A method and device for enhancing bass of fully open wearable headphones

Abstract

The present invention provides a method and device for bass enhancement of fully open wearable headphones, which relates to the technical field of headphone bass enhancement, and aims to optimize the low-frequency performance of fully open wearable headphones, including the following steps: performing frequency division processing on an input audio signal to obtain a first low-frequency signal and a first high-frequency signal; performing low-frequency gain filtering and dynamic compression processing on the first low-frequency signal in sequence to obtain a second low-frequency signal; performing signal fusion on the first high-frequency signal and the second low-frequency signal to obtain a fused signal; and performing dynamic compression processing on the fused signal. The present invention has the advantages of being able to effectively optimize the bass performance of fully open wearable headphones and significantly improving the overall stability of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of earphone bass enhancement, and in particular to a method and device for enhancing the bass of a fully open wearable earphone. Background Art

[0002] Open Wearable Stereo (OWS) is a widely used and promoted headset.

[0003] In the design process of fully open wearable headphones, bass escape is a common technical problem. Because the fully open design of fully open wearable headphones lacks physical restrictions on sound waves, and because low-frequency sound waves have the characteristics of long wavelengths, their energy is more likely to diffuse into the surrounding air when they propagate in an open environment. This diffusion phenomenon may cause users to have difficulty in obtaining ideal bass effects when using fully open wearable headphones. Specifically, the structural characteristics of the fully open square of the OWS headphones lead to serious low-frequency energy loss. Due to the structural characteristics of the fully open square of the OWS headphones, the low-frequency energy loss is more serious. The method of using a fixed equalizer (EQ) to improve the low-frequency response requires a high level of low-frequency gain. When the original digital signal is large, the total gain exceeds the output limit (such as the full-scale output value of the 0dBFS system), and digital clipping distortion will occur. Under the existing technology, although dynamic EQ can be used to adjust different gains according to volume changes to enhance low frequencies, this cannot completely avoid digital clipping distortion. In addition, if the EQ is dynamically adjusted through frequency response analysis, additional delay may be introduced, which is not ideal in some application scenarios. Existing technologies can also use dynamic range control to compress the dynamic range of audio signals within a specified range, which may cause the volume to fluctuate. This control method may have an unnecessary impact on high frequencies while improving low-frequency response, which is contrary to our original intention of improving low-frequency response. In addition, virtual bass enhancement technology based on psychoacoustics is another conventional method to improve low-frequency response. Its core principle is the frequency doubling effect, that is, the human ear can perceive the existence of the original low-frequency signal through the frequency doubling signal. This technology analyzes the audio signal through an algorithm and converts the low-frequency part into its frequency doubling signal. After these frequency doubling signals are combined with the original audio, although the speaker may not be able to directly emit extremely low-frequency sounds, the brain will "compensate" the perception and produce a rich bass effect. This process makes full use of the complex mechanism of sound processing by the human ear and brain. However, a large number of harmonics are introduced in the process of frequency doubling generation and signal reconstruction. These harmonics will cause severe nonlinear distortion, thereby reducing the realism of the audio. In the design process of OWS headphones, parametric equalizers are usually used for tuning to ensure that the audio signal output by the headphones meets the ideal frequency response. However, in the process of digital signal processing, due to the limited dynamic range of the signal, especially when adjusting the gain, once the signal gain exceeds the output limit (such as the full-scale output value of the 0dBFS system), it may cause clipping distortion. Although in practical applications, low-level signals can be adjusted by increasing positive gain without causing immediate distortion. However, when facing high-level signals, increasing positive gain may cause the signal amplitude to exceed the capacity limit of the system, thereby causing serious clipping distortion.

[0004] Therefore, how to optimize the low-frequency performance while maintaining a fully open design becomes a key issue that needs to be addressed when designing fully open wearable headphones. Summary of the invention

[0005] The object of the present invention is to provide a bass enhancement method for fully open wearable headphones, which can optimize the low-frequency part of the audio.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention provides a method for enhancing bass of a fully open wearable headset, comprising the following steps:

[0008] Performing frequency division processing on the input audio signal to obtain a first low-frequency signal and a first high-frequency signal;

[0009] Performing low-frequency gain filtering and dynamic compression processing on the first low-frequency signal in sequence to obtain a second low-frequency signal;

[0010] Fusing the first high-frequency signal and the second low-frequency signal to obtain a fused signal;

[0011] Dynamic compression processing is performed on the fused signal.

