Active noise reduction method for ear clip type Bluetooth headset

Abstract

The invention discloses an active noise reduction method for an ear clip type Bluetooth earphone. The method comprises the following steps: acquiring a contact area between the ear clip type Bluetooth earphone and an auricular conchae cavity; judging whether the contact area is greater than a preset area, acquiring continuous sound signals in a preset time period from the sound signals in the external environment, acquiring a plurality of samples from the continuous sound signals, and determining a noise reduction structure signal; performing quantization processing and audio coding on the noise reduction construction signal, and determining an energy threshold value and a left-right correlation threshold value of the noise reduction construction signal; if the energy threshold value of the noise reduction structure signal is greater than the preset energy threshold value, or the left-right correlation threshold value is smaller than the preset left-right correlation threshold value, a noise reduction mechanism of the earphone is triggered, so that sound waves for offsetting noise can be more accurately generated, and a better noise reduction effect is realized; a standard for triggering the automatic noise reduction function can be determined according to actual noise in the environment, and different active noise reduction conditions are formulated according to different sound pressure levels.

Description

Technical Field

[0001] The invention relates to the technical field of ear clip type Bluetooth headsets, in particular to an active noise reduction method for ear clip type Bluetooth headsets. Background Art

[0002] Headphones have been widely used in people's daily life and work. In addition to being used for enjoying music and entertainment, headphones are also widely used to isolate noise and maintain a relatively quiet environment. However, the noise isolation effect and ability of headphones for low-frequency noise are limited.

[0003] The existing active noise reduction technology uses a method to generate a signal with the same amplitude and opposite phase as the external noise to cancel the noise entering the headphones. However, the active noise reduction technology currently used in headphones is mostly fixed noise reduction technology, which has the following defects:

[0004] The external environment is constantly changing. When the external noise is equivalent to the fixed noise reduction amount, a better noise reduction effect will be produced. However, when the external noise is higher than the fixed noise reduction amount, the noise reduction effect will not be optimal. Or when the external noise is lower than the fixed noise reduction amount, the active noise reduction module will actually produce a new noise that reaches the human ear.

[0005] In the design of active noise reduction headphones, the energy signal ratio at the feedforward filter is generally collected and calculated, and then implemented through analog or digital methods. Although there is a noise reduction functional feature, how to safely use this mechanism, make it stable, conform to humanization and the usage habits of most consumers, and give them a good user experience, requires a stable triggering and stable shutting down mode for the noise mechanism.

[0006] Therefore, in the present invention, the applicant has carefully studied a new technical solution to solve the above problems. Summary of the invention

[0007] In view of this, the present invention aims to address the deficiencies in the prior art, and its main purpose is to provide an active noise reduction method for ear-clip type Bluetooth headsets, which can more accurately generate sound waves for offsetting noise, thereby achieving better noise reduction effects, and can also determine the criteria for triggering the automatic noise reduction function according to the actual noise in the environment, and formulate different active noise reduction conditions according to different sound pressure levels.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] An active noise reduction method for an ear clip type Bluetooth headset is implemented based on an ear clip type Bluetooth headset, characterized in that: the ear clip type Bluetooth headset comprises a first earphone housing, a connecting bridge and a second ear clip housing, the first earphone housing and the second earphone housing are connected via the connecting bridge; the second earphone housing is located in the concha cavity, a first microphone and a second microphone are arranged on the second earphone housing, the first microphone is used to collect sound signals in the external environment, the second microphone is installed in the second earphone housing and corresponds to the sound outlet hole on the second earphone housing, and the second microphone is used to collect sound signals heard by the user;

[0010] The method comprises the following steps:

[0011] S100, obtaining a contact area between the ear clip type Bluetooth headset and the concha cavity;

[0012] S200, determining whether the contact area is greater than a preset area, if so, determining that the ear clip type Bluetooth headset is in contact with the auricle cavity and then determining that the user is wearing the ear clip type Bluetooth headset correctly, and then executing S300; if not, prompting the user to wear the ear clip type Bluetooth headset correctly, and executing S100 after a preset time;

[0013] S300, obtaining a continuous sound signal within a preset time period from a sound signal in an external environment, and obtaining a plurality of samples from the continuous sound signal, and determining a noise reduction construction signal based on the plurality of samples;

