A whistling detection system and method for ANC / PSAP systems

Abstract

The present application relates to a howling detection system and method for an ANC / PSAP system, including a howling detection unit, which is configured to obtain an input audio signal of the system, and determine whether there is a howling risk in the audio signal based on the first energy value of the frequency point with maximum energy in the input audio signal spectrum and the relationship between each energy value at each harmonic of the frequency point and the average energy value of the spectrum. Then, the control parameters of the amplitude control unit are adjusted to obtain the second energy value at the maximum energy frequency point in the input audio signal spectrum again. When the first representative deviation between the second energy value and the first energy value is within a set threshold range, it is determined that the howling is a true howling. In this way, true and false howling can be accurately identified, and useful single-frequency signals in the environment can be avoided from being suppressed as howling signals, or true howling signals can be mistakenly retained without being suppressed, so as to improve the accuracy of noise reduction / hearing assistance of the ANC / PSAP system and improve the user experience.

Description

Technical Field

[0001] The present application relates to the field of audio processing, and more specifically, to a howling detection system and method for an ANC / PSAP system. Background Art

[0002] With the development of technology, active noise reduction headphones and personal sound amplifiers have been widely used. However, when active noise reduction technology and personal sound amplification technology are applied to headphone products, they often generate cancellation signals or compensation signals with opposite phases to achieve noise reduction or hearing aid effects. In these scenarios, when the cancellation / hearing aid signal generated by the ANC / PSAP system is played by the speaker, it will be picked up by the microphone, and the sound path will form a closed loop. The signal is continuously superimposed and amplified in the sound feedback loop to form positive feedback, generating single-frequency howling. However, there will also be useful single-frequency signals in the environment. At this time, the problem of true and false howling will arise. If this is not distinguished, but all single-frequency signals are suppressed and eliminated, it will affect the final noise reduction / hearing aid effect. Alternatively, if all single-frequency signals are retained without distinction, the performance of the ANC / PSAP system will be reduced, giving users a bad experience. Summary of the invention

[0003] The present application is provided to solve the above-mentioned problems existing in the prior art. A howling detection system and method for an ANC / PSAP system is needed, which can accurately identify true and false howling, avoid suppressing useful single-frequency signals in the environment as howling signals, or mistakenly retaining true howling signals without suppressing them, so as to improve the accuracy of noise reduction / hearing aid of the ANC / PSAP system and improve the user experience.

[0004] According to the first scheme of the present application, a howling detection system for an ANC / PSAP system is provided, wherein the ANC / PSAP system includes an amplitude control unit, wherein the amplitude control unit has a control parameter, wherein the control parameter is used to control the amplitude of an output signal, and wherein the howling detection system includes a howling detection unit, which is configured to obtain an input audio signal input to the ANC / PSAP system, and to determine whether there is a howling risk in the audio signal based on the first energy value of the frequency point with the maximum energy in the spectrum of the input audio signal and the relationship between each energy value at each harmonic of the frequency point and the average energy value of the spectrum. In the case of determining that there is a howling risk in the audio signal, the control parameter of the amplitude control unit is adjusted so that the amplitude of the output signal becomes smaller, and the second energy value of the frequency point with the maximum energy in the spectrum of the input audio signal after the control parameter is adjusted is determined again, and in the case where the first representative deviation between the second energy value and the first energy value exceeds a set threshold, the howling is determined to be true howling.

[0005] According to the second scheme of the present application, a howling detection method for an ANC / PSAP system is provided, wherein the ANC / PSAP system includes an amplitude control unit, wherein the amplitude control unit has a control parameter, wherein the control parameter is used to control the amplitude of an output signal, wherein the method includes obtaining an input audio signal input to the ANC / PSAP system via a howling detection unit, and judging whether there is a howling risk in the audio signal based on the first energy value of the frequency point with the maximum energy in the spectrum of the input audio signal and the relationship between each energy value at each harmonic of the frequency point and the average energy value of the spectrum. In the case of judging that there is a howling risk in the audio signal, adjusting the control parameter of the amplitude control unit so that the amplitude of the output signal becomes smaller, and determining again the second energy value of the frequency point with the maximum energy in the spectrum of the input audio signal after the control parameter is adjusted, and in the case that the first representative deviation between the second energy value and the first energy value exceeds a set threshold, judging that the howling is true howling.

