequency are used to obtain an image with a high spatial resolution and a fast blood flow is detected, the Doppler shift frequency exceeds the audible range. The problem arises that you can't hear. The embodiment described below solves such a problem. FIG. 11 is a block diagram of the former part of the characteristic part of the embodiment of the ultrasonic diagnostic apparatus of the present invention.

The ultrasonic signal S output from the delay adder 130 shown in FIG. 10 has two multiplication circuits 151A and 151A.
B, sine wave signal generation circuit 152, and phase conversion circuit 1
The signal is input to a quadrature detection circuit composed of 53 and quadrature detected. The configuration of this quadrature detection circuit is the same as the configuration of the complex signal conversion unit shown in FIG. 9, and duplicate description will be omitted. The signals output from the multiplication circuits 151A and 151B are input to the integrators 154A and 154B and integrated with a predetermined time constant. These integrators 154A and 154B are
Similar to the low pass filters 17A and 17B shown in FIG.
In addition to the function of extracting only the necessary signal from the signals output from the multiplication circuits 151A and 151B, it has the function of moving averaging in the direction along the scanning line extending into the subject. This is because the S / N is still poor with the blood flow information of only one target point in the subject, and the S / N is improved by obtaining the average blood flow information before and after the target point.

The signals output from the integrators 154A and 154B are input to the sample and hold circuits 155A and 155B, and while the ultrasonic waves are repeatedly transmitted and received along the scanning line passing through the point of interest in the subject, the point of interest. The signal due to the ultrasonic waves reflected by is repeatedly sampled and held. The signals sampled and held by the sample and hold circuits 155A and 155B are output to the high pass filters 156A and 156A, respectively.
6B, the blood flow component alone is extracted from the signal component (blood flow component) due to the motion of blood flow and the signal component (crack component) due to the motion of each tissue in the subject other than the blood flow. This blood flow component is output from the complex signal conversion unit in FIG. 11 and input to the phase change amount adjustment unit 157 shown in FIG.

FIG. 12 is a block diagram of the latter part of the characteristic part of the embodiment of the ultrasonic diagnostic apparatus of the present invention.
The complex signal output from the complex signal conversion unit shown in FIG. 11 is input to the phase change amount adjustment unit 157 shown in FIG. The phase change amount adjustment unit 157 has, for example, the circuit configuration described with reference to FIG. Here, the overlapping description is omitted.

Output from the phase change amount adjusting unit 157,
The complex signal whose phase has been changed is input to the addition / subtraction unit including the phase conversion circuit 158, the subtraction circuit 159A, and the addition circuit 159B. In the addition / subtraction unit, the above-mentioned (5)
~ The operation according to the expression (10) is executed. That is, the real number component of the complex signal output from the phase change amount adjustment unit 157 is directly used as the subtraction circuit 159A and the addition circuit 1.
59B, and the imaginary number component is input to the phase conversion circuit 1
The signal is input to 58, the phase is shifted by −π / 2, and then input to the subtraction circuit 159A and the addition circuit 159B. The subtraction circuit 159A and the addition circuit 159B perform the operations of the expressions (9) and (10), respectively. That is, the subtraction circuit 159A subtracts the imaginary number component after the phase shift from the real number component, and the addition circuit 159B adds the real number component and the imaginary number component after the phase shift.

Subtraction circuit 159A and addition circuit 159B
The signal obtained in (3) is output to the headphones 170 as a stereo audio signal S _C (see FIG. 10). With such a configuration, it is possible to generate a Doppler sound with a low frequency, and it is possible to avoid a situation in which the Doppler sound exceeds the audible range and cannot be heard.

In the embodiment shown in FIG. 12, the imaginary number component is phase-shifted by -π / 2, but the phase of the real number component is delayed from the imaginary number component by π / 2.
The purpose is to align the phase of this real number component and the phase of the imaginary number component. Here, it suffices that the phases of the real number component and the imaginary number component are aligned. Therefore, instead of shifting the phase of the imaginary number component by −π / 2, the phase of the real number component may be shifted by π / 2, or the real number component and the imaginary number component may be shifted. The phase may be shifted for both the components and the phases may be matched.

