A secure dialogue system that prevents eavesdropping

Abstract

This invention discloses a secure dialogue system to prevent eavesdropping, applied in the field of communications. It addresses the problem that existing technologies are ineffective against professional eavesdropping devices, especially in dynamically changing noise environments where noise reduction and anti-eavesdropping capabilities are limited. The noise-canceling headphones of this invention, by predicting noise patterns, can quickly reduce environmental noise without a learning process. Particularly for rapidly changing noise sources, they provide instant noise reduction capabilities not found in traditional noise-canceling headphones, effectively resisting eavesdropping and ensuring the security of communication content.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and specifically relates to a noise reduction and anti-eavesdropping technology. Background Technology

[0002] In the field of modern communication technology, the confidentiality of audio communications is of paramount importance. Especially in military communications, high-level corporate meetings, and other dialogue scenarios with high security requirements, the security of call content faces serious challenges from modern electronic devices such as recording equipment and smartphones. These devices have advanced recording capabilities, easily capturing and recording sensitive conversations, leading to a sharp increase in the risk of information leakage.

[0003] To enhance the security of audio communication, interference sources can be installed in special environments. Combined with dedicated noise-canceling headphones, both parties can communicate effectively, while those without noise-canceling headphones or recording equipment will be unable to discern useful audio information due to excessive noise. However, traditional noise-canceling headphone designs primarily focus on reducing ambient background noise, improving call quality through passive or active noise cancellation technologies. These traditional noise-canceling technologies mainly focus on reducing ambient background noise and lack the ability to adapt to rapidly changing noise. In dynamic noise environments, the noise cancellation effect of traditional headphones is limited and cannot effectively resist external noise interference.

[0004] Existing technologies mainly include passive and active noise-canceling headphones. Passive headphones use physical isolation or special structures on the headphones to block noise pollution as much as possible. Their principle is to use the physical properties of passive devices to achieve noise reduction and sound insulation, such as silicone ear tips and headband covers. Active headphones, on the other hand, use an active noise cancellation (ANC) chip to process the noise and generate a 180° phase-reversed sound wave. This wave is transmitted through the headphone speaker to the ear canal, creating a 180° phase difference with the noise, thus canceling out the ambient noise that the ear should hear, thereby achieving noise reduction. A structural diagram is shown below. Figure 1 As shown.

[0005] The parameters of active noise-canceling headphones are often fixed, so they cannot quickly adapt and adjust their phase according to changes in the external environment. Therefore, their active noise cancellation performance is affected by external factors and is unstable. They can only achieve good noise cancellation for some stable noises.

[0006] Passive noise-canceling headphones are primarily designed for high-frequency noise pollution, and are not very effective for noise pollution below 800Hz or even lower frequencies. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a secure dialogue system to prevent eavesdropping. Targeting pseudo-random dynamic interference sources, it can not only effectively reduce in-band interference and improve call quality, but also effectively interfere with illegal recording devices by introducing controllable dynamic noise sources, preventing the content of the call from being illegally recorded or eavesdropped on.

[0008] The technical solution adopted in this invention is: a secure communication system designed to provide a highly secure environment for communication. The system includes an external dynamic noise source and a headset for use with it. The external dynamic noise source is placed in the communication environment, such as a conference room, to generate dynamic noise during the conversation to interfere with potential eavesdropping. The headset is designed to use the same pseudo-random number seed as the external dynamic noise source to achieve precise noise cancellation.

[0009] An external dynamic noise source is a core innovation of this invention. It generates dynamic noise based on a preset pseudo-random number seed. This noise is designed to simulate and interfere with potential eavesdropping. Since the eavesdropper cannot obtain the preset pseudo-random number seed, they cannot eliminate the dynamic noise in their recorded signal, thus preventing illegal recording at the source. Simultaneously, a high-sensitivity microphone is responsible for capturing in real time all external noise, including dynamic noise and environmental noise, as well as the dialogue audio signal in the conversation scenario.