[0006] According to a third solution of the present application, a PSAP system is provided, the PSAP system comprising an amplitude control unit having a control parameter, the control parameter being used to control the amplitude of an output signal, and a howling detection system as described in various embodiments of the present application.

[0007] According to a fourth solution of the present application, an ANC system is provided, the ANC system comprising an amplitude control unit having a control parameter, the control parameter being used to control the amplitude of an output signal, and a howling detection system as described in various embodiments of the present application.

[0008] According to a fifth solution of the present application, a computer-readable storage medium is provided, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor executes the howling detection method described in each embodiment of the present application.

[0009] Compared with the prior art, the beneficial effects of the embodiments of the present application are:

[0010] The howling detection system provided by the present application can quickly determine whether there is a single-frequency signal with a large amplitude in the spectrum of the microphone in the first stage. When a single-frequency signal with large energy in the spectrum is determined, the single-frequency signal is not directly suppressed as a howling signal based on the judgment result of the first stage, but the amplitude control unit is further used to determine the true and false howling in the second stage. In the second stage, by adjusting the control parameters of the amplitude control unit, it is determined whether the input signal changes with the change of the output signal. By comparing the amplitude change of the single-frequency signal with the largest amplitude in the input audio signal, it can be accurately determined whether the signal is a frame howling generated by the system or a normal single-frequency signal in the environment. In addition, the existing amplitude control unit in the ANC / PSAP system is used to perform a secondary judgment on the howling, without the need for additional processing procedures and complex calculations, that is, it can efficiently and accurately complete the judgment of true and false howling when the user is basically unaware, so that the ANC / PSAP system can accurately process the true and false howling respectively based on the judgment results, thereby greatly improving the user experience.

[0011] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar components in different views. The drawings generally illustrate various embodiments by way of example and not limitation, and together with the description and claims, serve to illustrate the disclosed embodiments. When appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

[0013] Figure 1 A structural block diagram of a howling detection system according to an embodiment of the present application is shown;

[0014] Figure 2 A detection flow chart of howling detection performed by a howling detection system according to an embodiment of the present application is shown;

[0015] Figure 3 A flow chart showing a howling detection system according to another embodiment of the present application for determining whether there is a howling risk in an audio signal;

[0016] Figure 4 A schematic diagram showing a PSAP system using a howling detection system according to an embodiment of the present application;

[0017] Figure 5 A schematic diagram of an ANC system using the howling detection system according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific implementation methods. The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and specific embodiments, but are not intended to limit the present application. For the various steps described herein, if there is no necessity for a contextual relationship between each other, the order in which they are described as examples herein should not be regarded as a limitation, and those skilled in the art should know that they can be adjusted in order, as long as the logic between them is not destroyed, resulting in the inability to implement the entire process.

[0019] The words "first", "second" and similar words used in this application do not indicate any order, quantity or importance, but are only used to distinguish. Words such as "include" or "comprise" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements. In this application, the arrows shown in the figures of each step are only examples of the execution order, not limitations. The technical solution of this application is not limited to the execution order described in the embodiments. The various steps in the execution order can be combined, decomposed, or the order can be changed, as long as the logical relationship of the execution content is not affected.

[0020] All terms (including technical terms or scientific terms) used in this application have the same meaning as those understood by ordinary technicians in the field to which this application belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such here. Techniques, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the specification.

[0021] According to an embodiment of the present application, a howling detection system for an ANC / PSAP system is provided. The ANC / PSAP system includes an amplitude control unit, the amplitude control unit has a control parameter, and the control parameter is used to control the amplitude of an output signal. The howling detection system includes a howling detection unit, which performs corresponding steps in the howling detection method for the ANC / PSAP system according to each embodiment of the present application.

