Active noise reduction stethoscope
By using active noise-canceling stethoscopes to calculate sound correlation with main and secondary microphones and automatically determine noise reduction operation, the problem of sound interference in noisy environments caused by traditional stethoscopes is solved. This achieves noise reduction when needed without affecting the accuracy of the sound signal or the lifespan of the device.
Patent Information
- Application Number
- CN202411266692.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-08-23
- Filing Date
- 2024-09-11
- Publication Date
- 2026-03-03
AI Technical Summary
Traditional stethoscopes have difficulty effectively isolating the target sound from ambient noise in noisy environments, which can lead to interference or masking of sound judgment.
An active noise-canceling stethoscope is used to receive sound signals through main and secondary microphones, calculate their correlation, automatically determine whether to activate active noise cancellation, and use an equalizer to optimize the noise cancellation signal to reduce the impact of environmental noise.
It enables automatic activation of active noise cancellation when needed, reducing environmental noise interference and ensuring the accuracy of sound signals, while saving power and extending the service life of the equipment when not needed.
Smart Images
Figure CN121587761A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a stethoscope, and more particularly to a stethoscope that automatically determines whether to perform active noise reduction. Background Technology
[0002] Traditional analog stethoscopes have two sides for receiving sounds at different frequencies. However, the microphones in such stethoscopes not only pick up the desired sound (e.g., human voices) but also ambient sounds, such as ambulance sirens, other voices, and other noises, perhaps near a hospital. When these ambient sounds are too loud, they can interfere with or drown out the desired sound. Therefore, a new device is needed to address these problems. Summary of the Invention
[0003] According to one embodiment of this disclosure, an active noise-canceling stethoscope is provided, including a sound receiving device, a sound processing device, and a control unit. The sound receiving device has a main microphone and a secondary microphone, wherein the main microphone is configured to receive and output a first sound signal, and the secondary microphone is configured to receive and output a second sound signal. The sound processing device is configured to be coupled to the sound receiving device to receive the first and second sound signals, and to convert the first and second sound signals into a third and a fourth sound signal in digital mode, respectively. The control unit is configured to be coupled to the sound processing device and to calculate the correlation between the third and fourth sound signals to determine whether to perform an active noise cancellation operation.
[0004] According to another embodiment of this disclosure, the control unit further includes an active noise cancellation unit configured to perform active noise cancellation operation. The active noise cancellation operation includes: simultaneously capturing a first window and a second window for the third audio signal and a fourth audio signal, respectively; calculating a correlation coefficient between the third audio signal and the fourth audio signal during the first and second windows; and comparing the correlation coefficient with a reference correlation coefficient. If the correlation coefficient is greater than or equal to the reference correlation coefficient, the control unit automatically activates the active noise cancellation unit to perform active noise cancellation operation, and the active noise cancellation unit outputs a noise-reduced signal. If the correlation coefficient is less than the reference correlation coefficient, the control unit automatically deactivates the active noise cancellation unit to stop the active noise cancellation operation and receives the third audio signal from the audio processing device.
[0005] According to yet another embodiment of this disclosure, the control unit further includes an equalizer configured to receive a selection signal. When the active noise cancellation is enabled, the equalizer receives the noise-canceling signal and, based on the selection signal, selects one of a low-frequency mode, a high-frequency mode, and a mixed mode to optimize the noise-canceling signal, and outputs a first equalization signal. When the active noise cancellation is disabled, the equalizer receives a third audio signal and, based on the selection signal, selects one of a low-frequency mode, a high-frequency mode, and a mixed mode to optimize the third audio signal, and outputs a second equalization signal. Attached Figure Description
[0006] Figure 1 This is a block diagram of an active noise-canceling stethoscope described according to embodiments of the present disclosure.
[0007] Figure 2 This is a schematic diagram illustrating the determination process for performing active noise reduction operation according to the embodiments described in this disclosure.
[0008] Figure 3 This is a schematic diagram of an active noise cancellation stethoscope performing active noise cancellation operation according to an embodiment of this disclosure.
