Vehicle-mounted audio and sound effect adjusting system and method

Abstract

The invention relates to a vehicle-mounted audio and sound effect adjusting system and method. The adjusting system comprises a sound effect tone modification module, an equalizer module, a reverberation module, a central control module, a tone modification processing module and an audio output module. The adjusting method comprises the steps that 1, the central control module collects vehicle driving data and in-vehicle environment data and receives sound effect preference setting input by passengers; 2, the central control module analyzes a current suitable sound effect processing strategy; 3, the central control module adjusts the tone of the audio; 4, the equalizer module performs energy adjustment on different frequency bands of the audio frequency; 5, the reverberation module adds a corresponding reverberation effect to the audio; and 6, the audio output module outputs the audio signal after comprehensive processing, and high-quality audio experience is provided for passengers in the vehicle. The problems that an existing vehicle-mounted audio and sound effect adjusting system is single in function and cannot adjust sound effect parameters in a self-adaptive mode are solved, personalized vehicle-mounted audio and sound effects adapting to different scenes are achieved, and the hearing experience of vehicle-mounted audio is improved.

Description

Technical Field

[0001] The invention belongs to the field of automobile technology, and in particular to a vehicle-mounted audio sound effect adjustment system and method. Background Art

[0002] With the rapid development of the automotive industry, people spend more and more time in cars, and the requirements for in-car audio systems are getting higher and higher. Traditional in-car audio systems have relatively simple functions in sound adjustment and cannot meet users' needs for personalized and diversified sound effects. In addition, the existing in-car audio sound adjustment system cannot adaptively adjust the sound parameters under different vehicle driving conditions and environments, which affects the audio playback effect and the user's listening experience. Summary of the invention

[0003] To solve the above problems, the present invention provides a vehicle-mounted audio sound effect adjustment system and method, which can adjust the audio sound effects in real time according to changes in the vehicle environment and the personalized needs of passengers, so that the vehicle-mounted audio system always maintains the best playback effect, effectively reduces driving fatigue, and improves driving safety and riding comfort.

[0004] The technical solution of the present invention is described as follows in conjunction with the accompanying drawings:

[0005] In a first aspect, the present invention provides a vehicle-mounted audio sound effect adjustment system, comprising:

[0006] The sound effect pitch shifting module is used to receive an input audio signal and perform pitch shifting processing on the audio signal; adjust the amplitude and speed of the pitch shifting according to the user's settings or the instructions of the central control module; the sound effect pitch shifting module can achieve the pitch increase or decrease of the audio signal;

[0007] An equalizer module is used to perform gain or attenuation processing on different frequency components of the audio signal to adjust the frequency response of the audio signal; the equalizer module includes control channels of multiple frequency bands, and the user can adjust the gain value of each frequency band to achieve balanced adjustment of the audio signal;

[0008] The reverberation module is used to add reverberation effects to audio signals to simulate different acoustic space environments; according to the user's settings or the instructions of the central control module, the reverberation parameters are adjusted to achieve different reverberation effects;

[0009] The central control module is used to coordinate the work of the sound effect pitch shifting module, the equalizer module, and the reverberation module, and dynamically adjust the parameters of each module according to the user's settings, the vehicle's driving status, and the in-vehicle environment;

[0010] The pitch-shifting processing module is used to decompose the input audio signal into a short-time spectrum based on the phase vocoder principle, achieve the pitch change by scaling the frequency components in the spectrum, and then resynthesize the processed spectrum into a pitch-shifted audio signal;

[0011] An audio output module, used for outputting the audio signal after modulation;

[0012] The central control module is connected to the sound effect pitch shifting module, the equalizer module, and the reverberation module; the sound effect pitch shifting module, the equalizer module, and the reverberation module are connected to the pitch shifting processing module; and the pitch shifting processing module is connected to the audio output module.