[0022] Figure 1The structural block diagram of the howling detection system according to each embodiment of the present application is shown. Among them, the ANC / PSAP system includes an amplitude control unit 102, and the amplitude control unit 102 has a control parameter, and the control parameter is used to control the amplitude of the output signal. The howling detection system 100 includes a howling detection unit 101. Among them, the " / " in ANC / PSAP means the meaning of "or", which illustrates that the howling detection system 100 described in the present application can be used in an ANC (Active Noise Control, active noise reduction technology) system or a PSAP (Personal Sound Amplification Product, personal sound amplifier, also known as a hearing aid) system. The amplitude control unit 102 can be understood as a circuit or a combination of circuits that can process the input signal and control the amplitude of the output signal, for example, it can be a limiter, or it can be a device or circuit with the function of controlling the amplitude of the output signal, or a combination of circuits having the above multiple functions, etc., which is not specifically limited. The control parameter of the amplitude control unit 102 is used to control the amplitude of the output signal, which means that by adjusting the control parameter of the amplitude control unit 102, the amplitude of the output signal can be adjusted. For example, when the amplitude control unit 102 is a limiter, the control parameter may be a limit threshold, when the limit threshold is 0 dB, the amplitude of the output signal does not exceed 0 dB, when the limit threshold is -10 dB, the amplitude of the output signal is not less than -10 dB. Of course, there may be other control parameters that can realize the control of the amplitude of the output signal, and the above is only for exemplary description.

[0023] Figure 2 FIG. 2 is a flow chart showing a detection process of howling detection by the howling detection system according to various embodiments of the present application. Figure 2 , the process of howling detection performed by the howling detection unit 101 is described. In this embodiment, the howling detection unit 101 is configured to obtain an input audio signal input to the ANC / PSAP system, and determine whether there is a howling risk in the audio signal based on the first energy value of the frequency point with maximum energy in the spectrum of the input audio signal and the relationship between each energy value at each harmonic of the frequency point and the average energy value of the spectrum.

[0024] Specifically, Figure 2 As shown, the input audio signal can be obtained in step 201. For example, the audio signal collected by the microphone of the ANC / PSAP system can be sampled to obtain the input audio signal sent to the ANC / PSAP system, and the input audio signal can be transmitted to the howling detection unit 101.

[0025] In step 202, the input audio signal may be subjected to spectrum analysis to determine the first energy value of the frequency point with maximum energy and the energy values ​​at each harmonic of the frequency point, as well as the spectrum average energy value of the input audio signal. Specifically, for example, the input audio signal in the time domain may be transformed into the frequency domain using discrete Fourier transform to obtain the spectrum of the input audio signal. Based on the spectrum of the input audio signal obtained by the transformation, the frequency point with maximum energy and the frequency points corresponding to its harmonics may be determined, and the first energy value corresponding to the frequency point, the signal energy values ​​at each harmonic, and the average energy value in the entire spectrum range and other parameters may be obtained.

[0026] Next, in step 203, based on the relationship between the first energy value, the signal energy value at each harmonic and the average energy value of the spectrum, it is determined whether there is a risk of howling in the audio signal. When howling occurs, in addition to the detection of a high-intensity single-frequency signal in the input signal, due to the nonlinearity of the system load, the fundamental current is distorted, which will also lead to a signal with a large signal intensity at each harmonic of the fundamental wave. Therefore, it is possible to detect whether there is a single-frequency signal higher than a specific threshold of the average energy value in the spectrum of the input audio signal, and when the signal energy at each harmonic point such as the second harmonic and the third harmonic is also higher than the specific threshold of the average energy value, it is highly likely that there may be a risk of howling in the audio signal. For situations that are not howling, for example, when there is a normal high-intensity single tone (such as an alarm sound) in the environment, although a single-frequency signal much higher than the average energy value can be detected at the corresponding spectrum, since it does not cause howling, the signal energy at each harmonic point will not be very high, which can be distinguished from true howling. The above method can accurately and reliably determine whether there is a risk of howling in the input audio signal. When it is determined that there is a risk of howling in the audio signal, next, step 204 to step 207 are used to further determine whether the howling signal preliminarily determined before is a true howling.

[0027] In step 204, the control parameter of the amplitude control unit 102 is adjusted so that the amplitude of the output signal becomes smaller. That is, the amplitude of the output signal changes with the change of the control parameter of the amplitude control unit 102. Specifically, for example, when the amplitude control unit 102 is a limiter, and the control parameter is used to limit the maximum amplitude of the output signal, for example, when it is adjusted downward from 0 dB to -6 dB, the maximum amplitude of the output signal will decrease from 0 dB to -6 dB.

[0028] In step 205, the second energy value of the frequency point with maximum energy in the spectrum of the input audio signal after the control parameter is adjusted is determined again. Specifically, when determining the second energy value, a method similar to the method of determining the first energy value in step 202 as described above can be adopted, which will not be repeated here.