[0012] Preferably, the method of sequentially performing the low-frequency gain filtering on the first low-frequency signal is:

[0013] A second-order PEAKING filter is used for filtering, and parameters of the second-order PEAKING filter are adjusted according to required center frequency, gain and quality factor.

[0014] Preferably, the method for adjusting the parameters of the second-order PEAKING filter is:

[0015] Obtain the linear amplitude scale according to the gain:

[0016] ;

[0017] in, is the linear amplitude, is the gain;

[0018] Obtain the angular frequency from the center frequency:

[0019] ;

[0020] in, is the angular frequency, is the center frequency, is the sampling frequency;

[0021] The parameters of the second-order PEAKING filter are adjusted according to the quality factor, the linear amplitude and the angular frequency.

[0022] Preferably, the method for adjusting the parameters of the second-order PEAKING filter according to the quality factor, the linear amplitude and the angular frequency is:

[0023] ;

[0024] ;

[0025] ;

[0026] ;

[0027] ;

[0028] in, is the quality factor, , and is the forward coefficient, and is the backward coefficient, and The DC component of the input signal is affected. and Affects the frequency response of the second-order PEAKING filter, and Affects the feedback path of the second-order PEAKING filter.

[0029] Preferably, the method of performing the dynamic compression processing on the first low-frequency signal is:

[0030] A first dynamic compression filter is used to limit the amplitude of the first low-frequency signal.

[0031] Preferably, the amplitude of the first low frequency signal is limited to not exceed full amplitude 0 dBFS.

[0032] Preferably, the method for performing dynamic compression processing on the fusion signal is:

[0033] A second dynamic compression filter is used to limit the amplitude of the fused signal, and the amplitude of the fused signal is limited to not exceed the full amplitude 0dBFS.

[0034] Preferably, before performing the frequency division processing on the input audio signal, a tuning processing is performed on the input audio signal through a parametric equalizer.

[0035] In order to solve the above problems, the present invention further provides a bass enhancement device for fully open wearable headphones, which is applied to the above-mentioned bass enhancement method for fully open wearable headphones, comprising:

[0036] A frequency division module, used for performing frequency division processing on an input audio signal to obtain a first low-frequency signal and a first high-frequency signal;

[0037] A bass enhancement module, configured to sequentially perform low-frequency gain filtering and dynamic compression processing on the first low-frequency signal to obtain a second low-frequency signal;

[0038] a fusion module, configured to fuse the first high-frequency signal and the second low-frequency signal to obtain a fused signal;

[0039] The compression module is used to perform dynamic compression processing on the fused signal.

[0040] Preferably, a parameter equalizer is provided before the frequency division module for performing tuning processing on the input audio signal.

[0041] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0042] The present invention extracts high-frequency signals and low-frequency signals through frequency division, and performs targeted enhancement processing on low-frequency signals, which helps to enhance the bass effect. While maintaining a fully open design, the bass performance is significantly improved, providing users with a richer and more delicate auditory experience.

[0043] The present invention performs targeted parameter adjustment during the bass enhancement process, thereby achieving more reliable and accurate bass enhancement adjustment.

[0044] The signal after bass enhancement and fusion in the present invention will pass through the second dynamic compression filter. This step ensures the overall quality of the final output signal without clipping distortion.

[0045] The entire digital signal processing process of the present invention does not require the use of a buffer, so low-latency signal processing can be achieved;

[0046] The present invention introduces a parametric equalizer, which can perform fine tuning processing on the input signal according to actual needs. Combined with the final second dynamic compression filter that can effectively prevent clipping distortion, it provides greater flexibility for the setting of the parametric equalizer. The parametric equalizer can adjust parameters in a wider range, including using positive gain, thereby achieving more accurate and personalized signal processing effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of the principle of a bass enhancement method for fully open wearable headphones provided in Embodiment 1 of the present invention;

[0048] Figure 2 A schematic diagram of the principle of a bass enhancement method for fully open wearable headphones provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0050] Example 1

[0051] This embodiment provides a method for enhancing the bass of a fully open wearable headset. Figure 1 , including the following steps:

[0052] Performing frequency division processing on the input audio signal to obtain a first low-frequency signal and a first high-frequency signal, which can be specifically achieved by using a frequency division filter;

[0053] Performing low-frequency gain filtering and dynamic compression processing on the first low-frequency signal in sequence to obtain a second low-frequency signal;

[0054] Fusing the first high-frequency signal and the second low-frequency signal to obtain a fused signal;

[0055] Dynamic compression processing is performed on the fused signal.