[0009] Figure 4 This is a schematic diagram of an active noise-canceling stethoscope described according to an embodiment of the present disclosure that does not perform active noise cancellation.
[0010] [Symbol Explanation]
[0011] 100: Active noise-canceling stethoscope
[0012] 110: Power Supply
[0013] 120: Radio device
[0014] 122: Main Microphone
[0015] 124: Secondary microphone
[0016] 130: Sound Processor
[0017] 132: Analog-to-Digital Converter (ADC)
[0018] 134: Amplifier
[0019] 140: Control Unit
[0020] 150:Communication device
[0021] 310: Active Noise Cancellation (ANC)
[0022] 320: Equalizer (EQ)
[0023] 322: Low Frequency Mode
[0024] 324: High-frequency mode
[0025] 326: Mixed Mode
[0026] 330: Digital Amplifier
[0027] 340: Digital-to-Analog Converter (DAC)
[0028] S1: Target Sound
[0029] S2: Ambient Sounds
[0030] SM0: Main microphone audio signal
[0031] SS0: Secondary microphone audio signal
[0032] SM: Main audio signal
[0033] SS: Subsound signal
[0034] D0: Output signal
[0035] W: Preset window time
[0036] W1: First Window
[0037] W2: Second Window
[0038] Wn: nth window
[0039] Sd: Window spacing
[0040] Tc: Reference correlation coefficient
[0041] C1, C2, Cn: Correlation coefficients
[0042] t1, t2, tn: time
[0043] SA: Noise Reduction Signal
[0044] SEL: Selection signal
[0045] SE, SEA: Equalization signal Detailed Implementation
[0046] Several embodiments are described herein with reference to the accompanying illustrations, in which similar reference numerals are used to denote similar or equivalent elements. The illustrations are not necessarily drawn to scale and are for illustrative purposes only, illustrating aspects and features of this disclosure. Numerous specific details, relationships, and methods are set forth to provide a complete understanding of particular aspects and features of this disclosure; however, those skilled in the art will understand that these aspects and features can be practiced without one or more of the aforementioned specific details, in other relationships, or using other methods. In some instances, structures or operations well-known for illustrative purposes are not shown in detail. The various embodiments disclosed herein are not necessarily limited to the illustrative order of actions or events; some actions may occur in a different order and / or simultaneously with other actions or events. Furthermore, not all illustrative actions are necessary to implement particular aspects and features of this disclosure.
[0047] For the sake of detailed description, unless otherwise stated, the singular includes the plural, and vice versa, where appropriate. The word “including” means “including but not limited to”. Furthermore, words indicating approximation, such as “approximately,” “almost,” “roughly,” “probably,” and similar words may be used herein to mean “in,” “near,” “almost,” “within 3-5%,” “within acceptable manufacturing tolerances,” or any logical combination thereof. Similarly, the words “vertical” or “horizontal” additionally include “within 3-5% in the vertical or horizontal direction,” respectively. Furthermore, words indicating direction, such as “top,” “bottom,” “left,” “right,” “above,” and “below,” mean in relation to the equivalent direction described in the reference illustrations; the orientation should be understood relative to the referenced object or element, depending on the context, such as the location where an object or element is typically used; or according to other descriptions herein.
[0048] Figure 1 This is a block diagram of an active noise-canceling stethoscope 100 described according to embodiments of the present disclosure. Figure 1 As shown, the active noise-canceling stethoscope 100 includes a power supply 110, a radio 120, a sound processor 130, a control unit 140, and a communication device 150.