[0029] Then, in step 206, it is determined whether the first representative deviation between the second energy value and the first energy value exceeds a set threshold value. If so, the determination result that the howling is a true howling is output in step 207. If not, the control parameter of the amplitude control unit is restored (step 208). In some embodiments, the first representative deviation may be the difference or ratio between the absolute value of the second energy value and the absolute value of the first energy value, or may be a value obtained by performing a certain operation based on the difference or ratio between the second energy value and the first energy value, or a value calculated by other methods. This application does not limit this, as long as it can indicate the degree of change of the second energy value relative to the first energy value. In some embodiments, the set threshold value may be an appropriate value pre-set in the system according to experiments, and this application does not limit the specific value.

[0030] The inventor of the present application has found through repeated experiments that, since the true howling is generated inside the ANC / PSAP system and is processed by the amplitude control unit 102 before being output, the adjustment of the control parameters of the amplitude control unit 102 has a direct impact on the true howling signal, that is, if it is true howling, after the amplitude of the output signal is reduced by adjusting the control parameters, the energy of the howling signal in the input audio signal of the ANC / PSAP system collected again will be significantly reduced. On the contrary, if the high-energy single-frequency signal in the input audio signal is, for example, a normal single-frequency signal from the environment, that is, a false howling, then the adjustment of the control parameters of the amplitude control unit 102 will not have a significant impact on its amplitude. Therefore, it is possible to accurately determine whether the howling is true howling based on the deviation between the second energy value of the frequency point with the maximum energy in the spectrum of the input audio signal after the control parameters are adjusted and the first energy value determined previously.

[0031] In the existing PSAP system, in order to avoid missing useful signals, it is often inclined to retain the detected single-frequency signals without discrimination. In the existing ANC system, in order to reduce noise interference, it may be more inclined to suppress the high-energy single-frequency signals after they are detected. Since the above processing method does not judge whether the howling is true or false, it is very likely to perform counterproductive processing for the ANC / PSAP system, which greatly affects the noise reduction / hearing aid effect and also brings a bad experience to the user. In contrast, through Figure 2As shown in steps 201 to 207, the howling detection system for the ANC / PSAP system according to the embodiment of the present application judges the authenticity of the howling in two stages, which greatly improves the accuracy and credibility of the howling judgment. In the first-level judgment, it is detected whether there is a single-frequency signal with a large amplitude in the spectrum collected by the microphone. If there is a single-frequency signal with a large amplitude, it is considered that there is a risk of howling in the audio signal. After the first-level judgment, the present application does not directly suppress the howling by reducing the gain, but further uses the amplitude control unit 102 to adjust the control parameters and perform a second-level judgment to further improve the accuracy of the true and false howling judgment, so that the ANC / PSAP system can perform accurate and effective noise reduction / hearing aid measures in subsequent processing based on the true and false howling judgment results, thereby optimizing the user experience. In addition, the two-level judgment process of true and false howling implemented by steps 204-207 is easy to implement and does not introduce excessive processing and delay. In some other cases, for example, the reduction of the maximum amplitude of the limiter will not affect the amplitude of other signals except the signal amplitude of the howling signal and its harmonics, but can reduce the risk of the system generating howling due to self-aggression caused by excessive signals. In other words, the adjustment of the control parameters can greatly improve or even completely eliminate the true howling condition without affecting the original noise reduction / hearing aid effect of the ANC / PSAP system, which also helps to improve the user experience.

[0032] Please note that the howling detection unit 101 described in this article can be implemented by SOC (system on chip), for example, various RISC (reduced instruction set computer) processor IPs purchased from ARM and the like can be used as the processor of SOC to perform corresponding functions, and can be implemented as an embedded system. Specifically, there are many modules on the modules (IP) available on the market, such as but not limited to memory, cache, etc. The user can build an ASIC (application specific integrated circuit) based on the purchased IP or the self-developed module to build the howling detection unit 101 in order to reduce costs.

[0033] For example, hardware entity modules are used to implement howling detection. Taking programmable logic devices (PLD) as an example, its logic function is determined by the user's programming of the device. Designers can "integrate" a digital system on a PLD by programming themselves, without asking chip manufacturers to design and produce dedicated integrated circuit chips. This kind of programming can also be implemented using "logic compiler" software. The original code before compilation is written in a specific programming language, which is called hardware description language (HDL). There is not only one type of HDL, but many types, such as ABEL (Advanced Boolean Expression Language), AHDL (Altera Hardware Description Language), Confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), Lava, Lola, MyHDL, PALASM, RHDL (Ruby Hardware Description Language), etc. Those skilled in the art should also be aware that the howling detection process only needs to be slightly logically programmed using the above-mentioned hardware description languages ​​and then programmed into an integrated circuit, so that a hardware circuit that implements the logic method process can be easily obtained.