[0014] S400, performing quantization processing on the noise reduction structure signal to obtain a quantization processing result;

[0015] S500, performing audio encoding on the quantization processing result to obtain an audio encoding result;

[0016] S600, determining an energy threshold and a left-right correlation threshold for the noise reduction structure signal according to the audio encoding result;

[0017] S700. If the energy threshold of the noise reduction construction signal is greater than the preset energy threshold, or the left-right correlation threshold is less than the preset left-right correlation threshold, the noise reduction mechanism of the headset is triggered, and a noise cancellation signal is generated according to the noise reduction construction signal and the sound signal heard by the user, and is output from the ear-clip Bluetooth headset to achieve noise reduction.

[0018] As a preferred solution, the step of determining the noise reduction construction signal according to the plurality of samples includes:

[0019] According to a number of samples, a noise signal of a standard noise frequency corresponding to the frequency is obtained from a preset noise database and determined as a noise reduction construction signal.

[0020] As a preferred solution, the step of determining the noise reduction construction signal according to the plurality of samples includes:

[0021] According to a number of samples, the fundamental frequency and harmonic frequency are obtained, a constructed sound signal is determined by the fundamental frequency, harmonic frequency and generation function, and a noise reduction constructed signal is determined according to the constructed sound signal.

[0022] As a preferred solution, the expression of the generating function is:

[0023] M=Kv+w, and v=a*sin(2*π*A*f*t); wherein, M represents the noise reduction construction signal, K is the rate of change of the collected sound signal, a is the amplitude of the constructed sound signal, A is the harmonic coefficient, f is the frequency of the constructed sound signal, t is time, and w is a constant.

[0024] As a preferred solution, the quantization processing of the noise reduction structure signal to obtain the quantization processing result includes:

[0025] The continuous noise reduction constructed signal is sampled at equal intervals on the time axis to obtain a series of signal values ​​at specific time points, and the amplitude of each obtained signal value is quantized; the continuous amplitude value is mapped to a finite number of discrete values, the finite number of discrete values ​​is the quantization level, and the quantization level is the quantization processing result.

[0026] As a preferred solution, performing audio encoding on the quantization processing result to obtain the audio encoding result includes:

[0027] The quantization processing result is binary-encoded to obtain a number of binary digits. Each binary digit is arranged to obtain a digital information stream composed of a binary pulse string. The frequency of the binary pulse is equal to the product of the sampling frequency and the number of quantization bits, and the digital rate of the digital signal is obtained thereby. The digital rate is the audio encoding result.

[0028] As a preferred solution, the formula of the noise reduction signal is:

[0029] Among them, SPL is the noise cancellation signal, R is the sound signal collected by the second microphone, and A j is the cross-sectional area of ​​the sound outlet corresponding to the second microphone, r is the synthetic radius, and the value of the synthetic radius is determined according to the noise reduction

[0030]

[0031] The intensity of the constructed signal is determined, and F(S) is the spectral function, which is a function of the Strouhal number S.

[0032] As a preferred solution, the step S100 further includes: obtaining the temperature at the second microphone;

[0033] The step S200 includes: determining whether the temperature is within a preset range and determining whether the contact area is greater than a preset area. If both are true, determining that the ear clip-on Bluetooth headset fits the auricle cavity and then determining that the user is wearing the ear clip-on Bluetooth headset correctly, and then executing S300; otherwise, prompting the user to wear the ear clip-on Bluetooth headset correctly, and executing S100 after a preset time.

[0034] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical scheme that: it mainly collects sound signals from the external environment and the inside of the ear respectively through the first microphone and the second microphone, and determines the noise cancellation signal through these two sound signals, so as to more accurately generate sound waves for offsetting noise, thereby achieving better noise reduction effect. Moreover, by comparing with the preset energy threshold and the preset left and right correlation threshold, the standard for triggering the automatic noise reduction function can be determined according to the actual noise in the environment, and different active noise reduction conditions can be formulated according to different sound pressure levels.

[0035] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention is a flowchart of an active noise reduction method for an ear clip type Bluetooth headset. DETAILED DESCRIPTION

[0037] The following shows application examples of embodiments of the present invention.