[0049] A power supply 110, such as a battery, is used as the power source for the active noise-canceling stethoscope 100. The recording device 120 includes a main microphone 122 and a secondary microphone 124. The main microphone 122 is configured to receive a target sound S1 (e.g., a human voice) and an ambient sound S2 and output a main microphone sound signal SM0 (i.e., a sound containing both the target sound S1 and the ambient sound S2). The secondary microphone is configured to receive the ambient sound S2 and output a secondary microphone sound signal SS0 (i.e., a sound containing only the ambient sound S2). A sound processor 130 is configured to receive the main microphone sound signal SM0 and the secondary microphone sound signal SS0 from the recording device 120, amplify them using an amplifier 134 (e.g., amplify the secondary microphone sound signal SS0 by approximately 5 times), and convert the main microphone sound signal SM0 and the secondary microphone sound signal SS0 using an analog-to-digital converter (ADC) 132, outputting a main sound signal SM0 and a secondary sound signal SS0. That is, the main audio signal SM corresponds to the digital mode audio signal of the main microphone audio signal SM0, while the secondary audio signal SS corresponds to the digital mode audio signal of the secondary microphone audio signal SS0.
[0050] Control unit 140 is configured to perform active noise cancellation (ANC) on the main audio signal SM and the secondary audio signal SS, and to filter and integrate the main audio signal SM and the secondary audio signal SS. The active noise cancellation operation will be performed through the following... Figure 3 and Figure 4 A detailed description follows. The control unit 140 performs active noise reduction and filtering on the main audio signal SM and the secondary audio signal SS, generating an output signal D0 which is then output to the communication device 150. In one embodiment, the communication device 150 may be configured to store the output signal D0 (e.g., as a memory or cloud database). In another embodiment, the communication device 150 may further have a display screen configured to display the output signal D0 (e.g., display the waveform of the output signal D0), or allow selection of the desired output signal D0 data via an application program within the communication device 150.
[0051] Figure 2 This is a schematic diagram illustrating the determination process for active noise cancellation operation as described in the embodiments of this disclosure. The control unit 140 can automatically start or stop the active noise cancellation operation based on the correlation between the main audio signal SM and the secondary audio signal SS. For example... Figure 2As shown, the top timing diagram displays the waveform of the main audio signal SM (with solid and dashed lines), the middle timing diagram displays the waveform of the secondary audio signal SS (with only dashed lines), and the bottom timing diagram displays the correlation between the sounds from the main microphone 122 and the secondary microphone 124. Here, Tc represents the reference correlation coefficient, and Cn (n = 1, 2, ...) represents the correlation coefficient of the sounds received by the main microphone 122 and the secondary microphone 124 in the nth window. The correlation coefficient Cn can be calculated using the following formula:
[0052]
[0053] Where Wsi and Wai are the i-th sampling points in the n-th window of the main microphone 122 and the secondary microphone 124, respectively, and Ws and Wa are the average values of the sampling points in the n-th window of the main microphone 122 and the secondary microphone 124, respectively.
[0054] The method by which the control unit 140 determines whether to perform active noise reduction is as follows. First, the control unit 140 extracts a first window W1 based on a preset window time W, and calculates a correlation coefficient C1 for a time t1 during the first window W1, as the correlation coefficient of the first window W1. Then, the correlation coefficient C1 is compared with a reference correlation coefficient Tc. Figure 2 As shown, the correlation coefficient C1 is less than the reference correlation coefficient Tc, therefore the control unit 140 will not perform active noise reduction during the first window W1.
[0055] In one specific embodiment, the range of the reference correlation coefficient Tc can be obtained by trial and error or by averaging. Testing showed that a reference correlation coefficient Tc of 0.55 to 0.8 yielded better results. If the reference correlation coefficient Tc is too low, ANC will be activated too easily, causing audio signal distortion. If the reference correlation coefficient Tc is too high, ANC will be difficult to activate, resulting in poor active noise cancellation. Figure 2 The results are for reference when the correlation coefficient Tc = 0.6.
[0056] Then, after a window interval Sd, the control unit 140 extracts a second window W2 according to a preset window time W, and calculates a correlation coefficient C2 for a time t2 during the second window W2, as the correlation coefficient of the second window W2. Next, the correlation coefficient C2 is compared with a reference correlation coefficient Tc. Figure 2 As shown, the correlation coefficient C2 is greater than the reference correlation coefficient Tc, therefore the control unit 140 performs active noise reduction during the second window W2.
