Musical instrument line noise reduction method and musical instrument noise reduction effecter

Abstract

This invention belongs to the field of audio signal processing technology, and provides a method for noise reduction in instrument circuitry and an instrument noise reduction effect processor. The method includes: acquiring the input signal of the instrument circuitry in a state without performance signal or with user-initiated triggering, and extracting a spectral feature template of background noise from it; acquiring the input signal of the same instrument circuitry in a normal performance state, and extracting noise components from the input signal of the same instrument circuitry in the normal performance state based on the spectral feature template to obtain a time-domain noise signal; and delaying and phase-adjusting the time-domain noise signal so that the adjusted noise signal can cancel the original background noise in the instrument circuitry. This method accurately removes background noise from the circuitry regardless of whether the instrument is being played. During performance, noise components are extracted from the input signal of the same instrument circuitry in the normal performance state using the spectral feature template, resulting in a particularly significant noise reduction effect when the instrument is connected to a speaker with very high gain.

Description

Technical Field

[0001] This invention belongs to the field of music equipment technology, and in particular to a method for noise reduction of musical instrument circuits and a noise reduction effect device for musical instruments. Background Technology

[0002] In electric guitar playing systems, noise reduction effects are typically connected between the electric guitar and the amplifier or other effects units to reduce background noise, hum, and hiss introduced by pickups, cables, distortion / overdrive effects, high-gain amplifiers, and the ambient electromagnetic environment.

[0003] Currently, common guitar noise reduction stompboxes mainly employ noise gates, dynamic extension, frequency filtering, multi-band dynamic processing, or sidechain detection. Among them, the noise gate scheme attenuates or cuts off the output based on whether the signal level is below a preset threshold; the dynamic extension scheme continuously adjusts the gain according to the signal strength; the filtering scheme achieves noise reduction by weakening noise in specific frequency bands; and the sidechain detection scheme can use a relatively clean original signal to control the on / off state of high-noise signal chains.

[0004] While the above solutions can reduce background noise and high-gain noise during performance breaks to some extent, they still have significant shortcomings: (1) There is delay and loss of sound quality. Apart from pure analog noise gates and dynamic processors, existing digital noise reduction solutions all require the guitar signal to be input to a DSP chip via an AD converter, processed digitally, and then output via a DA converter. This process inevitably introduces additional latency, and the AD / DA conversion also results in a loss of sound quality, affecting the real-time feel of the performance and the purity of the tone.

[0005] (2) Sound quality damage Noise gates and dynamic processing schemes essentially reduce noise by attenuating low-level signals. However, they can easily and mistakenly eliminate vital musical signals such as soft notes, trailing notes, and overtones, resulting in lost attack, truncated sustain, or unnatural dynamic response. Filtered noise reduction, on the other hand, directly attenuates specific frequency bands, thereby altering the guitar's frequency response and damaging the texture of plucking and tonal details.

[0006] (3) Limited noise reduction capability Noise gates and dynamic processing cannot eliminate background noise mixed with the guitar sound—when the guitar is being played, the signal level is above the threshold, the noise gate is fully open, and the background noise is output along with the guitar sound. Noise reduction only works during breaks or soft passages. Filtering schemes treat noise and guitar sound indiscriminately, further degrading sound quality. While multi-band or digital noise reduction has strong processing capabilities, it is usually complex in structure, expensive, and inconvenient to adjust. Sidechain noise reduction, on the other hand, has high requirements for wiring and the order of effects pedals.

