Testing system and testing method for electroacoustic indexes of phonocardiogram instrument

Abstract

The invention discloses a system and a method for testing electroacoustic indexes of a phonocardiogram instrument, and belongs to the technical field of phonocardiograms. The system comprises a phonocardiogram instrument, a signal generator, a power amplifier, a sound source calibrator, a standard sensor, a signal acquisition card and an upper computer test module, the signal generator and the power amplifier are connected to form a test sound source, and the sound source calibrator calibrates the test sound source; the standard sensor and the phonocardiogram instrument are placed at the same position and are used for receiving a signal sent by the test sound source and converting the received sound signal into an electric signal; the signal acquisition card is respectively connected with the standard sensor and the phonocardiogram instrument and is used for converting the electric signal into a digital signal; and the upper computer test module is connected with the signal acquisition card and is used for processing and analyzing the converted digital signal so as to measure the signal-to-noise ratio and frequency response of the phonocardiogram instrument and carry out sensitivity test. The system provided by the invention can quickly and conveniently test the electroacoustic index of the phonocardiogram.

Description

Technical Field

[0001] The invention belongs to the technical field of phonocardiographs, and in particular is a testing system and a testing method for electroacoustic indicators of a phonocardiograph. Background Art

[0002] Phonocardiograph is one of the most commonly used instruments in the medical field. It is mainly used to monitor the normal and abnormal conditions of heart sounds, thereby helping medical staff to make the initial diagnosis, screening and assessment of the health status of the patient's heart system. It plays an important role in clinical practice.

[0003] Auscultation has always been an effective means to solve the problem of early detection of cardiovascular disease. However, auscultation of heart sounds is a subjective method. Traditional stethoscopes require rich clinical experience and good listening skills, and the audio segments of auscultation cannot be stored for subsequent analysis. Therefore, in recent years, phonocardiographs have been invented to record and analyze the sound signals of the heart to evaluate heart function and diagnose heart disease. It usually consists of one or more sensors and a data recording system. The sensor usually receives the heart sound signal through a stethoscope or a conductor placed on the patient's chest. These sensors can convert the sound of the heart into electrical signals and transmit them to the data recording system for processing and analysis. The data recording system converts the received heart sound signal into a visual waveform or heart sound spectrum. In addition, some modern phonocardiographs can also be used in conjunction with computer software to help medical staff interpret and diagnose heart sound signals through automatic analysis algorithms. These algorithms can help improve the accuracy and efficiency of diagnosis.

[0004] When using a phonocardiograph to monitor the patient's heart sounds, it is necessary to ensure that the sound transmission characteristics of the phonocardiograph meet the use requirements, such as calibrating or identifying the phonocardiograph through regular testing to avoid the degradation of the electroacoustic performance of the phonocardiograph due to aging of electronic components, thereby affecting the monitoring effect of heart sounds. However, there is currently a lack of systems on the market that can quickly and conveniently test the audio performance of phonocardiographs. Therefore, ensuring the accuracy and performance of phonocardiographs still requires regular calibration and identification. This can include testing the phonocardiograph using a standard signal source, comparing the output results with a known standard reference signal for verification and adjustment. Summary of the invention

[0005] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art and to provide a testing system for testing the electroacoustic indexes of a phonocardiograph.

[0006] The present invention is achieved through the following technical solutions: A test system for electroacoustic indicators of a phonocardiograph comprises a phonocardiograph, a signal generator, a power amplifier, a sound source calibrator, a standard sensor, a signal acquisition card and a host computer test module; the phonocardiograph, the signal generator, the power amplifier, the sound source calibrator, the standard sensor and the signal acquisition card are all arranged in a soundproof box; the signal generator is connected to the power amplifier to form a test sound source; the sound source calibrator calibrates the test sound source; the standard sensor and the phonocardiograph are placed at the same position to receive a signal from the test sound source and convert the received sound signal into an electrical signal; the signal acquisition card is respectively connected to the standard sensor and the phonocardiograph to convert the electrical signal into a digital signal; the host computer test module is connected to the signal acquisition card to process and analyze the converted digital signal to measure the signal-to-noise ratio and frequency response of the phonocardiograph and to perform a sensitivity test.