[0057] Next, the control unit 140 extracts an nth window Wn based on a preset window time W, and calculates a correlation coefficient Cn for a time tn during the nth window Wn, which is used as the correlation coefficient of the nth window Wn. Then, the correlation coefficient Cn is compared with a reference correlation coefficient Tc. Figure 2 As shown, the correlation coefficient Cn is less than the reference correlation coefficient Tc, therefore the control unit 140 will not perform active noise reduction during the nth window Wn.
[0058] In other words, if the correlation coefficient of the current window is less than the reference correlation coefficient Tc, the control unit 140 does not perform active noise reduction during the current window. Conversely, if the correlation coefficient of the current window is greater than or equal to the reference correlation coefficient Tc, the control unit 140 performs active noise reduction during the current window. Furthermore, although... Figure 2 As shown, the first window W1 and the second window W2 do not overlap. However, in some embodiments, the duration of the first window W1 and the second window W2 (or any two adjacent windows) can overlap by adjusting the preset window time W and the window interval Sd, thereby reducing the sampling time difference between the correlation coefficients C1 and C2, and increasing the sensitivity and accuracy of the control unit 140 in determining whether to perform active noise reduction.
[0059] Figure 3 This is a schematic diagram of an active noise cancellation stethoscope 100 performing active noise cancellation operation according to an embodiment of the present disclosure. Figure 3 This demonstrates the program that performs active noise reduction on the sound when the control unit 140 determines that the correlation coefficient Cn is greater than or equal to the reference correlation coefficient Tc. For the sake of brevity, [the following is omitted as it is not part of the program description]. Figure 1 The power supply 110, sound processor 130, and communication device 150 are omitted. The main microphone 122 receives the target sound S1 and the surrounding sound S2, and outputs the main sound signal SM after conversion by the sound processor 130. The secondary microphone 124 receives the surrounding sound S2, and outputs the secondary sound signal SS after conversion by the sound processor 130. The surrounding sound S2 received by the secondary microphone 124 can be amplified by the amplifier 134 in the sound processor 130, so that the active noise cancellation effect can be obtained in the subsequent active noise cancellation operation.
[0060] Next, the main audio signal SM and the secondary audio signal SS are output to an active noise canceller 310 for processing such as... Figure 2 This shows the determination of whether to perform active noise cancellation. For detailed determination procedures, please refer to [link / reference needed]. Figure 2As described above, it will not be repeated here. After the active noise cancellation operation is completed, the active noise canceller 310 generates a noise-canceling signal SA and outputs the noise-canceling signal SA to an equalizer (EQ) 320. The equalizer 320 has three modes: a low-frequency mode 322, a high-frequency mode 324, and a mixed mode 326. The equalizer 320 can determine the mode to be triggered based on a selection signal SEL. The selection signal SEL can be manually input by the user before using the active noise-canceling stethoscope 100. In addition, the equalizer 320 can further optimize the sound signal for different frequency ranges of the three modes using a band-stop filter, a high-pass filter (HPF), a low-pass filter (LPF), or a combination of the above.
[0061] For example, such as Figure 3 As shown, when the active noise cancellation 310 is enabled (i.e., when active noise cancellation is required), if the selection signal SEL indicates that low-frequency mode 322 needs to be triggered, the equalizer 320 can optimize the low-frequency performance of the noise-canceling signal SA by combining a high-pass filter with a cutoff frequency of 200Hz and a low-pass filter with a cutoff frequency of 1000Hz. If the selection signal SEL indicates that high-frequency mode 324 needs to be triggered, the equalizer 320 can optimize the high-frequency performance of the noise-canceling signal SA by combining a high-pass filter with a cutoff frequency of 100Hz, band-stop filters with cutoff frequencies of 350Hz and 1500Hz, and a low-pass filter with a cutoff frequency of 1000Hz. If the selection signal SEL indicates that mixed mode 322 needs to be triggered, the equalizer 320 can optimize the overall performance of the noise-canceling signal SA by combining band-stop filters with cutoff frequencies of 80Hz and 1500Hz, and a low-pass filter with a cutoff frequency of 1000Hz.