[0010] The headset includes: a power module, a microphone, an external dynamic noise source, a dynamic noise cancellation speaker, an ambient noise cancellation speaker, an ANC adaptive filter, and an audio communication speaker; the power module provides power to the microphone, the external dynamic noise source, the dynamic noise cancellation speaker, the ambient noise cancellation speaker, the ANC adaptive filter, and the audio communication speaker.

[0011] The dynamic noise cancellation speaker uses the same pseudo-random number seed as the external dynamic noise source to generate an inverse signal corresponding to the current dynamic noise in real time, accurately eliminating dynamic noise. This process eliminates the learning phase required by traditional noise-canceling headphones, achieving instant noise cancellation. Furthermore, the ANC adaptive filter uses spectral subtraction to generate cancellation signals for ambient noise. These signals are then input into the ambient noise cancellation speaker to eliminate background noise, further purifying the call environment.

[0012] Ultimately, the audio communication speaker is responsible for outputting a clean sound signal after dual noise reduction processing, ensuring the clarity and naturalness of the communication. This invention's noise-canceling headphone system, through this unique component collaborative working mechanism, not only significantly improves adaptability to rapidly changing noise and noise reduction efficiency, but also provides an unprecedented level of protection for communication security, especially in communication scenarios requiring high confidentiality.

[0013] The beneficial effects of the present invention are as follows: Compared with the prior art, the anti-eavesdropping secure dialogue system of the present invention can effectively prevent intentional eavesdropping while maintaining the clarity and naturalness of audio communication.

[0014] The focus of this invention is to develop a system that enables noise-canceling headphones to work in conjunction with an external noise source to generate inverse dynamic noise based on a pseudo-random number seed, adapting to different communication environments. This dynamic noise source design can effectively interfere with potential eavesdropping without affecting normal communication, providing necessary protection for high-security communications.

[0015] In the application scenario, each participant wears an earphone as described in this invention. These earphones are capable of synchronizing with an external dynamic noise source to generate an inverse dynamic noise signal, thereby eliminating interference from the noise source in real time. Unlike traditional noise-canceling earphones, the earphones of this invention, after being matched with an external dynamic noise source, can quickly adapt to changes in the dynamic noise source, maintaining clear communication quality even in environments with frequently changing noise levels.

[0016] By implementing this invention, users can enjoy clear sound quality while obtaining a higher level of communication security, effectively preventing information leakage and eavesdropping risks, and meeting the needs of military, business and other occasions with special requirements for communication confidentiality. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an active noise-canceling headphone.

[0018] Figure 2 This is a diagram illustrating the system's application scenarios.

[0019] Figure 3 This is a system structure module diagram.

[0020] Figure 4 This is a schematic diagram of dynamic noise signals and cancellation signals.

[0021] Figure 5 The graph shows dynamic noise, noisy signals, dynamic inverse signals, and a mixture of noisy signals.

[0022] Figure 6 This is a schematic diagram of the principle of spectral subtraction.

[0023] Figure 7 This is a timing comparison chart for low-frequency noise cancellation.

[0024] Figure 8 This is a timing comparison chart for high-frequency noise cancellation.

[0025] Figure 9 This is a flowchart illustrating the workflow of noise-canceling headphones. Detailed Implementation

[0026] To facilitate understanding of the technical content of this invention by those skilled in the art, the following description, in conjunction with the accompanying drawings, further illustrates the invention.

[0027] like Figure 2 The system application scenario diagram illustrates the layout and operation of this invention in a real-world conversation environment. In a sensitive conversation environment where eavesdropping is possible, such as a conference room or business meeting area, this invention creates a protective audio barrier by deploying an external dynamic noise source. This noise source generates unpredictable dynamic noise based on a preset pseudo-random number seed. This noise is sufficient to interfere with potential eavesdropping devices, making it impossible for unauthorized personnel to hear the conversation.