[0007] In conclusion, existing independent guitar noise-canceling pedals struggle to achieve a good balance between strong noise reduction, low latency, low-frequency tone loss, natural sustain, and ease of use. Therefore, it is necessary to propose an improved guitar noise-canceling pedal technology to overcome these shortcomings. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention proposes a method for noise reduction of musical instrument circuits and a noise reduction effect device for musical instruments.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On one hand, the present invention provides a method for noise reduction in musical instrument circuitry, comprising the following steps: The input signal of the instrument circuit is acquired when there is no performance signal or when the user actively triggers it, and the spectral feature template of the background noise is extracted from it. The input signal of the same instrument circuit under normal playing conditions is obtained, and the noise component is extracted from the input signal of the same instrument circuit under normal playing conditions based on the spectral feature template to obtain the time-domain noise signal; The time-domain noise signal is delayed and phase-adjusted so that the adjusted noise signal can cancel the original background noise in the instrument circuitry.

[0010] Further, the spectral feature template of the background noise is extracted, including: performing analog-to-digital conversion sampling on the input signal of the instrument circuit under no performance signal or user-triggered state at a predetermined sampling rate, extracting sample blocks of predetermined length according to a predetermined step interval, applying a window function to each sample block and performing Fourier transform, calculating the amplitude value of each frequency point to obtain the amplitude frequency of each sample block, and calculating the squared average of the amplitude frequencies of all sample blocks of the entire input signal to obtain the spectral feature template of the background noise.

[0011] Furthermore, based on the spectral feature template, noise components are extracted from the input signal of the same instrument circuit under normal playing conditions to obtain a time-domain noise signal, including: The input signal of the same instrument circuit under normal playing conditions is sampled by analog-to-digital conversion at the same predetermined sampling rate, and sample blocks of predetermined length are extracted at the same predetermined step interval. After applying a window function to the current sample block, Fourier transform is performed to obtain the spectrum of the current sample block. For each frequency point, the minimum value between the amplitude value of that frequency point in the current sample block spectrum and the amplitude value of the corresponding frequency point in the spectrum feature template is taken as the amplitude of the noise component at that frequency point, and the phase of that frequency point in the current sample block spectrum is taken as the phase of the noise component at that frequency point, thereby obtaining the noise spectrum of the current sample block; The noise spectrum of each sample block is subjected to inverse Fourier transform and a window function is applied. Then, the noise signals are obtained by overlapping, adding and merging.

[0012] Further, the time-domain noise signal is delayed and phase-adjusted, including: The pitch period p is obtained by performing pitch period detection on the time-domain noise signal. Let the fixed delay of the system be D, and apply a fixed additional delay to the time-domain noise signal. n is a positive integer; By inverting the time-domain noise signal with a fixed additional delay, the total delay of the adjusted noise signal is p×n and the phase is opposite to that of the original background noise, which can cancel the original background noise in the instrument circuit.

[0013] Furthermore, an adaptive filter can be used to delay and adjust the phase of the time-domain noise signal, including: using the time-domain noise signal as the reference input of the adaptive filter, feeding back the residual error signal in the instrument circuit after noise reduction to the adaptive filter, and dynamically adjusting the filter coefficients of the adaptive filter with the goal of minimizing the error signal, thereby adaptively adjusting the delay and phase of the time-domain noise signal, so that the output of the adaptive filter, after being inverted, can cancel the original background noise in the instrument circuit to the greatest extent.

[0014] Furthermore, the musical instrument is an electric guitar, and the circuit input signal of the musical instrument is an analog signal output from the guitar pickup.

[0015] On the other hand, a musical instrument noise reduction effect is provided, including: At least one stepper is used to trigger noise learning or switch the noise reduction function; Input interface, used to receive instrument circuit input signals; A simulated direct path is provided, with its input end connected to the input interface, for passing the input signal directly to its output end without additional delay or loss of sound quality; An analog-to-digital converter, connected to the input interface, is used to convert the input signal into digital form; A digital signal processing unit, connected to the analog-to-digital conversion unit, is used to execute the instrument circuit noise reduction method and output the adjusted digital noise signal; The digital-to-analog converter unit is used to convert the adjusted digital noise signal into an analog signal and output it to the output terminal of the analog through path; At the output of the analog through path, the adjusted digital noise signal, converted to an analog signal, is superimposed on the input signal to achieve noise cancellation before output.