[0007] Preferably, the signal generator generates a continuously variable sinusoidal signal not narrower than 2 Hz to 80 kHz.

[0008] Preferably, the sound source calibrator generates a sound pressure signal of 114 dB or 94 dB and a frequency of 1000 Hz to calibrate the test sound source.

[0009] Preferably, the phonocardiograph is mounted on the test sound source via a phonocardiograph fixing fixture.

[0010] Preferably, the reference sensitivity of the standard sensor is 50mv / Pa.

[0011] Preferably, the interface of the signal acquisition card is a USB 2.0 interface.

[0012] Furthermore, the present invention also provides a method for testing the electroacoustic index testing system of the above-mentioned phonocardiograph, comprising the following steps: 1) Hardware system preparation: In the test, a signal generator and a power amplifier are used as the test sound source; the signal generator can generate a continuously variable frequency sinusoidal signal with a frequency range of 2Hz to 80kHz. The sinusoidal signal is amplified by the power amplifier and transmitted to the phonocardiograph for testing.

[0013] 2) Preparation for sound pressure level calibration: Use a sound source calibrator to ensure the accuracy and consistency of the sound signal; the sound source calibrator has a power button, a 94dB / 114dB switching function button and a sound pressure indicator light. The 94dB / 114dB switching function button can be used to select a sound signal with a sound pressure level of 94dB or 114dB. The sound pressure indicator light is used to indicate the current sound pressure level.

[0014] 3) Test preparation: Before the test, prepare a phonocardiograph and a phonocardiograph fixing fixture. The phonocardiograph is mounted on the test sound source and fixed in a suitable position through the phonocardiograph fixing fixture. At the same time, place a standard sensor at the same position as the phonocardiograph to receive the signal from the test sound source and convert the received sound signal into an electrical signal.

[0015] 4) Data collection and processing: A signal acquisition card is used to convert electrical signals into digital signals and transmit them to the host computer test module for processing and analysis; the signal acquisition card uses a USB2.0 interface and is suitable for various application environments.

[0016] 5) Waveform data processing: The collected voltage data is converted into waveform data through a reading program written in C# in the host computer test module for subsequent waveform processing and analysis.

[0017] 6) Measurement program writing: The signal-to-noise ratio parameters of the phonocardiograph are measured by the measurement program written in C# in the host computer test module, and the sensitivity test is performed. The shape and characteristics of the waveform can be intuitively observed, and the performance indicators of the phonocardiograph can be evaluated.

[0018] 7) Sensitivity test: Sound signals of different amplitudes or intensities are used as input, and the corresponding voltage values ​​and sound pressure level characteristics are recorded; by analyzing these data, the sensitivity of the device, that is, the response ability of the device under different sound intensities, is calculated.

[0019] 8) Frequency response test: When calculating the frequency response, the change in the amplitude gain of the amplitude-frequency characteristic between two adjacent sweep frequency points is set, the amplitude-frequency characteristic data corresponding to the current sweep frequency point and the previous sweep frequency point are read, the processed time domain signal is converted into a frequency domain signal using the FFT algorithm, and the FFT result is analyzed to calculate the amplitude response of the phonocardiograph at different frequencies, the sweep frequency point and its corresponding amplitude-frequency characteristic data are selected, the frequency value of the next sweep frequency point is predicted and calculated through numerical analysis, and then it is determined whether the sweep is complete. If it is complete, it ends, and if not, it returns to the third step and loops until the sweep is complete. In this way, an amplitude spectrum curve can be obtained, which intuitively represents the frequency response characteristics.

[0020] 9) Signal-to-noise ratio test: When testing the signal-to-noise ratio, use a signal generator to send out a sinusoidal excitation signal and record the total noise energy in the system; then, stop sending the sinusoidal excitation signal and record the total noise energy in the system; and obtain the signal-to-noise ratio by calculating the ratio of the total signal energy to the total noise energy.