[0028] In this configuration, each authorized participant in the conversation wears a specially designed noise-canceling headset (hereinafter referred to as the "inventor headset"). By sharing the same pseudo-random number seed with the external noise source, these headsets are able to accurately predict and generate a signal that is the opposite of the dynamic noise emitted by the noise source. In this way, the headsets can not only eliminate interference generated by the noise source in real time, but also effectively reduce other background noise, ensuring the clarity and privacy of the conversation.

[0029] Figure 3 A system structure block diagram of the present invention is shown, revealing the noise source, the headphones, and the internal components and their collaborative operation. The core innovation of the headphones lies in its dynamic noise cancellation speaker, which is specifically designed to eliminate noise generated by an external dynamic noise source. This noise source generates unpredictable dynamic noise based on a preset pseudo-random number seed, aiming to interfere with potential eavesdropping.

[0030] During communication between the headphones and the noise source, the noise source sends a pseudo-random number seed to the headphones via the MCU. Before activating, the noise source sends a control command to the headphones, notifying them of the impending change in noise pattern. The headphones then adjust their operating state accordingly to ensure timely response to noise changes. In some cases, the noise source may pause noise generation and only send control commands when switching noise channels. After receiving and responding to these commands, the noise source begins generating noise.

[0031] In addition, the headset includes an ANC adaptive filter to generate cancellation signals for ambient noise. These signals are then fed into the ambient noise cancellation speaker to eliminate background noise and further clean up the call environment. However, compared to the dynamic noise cancellation process, the ANC adaptive filter plays a supplementary role, primarily targeting more stable ambient noise.

[0032] The noise-canceling headphones of this invention overcome the limitations of traditional ANC technology. By using a pre-set pseudo-random number seed, they can instantly generate a cancellation signal completely opposite to the dynamic noise source, achieving efficient noise cancellation without a learning process. This rapid response mechanism allows the headphones to adjust their noise cancellation strategy instantly as the noise source changes, effectively reducing the impact of rapidly changing noise on communication quality. The noise-canceling headphones generate the inverse cancellation signal through a noise-canceling speaker, such as... Figure 4 As shown:

[0033] The pseudo-random number seed used to generate the dynamic noise signal is the same as that used to cancel the signal. The noise-canceling headphones generate a sound wave with a 180° phase difference, which is transmitted to the ear canal through the headphone speaker. This creates a 180° phase difference with the noise, canceling out the dynamic noise that the ear should hear, thus achieving the purpose of noise reduction.

[0034] like Figure 5 As shown, a schematic diagram is given of dynamic noise signal, noisy signal, and noisy signal mixed with dynamic inverse signal. It can be clearly seen that only environmental noise remains after mixing.

[0035] This invention employs a classic speech enhancement technique—spectral subtraction—to eliminate noise. This technique significantly improves speech clarity when processing additive mixtures of speech signals and noise. Spectral subtraction is based on a core assumption: speech signals and noise are statistically independent, and noise possesses stable statistical properties. Utilizing this assumption, this invention processes noisy speech signals using Short-Time Fourier Transform (STFT). First, the spectral components of noise are separated from the signal; then, by subtracting these noise components, a clearer spectral representation of the speech signal is obtained.

[0036] After processing in the frequency domain, this invention performs an inverse Fourier transform on the processed signal to convert it back to the time domain. This process enables the invention to effectively recover the enhanced speech signal while maintaining its naturalness and clarity. This invention places particular emphasis on the statistical stationarity of noise, which allows the use of a stable noise model to estimate the noise spectrum during a call. This estimation method is based on a mean-based algorithm that assumes the expected value of the noise amplitude spectrum remains constant throughout the call, regardless of whether there is speech activity or silence intervals.

[0037] Furthermore, the method of this invention is based on the assumption of short-time stationarity of speech signals, meaning that the statistical properties of speech signals can be considered constant over a short period. In this way, the invention can accurately estimate the short-time spectrum of clean speech within a noisy speech signal, which is achieved by subtracting the short-time spectrum of noise from the short-time spectrum of the noisy speech signal. In the mathematical model, if the time-domain sampled signal of clean speech is represented as s(n) and the time-domain sampled signal of noise is represented as d(n), then the time-domain signal y(n) of noisy speech can be represented as a linear combination of s(n) and d(n).