[0034] In some embodiments of the present application, the control parameter includes at least a clipping threshold of the amplitude control unit 102, and adjusting the control parameter of the amplitude control unit 102 further includes lowering the clipping threshold to a first clipping threshold, and the first clipping threshold is not less than the first threshold. The first threshold may be an appropriate value pre-set in the system according to an experiment, and usually, the first threshold is a larger value, so that the normal processing of the signal is not excessively affected before the final determination of true or false howling.

[0035] Specifically, for example, when no howling occurs, the limiting threshold of the amplitude control unit 102 may be adjusted to -3dB, and when the first-level judgment result shows that there is a risk of howling, the limiting threshold is further lowered to -6dB. At this time, if the maximum energy value of the audio signal input by the microphone changes accordingly, it can be accurately judged that the howling is generated by the system itself rather than the external environment, and the howling can be judged as a true howling. In this way, under the condition of not affecting the ANC and PSAP functions as much as possible, it can be judged whether the howling is generated by the outside world or the system itself. Please note that in the secondary judgment process, the first limiting threshold is not less than the first threshold. By limiting the first limiting threshold to be not less than the first threshold, the secondary judgment can be completed when the user has no obvious perception of the change in signal strength, and will not affect the user's experience. However, this application does not limit the specific value of the first threshold.

[0036] In some embodiments, the howling detection unit 101 is further configured to suppress the howling when determining that the howling is true howling, specifically including further lowering the limit threshold to a second limit threshold, the second limit threshold is not higher than the second threshold, and the second threshold is less than the first threshold, so that only the true howling and its harmonic signals with the maximum energy can be suppressed without affecting the signal strength of other frequency points, and as mentioned above, the suppression of the high energy signal amplitude will also improve or eliminate the howling condition. In this way, the true howling can be suppressed efficiently and accurately, the noise reduction / hearing aid effect of the ANC / PSAP system can be improved, and the user experience can be improved.

[0037] Specifically, when the true howling is suppressed by controlling the gain, after reducing the gain, not only the signal strength of the frequency point with the maximum energy is suppressed, but also the signal strength at other frequencies is suppressed, which will not only reduce the noise reduction / hearing aid effect of the ANC / PSAP system, but also, in the process of adjusting the gain to suppress the howling, the user can feel the uncomfortable changes caused by the howling suppression, thereby reducing the user experience. The embodiment of the present application uses the amplitude control unit 102 to adjust the limiting threshold, which only affects the signal strength of the frequency point with the maximum energy, but does not affect the signal strength of other frequencies, which can suppress the howling without affecting the user experience. Of course, in the process of suppressing the howling, the second limiting threshold is not higher than the second threshold, and the second threshold is less than the first threshold, so as to achieve effective suppression of the howling and its harmonic signals. For example, assuming that in the secondary judgment process, the first threshold is -5dB, and in the howling suppression stage, the second threshold is -20dB, so that the howling can be quickly suppressed without affecting the user experience.

[0038] Figure 3A flow chart showing a howling detection system according to another embodiment of the present application for determining whether there is a howling risk in an audio signal. The input audio signal includes a first audio signal acquired by a feedback microphone and a second audio signal acquired by a feedforward microphone, and based on the frequency point with maximum energy in the spectrum of the input audio signal and the relationship between each energy value at each harmonic of the frequency point and the average energy value of the spectrum, determining whether the audio signal contains a howling risk specifically includes:

[0039] In step 301, a feedback microphone acquires a first audio signal. In step 302, the first power of a first frequency point with maximum energy in the spectrum of the first audio signal and the first harmonic powers corresponding to the first harmonics of the first frequency point, as well as the first average power of the first audio signal are determined. There is no specific limitation on the calculation method of each power, and any existing method can be used to obtain each power. In step 304, a feedforward microphone acquires a second audio signal. In step 305, the second power of a second frequency point with maximum energy in the spectrum of the second audio signal and the second harmonic powers corresponding to the second harmonics of the second frequency point, as well as the second average power of the second audio signal are determined.