[0062] After optimizing the noise-reduced signal SA, equalizer 320 generates an equalized signal SE and outputs it to a digital amplifier 330 for amplification. Next, digital amplifier 330 generates an amplified equalized signal SEA and outputs it to a digital-to-analog converter (DAC) 340. DAC 340 converts the equalized signal SEA into an analog output signal D0 and outputs it to communication device 150 for storage or user viewing. Since digital amplifier 330 is only used to amplify the equalized signal SE, it can be omitted if the amplitude of the equalized signal SE is sufficient.
[0063] Figure 4 This is a schematic diagram of an active noise-canceling stethoscope 100 described according to an embodiment of the present disclosure not performing active noise cancellation. Figure 4 This demonstrates the procedure where, when the control unit 140 determines that the correlation coefficient Cn is less than the reference correlation coefficient Tc, no active noise reduction is performed. For simplicity, the following is a simplified explanation: Figure 1 The power supply 110, sound processor 130, and communication device 150 are omitted. Furthermore, due to... Figure 4 The process shown does not require active noise cancellation, and the secondary microphone 124 and active noise canceller 310 are also omitted.
[0064] The main microphone 122 receives the target sound S1 and the surrounding sound S2, and outputs the main sound signal SM after conversion by the sound processor 130. At this time, since the control unit 140 does not perform active noise cancellation, the active noise cancellation unit 310 is turned off, and the main sound signal SM is directly output to the equalizer 320. For example, if the selection signal SEL indicates that the low-frequency mode 322 needs to be triggered, the equalizer 320 can optimize the low-frequency performance of the noise-canceling signal SA by combining a high-pass filter with a cutoff frequency of 60Hz, band-stop filters of 10Hz and 50Hz, and a low-pass filter of 254Hz. If the selection signal SEL indicates that the high-frequency mode 322 needs to be triggered, the equalizer 320 can optimize the high-frequency performance of the noise-canceling signal SA by combining a high-pass filter with a cutoff frequency of 115Hz and a low-pass filter of 575Hz. If the selection signal SEL indicates that the high-frequency mode 322 needs to be triggered, the equalizer 320 can optimize the overall performance of the noise-reduced signal SA by combining a high-pass filter with a cutoff frequency of 50Hz, band-stop filters of 10Hz and 60Hz, and a low-pass filter of 600Hz.
[0065] After optimizing the main audio signal SM, equalizer 320 generates an equalization signal SE and outputs it to digital amplifier 330 for amplification. Next, digital amplifier 330 generates the amplified equalization signal SEA and outputs it to digital-to-analog converter (DAC) 340. DAC 340 converts the equalization signal SEA into an analog output signal D0 and outputs it to communication device 150 for storage or user review. Since digital amplifier 330 is only used to amplify the equalization signal SE, it can be omitted if the amplitude of the equalization signal SE is sufficient.
[0066] This disclosure provides an active noise-canceling stethoscope configured to automatically determine whether to activate an active noise cancelling device (ANDD) for active noise cancellation based on the correlation between the sounds received by a main microphone (for receiving target sound and ambient sound) and a secondary microphone (for receiving ambient sound). Specifically, if the correlation coefficient between the sounds received by the main and secondary microphones is greater than or equal to a reference correlation coefficient, the ANDD is automatically activated for active noise cancellation. Conversely, if the correlation coefficient between the sounds received by the main and secondary microphones is less than the reference correlation coefficient, the ANDD is automatically deactivated and active noise cancellation is stopped.