[0013] In a second aspect, the present invention further provides a method for adjusting a vehicle-mounted audio sound effect adjustment system, comprising the following steps:

[0014] Step 1: The central control module collects vehicle driving data and in-vehicle environment data in real time through various sensors and receives sound effect preference settings input by passengers;

[0015] Step 2: The central control module analyzes and determines the current appropriate sound effect processing strategy based on the collected data and settings;

[0016] Step 3: The central control module sends a command to the sound effect pitch change module to adjust the pitch of the audio;

[0017] Step 4: The central control module sends instructions to the equalizer module to adjust the energy of different frequency bands of the audio;

[0018] Step 5: The central control module sends instructions to the reverberation module to add corresponding reverberation effects to the audio;

[0019] Step 6: The audio output module outputs the audio signal after comprehensive processing to provide high-quality audio experience for passengers in the car.

[0020] Furthermore, in step one, the vehicle driving data includes vehicle speed and road conditions; and the in-vehicle environment data includes noise level.

[0021] Furthermore, in step one, the central control module sets priorities for different types of data according to the frequency of collecting vehicle driving data, and establishes a temporary data storage area for caching the vehicle driving data collected in the most recent period of time.

[0022] Furthermore, the specific method of step 2 is as follows:

[0023] After receiving the original sensor data, a filtering algorithm is used to smooth the data to reduce the impact of noise and instantaneous fluctuations on the sound effect adjustment decision. The preset equation of the filtering algorithm is as follows:

[0024]

[0025] P k|k-1 = AP k-1|k-1 A T + Q

[0026] Update equation:

[0027] K k = P k|k-1 H T (HP k|k-1 H T + R) -1

[0028]

[0029] P k|k = (I - K k H)P k|k-1

[0030] In the formula, is the prior estimate value, i.e., the predicted value; is the posterior estimate value, i.e., the updated value; A is the state transition matrix; B is the control input matrix; u k is the control quantity; H is the observation matrix; z k is the observed value; P k|k-1 is the prior estimate error covariance matrix; P k|k is the posterior estimate error covariance matrix; Q is the process noise covariance matrix; R is the observation noise covariance matrix; K k is the Kalman gain;

[0031] Standardize the collected data and settings, assign weights to each data according to the importance of the audio effect adjustment for different data, and calculate the comprehensive score S according to the formula,

[0032] S = W1X1 + W2X2 + ··· + WnXn

[0033] In the formula, Wi is the weight of the i-th data; Xi is the i-th standardized data;

[0034] Determine the corresponding audio effect adjustment strategy according to the range where the comprehensive score is located;

[0035] If S < T1, adopt strategy A;

[0036] If T1 ≤ S < T2, adopt strategy B;

[0037] If S ≥ T2, adopt strategy C.

[0038] Furthermore, the strategy A is to lower the pitch, enhance the bass, and reduce the reverberation time; the strategy B is to keep the pitch moderate, set the equalizer to a medium level, and have a moderate reverberation time; the strategy C is to raise the pitch, enhance the treble, and increase the reverberation time.

[0039] Furthermore, the specific method of step three is as follows:

[0040] The input audio signal is decomposed into a short-time spectrum, the pitch is changed by scaling the frequency components in the spectrum, and then the processed spectrum is resynthesized into an audio signal.

[0041] Furthermore, the specific method of step 4 is as follows:

[0042] The finite impulse response filter is used to achieve the effect of the equalizer. The output signal is the linear convolution of the input signal and the filter coefficient. Its impulse response is non-zero within a finite time range, that is, H(n) has a value in the range of 0≤n≤N-1, where N is the length of the filter. The mathematical expression is as follows:

[0043]

[0044] In order to obtain high-density echo, 4 Comb Filters are connected in parallel, and the delay of each Comb Filter is different.

[0045] Furthermore, the specific method of step five is as follows:

[0046] The RT60 estimation model is used to set the value of g in the Comb Filter. The estimation model formula is as follows:

[0047]

[0048] Where Ts is the sampling rate;

[0049] Two All-pass Filters are connected after the four Comb Filters. The first four Comb Filters perform addition to add the number of echoes, and the following All-pass Filters perform multiplication to further increase the number of echoes.