[0016] This solution employs a direct analog path, transmitting the raw signal directly to the output without any AD conversion, DSP processing, or DA conversion. Therefore, the signal transmission delay is zero, unaffected by digital processing. Performers experience no perceptible delay, fully preserving the real-time response characteristics of traditional analog effects processors.

[0017] On the other hand, a noise reduction effect for musical instruments is provided, characterized by comprising: At least one stepper is used to trigger noise learning or switch the noise reduction function; Input interface, used to receive instrument circuit input signals; An analog-to-digital converter, connected to the input interface, is used to convert the input signal into digital form; A digital signal processing unit, connected to the analog-to-digital conversion unit, is used to execute the instrument circuit noise reduction method and output the adjusted digital noise signal; The pure digital processing path superimposes the adjusted digital noise signal with the digital input signal to cancel out the noise and obtain the denoised digital signal.

[0018] The digital-to-analog converter unit is used to convert the noise-reduced digital signal into an analog signal and output it.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for noise reduction in musical instrument circuitry, comprising: acquiring the input signal of the musical instrument circuitry in a state without performance signal or user-triggered state, and extracting a spectral feature template of background noise from it; acquiring the input signal of the same musical instrument circuitry in a normal performance state, and extracting noise components from the input signal of the same musical instrument circuitry in the normal performance state based on the spectral feature template to obtain a time-domain noise signal; and delaying and phase-adjusting the time-domain noise signal so that the adjusted noise signal can cancel the original background noise in the musical instrument circuitry. This method can accurately remove background noise from the circuitry regardless of whether the instrument is being played. When playing, the noise components are extracted from the input signal of the same musical instrument circuitry in a normal performance state using the spectral feature template. The noise reduction effect is particularly significant when the instrument is connected to a speaker with very high gain, and is significantly better than current noise gate and other similar methods. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a method for noise reduction of musical instrument circuitry in one embodiment; Figure 2 This is a schematic diagram of the principle framework of a noise reduction method for musical instrument circuitry in one embodiment; Figure 3 This is a schematic diagram of the principle framework of a noise reduction method for musical instrument circuitry in one embodiment; Figure 4 This is a schematic diagram of the principle framework of a noise reduction method for musical instrument circuitry in one embodiment; Figure 5 This is a schematic diagram of the principle framework of a noise reduction method for musical instrument circuitry in one embodiment; Figure 6 This is a waveform diagram showing the actual noise reduction effect in one embodiment. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Reference Figure 1 One embodiment provides a method for noise reduction in musical instrument circuitry, comprising the following steps: The input signal of the instrument circuit is acquired when there is no performance signal or when the user actively triggers it, and the spectral feature template of the background noise is extracted from it. The input signal of the same instrument circuit under normal playing conditions is obtained, and the noise component is extracted from the input signal of the same instrument circuit under normal playing conditions based on the spectral feature template to obtain the time-domain noise signal; The time-domain noise signal is delayed and phase-adjusted so that the adjusted noise signal can cancel the original background noise in the instrument circuitry.

[0024] The first step in the above embodiments is actually noise learning. Generally, the background noise of musical instrument circuits is relatively stable and is mostly caused by the power supply system, environmental electromagnetic waves, etc. In one embodiment, extracting the spectral feature template of background noise from the input signal of the musical instrument circuit in the absence of a performance signal or in a user-triggered state includes the following steps: The input signal of the instrument circuit in the absence of a performance signal or in the state of user-initiated triggering is sampled by analog-to-digital conversion at a predetermined sampling rate, and sample blocks of predetermined length are extracted according to a predetermined step size interval. After applying a window function to each sample block, Fourier transform is performed, and the amplitude value of each frequency point is calculated to obtain the amplitude frequency of each sample block. The squared average of the amplitude frequencies of all sample blocks of the entire input signal is calculated to obtain the spectral feature template of the background noise.