[0021] 10) Test environment: All testing work is carried out in an anechoic box to ensure the accuracy and reliability of the test results and avoid the influence of external environmental noise on the test results.

[0022] In the test system of the present invention, a signal generator capable of generating a continuously variable sinusoidal signal not narrower than 2Hz~80kHz is connected to a power amplifier as a test sound source for playing a sound signal. Preparation work before the test: according to the test requirements, a power-on key, a 94 / 114dB switching function key and a sound pressure indicator light are provided on the sound source calibrator, and a sound pressure signal with a sound pressure level of 94dB or 114dB and a frequency of 1000Hz is generated by the sound source calibrator to calibrate the test sound source. Then, a phonocardiogram fixing fixture is used to install the phonocardiogram on the test sound source, and a standard sensor (reference sensitivity 50mv / Pa) and the phonocardiogram are placed in the same position to receive the sound signal emitted by the test sound source, and the received sound signal is converted into an electrical signal. The electrical signal is converted into a digital signal by a signal acquisition card, and is transmitted to a data recording system for processing and analysis. The interface form of the signal acquisition card selects a USB2.0 interface, which is suitable for various application environments. Through the USB signal acquisition card, the acquisition of dynamic analog voltage signals can be realized, and it can be converted into a signal type that can be received by the host computer test module. After obtaining the voltage signal output by the signal acquisition card in the host computer test module, the voltage data can be converted into waveform data using the reading program written in C#. In this way, the continuous voltage value can be converted into discrete sampling points for subsequent waveform processing and analysis, which is convenient for visualization and analysis operations, and the shape and characteristics of the waveform can be observed intuitively. In the host computer test module, the measurement program written in C# can be used to measure the signal-to-noise ratio parameters of the phonocardiograph and perform sensitivity tests. The heart sounds collected by the phonocardiograph can be played through the host computer test module. When calculating the sensitivity, the voltage value is converted into the corresponding sound pressure level. During the test, sound signals of different amplitudes or intensities can be used as input, and then the corresponding voltage values ​​and sound pressure level characteristics are recorded. By analyzing these data, the sensitivity of the device can be calculated, that is, the responsiveness of the device under different sound intensities. When calculating the frequency response, the processed waveform data is applied with the FFT algorithm to convert the time domain signal into the frequency domain signal. FFT decomposes the signal into the amplitude and phase information of different frequency components. By analyzing the FFT results, the amplitude response of the phonocardiograph at different frequencies can be calculated, the amplitude spectrum information can be extracted, and converted to a linear or logarithmic scale to obtain a more intuitive result. The calculated frequency response data can be displayed in the form of an image, and an amplitude spectrum curve can be drawn, with the horizontal axis representing the frequency and the vertical axis representing the amplitude response. When testing the signal-to-noise ratio, the signal-to-noise ratio is calculated by testing the energy. In the signal-to-noise ratio test process, a sinusoidal excitation signal is first sent out using a signal generator, and the phonocardiograph receives the signal. Then, the host computer test module calculates the total energy of the sinusoidal excitation signal in the test system. Next, stop sending the sinusoidal excitation signal and leave the test system in an idle state, that is, only noise exists.Let the empty sampling signal enter the host computer test module in the test system, and then calculate the total noise energy in the system. According to the calculation results of the total signal energy and the total noise energy, the value of the signal-to-noise ratio can be obtained. The signal-to-noise ratio represents the relative strength or clarity of the signal and the noise, usually in decibels (dB). By performing the signal-to-noise ratio test process, the clarity of the signal in the system and the degree of influence of noise can be evaluated. The entire test is carried out in an anechoic box to avoid interference from external sounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. The drawings herein are used to provide further explanation of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their description are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0024] Figure 1 It is a system block diagram of the present invention.

[0025] Figure 2 Flow chart for phonocardiograph sensitivity testing.

[0026] Figure 3 This is a flow chart for the frequency response test of a phonocardiograph.