[0050] The beneficial effects of the present invention are:

[0051] 1) The present invention can adjust the audio effects in real time according to the changes in the vehicle environment and the personalized needs of passengers, so that the vehicle audio system always maintains the best playback effect;

[0052] 2) The present invention can effectively reduce driving fatigue and improve driving safety and riding comfort by optimizing sound effect processing;

[0053] 3) The present invention has good compatibility and scalability and can be easily integrated with different types of vehicle audio equipment and vehicle systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0055] Figure 1 It is a structural schematic diagram of a vehicle-mounted audio sound effect adjustment system according to the present invention;

[0056] Figure 2 It is a schematic diagram of the principle of the audio tone change process;

[0057] Figure 3 Schematic diagram for setting up the RT60 estimation model;

[0058] Figure 4 Schematic diagram of the reverberation structure. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0061] Embodiment 1

[0062] See also Figure 1 , provides a vehicle-mounted audio sound effect adjustment system, including a sound effect pitch shifting module, an equalizer module, a reverberation module, a central control module, a pitch shifting processing module and an audio output module.

[0063] The sound effect pitch shifting module is used to receive an input audio signal and perform pitch shifting processing on the audio signal; adjust the amplitude and speed of the pitch shifting according to the user's settings or the instructions of the central control module; the sound effect pitch shifting module can achieve the pitch increase or decrease of the audio signal;

[0064] An equalizer module is used to perform gain or attenuation processing on different frequency components of the audio signal to adjust the frequency response of the audio signal; the equalizer module includes control channels of multiple frequency bands, and the user can adjust the gain value of each frequency band to achieve balanced adjustment of the audio signal;

[0065] The reverberation module is used to add reverberation effects to audio signals to simulate different acoustic space environments; according to the user's settings or the instructions of the central control module, the reverberation parameters are adjusted to achieve different reverberation effects;

[0066] The central control module is used to coordinate the work of the sound effect pitch shifting module, the equalizer module, and the reverberation module, and dynamically adjust the parameters of each module according to the user's settings, the vehicle's driving status, and the in-vehicle environment;

[0067] The pitch-shifting processing module is used to decompose the input audio signal into a short-time spectrum based on the phase vocoder principle, achieve the pitch change by scaling the frequency components in the spectrum, and then resynthesize the processed spectrum into a pitch-shifted audio signal;

[0068] An audio output module, used for outputting the audio signal after modulation;

[0069] The central control module is connected to the sound effect pitch shifting module, the equalizer module, and the reverberation module; the sound effect pitch shifting module, the equalizer module, and the reverberation module are connected to the pitch shifting processing module; and the pitch shifting processing module is connected to the audio output module.

[0070] Embodiment 2

[0071] This embodiment provides a method for adjusting a vehicle audio sound effect adjustment system, comprising the following steps:

[0072] Step 1: The central control module collects vehicle driving data and in-vehicle environment data in real time through various sensors and receives sound effect preference settings input by passengers;

[0073] Among them, vehicle driving data includes vehicle speed and road conditions; in-vehicle environment data includes noise level.

[0074] The central control module sets priorities for different types of data based on the frequency of vehicle driving data collection, and establishes a temporary data storage area to cache vehicle driving data collected in the recent period; this helps the central processor to refer to historical data trends and make more accurate decisions when performing complex sound adjustment calculations; the central control module communicates and coordinates with other electronic systems of the vehicle to ensure that the normal operation of the vehicle's key systems will not be interfered with in the process of acquiring data.

[0075] Step 2: The central control module analyzes and determines the current appropriate sound effect processing strategy based on the collected data and settings, as follows:

[0076] After receiving the original sensor data, a filtering algorithm is used to smooth the data to reduce the impact of noise and instantaneous fluctuations on the sound effect adjustment decision. The preset equation of the filtering algorithm is as follows:

[0077]

[0078] P k|k-1 =AP k-1|k-1 A T +Q

[0079] Update equation:

[0080] K k =P k|k-1 H T (HP k|k-1 H T +R) -1

[0081]

[0082] P k|k =(IK k H)P k|k-1

[0083] In the formula, is the prior estimate, i.e. the predicted value; is the posterior estimate, i.e., the update value; A is the state transfer matrix; B is the control input matrix; u k is the control quantity; H is the observation matrix; z k is the observed value; P k|k-1 is the prior estimation error covariance matrix; P k|k is the posterior estimation error covariance matrix; Q is the process noise covariance matrix; R is the observation noise covariance matrix; K k is the Kalman gain;

[0084] The collected data and settings are standardized, and weights are assigned to each data according to its importance to the sound effect adjustment. The comprehensive score S is calculated according to the formula.