[0038] y(n)=s(n)+d(n),0≤n≤N-1 (1)

[0039] In this embodiment, a clean speech signal is defined as s(n), and a stationary additive noise signal is represented as d(n). To reduce the truncation effect introduced by framing operations in signal processing, this embodiment implements a windowing technique on the noisy speech signal y(n). Through this step, the present invention can process the edges of the signal more smoothly, thereby reducing distortion during processing.

[0040] During the Fourier transform process, the transformed result of the noisy speech signal y(n) is represented as Y. K The transformation result of the pure speech signal s(n) is represented as S K The transformation result of the noise signal d(n) is expressed as D. K .

[0041] Figure 6 In the equation, after y(n) undergoes an FFT transformation, we have Y K =S K +D K Therefore, we can conclude that:

[0042] |Y K | 2 =|S K | 2 +|D K | 2 +S K D K * +D K S K * (2)

[0043] For noise signal D K and voice signal S K Their conjugates are represented as D. K * and S K *Since it is assumed that the speech signal s(n) and the noise signal d(n) are statistically independent, this means that there is no correlation between them. This independence further implies that the autocorrelation function S of the speech signal... K The autocorrelation function Y of the noisy signal K They are also independent of each other. Furthermore, the statistical properties of the noise signal d(n), such as its zero mean and Gaussian distribution, ensure that its autocorrelation function D... K It also has the Gaussian distribution property of zero mean, so we have:

[0044] E||Y K | 2 |=E||S K | 2 |+E||D K | 2 | (3)

[0045] For a short-time stationary process within an analysis frame, we have:

[0046] |Y K | 2 =|S K | 2 +λ n (k) (4)

[0047] λ n (k) represents the case without speech |D K | 2 The statistical average of the original speech is used to estimate the original speech as follows, where It is the amplitude of the enhanced speech signal.

[0048] |S K | 2 =|Y K | 2 -λ n (k) (5)

[0049]

[0050]

[0051] definition and the posterior signal-to-noise ratio γ K =|Y K | 2 / λ n (k)

[0052]

[0053] G K =(1-1 / γ) K ) 1 / 2(9)

[0054] This method involves decomposing the speech signal into its spectral components and processing each component meticulously. During processing, the attenuation coefficient is adjusted based on the presence of speech and the signal-to-noise ratio (SNR). A smaller attenuation coefficient is used when the SNR is high to preserve more speech information, while the attenuation coefficient is increased in regions with low SNR to reduce the impact of noise. The power spectrum of the clean speech signal is obtained by calculating the power spectra of the noisy speech and the noise, and then subtracting the power spectrum of the noise from the power spectrum of the noisy speech. The amplitude spectrum of the speech signal is then obtained by taking the square root of this power spectrum. Finally, these spectral components are recombined into a time-domain signal using an inverse Fourier transform, resulting in the enhanced speech signal.

[0055] like Figure 7 and Figure 8 As shown, the noise-canceling headphones of this invention (hereinafter referred to as "the headphones of the invention") exhibit significant technical advantages in handling dynamic noise, especially in low-frequency and high-frequency noise environments. These timing diagrams illustrate in detail the noise processing strategies and effects of conventional noise-canceling headphones (hereinafter referred to as "conventional headphones") and the headphones of this invention at different frequencies.

[0056] Figure 7 This figure illustrates a time-series comparison of noise cancellation performance between the noise-canceling headphones of this invention (hereinafter referred to as "the invented headphones") and conventional noise-canceling headphones (hereinafter referred to as "conventional headphones") in a low-frequency dynamic noise environment. In this figure, noise sources sequentially generate noise 1 to noise n, with each noise event represented by a numerical marker. Conventional headphones require a learning period (represented by the red area) to adapt to the noise pattern initially, during which time they cannot provide effective noise cancellation. In contrast, the invented headphones utilize a pseudo-random number seed synchronized with the external noise source, enabling them to directly emit a reverse cancellation signal without a learning phase, achieving instantaneous noise cancellation. This significantly improves noise cancellation efficiency, ensuring clear and natural communication.