[0056] The algorithm of this embodiment first performs frequency division processing on the input audio signal, splitting it into two parts: a low-frequency signal and a high-frequency signal, and then fuses the low-frequency signal after processing. This process ensures that the low-frequency and high-frequency signals can be processed independently, thereby achieving more refined sound effect optimization.

[0057] The filter implemented in this paper can realize various filtering types, including peak filtering, low pass, high pass, band pass, etc. Its time domain and frequency domain representations are as follows:

[0058] Time domain representation:

[0059] ;

[0060] Frequency domain representation:

[0061] ;

[0062] in, , and is the forward coefficient, and is the backward coefficient, , and are the output signals at the nth moment, the n-1th moment, and the n-2th moment respectively, , and are the input signals at the nth moment, the n-1th moment, and the n-2th moment respectively, The transfer function represents the frequency response of the system to the input signal. is the z-transform of the output signal, is the z-transform of the input signal, represents a delay of one moment, Represents the delay between two moments.

[0063] In view of the characteristics of the filter, the frequency response of the filter can be finely adjusted based on the three adjustable parameters of center frequency, gain and quality factor. Among them, the quality factor Q can also be expressed as bandwidth (Bandwidth, BW), and its calculation relationship is:

[0064] ;

[0065] ;

[0066] Where N is the number of octaves.

[0067] As a preferred solution of this embodiment, a method for sequentially performing the low-frequency gain filtering on the first low-frequency signal is:

[0068] A second-order PEAKING filter is used as a low-frequency gain filter for filtering, and the parameters of the second-order PEAKING filter are adjusted according to the required center frequency, gain and quality factor. The filter coefficient can then be calculated based on the set center frequency Fc, gain G, quality factor Q and signal sampling rate Fs. , , , and , the specific method is as follows:

[0069] In this embodiment, the method for adjusting the parameters of the second-order PEAKING filter is:

[0070] Obtain the linear amplitude scale according to the gain:

[0071] ;

[0072] in, is the linear amplitude, is the gain;

[0073] Obtain the angular frequency from the center frequency:

[0074] ;

[0075] in, is the angular frequency, is the center frequency, is the sampling frequency;

[0076] The parameters of the second-order PEAKING filter are adjusted according to the quality factor, the linear amplitude and the angular frequency.

[0077] Further, the method of adjusting the parameters of the second-order PEAKING filter according to the quality factor, the linear amplitude and the angular frequency is:

[0078] ;

[0079] ;

[0080] ;

[0081] ;

[0082] ;

[0083] in, is the quality factor, , and is the forward coefficient, and is the backward coefficient, and The DC component of the input signal is affected. and Affects the frequency response of the second-order PEAKING filter, and Affects the feedback path of the second-order PEAKING filter.

[0084] In the above scheme, by adjusting these parameters, a second-order PEAKING filter for low-frequency signals can be designed to achieve the desired gain effect.

[0085] In the following process, the method of performing the dynamic compression processing on the first low-frequency signal is:

[0086] A first dynamic compression filter is used to limit the amplitude of the first low-frequency signal.

[0087] Furthermore, the amplitude of the first low-frequency signal is limited to not exceed full amplitude 0 dBFS.

[0088] Finally, the method for performing dynamic compression processing on the fusion signal is:

[0089] A second dynamic compression filter is used to limit the amplitude of the fused signal. Similarly, the amplitude of the fused signal is limited to not exceed the full amplitude 0dBFS.

[0090] In digital audio processing, 0 dBFS (full amplitude) represents the maximum amplitude that the system can represent. When the signal exceeds 0dBFS, clipping distortion occurs, that is, the signal peak is truncated, resulting in distortion and degraded sound quality. Therefore, it is necessary to ensure that the signal amplitude is maintained below 0 dBFS. To this end, the first dynamic compression filter is added to the signal after low-frequency enhancement to limit the signal amplitude, and the second dynamic compression filter is added to the fused signal to limit the signal amplitude. Through two-stage dynamic compression processing, the system can ensure that the signal amplitude in each frequency band is always kept within the set safety limit. In addition, this processing step effectively suppresses the signal overload caused by frequency fusion, significantly improving the overall stability of the system.

[0091] The dynamic compression filter mainly has the following main parameters:

[0092] Threshold: The level at which compression begins. When the signal exceeds this threshold, the compressor starts to work. Setting it too low will result in frequent compression, while setting it too high may not effectively limit high-amplitude signals.