[0085] S=W1X1+W2X2+···+WnXn

[0086] In the formula, Wi is the weight of the i-th data; Xi is the i-th standardized data;

[0087] Determine the corresponding sound effect adjustment strategy based on the comprehensive score range;

[0088] If S < T1, adopt Strategy A, such as lowering the pitch, enhancing the bass, reducing the reverberation time, etc., to adapt to low-speed and smooth driving conditions;

[0089] If T1 ≤ S < T2, adopt Strategy B, such as keeping the pitch moderate, setting the equalizer to a medium level, and having a moderate reverberation time, which is applicable to medium speeds and ordinary road conditions;

[0090] If S ≥ T2, adopt Strategy C, such as raising the pitch, enhancing the treble, increasing the reverberation time, etc., to match high-speed driving and a possibly noisier environment.

[0091] Step Three: The central control module sends instructions to the audio pitch-changing module to adjust the pitch of the audio, specifically as follows:

[0092] Decompose the input audio signal into short-time spectra, change the pitch by scaling each frequency component in the spectrum, and then recompose the processed spectrum into an audio signal, as Figure 2 shown, where x is the input signal and y is the output signal. Figure 2 Regarding the order of b, c, d in: Take one frame xm, select the next frame xm+1 with an interval length of Ha, and then after windowing these two frames, overlap and add the two frames together with a step size of Hs. Obviously, the ratio of Ha to Hs is the ratio of the lengths of the original signal and the output signal. In this way, the original audio can be spliced into audio of different lengths, and then through resampling, the audio is restored to the same length as the original audio and then played;

[0093] Furthermore:

[0094] Receive audio files in various formats (such as.wav,.mp3, etc.) or real-time audio streams as input;

[0095] Use the audio codec library FFmpeg to decode the input audio file to obtain the original audio data; for real-time audio streams, obtain the audio data through an audio input interface (such as a microphone input or a network audio stream receiving interface);

[0096] Segment the input audio signal into short-time frames and perform Fourier transform on each frame to obtain short-time spectra;

[0097] Implement using the fast Fourier transform FFT algorithm; determine appropriate frame lengths and frame shifts to ensure a good balance in time and frequency resolutions;

[0098] According to the pitch-changing ratio set by the user, scale the frequency components in the short-time spectra;

[0099] For each frequency component, multiply it by the corresponding pitch-changing ratio;

[0100] Perform inverse Fourier transform on the frequency-scaled short-time spectrum to obtain an audio frame in the time domain;

[0101] The audio frames obtained in the time domain are synthesized according to the original order and time interval to obtain a complete pitch-shifted audio signal;

[0102] The modulated audio signal is output in a specified format (such as .wav, .mp3, etc.), or played in real time through an audio output device (such as a speaker).

[0103] Step 4: The central control module sends instructions to the equalizer module to adjust the energy of different frequency bands of the audio, as follows:

[0104] The finite impulse response filter is used to achieve the effect of the equalizer. The output signal is the linear convolution of the input signal and the filter coefficient. Its impulse response is non-zero within a finite time range, that is, H(n) has a value in the range of 0≤n≤N-1, where N is the length of the filter. The mathematical expression is as follows:

[0105]

[0106] In order to obtain high-density echo, four Comb Filters are connected in parallel, and the delay of each Comb Filter is different, such as Figure 3 shown.

[0107] Further:

[0108] Use the audio interface library PortAudio to support different audio input devices and data sources, and convert the input audio data into a unified digital format for subsequent processing;

[0109] For the equalization requirements of each frequency band, a second-order digital filter cascade is used to construct the filter. The filter coefficients are calculated according to the selected filter type (such as Butterworth, Chebyshev, etc.). Tools such as MATLAB can be used to design and calculate the filter coefficients, and then the coefficients can be imported into the equalizer system;

[0110] The audio data is processed in frames by using multi-threading or parallel processing. Each frame of data is passed through each filter in turn for gain or attenuation operation to obtain the equalized audio data.