[0025] There are several common ways to trigger the noise learning phase, including but not limited to the following three: The first type is user-initiated. For example, on an effects pedal, the user can stop playing and learn noise by repeatedly pressing the bass button.

[0026] The second type is automatic triggering. The system automatically detects whether the user is playing, and automatically detects the playing energy or uses a neural network to determine the playing state. It automatically triggers the function when the user is not playing.

[0027] The third method involves learning by acquiring environmental noise signals in real time using an additional antenna independent of the instrument's circuitry.

[0028] This invention acquires the input signal of the instrument circuit in the absence of a performance signal or in a user-triggered state, and extracts the spectral feature template of the background noise from it. In practical applications, the purpose of noise learning in this step is to acquire the features of the background noise, and the noise features are not limited to the spectral feature template.

[0029] In one embodiment, noise components are extracted from the input signal of the same instrument circuit under normal playing conditions based on the spectral feature template to obtain a time-domain noise signal, including the following steps: The input signal of the same instrument circuit under normal playing conditions is sampled by analog-to-digital conversion at the same predetermined sampling rate, and sample blocks of predetermined length are extracted at the same predetermined step interval. After applying a window function to the current sample block, Fourier transform is performed to obtain the spectrum of the current sample block. For each frequency point, the minimum value between the amplitude value of that frequency point in the current sample block spectrum and the amplitude value of the corresponding frequency point in the spectrum feature template is taken as the amplitude of the noise component at that frequency point, and the phase of that frequency point in the current sample block spectrum is taken as the phase of the noise component at that frequency point, thereby obtaining the noise spectrum of the current sample block; The noise spectrum of each sample block is subjected to inverse Fourier transform and a window function is applied. Then, the noise signals are obtained by overlapping, adding and merging.

[0030] In the above embodiments, the type of window function is not limited, such as using a Hanning window.

[0031] Finally, the extracted noise signal is adjusted to output a state that can just cancel out the noise in the analog circuit. The method of adjusting the extracted time-domain noise signal is not limited.

[0032] In one embodiment, the proposed method for delaying and phase-adjusting the time-domain noise signal includes the following steps: The pitch period p is obtained by performing pitch period detection on the time-domain noise signal. Let the fixed delay of the system be D, and apply a fixed additional delay to the time-domain noise signal. Let n be a positive integer. Further, select the smallest integer n such that... A fixed additional delay is applied to the time-domain noise signal. .

[0033] By inverting the time-domain noise signal with a fixed additional delay, the total delay of the adjusted noise signal is p×n and the phase is opposite to that of the original background noise, which can cancel the original background noise in the instrument circuit.

[0034] In another embodiment, an adaptive filter is proposed to delay and adjust the phase of the time-domain noise signal, including: using the time-domain noise signal as a reference input of the adaptive filter, feeding back the residual error signal in the instrument circuit after noise reduction to the adaptive filter, and dynamically adjusting the filter coefficients of the adaptive filter with the goal of minimizing the error signal, thereby adaptively adjusting the delay and phase of the time-domain noise signal, so that the output of the adaptive filter, after being inverted, can cancel the original background noise in the instrument circuit to the greatest extent.

[0035] In any of the above embodiments, the type of musical instrument is not limited. Typically, the musical instrument is an electric guitar, and the instrument circuit input signal is an analog signal output by the guitar pickup.

[0036] Reference Figure 2 In one embodiment, the framework principle of instrument circuit noise reduction involves the input signal first undergoing an analog-to-digital (AD) converter. The converted digital signal is then simultaneously fed into a noise learning module and a noise separation module. The noise learning module extracts features from the signal in a non-playing or actively triggered state to obtain a spectral feature template of the background noise. This template is then used to guide noise separation to extract the time-domain noise signal from the normal playing signal. Subsequently, the extracted time-domain noise signal undergoes adaptive filtering to adjust its phase, ensuring that its delay and phase satisfy the cancellation condition. Finally, it is converted by an analog-to-digital (DA) converter to output an inverted noise signal, which is superimposed on and cancels out the original background noise in the input signal in the analog path, thereby achieving noise reduction and outputting a denoised signal. The noise learning can be triggered automatically or manually (e.g., by setting a footstool).