[0093] Compression ratio: Indicates the proportional relationship between the input signal and the output signal. For example, a compression ratio of 2:1 means that for every 2 dB increase in the input signal, the output signal only increases by 1 dB.

[0094] Attack Time: How quickly the compressor responds to a signal exceeding the threshold. A short attack time is suitable for quick response to burst signals, while a long attack time is suitable for smooth compression of continuous signals.

[0095] Release Time: The time it takes for the compressor to stop compressing and return to normal gain. A long release time is suitable for smooth processing of continuous low-volume signals, while a short release time is suitable for rapidly changing signals.

[0096] In common usage scenarios such as OWS headphones, the original signal amplitude is usually small. After the low-frequency gain processing of the second-order PEAKING filter designed in this embodiment, the signal amplitude will not easily exceed the threshold of the DRC filter, thereby achieving the expected low-frequency enhancement effect. When the original signal amplitude is large, it may exceed the threshold after gain processing. At this time, the first dynamic compression filter will be activated to enhance the low frequency and prevent clipping distortion. Therefore, this embodiment can effectively enhance the bass effect and make the low frequency fuller. At the same time, due to the reasonable selection and adjustment of the filter parameters, the signal quality and system stability are ensured, which is also the key to achieving high-quality audio processing.

[0097] Example 2

[0098] This embodiment is based on the technical solution of Embodiment 1 and further processes the input audio signal.

[0099] This embodiment provides a method for enhancing the bass of a fully open wearable headset. Figure 2 , including the following steps:

[0100] The input audio signal is tuned by a parametric equalizer;

[0101] Performing frequency division processing on the input audio signal to obtain a first low-frequency signal and a first high-frequency signal may be achieved by using a frequency division filter;

[0102] Performing low-frequency gain filtering and dynamic compression processing on the first low-frequency signal in sequence to obtain a second low-frequency signal;

[0103] Fusing the first high-frequency signal and the second low-frequency signal to obtain a fused signal;

[0104] Dynamic compression processing is performed on the fused signal.

[0105] The filter implemented in this paper can realize various filtering types, including peak filtering, low pass, high pass, band pass, etc. Its time domain and frequency domain representations are as follows:

[0106] Time domain representation:

[0107] ;

[0108] Frequency domain representation:

[0109] ;

[0110] in, , and is the forward coefficient, and is the backward coefficient, , and are the output signals at the nth moment, the n-1th moment, and the n-2th moment respectively, , and are the input signals at the nth moment, the n-1th moment, and the n-2th moment respectively, The transfer function represents the frequency response of the system to the input signal. is the z-transform of the output signal, is the z-transform of the input signal, represents a delay of one moment, Represents the delay between two moments.

[0111] In view of the characteristics of the filter, the frequency response of the filter can be finely adjusted based on the three adjustable parameters of center frequency, gain and quality factor. Among them, the quality factor Q can also be expressed as bandwidth (Bandwidth, BW), and its calculation relationship is:

[0112] ;

[0113] ;

[0114] Where N is the number of octaves.

[0115] As a preferred solution of this embodiment, a method for sequentially performing the low-frequency gain filtering on the first low-frequency signal is:

[0116] A second-order PEAKING filter is used as a low-frequency gain filter for filtering, and the parameters of the second-order PEAKING filter are adjusted according to the required center frequency, gain and quality factor. The filter coefficient can then be calculated based on the set center frequency Fc, gain G, quality factor Q and signal sampling rate Fs. , , , and , the specific method is as follows:

[0117] In this embodiment, the method for adjusting the parameters of the second-order PEAKING filter is:

[0118] Obtain the linear amplitude scale according to the gain:

[0119] ;

[0120] in, is the linear amplitude, is the gain;

[0121] Obtain the angular frequency based on the center frequency:

[0122] ;

[0123] in, is the angular frequency, is the center frequency, is the sampling frequency;

[0124] The parameters of the second-order PEAKING filter are adjusted according to the quality factor, the linear amplitude and the angular frequency.

[0125] Further, the method of adjusting the parameters of the second-order PEAKING filter according to the quality factor, the linear amplitude and the angular frequency is:

[0126] ;

[0127] ;

[0128] ;

[0129] ;

[0130] ;

[0131] in, is the quality factor, , and is the forward coefficient, and is the backward coefficient, and The DC component of the input signal is affected by and Affects the frequency response of the second-order PEAKING filter, and Affects the feedback path of the second-order PEAKING filter.

[0132] In the following process, the method of performing the dynamic compression processing on the first low-frequency signal is:

[0133] A first dynamic compression filter is used to limit the amplitude of the first low-frequency signal.