[0027] Figure 4 This is a flow chart for the signal-to-noise ratio test of a phonocardiograph. DETAILED DESCRIPTION

[0028] The embodiments of the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and the protection scope of the present invention cannot be limited thereto. It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should be the common meanings understood by those skilled in the art to which the present invention belongs.

[0029] For a phonocardiograph, the frequency response range should be able to cover the frequency band of human heart sounds, usually between 20Hz and 600 Hz. Since the heart sound signals are weak when transmitted to the body surface, the phonocardiograph needs to have a high sensitivity to capture these low-amplitude signals. High sensitivity helps to provide a better frequency response effect, enabling the phonocardiograph to better receive and amplify heart sound signals. However, a wide frequency response range and high sensitivity may introduce system noise, including electromagnetic interference inside the hardware, cable noise, resistor and op amp noise, current noise, and quantization noise of the digital-to-analog converter. Therefore, the signal-to-noise ratio is also one of the key indicators for evaluating the working performance of a phonocardiograph. A higher signal-to-noise ratio helps to reduce the impact of noise on heart sound signals and improve the clarity and reliability of the signal.

[0030] To this end, this embodiment provides a test system for electroacoustic indicators of a phonocardiograph, which is used to test three main electroacoustic performance indicators of a phonocardiograph: sensitivity, frequency response, and signal-to-noise ratio. Figure 1 As shown, the system of this embodiment includes a phonocardiograph, a signal generator, a power amplifier, a sound source calibrator, a standard sensor, a signal acquisition card and a host computer test module; the phonocardiograph, the signal generator, the power amplifier, the sound source calibrator, the standard sensor, and the signal acquisition card are all arranged in a soundproof box; the signal generator generates a continuously variable sinusoidal signal not narrower than 2Hz~80kHz, and the signal generator is connected to the power amplifier to form a test sound source; the sound source calibrator calibrates the test sound source, and the sound source calibrator generates a sound pressure signal of 94dB or 114dB and a frequency of 1000Hz to calibrate the test sound source; the phonocardiograph is installed on the test sound source through a phonocardiograph fixing fixture; the standard sensor and the phonocardiograph are placed in the same position to receive the signal emitted by the test sound source and convert the received sound signal into an electrical signal. The reference sensitivity of the standard sensor is 50mv / Pa; the interface of the signal acquisition card is a USB2.0 interface, which is connected to the standard sensor and the phonocardiograph respectively to convert the electrical signal into a digital signal; the host computer test module is connected to the signal acquisition card to process and analyze the converted digital signal to measure the signal-to-noise ratio and frequency response of the phonocardiograph and perform a sensitivity test; specifically, the host computer test module uses a PC, which is equipped with a reading program written in C#, a waveform data conversion program and a measurement program; the reading program written in C# can convert the collected voltage data into waveform data The waveform data can be converted into waveform data for subsequent waveform processing and analysis; the waveform data conversion program written in C# can parse and process the voltage data, express it in waveform form, and intuitively display the sensitivity of the phonocardiograph in the form of a curve for visualization and analysis; the measurement program written in C# can be used to calculate the signal-to-noise ratio and frequency response of the phonocardiograph, and perform sensitivity tests. By analyzing the recorded voltage values ​​and sound pressure level characteristics, the sensitivity of the device can be calculated, that is, the responsiveness of the device under different sound intensities. The signal-to-noise ratio test calculates the energy of the signal and noise to evaluate the clarity of the signal in the system and the degree of noise influence.

[0031] The testing method of the above-mentioned phonocardiograph electroacoustic index testing system comprises the following steps: 1) Hardware system preparation: In the test, a signal generator and a power amplifier are used as the test sound source. The signal generator can generate a continuously variable frequency sinusoidal signal with a frequency range of 2Hz to 80kHz. This signal will be amplified by the power amplifier and transmitted to the phonocardiograph for testing.

[0032] 2) Preparation for sound pressure level calibration: Use a sound source calibrator to ensure the accuracy and consistency of the sound signal; the sound source calibrator has a power button, a 94dB / 114dB switching function button and a sound pressure indicator light. The 94dB / 114dB switching function button can be used to select a sound signal with a sound pressure level of 94dB or 114dB. The sound pressure indicator light is used to indicate the current sound pressure level.