[0037] Figure 3 It also provides a framework principle for noise reduction in musical instrument circuits, which is different from... Figure 2 The framework principle of the instrument circuit noise reduction shown is that this scheme does not use an adaptive filter to delay and adjust the phase of the time-domain noise signal. Figure 3 The noise delay and phase adjustment scheme is as follows: The pitch period of the time-domain noise signal is detected to obtain the pitch period p; assuming the fixed delay of the system is D, a fixed additional delay is applied to the time-domain noise signal. , where n is a positive integer. The time-domain noise signal with a fixed additional delay is inverted to obtain an adjusted noise signal with a total delay of p×n and a phase opposite to the original background noise, thus canceling the original background noise in the instrument circuitry. The noise learning can be triggered automatically or manually (e.g., by setting a footstool).

[0038] Figure 4 It also provides a framework principle for noise reduction in musical instrument circuits, which is different from... Figure 2 The framework principle of the instrument circuit noise reduction scheme shown is as follows: the noise learning is triggered by acquiring ambient noise signals in real time through an additional antenna independent of the instrument circuit. After collecting noise through the additional antenna and performing A / D conversion, noise learning is performed to obtain the spectral feature template of the background noise. The spectral feature template is then used to guide noise separation to extract the time-domain noise signal from the normal performance signal.

[0039] Figure 2 , Figure 3 and Figure 4 The instrument circuit noise reduction method shown employs an analog straight-through path. The instrument circuit input signal is transmitted directly to the output without any AD conversion, DSP processing, or DA conversion. Simultaneously, the input signal undergoes a zero-delay circuit noise reduction method involving noise extraction and cancellation, resulting in an adjusted digital noise signal. This digital noise signal is then converted to analog noise via DA conversion and superimposed on the instrument circuit input signal at the output, achieving noise cancellation before output. Therefore, the transmission delay of the instrument circuit input signal is zero and unaffected by digital processing. The performer experiences no perceptible delay, fully maintaining the real-time response characteristics of traditional analog effects units. Since the instrument circuit input signal remains entirely in the analog domain without any digital processing, issues such as AD / DA quantization noise, sampling rate truncation, and digital filtering phase distortion are eliminated.

[0040] Figure 5 It also provides a framework principle for noise reduction in musical instrument circuits, which is different from... Figure 2 , Figure 3 and Figure 4 The instrument circuit noise reduction method shown uses a simulated straight-through path to transmit the instrument circuit input signal. Figure 5 The instrument circuit input signal is converted into digital form via AD sampling and transmitted to the output through a pure digital processing path. The digital instrument circuit input signal is then subjected to a zero-delay line noise reduction method for noise extraction and cancellation, and an adjusted digital noise signal is output. The adjusted digital noise signal is superimposed on the digital input signal to achieve noise cancellation, resulting in a noise-reduced digital signal, which is then converted into a DA converter and output.

[0041] The background noise spectral feature template in this invention can be updated in real time or instantaneously according to the environment (e.g., user long-term use of the guitar accelerator or automatic detection of quiet periods). This invention extracts the background noise spectral feature template and generates an inverse noise signal that is injected into the analog circuit, continuously and dynamically canceling the background noise in the circuit regardless of whether the guitar is being played.