[0134] Furthermore, the amplitude of the first low-frequency signal is limited to not exceed full amplitude 0 dBFS.

[0135] Finally, the method for performing dynamic compression processing on the fusion signal is:

[0136] A second dynamic compression filter is used to limit the amplitude of the fused signal. Similarly, the amplitude of the fused signal is limited to not exceed the full amplitude 0dBFS.

[0137] Compared with Example 1, this embodiment mainly introduces a parametric equalizer, which can be applied to different products. The function of this parametric equalizer is to perform fine tuning processing on the input signal according to actual needs. Since a dynamic compression filter is installed in the system, the filter can effectively prevent the digital signal from being clipped during transmission, which provides greater flexibility for the setting of the parametric equalizer. Under this protection mechanism, the parametric equalizer can adjust parameters in a wider range, including using positive gain, so as to achieve more accurate and personalized signal processing effects.

[0138] Example 3

[0139] This embodiment provides a bass enhancement device for a fully open wearable headset, which is applied to a bass enhancement method for a fully open wearable headset in the above embodiment, including:

[0140] A frequency division module, used for performing frequency division processing on an input audio signal to obtain a first low-frequency signal and a first high-frequency signal;

[0141] A bass enhancement module, configured to sequentially perform low-frequency gain filtering and dynamic compression processing on the first low-frequency signal to obtain a second low-frequency signal;

[0142] a fusion module, configured to fuse the first high-frequency signal and the second low-frequency signal to obtain a fused signal;

[0143] The compression module is used to perform dynamic compression processing on the fused signal.

[0144] As a further preferred solution, a parameter equalizer is further arranged before the frequency division module for performing tuning processing on the input audio signal.

[0145] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for enhancing bass of fully open wearable headphones, characterized in that: The following steps are involved: Performing frequency division processing on the input audio signal to obtain a first low-frequency signal and a first high-frequency signal; Performing low-frequency gain filtering and dynamic compression processing on the first low-frequency signal in sequence to obtain a second low-frequency signal; Fusing the first high-frequency signal and the second low-frequency signal to obtain a fused signal; Performing dynamic compression processing on the fused signal; The method of sequentially performing the low-frequency gain filtering on the first low-frequency signal is: Using a second-order PEAKING filter for filtering, and adjusting the parameters of the second-order PEAKING filter according to the required center frequency, gain and quality factor; The method for adjusting the parameters of the second-order PEAKING filter is: Obtain the linear amplitude scale according to the gain: ； in, is the linear amplitude, is the gain; Obtain the angular frequency based on the center frequency: ； in, is the angular frequency, is the center frequency, is the sampling frequency; adjusting parameters of the second-order PEAKING filter according to the quality factor, the linear amplitude and the angular frequency; The method of adjusting the parameters of the second-order PEAKING filter according to the quality factor, the linear amplitude and the angular frequency is: ； ； ； ； ； in, is the quality factor, , and is the forward coefficient, and is the backward coefficient, and The DC component of the input signal is affected. and Affects the frequency response of the second-order PEAKING filter, and A feedback path affecting the second-order PEAKING filter; The method of performing the dynamic compression processing on the first low-frequency signal is: Using a first dynamic compression filter to limit the amplitude of the first low-frequency signal; The amplitude of the first low frequency signal is limited to not exceed full amplitude 0dBFS; The method of performing dynamic compression processing on the fusion signal is: A second dynamic compression filter is used to limit the amplitude of the fused signal, where the amplitude of the fused signal is limited to not exceed the full amplitude 0dBFS; Before performing the frequency division processing on the input audio signal, a tuning processing is performed on the input audio signal through a parameter equalizer.

2. A bass enhancement device for fully open wearable headphones, applied to a bass enhancement method for fully open wearable headphones as claimed in claim 1, characterized in that: include: A frequency division module, used for performing frequency division processing on an input audio signal to obtain a first low-frequency signal and a first high-frequency signal; A bass enhancement module, configured to sequentially perform low-frequency gain filtering and dynamic compression processing on the first low-frequency signal to obtain a second low-frequency signal; a fusion module, configured to fuse the first high-frequency signal and the second low-frequency signal to obtain a fused signal; The compression module is used to perform dynamic compression processing on the fused signal.

3. A bass enhancement device for fully open wearable headphones according to claim 2, characterized in that: A parameter equalizer is also arranged before the frequency division module to perform tuning processing on the input audio signal.

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