[0057] Figure 8 This demonstrates the situation in a high-frequency dynamic noise environment, where the noise source changes much faster than traditional headphones can process. In this scenario, by the time traditional headphones attempt to learn and adapt to the current noise pattern, the noise has already changed, rendering them ineffective at noise reduction.

[0058] In contrast, the invented headphones, because they do not require a learning phase, can continuously and rapidly predict and cancel high-frequency dynamic noise. This means that no matter how rapidly the noise changes, the invented headphones can maintain efficient noise cancellation performance, providing users with a stable and clear listening environment.

[0059] The noise-canceling headphones of this invention exhibit superior performance in both low-frequency and high-frequency dynamic noise environments. By employing a pre-pairing strategy, the headphones not only improve noise cancellation efficiency but also ensure a clear listening experience under dynamic noise conditions. These advantages make the headphones a superior choice in environments requiring instant, clear, and secure communication. Compared to traditional noise-canceling headphones, this invention provides an innovative solution to meet the stringent requirements of modern communication technologies for high security and sound quality.

[0060] The secure, eavesdropping-proof dialogue system of this invention is designed as a highly complex and precise audio management device, whose workflow begins with the activation of an external noise source. For example... Figure 9 As shown:

[0061] This external noise source generates dynamic noise based on a pseudo-random number seed. This noise is specifically designed to interfere with illegal recording devices and prevent the leakage of sensitive call content. Upon startup, the headset first pairs with the external noise source. The noise source sends the pseudo-random number seed of this dynamic noise to the headset via its MCU; this signal also includes a clock synchronization signal. After receiving the signal from the noise source through its internal MCU, the headset replies with an acknowledgment signal and synchronously sends a cancellation signal under clock control. At this point, pairing is considered successful. Using the same pseudo-random number seed ensures that the headset's internal sound source can generate a cancellation signal that is completely opposite to the external noise.

[0062] After pairing is complete, the microphones inside the earphones begin collecting ambient noise. These collected ambient noise signals are then mixed with a cancellation signal generated inside the earphones in the signal processing unit. The mixing process is crucial for noise cancellation effectiveness and requires precise time synchronization and phase matching.

[0063] Next, the signal processing unit employs advanced adaptive filtering techniques, particularly spectral subtraction, to process the mixed signal. Spectral subtraction decomposes the signal into spectral components using a short-time Fourier transform, separating noise and speech in the frequency domain. Since noise is statistically stationary, and speech signals are short-time stationary, spectral subtraction effectively subtracts the power spectrum of the noise from the noisy speech signal, thereby estimating the clean speech power spectrum. Then, by taking the square root of the estimated clean speech power spectrum and performing an inverse Fourier transform, the signal is restored to the time domain, yielding the enhanced speech signal.

[0064] The adaptive filtering algorithm dynamically adjusts the cancellation signal based on the real-time detected noise characteristics, ensuring optimal noise reduction even when the noise environment changes. The optimized signal is played through the headphone speakers to cancel out the ambient noise, achieving active noise cancellation and delivering clear audio to the user.

[0065] Throughout the process, the system continuously detects sound input and noise, adjusting noise reduction strategies in real time to ensure sound clarity and communication security. This is achieved through a collaborative mechanism between internal and external sound sources.

[0066] The noise-canceling headphones of this invention significantly reduce in-band interference and effectively resist eavesdropping due to their unique system design and collaborative working mechanism. Unlike existing technologies that enhance speech solely through spectral subtraction, this invention employs an innovative collaborative cancellation strategy for dynamic noise sources and environmental noise. This strategy not only utilizes spectral subtraction to remove environmental noise but also introduces an innovative dynamic noise generation and cancellation mechanism, which is unprecedented in existing solutions.