[0042] In another embodiment, a musical instrument noise reduction effect is provided, comprising: At least one stepper is used to trigger noise learning or switch the noise reduction function; Input interface, used to receive instrument circuit input signals; A simulated direct path is provided, with its input end connected to the input interface, for passing the input signal directly to its output end without additional delay or loss of sound quality; An analog-to-digital converter, connected to the input interface, is used to convert the input signal into digital form; A digital signal processing unit, connected to the analog-to-digital conversion unit, is used for instrument circuit noise reduction methods and outputs an adjusted digital noise signal; The digital-to-analog converter unit is used to convert the adjusted digital noise signal into an analog signal and output it to the output terminal of the analog through path; At the output of the analog through path, the adjusted digital noise signal, converted to an analog signal, is superimposed on the input signal to achieve noise cancellation before output.

[0043] Employing a direct analog path, the instrument circuitry input signal is transmitted directly to the output without any AD conversion, DSP processing, or DA conversion. Therefore, the transmission delay of the guitar performance signal is zero, unaffected by digital processing. The performer experiences no perceptible delay, fully maintaining the real-time response characteristics of traditional analog effects units. Since the instrument circuitry input signal remains entirely in the analog domain without any digital processing, issues such as AD / DA quantization noise, sampling rate truncation, and digital filtering phase distortion are eliminated.

[0044] In another embodiment, a musical instrument noise reduction effect is proposed, comprising: At least one stepper is used to trigger noise learning or switch the noise reduction function; Input interface, used to receive instrument circuit input signals; An analog-to-digital converter, connected to the input interface, is used to convert the input signal into digital form; A digital signal processing unit, connected to the analog-to-digital conversion unit, is used to execute a musical instrument circuit noise reduction method and output an adjusted digital noise signal; The pure digital processing path superimposes the adjusted digital noise signal with the digital input signal to cancel out the noise and obtain the denoised digital signal.

[0045] The digital-to-analog converter unit is used to convert the noise-reduced digital signal into an analog signal and output it.

[0046] In one embodiment, an electric guitar noise reduction effect is provided, the effect being based on Figure 3 The link structure shown has an effect pedal with a footstool. A long footstool is used to trigger noise learning, and a short footstool is used to control the noise reduction function.

[0047] When the user presses the foot pedal for an extended period, the effect processor enters the noise learning phase. During this phase, the effect processor processes the input signal as follows: Sampling and Blocking: The input signal is sampled at a sampling rate of 48kHz, i.e., 48,000 samples are collected per second. Every 256 samples, the latest 1024 samples are extracted as a sample block (there is a 768-point overlap between sample blocks).

[0048] Windowing: Each sample block is multiplied by a Hanning window of length 1024 to reduce spectral leakage.

[0049] Fourier Transform: Perform a Fast Fourier Transform (FFT) on the windowed data block and calculate the absolute value of the amplitude at each frequency point to obtain the amplitude-frequency response of the current block.

[0050] Statistics: For the amplitude-frequency response of all blocks throughout the entire sampling process, the squared average is calculated at each frequency point, resulting in an amplitude sequence of length 1024, denoted as F. This sequence serves as the spectral characteristic template for the background noise.

[0051] After noise learning, the effect pedal automatically enters the noise reduction processing stage. Users can toggle the noise reduction function on or off by shorting the footswitch.

[0052] During the noise reduction stage, the effects processor performs the same sampling, block segmentation, windowing, and Fourier transform processing on the real-time input signal (denoted as x) as in the learning stage: For the input signal x, extract 1024 samples every 256 samples as a sample block; The sample block is multiplied by a Hanning window and then subjected to a Fourier transform to obtain the spectrum of the current sample block; For each frequency point, the minimum value between the amplitude value of that frequency point in the current sample block spectrum and the amplitude value of the corresponding frequency point in the spectrum feature template is taken as the amplitude of the noise component at that frequency point, and the phase of that frequency point in the current sample block spectrum is taken as the phase of the noise component at that frequency point, thereby obtaining the noise spectrum of the current sample block; The noise spectrum of each sample block is subjected to inverse Fourier transform and a window function is applied. Then, the noise signals are obtained by overlapping, adding and merging.