[0040] In step 303, it is determined whether the first power is greater than N times the first average power and whether the first harmonic power is greater than M times the first average power. If yes, step 307 is continued to be performed, and if no, the process returns to step 303 for further determination. Similarly, in step 306, it is determined whether the second power is greater than N times the second average power and whether the second harmonic power is greater than M times the second average power. If yes, step 307 is continued to be performed, and if no, the process returns to step 306 for further determination. In addition, it is also determined whether the first power is greater than Q times the second power (step 307). In the case that the first power is greater than N times the first average power, the second power is greater than N times the second average power, and each first harmonic power is greater than M times the first average power, each second harmonic power is greater than M times the second average power, and the first power is greater than Q times the second power, it is determined that there is a risk of howling in the audio signal (step 308), wherein N, M, and Q are all non-zero positive integers. Specifically, the feedback microphone is closer to the speaker than the feedforward microphone. Therefore, the signal generated inside the system reaches the feedback microphone before the feedforward microphone, and the signal energy received by the feedback microphone is higher than the signal energy received by the feedforward microphone. In the primary judgment process, the same primary judgment method is used for the feedforward microphone and the feedback microphone, and each spectrum has a maximum energy value. After judging the feedback microphone and the feedforward microphone respectively, the first power and the second power are compared at the same time. In this way, the accuracy of the primary judgment of whether there is a howling risk in the input audio signal can be improved. For example, when the first power is greater than 8 times the first average power, the second power is greater than 8 times the second average power, and each first harmonic power is greater than 2 times the first average power, each second harmonic power is greater than 2 times the second average power, and the first power is greater than 4 times the second power, it can be accurately judged that there is a howling risk in the audio signal.

[0041] In some embodiments of the present application, the harmonics include at least the second harmonic, or the second harmonic, the third harmonic and higher harmonics. By further considering the energy of each harmonic, the accuracy and reliability of the primary judgment of whether there is a howling risk in the audio signal are further improved.

[0042] In some embodiments, the ANC / PSAP system includes an amplitude control unit, the amplitude control unit has a control parameter, and the control parameter is used to control the amplitude of the output signal. The method includes obtaining an input audio signal input to the ANC / PSAP system via a howling detection unit, and judging whether there is a howling risk in the audio signal based on the first energy value of the frequency point with the maximum energy in the spectrum of the input audio signal and the relationship between each energy value at each harmonic of the frequency point and the average energy value of the spectrum. When it is judged that there is a howling risk in the audio signal, the control parameter of the amplitude control unit is adjusted so that the amplitude of the output signal becomes smaller, and the second energy value of the frequency point with the maximum energy in the spectrum of the input audio signal after the control parameter is adjusted is determined again. When the first representative deviation between the second energy value and the first energy value exceeds a set threshold, it is judged that the howling is a true howling. In this way, true and false howling can be accurately identified, and useful single-frequency signals in the environment are avoided from being suppressed as howling signals, or true howling signals are mistakenly retained without being suppressed, so as to improve the accuracy of noise reduction / hearing assistance of the ANC / PSAP system and improve user experience.

[0043] In some embodiments of the present application, the control parameters include at least a limiting threshold of the amplitude control unit, and adjusting the control parameters of the amplitude control unit further includes lowering the limiting threshold to a first limiting threshold, and the first limiting threshold is not less than the first threshold. In this way, the accuracy of judging true and false howling can be improved and misjudgment can be avoided without reducing the user experience.

[0044] In some embodiments of the present application, the howling detection method further includes suppressing the howling when it is determined that the howling is true howling, specifically including further lowering the limiting threshold to a second limiting threshold; the second limiting threshold is not higher than the second threshold, and the second threshold is less than the first threshold, so that the true howling can be efficiently suppressed.

[0045] In some embodiments of the present application, the input audio signal includes a first audio signal obtained by a feedback microphone and a second audio signal obtained by a feedforward microphone. Based on the relationship between the frequency point with maximum energy in the spectrum of the input audio signal and each energy value at each harmonic of the frequency point and the average energy value of the spectrum, determining whether the audio signal contains a howling risk specifically includes determining the first power of the first frequency point with maximum energy in the spectrum of the first audio signal and each first harmonic power corresponding to each harmonic of the first frequency point, and the first average power of the first audio signal. Determine the second power of the second frequency point with maximum energy in the spectrum of the second audio signal and each second harmonic power corresponding to each harmonic of the second frequency point, and the second average power of the second audio signal. When the first power is greater than N times the first average power, the second power is greater than N times the second average power, and each first harmonic power is greater than M times the first average power, each second harmonic power is greater than M times the second average power, and the first power is greater than Q times the second power, it is determined that there is a howling risk in the audio signal, wherein N, M and Q are all non-zero positive integers. This is helpful to further improve the accuracy of the first-level judgment on whether there is a howling risk in the input audio signal.