[0033] 3) Test preparation: Before the test, the phonocardiograph and the related phonocardiograph fixture need to be prepared. The phonocardiograph will be installed on the test sound source through the phonocardiograph fixture and fixed in a suitable position. At the same time, the standard sensor and the phonocardiograph will be placed in the same position to receive the signal from the test sound source and convert the received sound signal into an electrical signal.

[0034] 4) Data collection and processing: The signal acquisition card is used to convert the electrical signal into a digital signal and transmit it to the host computer test module for processing and analysis. The signal acquisition card uses a USB2.0 interface and is suitable for various application environments.

[0035] 5) Waveform data processing: The collected voltage data will be converted into waveform data through the reading program written in C# in the host computer test module for subsequent waveform processing and analysis; 6) Measurement program writing: The signal-to-noise ratio parameters of the phonocardiograph are measured by the measurement program written in C# in the host computer test module, and the sensitivity test is performed. The shape and characteristics of the waveform can be intuitively observed, and the performance indicators of the phonocardiograph can be evaluated.

[0036] 7) Sensitivity test: The sound signal of different amplitude or intensity is used as input, and the corresponding voltage value and sound pressure level characteristics are recorded. By analyzing these data, the sensitivity of the device can be calculated, that is, the response ability of the device under different sound intensities, such as Figure 2 shown.

[0037] 8) Frequency response test: When calculating the frequency response, set the change in the amplitude gain of the amplitude-frequency characteristic between two adjacent sweep frequency points, read the amplitude-frequency characteristic data corresponding to the current sweep frequency point and the previous sweep frequency point, use the FFT algorithm to convert the processed waveform data into a frequency domain signal, and analyze the FFT results to calculate the amplitude response of the phonocardiograph at different frequencies, select the sweep frequency point and its corresponding amplitude-frequency characteristic data, and calculate the frequency value of the next sweep frequency point through numerical analysis prediction, and then determine whether the sweep is complete. If it is complete, end it. If not, return to the third step and loop until the sweep is complete. In this way, an amplitude spectrum curve can be obtained, which intuitively represents the frequency response characteristics, such as Figure 3 shown.

[0038] 9) Signal-to-noise ratio test: When testing the signal-to-noise ratio, use a signal generator to send out a sinusoidal excitation signal and record the total noise energy in the system. Then, stop sending the sinusoidal excitation signal and record the total noise energy in the system. By calculating the ratio of the total signal energy to the total noise energy, the value of the signal-to-noise ratio can be obtained, such as Figure 4 shown.

[0039] 10) Test environment: All testing work is carried out in an anechoic box to ensure the accuracy and reliability of the test results and avoid the influence of external environmental noise on the test results.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A system for testing electroacoustic indicators of a phonocardiograph, comprising a phonocardiograph, characterized in that: It also includes a signal generator, a power amplifier, a sound source calibrator, a standard sensor, a signal acquisition card and a host computer test module; the phonocardiograph, the signal generator, the power amplifier, the sound source calibrator, the standard sensor, and the signal acquisition card are all arranged in a soundproof box; the signal generator is connected to the power amplifier to form a test sound source; the sound source calibrator calibrates the test sound source; the standard sensor and the phonocardiograph are placed in the same position to receive the signal emitted by the test sound source and convert the received sound signal into an electrical signal; the signal acquisition card is connected to the standard sensor and the phonocardiograph respectively to convert the electrical signal into a digital signal; the host computer test module is connected to the signal acquisition card to process and analyze the converted digital signal to measure the signal-to-noise ratio and frequency response of the phonocardiograph and perform a sensitivity test.

2. The test system for electroacoustic indexes of a phonocardiograph according to claim 1, characterized in that: The signal generator generates a continuously variable sinusoidal signal with a range not narrower than 2Hz~80kHz.