[0053] Through the above process, a time-domain noise signal containing only background noise components is extracted from the original input signal.

[0054] After obtaining the time-domain noise signal, the noise adjustment and cancellation stage begins: Pitch period detection: The extracted time-domain noise signal is subjected to pitch period detection (e.g., using autocorrelation or cepstral method). Because the frequency of the line ambient noise is very stable (usually the local AC frequency, such as 50Hz or 60Hz), the detected pitch period p is very accurate.

[0055] Let the fixed delay of the system be D, and apply a fixed additional delay to the time-domain noise signal. Let n be a positive integer. Further, select the smallest integer n such that... A fixed additional delay is applied to the time-domain noise signal. The time-domain noise signal is delayed by a fixed additional delay amount. After that, its total delay becomes That is, it is exactly an integer multiple of the pitch period p.

[0056] The time-domain noise signal with a fixed additional delay is inverted. The total delay of the inverted noise signal is p×n and its phase is opposite to that of the original background noise, which can cancel the original background noise in the instrument circuit.

[0057] The inverted noise signal is converted from digital to analog and then injected into the analog circuit, where it is superimposed on the original background noise. Because the adjusted noise signal and the original noise have the same frequency, similar amplitude, opposite phase, and a delay difference of an integer number of cycles, they can cancel each other out, thus significantly reducing or even eliminating the circuit noise floor. Simultaneously, the original guitar signal is output directly via an analog through-path without delay or loss, unaffected by any digital processing.

[0058] Figure 6 This is a waveform diagram of the actual noise reduction effect. The horizontal axis represents time, and the vertical axis represents amplitude. The waveform on the left is the waveform before noise reduction, and the waveform on the right is the wavelength after noise reduction is enabled. This embodiment achieved significant results in electric guitar performance tests: the additional latency of guitar playing was zero, and the player could not perceive any latency at all. The guitar tone was not subjected to any AD / DA conversion or DSP processing, maintaining its original harmonic structure and dynamic response. Background noise was effectively eliminated both when the guitar was stationary and when playing, and the noise reduction effect was particularly noticeable in high-gain distortion scenarios.

[0059] Because the noise feature template can be relearned based on the environment, and the extraction process is based on real-time comparison of frequency points, it can adapt to various usage scenarios (such as switching pickups, adjusting volume, plugging and unplugging cables, etc.). In summary, this embodiment successfully achieves a guitar circuit noise reduction solution with zero latency, zero tone loss, and strong noise reduction effect. Matters not covered in this invention are common knowledge.

[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for noise reduction in musical instrument circuitry, characterized in that, Includes the following steps: The input signal of the instrument circuit is acquired when there is no performance signal or when the user actively triggers it, and the spectral feature template of the background noise is extracted from it. The input signal of the same instrument circuit under normal playing conditions is obtained, and the noise component is extracted from the input signal of the same instrument circuit under normal playing conditions based on the spectral feature template to obtain the time-domain noise signal; The time-domain noise signal is delayed and phase-adjusted so that the adjusted noise signal can cancel the original background noise in the instrument circuitry.

2. The instrument circuit noise reduction method according to claim 1, characterized in that, Extracting the spectral feature template of background noise includes: performing analog-to-digital conversion sampling on the input signal of the instrument circuit under no performance signal or user-triggered state at a predetermined sampling rate, extracting sample blocks of predetermined length according to a predetermined step interval, applying a window function to each sample block and performing Fourier transform, calculating the amplitude value of each frequency point to obtain the amplitude frequency of each sample block, and calculating the squared average of the amplitude frequencies of all sample blocks of the entire input signal to obtain the spectral feature template of background noise.