[0067] In addition to performing active noise cancellation to reduce or eliminate the influence of ambient sounds on the target sound, this disclosure also outputs the noise-canceling audio signal to an equalizer for optimization. By using a user-input selection signal, the equalizer can be set to optimize the low-frequency, high-frequency, or overall portion of the audio signal, further eliminating the influence of ambient sounds. Furthermore, this disclosure features an automatic on / off function for the active noise cancellation unit, ensuring that active noise cancellation is only performed when needed (e.g., when ambient sounds are too loud). This not only ensures that the audio signal is not significantly distorted due to active noise cancellation but also reduces power consumption when active noise cancellation is not required, extending the lifespan of the active noise-canceling stethoscope.
Claims
1. An active noise-canceling stethoscope, comprising: A sound receiving device having a main microphone and a secondary microphone, wherein the main microphone is configured to receive and output a first sound signal, and the secondary microphone is configured to receive and output a second sound signal; A sound processing device is configured to be coupled to the aforementioned sound receiving device, receive the aforementioned first sound signal and the aforementioned second sound signal, and convert the aforementioned first sound signal and the aforementioned second sound signal into digital mode third sound signal and fourth sound signal, respectively; as well as The control unit is configured to be coupled to the aforementioned sound processing device and to calculate the correlation between the aforementioned third sound signal and the aforementioned fourth sound signal in order to determine whether to perform active noise cancellation.
2. The active noise-canceling stethoscope as claimed in claim 1, wherein the first sound signal corresponds to the target sound and the surrounding sound, and the second sound signal corresponds to the surrounding sound.
3. The active noise-canceling stethoscope as described in claim 1, wherein the sound processing device comprises: An amplifier is configured to amplify the aforementioned second audio signal; as well as An analog-to-digital converter is configured to convert the first sound signal and the amplified second sound signal into the third sound signal and the fourth sound signal, respectively.
4. The active noise-canceling stethoscope of claim 1, wherein the control unit further includes an active noise canceller configured to perform the active noise cancellation operation, and the active noise cancellation operation includes: Simultaneously, the first and second windows are respectively extracted from the third and fourth audio signals mentioned above; Calculate the correlation coefficient between the third and fourth audio signals during the first and second viewing windows; and Compare the magnitudes of the above correlation coefficients and the reference correlation coefficient. Wherein, if the aforementioned correlation coefficient is greater than or equal to the aforementioned reference correlation coefficient, the aforementioned control unit automatically activates the aforementioned active noise cancellation device to perform the aforementioned active noise cancellation operation, and the aforementioned active noise cancellation device outputs a noise reduction signal; and If the correlation coefficient is less than the reference correlation coefficient, the control unit automatically shuts down the active noise cancellation device to stop the active noise cancellation operation and receives the third sound signal from the sound processing device.
5. The active noise-canceling stethoscope of claim 4, wherein the control unit further comprises an equalizer configured to receive a selection signal, and wherein: When the active noise cancellation is turned on, the equalizer receives the noise cancellation signal and selects one of the low-frequency mode, high-frequency mode and mixed mode according to the selection signal to optimize the noise cancellation signal and outputs the first equalization signal. as well as When the active noise cancellation is turned off, the equalizer receives the third audio signal and selects one of the low-frequency mode, the high-frequency mode, and the mixing mode to optimize the third audio signal according to the selection signal, and outputs the second equalization signal.
6. The active noise-canceling stethoscope of claim 5 further includes a digital amplifier configured to be coupled to the equalizer to receive and amplify the first equalization signal or the second equalization signal, and output the amplified first equalization signal or the second equalization signal to a digital-to-analog converter.
7. The active noise-canceling stethoscope as claimed in claim 6, wherein the digital-to-analog converter converts the amplified first equalization signal or the second equalization signal to generate an output signal and output it to a communication device.
8. The active noise-canceling stethoscope of claim 5 further includes a digital-to-analog converter configured to convert the first equalization signal or the second equalization signal to generate an output signal and output it to a communication device.
9. The active noise-canceling stethoscope as claimed in claim 7 or 8, wherein the communication device is configured to store the output signal or display the output signal on a screen.
10. The active noise-canceling stethoscope as claimed in claim 1 further includes a power supply, wherein the power supply is a battery.