[0111] Develop a user parameter setting interface based on the graphical user interface GUI framework, and pass the user input parameters to the background processing module through event monitoring and parameter passing mechanism;

[0112] For real-time audio output, the processed audio data is sent to the audio output device through the audio interface library; for audio file output, the audio encoding library (such as LAME for MP3 encoding) is used to encode the audio data and save it as a file in a specified format;

[0113] The calculation and processing process of the filter is optimized, and fast algorithms and fixed-point operations are used to improve processing speed and reduce computing resource consumption.

[0114] Step 5: The central control module sends instructions to the reverberation module to add corresponding reverberation effects to the audio, as follows:

[0115] In order to simulate a more realistic reverberation, the RT60 estimation model is used to set the value of g in the Comb Filter. The estimation model formula is as follows:

[0116]

[0117] Where Ts is the sampling rate;

[0118] Connect 2 All-pass Filters after 4 Comb Filters. The first four Comb Filters perform addition to increase the number of echoes, and the following All-pass Filters perform multiplication to further increase the number of echoes. Figure 4 shown.

[0119] Further:

[0120] Convolution reverberation The convolution of two signals in the time domain is equal to their product in the frequency domain. By obtaining the impulse response of an actual acoustic space (such as a room, hall, etc.), the input audio signal is convolved with the impulse response to simulate the reverberation effect of the space;

[0121] The comb filter is used to simulate the reflection of sound, and its transfer function is:

[0122]

[0123] In the formula, r is the feedback coefficient; Mwield is the delay time; by adjusting the values ​​of r and M, the intensity and time interval of the reflection can be changed.

[0124] The all-pass filter is used to increase the diffusion of reflected sound, and its transfer function is:

[0125]

[0126] In the formula, a is the filter coefficient; M is the delay time; by adjusting the values ​​of a and M, the timbre and decay time of the reverberation can be changed.

[0127] Step 6: The audio output module outputs the audio signal after comprehensive processing to provide high-quality audio experience for passengers in the car.

[0128] In summary, the present invention solves the problem that the existing vehicle audio sound effect adjustment system has a single function and cannot adaptively adjust the sound effect parameters, realizes personalized vehicle audio sound effects that adapt to different scenarios, and improves the auditory experience of vehicle audio.

[0129] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the protection scope of the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention. These simple variations all belong to the protection scope of the present invention.

[0130] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0131] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A vehicle audio sound effect adjustment system, characterized in that: include: The audio effect pitch shifting module is used to receive an input audio signal and perform pitch shifting processing on the audio signal; According to the user's settings or the instructions of the central control module, the amplitude and speed of the pitch change are adjusted; the sound effect pitch change module can increase or decrease the pitch of the audio signal; An equalizer module is used to perform gain or attenuation processing on different frequency components of the audio signal to adjust the frequency response of the audio signal; the equalizer module includes control channels of multiple frequency bands, and the user can adjust the gain value of each frequency band to achieve balanced adjustment of the audio signal; The reverberation module is used to add reverberation effects to audio signals to simulate different acoustic space environments; according to the user's settings or the instructions of the central control module, the reverberation parameters are adjusted to achieve different reverberation effects; The central control module is used to coordinate the work of the sound effect pitch shifting module, the equalizer module, and the reverberation module, and dynamically adjust the parameters of each module according to the user's settings, the vehicle's driving status, and the in-vehicle environment; The pitch-shifting processing module is used to decompose the input audio signal into a short-time spectrum based on the phase vocoder principle, achieve the pitch change by scaling the frequency components in the spectrum, and then resynthesize the processed spectrum into a pitch-shifted audio signal; An audio output module, used for outputting the audio signal after modulation; The central control module is connected to the sound effect pitch shifting module, the equalizer module, and the reverberation module; the sound effect pitch shifting module, the equalizer module, and the reverberation module are connected to the pitch shifting processing module; and the pitch shifting processing module is connected to the audio output module.