[0067] Specifically, the dynamic noise source of the present invention can generate a matching noise signal based on a pseudo-random number seed, which is matched with a known dynamic noise source. This mechanism enables the headphones to adjust the noise reduction strategy instantly when the known noise source changes, effectively reducing the impact of rapidly changing noise on communication quality.

[0068] Therefore, the noise reduction effect achieved by the noise-canceling headphones of the present invention, through innovative system design, realizes the utilization and elimination of dynamic noise, which not only improves noise reduction efficiency, but also enhances communication security, especially when countering professional eavesdropping devices, demonstrating significant technical advantages.

[0069] The inventiveness of this invention lies not only in its comprehensive application of existing technologies, but also in its innovative anti-eavesdropping strategy utilizing dynamic noise sources. This invention is not only innovative in its solution, but also demonstrates significant practical value and market potential in real-world applications, particularly in military, commercial, and other fields requiring high-security communication.

[0070] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of the claims of the invention.

Claims

1. A secure dialogue system to prevent eavesdropping, characterized in that, The application's dialogue environment includes several dialogue objects and a high-frequency dynamic noise source set in the dialogue environment. Each dialogue object wears a headset. Before the formal dialogue begins, the high-frequency dynamic noise source is matched with the headset in the dialogue environment. After a successful match, the high-frequency dynamic noise source and the headphones share the pseudo-random number seed; The headset includes: a power module, a microphone, a dynamic noise cancellation speaker, an ambient noise cancellation speaker, an ANC adaptive filter, and an audio communication speaker; the power module provides power to the microphone, the dynamic noise cancellation speaker, the ambient noise cancellation speaker, the ANC adaptive filter, and the audio communication speaker. Microphones are used to collect sound signals; The dynamic noise cancellation speaker shares a pseudo-random number seed with the external noise source, generating a signal that is opposite to the high-frequency dynamic noise source in real time. The ANC adaptive filter uses spectral subtraction to generate a cancellation signal that is opposite to the ambient noise, and transmits the cancellation signal to the ambient noise cancellation speaker to eliminate the ambient noise; thus obtaining a clean dialogue audio signal. Audio communication speakers are used to output clean conversational audio signals within headphones; Once the conversation begins, the sound signal collected by the earphone is a mixture of three independent signals: conversation audio signal, high-frequency dynamic noise, and environmental noise. The earphone eliminates the high-frequency dynamic noise by generating a signal that is opposite to the source of the high-frequency dynamic noise. The specific process for eliminating environmental noise is as follows: Before the dialogue begins, the headphones collect external noise, and the high-frequency dynamic noise cancellation speaker generates a signal opposite to the high-frequency dynamic noise source in real time to cancel the high-frequency dynamic noise collected by the headphones; thus, the individual ambient noise is obtained; and the power spectrum of the ambient noise is calculated. After the dialogue begins, calculate the power spectrum of the dialogue audio signal with accompanying environmental noise. The power spectrum of the clean dialogue audio signal is obtained by subtracting the power spectrum of the ambient noise from the power spectrum of the dialogue audio signal with ambient noise. The amplitude spectrum of the dialogue audio signal is obtained by taking the square root of the power spectrum of this pure dialogue audio signal. Finally, the enhanced dialogue audio signal was obtained through inverse Fourier transform.

2. The secure dialogue system against eavesdropping according to claim 1, characterized in that, The sound signals collected by the headphones include conversation audio signals and external noise, which includes high-frequency dynamic noise and environmental noise.

3. A secure dialogue system against eavesdropping according to claim 2, characterized in that, The dynamic noise cancellation occurs when the high-frequency dynamic noise source is successfully matched with the headphones in the dialogue environment. The dynamic noise cancellation speaker generates a signal opposite to that of the high-frequency dynamic noise source in real time to cancel the high-frequency dynamic noise collected by the headphones.

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