3. The test system for electroacoustic indexes of a phonocardiograph according to claim 1, characterized in that: The sound source calibrator generates a sound pressure signal of 114dB or 94dB and a frequency of 1000Hz to calibrate the test sound source.

4. The test system for testing electroacoustic indicators of a phonocardiograph according to claim 1, characterized in that: The phonocardiograph is mounted on the test sound source by means of a phonocardiograph fixing fixture.

5. The testing system for electroacoustic indexes of a phonocardiograph according to claim 1, characterized in that: The standard sensor reference sensitivity is 50mv / Pa.

6. The test system for testing electroacoustic indicators of a phonocardiograph according to claim 1, characterized in that: The interface of the signal acquisition card is USB2.0 interface.

7. The testing method of the testing system of the electroacoustic index of the phonocardiograph as claimed in claim 1, characterized in that: The steps include: 1) Hardware system preparation: In the test, a signal generator, a power amplifier and a speaker are used as the test sound source; the signal generator can generate a continuously variable frequency sinusoidal signal with a frequency range of 2Hz to 80kHz, which is amplified by the power amplifier and transmitted to the phonocardiograph for testing; 2) Preparation for sound pressure level calibration: Use a sound source calibrator to ensure the accuracy and consistency of the sound signal; the sound source calibrator has a power button, a 94dB / 114dB switching function button and a sound pressure indicator light. The 94dB / 114dB switching function button can be used to select a sound signal with a sound pressure level of 94dB or 114dB. The sound pressure indicator light is used to indicate the current sound pressure level. 3) Test preparation: Before the test, prepare a phonocardiograph and a phonocardiograph fixing fixture, and install the phonocardiograph on the test sound source through the phonocardiograph fixing fixture and fix it in a suitable position; at the same time, place a standard sensor at the same position as the phonocardiograph to receive the signal from the test sound source and convert the received sound signal into an electrical signal; 4) Data collection and processing: Use the signal acquisition card to convert the electrical signal into a digital signal and transmit it to the host computer test module for processing and analysis; the signal acquisition card uses a USB2.0 interface and is suitable for various application environments; 5) Waveform data processing: The collected voltage data is converted into waveform data through a reading program written in C# in the host computer test module for subsequent waveform processing and analysis; 6) Measurement program writing: The measurement program written in C# in the host computer test module is used to measure the signal-to-noise ratio parameters of the phonocardiograph and perform sensitivity tests. The shape and characteristics of the waveform can be observed intuitively, and the performance indicators of the phonocardiograph can be evaluated. 7) Sensitivity test: It uses sound signals of different amplitudes or intensities as input and records the corresponding voltage values ​​and sound pressure level characteristics; by analyzing these data, it calculates the sensitivity of the device, that is, the device's response ability under different sound intensities; 8) Frequency response test: When calculating the frequency response, the change in the amplitude gain of the amplitude-frequency characteristic between two adjacent sweep frequency points is set, the amplitude-frequency characteristic data corresponding to the current sweep frequency point and the previous sweep frequency point are read, the processed time domain signal is converted into a frequency domain signal using the FFT algorithm, and the FFT result is analyzed to calculate the amplitude response of the phonocardiograph at different frequencies, the sweep frequency point and its corresponding amplitude-frequency characteristic data are selected, the frequency value of the next sweep frequency point is predicted and calculated through numerical analysis, and then it is determined whether the sweep frequency is complete, if it is complete, it ends, if not, it returns to the third step and loops until the sweep frequency is complete, so that an amplitude spectrum curve can be obtained, which intuitively represents the frequency response characteristics; 9) Signal-to-noise ratio test: When testing the signal-to-noise ratio, use a signal generator to send out a sinusoidal excitation signal and record the total noise energy in the system; then stop sending the sinusoidal excitation signal and record the total noise energy in the system; and calculate the ratio of the total signal energy to the total noise energy to obtain the value of the signal-to-noise ratio. 10) Test environment: All testing work is carried out in an anechoic box to ensure the accuracy and reliability of the test results and avoid the influence of external environmental noise on the test results.

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