[0046] In some embodiments of the present application, the harmonics include at least a second harmonic, or a second harmonic, a third harmonic, and higher harmonics.

[0047] In some embodiments of the present application, a PSAP system is provided, the PSAP system includes an amplitude control unit, the amplitude control unit has a control parameter, the control parameter is used to control the amplitude of the output signal, and the PSAP system includes the howling detection system described in each embodiment of the present application. Specifically, Figure 4 As shown, x(n) represents the input audio signal, y(n) represents the output audio signal, Gain is the gain, DRC is the dynamic compressor, and Limiter is the limiter. The collected input audio signal x(n) is sent to the PSAP system, and the howling detection unit 101 and the amplitude control unit 102 cooperate to analyze and detect the input audio signal. The processed input audio signal generates the output audio signal y(n), which is output by the speaker. During the howling detection process, the amplitude control unit 102 lowers the limit threshold, the output audio signal y(n) decreases, and the input audio signal continues to be collected. If the signal of the maximum energy value of the collected input audio signal x(n) also decreases accordingly, it means that the howling is a true howling generated by the system itself, and the audio signal can be output after the true howling is suppressed.

[0048] In some embodiments of the present application, an ANC system is provided, the ANC system comprising an amplitude control unit, the amplitude control unit having a control parameter, the control parameter being used to control the amplitude of an output signal, the ANC system comprising the howling detection system described in each embodiment of the present application. Specifically, Figure 5 As shown, similarly, x(n) represents the input audio signal and y(n) represents the output audio signal. The collected input audio signal x(n) is sent to the ANC system, and the howling detection unit 101 cooperates with the amplitude control unit 102 to analyze and detect the input audio signal. The processed input audio signal generates the output audio signal y(n), which is output by the speaker. During the howling detection process, the amplitude control unit 102 lowers the limit threshold, the output audio signal y(n) decreases, and the input audio signal continues to be collected. If the signal of the maximum energy value of the collected input audio signal x(n) also decreases accordingly, it means that the howling is a true howling generated by the system itself, and the audio signal can be output after the true howling is suppressed.

[0049] In some embodiments of the present application, a computer-readable storage medium is provided, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor executes the howling detection method described in each embodiment of the present application.

[0050] In addition, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present application with equivalent elements, modifications, omissions, combinations (e.g., various embodiments intersecting schemes), adaptations or changes. The elements in the claims will be interpreted broadly based on the language adopted in the claims, and are not limited to the examples described in this specification or during the implementation of the application, and the examples will be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered as examples only, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0051] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more of them) can be used in combination with each other. For example, those of ordinary skill in the art can use other embodiments when reading the above description. In addition, in the above-mentioned specific embodiments, various features can be grouped together to simplify the application. This should not be interpreted as an intention that a disclosed feature that does not require protection is necessary for any claim. On the contrary, the subject matter of the present application may be less than all the features of a specific disclosed embodiment. Thus, the following claims are incorporated into the specific embodiments as examples or embodiments, wherein each claim is independently used as a separate embodiment, and it is considered that these embodiments can be combined with each other in various combinations or arrangements. The scope of the present invention should be determined with reference to the full scope of the equivalent forms of the attached claims and these claims.