3. The instrument circuit noise reduction method according to claim 2, characterized in that, Based on the aforementioned spectral feature template, noise components are extracted from the input signal of the same instrument circuit under normal playing conditions to obtain a time-domain noise signal, including: The input signal of the same instrument circuit under normal playing conditions is sampled by analog-to-digital conversion at the same predetermined sampling rate, and sample blocks of predetermined length are extracted at the same predetermined step interval. After applying a window function to the current sample block, Fourier transform is performed to obtain the spectrum of the current sample block. For each frequency point, the minimum value between the amplitude value of that frequency point in the current sample block spectrum and the amplitude value of the corresponding frequency point in the spectrum feature template is taken as the amplitude of the noise component at that frequency point, and the phase of that frequency point in the current sample block spectrum is taken as the phase of the noise component at that frequency point, thereby obtaining the noise spectrum of the current sample block; The noise spectrum of each sample block is subjected to inverse Fourier transform and a window function is applied. Then, the noise signals are obtained by overlapping, adding and merging.

4. The instrument circuit noise reduction method according to claim 2 or 3, characterized in that, The window function is the Hanning window.

5. The instrument circuit noise reduction method according to claim 3, characterized in that, Delaying and phase adjusting the time-domain noise signal includes: The pitch period p is obtained by performing pitch period detection on the time-domain noise signal. Let the fixed delay of the system be D, and apply a fixed additional delay to the time-domain noise signal. n is a positive integer; By inverting the time-domain noise signal with a fixed additional delay, the total delay of the adjusted noise signal is p×n and the phase is opposite to that of the original background noise, which can cancel the original background noise in the instrument circuit.

6. The instrument circuit noise reduction method according to claim 5, characterized in that, Choose the smallest integer n such that .

7. The instrument circuit noise reduction method according to claim 3, characterized in that, The method of delaying and adjusting the phase of the time-domain noise signal using an adaptive filter includes: using the time-domain noise signal as the reference input of the adaptive filter; feeding back the residual error signal in the instrument circuit after noise reduction to the adaptive filter; and dynamically adjusting the filter coefficients of the adaptive filter with the goal of minimizing the error signal, thereby adaptively adjusting the delay and phase of the time-domain noise signal so that the output of the adaptive filter, after being inverted, can cancel the original background noise in the instrument circuit to the greatest extent.

8. The instrument circuit noise reduction method according to claim 1, 2, 3, 5, 6, or 7, characterized in that, The musical instrument is an electric guitar, and the circuit input signal of the musical instrument is an analog signal output from the guitar pickup.

9. A noise reduction effect for musical instruments, characterized in that, include: At least one stepper is used to trigger noise learning or switch the noise reduction function; Input interface, used to receive instrument circuit input signals; A simulated direct path is provided, with its input end connected to the input interface, for passing the input signal directly to its output end without additional delay or loss of sound quality; An analog-to-digital converter, connected to the input interface, is used to convert the input signal into digital form; A digital signal processing unit, connected to the analog-to-digital conversion unit, is used to execute the instrument circuit noise reduction method as described in claim 1, 2, 3, 5, 6, or 7, and output an adjusted digital noise signal. The digital-to-analog converter unit is used to convert the adjusted digital noise signal into an analog signal and output it to the output terminal of the analog through path; At the output of the analog through path, the adjusted digital noise signal, converted to an analog signal, is superimposed on the input signal to achieve noise cancellation before output.

10. A musical instrument noise reduction effect processor, characterized in that, include: At least one stepper is used to trigger noise learning or switch the noise reduction function; Input interface, used to receive instrument circuit input signals; An analog-to-digital converter, connected to the input interface, is used to convert the input signal into digital form; A digital signal processing unit, connected to the analog-to-digital conversion unit, is used to execute the instrument circuit noise reduction method as described in claim 1, 2, 3, 5, 6, or 7, and output an adjusted digital noise signal. The pure digital processing path superimposes the adjusted digital noise signal with the digital input signal to cancel out the noise and obtain the denoised digital signal. The digital-to-analog converter unit is used to convert the noise-reduced digital signal into an analog signal and output it.

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