2. The method for adjusting the vehicle audio sound effect adjustment system according to claim 1, characterized in that: The following steps are involved: Step 1: The central control module collects vehicle driving data and in-vehicle environment data in real time through various sensors and receives sound effect preference settings input by passengers; Step 2: The central control module analyzes and determines the current appropriate sound effect processing strategy based on the collected data and settings; Step 3: The central control module sends a command to the sound effect pitch change module to adjust the pitch of the audio; Step 4: The central control module sends instructions to the equalizer module to adjust the energy of different frequency bands of the audio; Step 5: The central control module sends instructions to the reverberation module to add corresponding reverberation effects to the audio; Step 6: The audio output module outputs the audio signal after comprehensive processing to provide high-quality audio experience for passengers in the car.

3. A method for adjusting vehicle audio sound effects according to claim 2, characterized in that: In the step 1, the vehicle driving data includes vehicle speed and road conditions; the in-vehicle environment data includes noise level.

4. The method for adjusting the in-vehicle audio sound effect according to claim 3, characterized in that: In the step 1, the central control module sets priorities for different types of data according to the frequency of collecting vehicle driving data, and establishes a temporary data storage area for caching the vehicle driving data collected in the recent period of time.

5. The method for adjusting the in-vehicle audio sound effect according to claim 2, characterized in that: The specific method of step 2 is as follows: After receiving the original sensor data, a filtering algorithm is used to smooth the data to reduce the impact of noise and instantaneous fluctuations on the sound effect adjustment decision. The preset equation of the filtering algorithm is as follows: P k|k-1 =AP k-1|k-1 From T +Q Update equation: K k =P k|k-1 H T (hP k|k-1 h T +R) -1 P k|k =(I-K k H)P k|k-1 In the formula, is the prior estimate, i.e. the predicted value; is the posterior estimate, i.e., the update value; A is the state transfer matrix; B is the control input matrix; u k is the control quantity; H is the observation matrix; z k is the observed value; P k|k-1 is the prior estimation error covariance matrix; P k|k is the posterior estimation error covariance matrix; Q is the process noise covariance matrix; R is the observation noise covariance matrix; K k is the Kalman gain; The collected data and settings are standardized, and weights are assigned to each data according to its importance to the sound effect adjustment. The comprehensive score S is calculated according to the formula. S=W1X1+W2X2+···+WnXn Wherein, Wi is the weight of the i-th data; Xi is the i-th normalized data; Determine the corresponding sound effect adjustment strategy according to the range where the comprehensive score is located; If S < T1, adopt Strategy A; If T1 ≤ S < T2, adopt Strategy B; If S ≥ T2, adopt Strategy C.

6. The method for adjusting the in-vehicle audio sound effect according to claim 5, characterized in that: The said Strategy A is to lower the pitch, enhance the bass, and reduce the reverberation time; the said Strategy B is to keep the pitch moderate, set the equalizer to a medium level, and the reverberation time to be moderate; the said Strategy C is to raise the pitch, enhance the treble, and increase the reverberation time.

7. The method for adjusting the in-vehicle audio sound effect according to claim 2, characterized in that: The specific method of the said Step 3 is as follows: Decompose the input audio signal into short-time spectra, change the pitch by scaling each frequency component in the spectra, and then recombine the processed spectra into an audio signal.

8. The method for adjusting the in-vehicle audio sound effect according to claim 2, characterized in that: The specific method of the said Step 4 is as follows: Adopt a finite impulse response filter to achieve the effect of an equalizer. The output signal is the linear convolution of the input signal and the filter coefficients. Its impulse response is non-zero within a finite time range, that is, H(n) has values in the range of 0 ≤ n ≤ N - 1, where N is the length of the filter, and the mathematical expression is as follows: In order to obtain a high-density echo, 4 Comb Filters are arranged in parallel, and the delay of each Comb Filter is different.

9. The method for adjusting the in-vehicle audio sound effect according to claim 2, characterized in that: The specific method of the said Step 5 is as follows: Adopt an RT60 estimation model to set the value of g in the Comb Filter. The estimation model formula is as follows: Wherein, Ts is the sampling rate; Connect 2 All-pass Filters after the 4 Comb Filters. The first four Comb Filters perform addition to stack the number of echoes, and the subsequent All-pass Filters perform multiplication to further increase the number of echoes.

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