[0052] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A howling detection system for an ANC / PSAP system, characterized in that: The ANC / PSAP system includes an amplitude control unit, the amplitude control unit has a control parameter, and the control parameter is used to control the amplitude of the output signal. The howling detection system includes a howling detection unit, which is configured as follows: Acquire an input audio signal input to the ANC / PSAP system, wherein the input audio signal includes a first audio signal acquired by a feedback microphone and a second audio signal acquired by a feedforward microphone; Determine a first power of a first frequency point having maximum energy in the frequency spectrum of the first audio signal, first harmonic powers corresponding to respective harmonics of the first frequency point, and a first average power of the first audio signal; Determine a second power of a second frequency point having maximum energy in the frequency spectrum of the second audio signal, second harmonic powers corresponding to respective harmonics of the second frequency point, and a second average power of the second audio signal; When the first power is greater than N times the first average power, the second power is greater than N times the second average power, each first harmonic power is greater than M times the first average power, each second harmonic power is greater than M times the second average power, and the first power is greater than Q times the second power, it is determined that there is a howling risk in the audio signal, where N, M and Q are all non-zero positive integers; In the case where it is determined that there is a risk of howling in the audio signal, Adjusting the control parameter of the amplitude control unit so that the amplitude of the output signal becomes smaller; determining again a second energy value of a frequency point with maximum energy in the frequency spectrum of the input audio signal after the control parameter is adjusted; When a first representative deviation between the second energy value and the first energy value exceeds a set threshold, it is determined that the howling is true howling.

2. The howling detection system according to claim 1, characterized in that: The control parameters at least include a limiting threshold of the amplitude control unit, and adjusting the control parameters of the amplitude control unit further includes: The clipping threshold is lowered to a first clipping threshold, and the first clipping threshold is not less than the first threshold.

3. The howling detection system according to claim 2, characterized in that: The howling detection unit is further configured to: when determining that the howling is true howling, suppress the howling, specifically including: further lowering the clipping threshold to a second clipping threshold; the second clipping threshold is not higher than the second threshold, and the second threshold is less than the first threshold.

4. The howling detection system according to claim 2 or 3, characterized in that: The harmonics include at least the second harmonic, or the second harmonic, the third harmonic and higher harmonics.

5. A howling detection method for an ANC / PSAP system, characterized in that: The ANC / PSAP system comprises an amplitude control unit, the amplitude control unit having a control parameter, the control parameter being used to control the amplitude of an output signal, the method comprising, via a howling detection unit: Acquire an input audio signal input to the ANC / PSAP system, wherein the input audio signal includes a first audio signal acquired by a feedback microphone and a second audio signal acquired by a feedforward microphone; Determine a first power of a first frequency point having maximum energy in the frequency spectrum of the first audio signal, first harmonic powers corresponding to respective harmonics of the first frequency point, and a first average power of the first audio signal; Determine a second power of a second frequency point having maximum energy in the frequency spectrum of the second audio signal, second harmonic powers corresponding to respective harmonics of the second frequency point, and a second average power of the second audio signal; When the first power is greater than N times the first average power, the second power is greater than N times the second average power, each first harmonic power is greater than M times the first average power, each second harmonic power is greater than M times the second average power, and the first power is greater than Q times the second power, it is determined that there is a howling risk in the audio signal, where N, M and Q are all non-zero positive integers; In the case where it is determined that there is a risk of howling in the audio signal, Adjusting the control parameter of the amplitude control unit so that the amplitude of the output signal becomes smaller; determining again a second energy value of a frequency point with maximum energy in the frequency spectrum of the input audio signal after the control parameter is adjusted; When a first representative deviation between the second energy value and the first energy value exceeds a set threshold, it is determined that the howling is true howling.

6. The howling detection method according to claim 5, characterized in that: The control parameters at least include a limiting threshold of the amplitude control unit, and adjusting the control parameters of the amplitude control unit further includes: The clipping threshold is lowered to a first clipping threshold, and the first clipping threshold is not less than the first threshold.

7. The howling detection method according to claim 6, characterized in that: The howling detection method further comprises: When it is determined that the howling is true howling, suppressing the howling specifically includes: further lowering the clipping threshold to a second clipping threshold; the second clipping threshold is not higher than a second threshold, and the second threshold is lower than the first threshold.

8. The howling detection method according to claim 5, characterized in that: The harmonics include at least the second harmonic, or the second harmonic, the third harmonic and higher harmonics.

9. A PSAP system, characterized in that: The PSAP system comprises an amplitude control unit having a control parameter, wherein the control parameter is used to control the amplitude of an output signal, and the howling detection system according to any one of claims 1 to 4.

10. An ANC system, characterized in that: The ANC system comprises an amplitude control unit having a control parameter, wherein the control parameter is used to control the amplitude of an output signal, and the howling detection system according to any one of claims 1 to 4.

11. A computer-readable storage medium having computer program instructions stored thereon, wherein when the computer program instructions are executed by a processor, the processor is enabled to execute the howling detection method according to any one of claims 5 to 7.

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