FIG. 13 is a block diagram showing another structural example of the characteristic portion of the ultrasonic diagnostic apparatus of the present invention. Only differences from FIGS. 11 and 12 will be described.
In the configuration shown in FIG. 13, quadrature detection is performed and each integrator 15 is detected.
The complex signal that has passed through 4A and 154B is first input to the phase change amount adjusting unit 157 to undergo a phase change, and then input to each sample hold circuit 155A and 155B, and the signal reflected at the target point is repeatedly sampled and held. .

As described above, either the sample hold circuit or the phase change amount adjusting section may be arranged on the front stage side or the rear stage side. In addition, here, although the example of the circuit that handles an analog signal as the ultrasonic signal has been described, a digital ultrasonic signal may be handled. In that case, the sample hold circuits 155, 155A, and 155B are replaced with, for example, a register or the like that stores a digital signal corresponding to the target point. In the present invention, such a register and the like are referred to as sample hold means.

[0046]

As described above, according to the present invention,
The pitch of the sound can be changed while maintaining the original voice speed, and the invention can be applied to, for example, conversion of accompaniment keys in karaoke, a device for not specifying the speaker, and the like.
It can also be used as a special sound effect adding function of an electronic musical instrument. This is because the sound composed of a plurality of frequencies seems to be shifted in frequency due to being dragged by the one having a larger power, so that a sound effect different from simple frequency compression / expansion can be obtained. For example, when the frequency of the voice is converted to double, the voice is originally 4
If you have an instantaneous frequency of 40Hz and 400Hz,
Instead of hearing sounds of 880Hz and 800Hz,
An effect that can be heard as sounds of 60 Hz and 820 Hz is obtained.

Furthermore, when the audio signal converter of the present invention is applied to an ultrasonic diagnostic apparatus, or according to the ultrasonic diagnostic apparatus of the present invention, it is possible to avoid a situation in which the Doppler sound exceeds the audible range. it can. Further, in the case where the audio signal converting device of the present invention is provided with the time expanding / contracting means, it is possible to change only the voice speed while keeping the pitch as it is, or to change the pitch and the voice speed at the same time. It is possible, for example, to speed up or slow down the voice speed for foreign language acquisition, or to change the voice speed without changing the pitch on the video device.

Thus, the present invention has a wide range of applications.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of an audio signal conversion device of the invention.

FIG. 2 is an explanatory diagram of the audio signal conversion device shown in FIG.

FIG. 3 is a block diagram showing a second embodiment of the audio signal conversion device of the invention.

FIG. 4 is an explanatory diagram of the audio signal conversion device shown in FIG.

FIG. 5 is a block diagram showing a third embodiment of the audio signal conversion device of the invention.

FIG. 6 is a block diagram showing a configuration example of a complex signal conversion unit.

FIG. 7 is a block diagram illustrating another configuration example of a complex signal conversion unit.

FIG. 8 is a block diagram showing another configuration example of a complex signal conversion unit.

FIG. 9 is a block diagram showing still another configuration example of the complex signal conversion unit.

FIG. 10 is a schematic configuration diagram of an ultrasonic diagnostic apparatus.

FIG. 11 is a block diagram of a front part of a characteristic part of one embodiment of the ultrasonic diagnostic apparatus of the present invention.

FIG. 12 is a block diagram of a latter part of a characteristic part of one embodiment of the ultrasonic diagnostic apparatus of the present invention.

FIG. 13 is a block diagram showing another configuration example of the characteristic part in the ultrasonic diagnostic apparatus of the present invention.

[Explanation of symbols]

 10 complex signal conversion unit 12 FFT circuit 13 circuit 14 IFFT circuit 15 shift circuit 16A, 16B multiplication circuit 17A, 17B low-pass filter 18 sine wave signal generation circuit 19 phase conversion circuit 20 phase change amount adjustment unit 21 absolute value calculation circuit 22 complex conjugate Arithmetic circuit 23 Delay circuit 24 Polar coordinate-Cartesian coordinate conversion circuit 25 Multiplier circuit 26 Arctangent arithmetic circuit 27 Multiplier circuit 28 Integrator circuit 30A, 30B Time expansion / contraction unit 150 Blood flow information detection unit 151, 151B Multiplier circuit 152 Sine wave signal generation circuit 153 Phase conversion circuit 154, 154A, 154B Integrator 154C, 154D Low-pass filter 155, 155A, 155B Integrator 155A, 155B Sample hold circuit 157 Phase change amount adjustment unit 158 Phase conversion circuit 159A, 159B Subtraction circuit 170 headphones

Claims (9)

[Claims] 1. A complex signal converting means for inputting a voice signal and converting the input voice signal into a complex signal, and a complex signal obtained by the complex signal converting means, or generated based on the complex signal. And a phase change amount adjusting means for changing the phase of the input complex signal so that the angular velocity of the input complex signal increases or decreases by a predetermined first magnification. Audio signal converter. 2. The audio signal before being input to the complex signal converting means, the complex signal after being output from the complex signal converting means and before being input to the phase change amount adjusting means, and the phase change amount adjusting means. A time expansion / contraction unit for expanding / compressing a complex signal after the phase is changed and one of the signals generated based on the complex signal by a predetermined second magnification in the time axis direction is provided. The audio signal conversion device according to claim 1, wherein 3. The phase change amount adjustment means and the time expansion / contraction means are adjusted so that the first magnification and the second magnification are the same.
The audio signal conversion device described. 4. The complex signal converting means applies Hilbert transform to the input audio signal, and outputs the input audio signal and the signal obtained by applying the Hilbert transform to the input audio signal. 4. The audio signal conversion device according to claim 1, wherein the audio signal conversion device obtains a complex signal. 5. The complex signal converting means obtains a complex signal by performing an inverse Fourier transform after Fourier transforming an input audio signal to remove a negative frequency component. 5. The audio signal conversion device according to any one of 1 to 3. 6. The complex signal transforming means transforms a complex signal by Fourier transforming an input audio signal to remove a negative frequency component, shifting a positive frequency component in a low frequency direction, and then performing an inverse Fourier transform. An audio signal converter according to any one of claims 1 to 3, which is obtained. 7. The audio signal conversion according to claim 1, wherein the complex signal conversion means obtains a complex signal by performing quadrature detection on the input audio signal. apparatus. 8. An ultrasonic signal is obtained by transmitting an ultrasonic wave into a subject and receiving the ultrasonic wave reflected in the subject,
In an ultrasonic diagnostic apparatus for obtaining information on the inside of a subject based on the ultrasonic signal, complex signal converting means for inputting the ultrasonic signal and converting the input ultrasonic signal into a complex signal, the complex signal Of the complex signals obtained by the converting means, sample-hold means for repeatedly sample-holding a complex signal corresponding to the ultrasonic signal obtained by the ultrasonic waves reflected at a predetermined point in the subject, and the sample-hold means Phase change amount adjusting means for inputting the sample-held complex signal and changing the phase of the input complex signal so that the angular velocity of the input complex signal increases or decreases by a predetermined magnification. The addition and subtraction means for adding and subtracting the real number component and the imaginary number component of the complex signal whose phases have been changed by the means so as to be aligned with each other. Ultrasonic diagnostic equipment. 9. An ultrasonic signal is obtained by transmitting an ultrasonic wave into a subject and receiving the ultrasonic wave reflected in the subject,
In an ultrasonic diagnostic apparatus for obtaining information on the inside of a subject based on the ultrasonic signal, complex signal converting means for inputting the ultrasonic signal and converting the input ultrasonic signal into a complex signal, the complex signal Phase change amount adjusting means for inputting the complex signal obtained by the converting means and changing the phase of the input complex signal so that the angular velocity of the input complex signal increases or decreases by a predetermined magnification, and the phase change Of the complex signal after the phase has been changed by the amount adjusting means, sample-hold means for repeatedly sample-holding a complex signal corresponding to the ultrasonic signal obtained by the ultrasonic wave reflected at a predetermined point in the subject, The sample and hold means is provided with adder / subtractor means for aligning the phases of the real number component and the imaginary number component of the sampled and held complex signal and adding and subtracting them. Ultrasonic diagnostic equipment.