[0038] See also Figure 1 , an active noise reduction method for an ear clip type Bluetooth headset, the method is implemented based on an ear clip type Bluetooth headset, the ear clip type Bluetooth headset comprises a first earphone housing, a connecting bridge and a second ear clip housing, the first earphone housing and the second earphone housing are connected by the connecting bridge; the second earphone housing is located in the concha cavity, the second earphone housing is provided with a first microphone and a second microphone, the first microphone is installed on a side of the second earphone housing away from the ear canal and is used to collect sound signals in the external environment, the second microphone is installed in the second earphone housing and corresponds to a sound outlet hole on the second earphone housing, the sound outlet hole faces the ear canal opening, and the second microphone is used to collect sound signals heard by the user;

[0039] The method comprises the following steps:

[0040] S100, obtaining a contact area between the ear clip type Bluetooth headset and the concha cavity;

[0041] In this embodiment, obtaining the contact area between the ear clip-type Bluetooth headset and the concha cavity is actually obtaining the contact area between the second earphone shell and the skin of the concha cavity. The specific obtaining method is: a skin contact sensing component (such as a skin charge sensor) is set on a side where the second earphone shell is located. The skin contact sensing component can convert skin signals into electrical signals, and perform signal processing and analysis. The larger the contact area, the stronger the corresponding electrical signal (the reason is that the larger the contact area, the more skin tissues involved in conduction, thereby providing more ion channels and conductive pathways, resulting in an increase in current. And a larger contact area can increase the capacitance effect between the electrode and the skin, making it easier for the charge to flow, which is manifested as an increase in current). Therefore, the contact area range between the earphone and the ear can be calculated according to the strength of the obtained electrical signal. When the current signal reaches a certain threshold, it can be considered that the fitting area between the second earphone shell and the skin of the concha cavity meets the conditions for correct wearing.

[0042] S200, determining whether the contact area is greater than a preset area, if so, determining that the ear clip type Bluetooth headset is in contact with the auricle cavity and then determining that the user is wearing the ear clip type Bluetooth headset correctly, and then executing S300; if not, prompting the user to wear the ear clip type Bluetooth headset correctly, and executing S100 after a preset time;

[0043] In this embodiment, whether the earphone is worn correctly is mainly determined by the contact area between the earphone and the ear.

[0044] In a further embodiment, S100 also includes obtaining the temperature at the second microphone; the S200 includes: determining whether the temperature is within a preset range and determining whether the contact area is greater than a preset area. If both are true, determining that the ear clip-type Bluetooth headset is in contact with the auricle cavity and then determining that the user is wearing the ear clip-type Bluetooth headset correctly, and then executing S300; otherwise, prompting the user to wear the ear clip-type Bluetooth headset correctly, and executing S100 after a preset time.

[0045] Among them, the second microphone is installed inside the second earphone shell, but will be close to the human skin of the concha cavity through the sound hole on the shell. When the earphone is in a worn state, the temperature of the ear will be transmitted to the sound hole and the second microphone. Therefore, by monitoring the contact area between the earphone and the ear, and the temperature of the second microphone or the sound hole, it can be determined whether the earphone is in a worn state and whether it is worn correctly.

[0046] Specifically, in this further solution, the temperature and contact area need to meet the corresponding conditions at the same time to determine that the earphone is in the correct wearing state, such as when the temperature at the second microphone is between 30℃ and 37.5℃, and the contact area between the earphone and the concha cavity is greater than 40mm. 2When the temperature and the contact area meet the conditions, the earphone is judged to be in the correct wearing state; when only one of the temperature and the contact area meets the conditions, or both do not meet the conditions, the earphone is judged to be not in the correct wearing state and the earphone position needs to be adjusted.

[0047] Of course, the temperature will be different due to the body temperature of different users, when the body is in different states, and when it is in different environments. Therefore, the temperature judgment condition of this further scheme refers to the temperature judgment condition when the user is in a normal state, that is, the user is a normal general user, with normal physical condition, not in a fever, low temperature, etc., and is in a normal environment.

[0048] S300, obtaining a continuous sound signal within a preset time period from a sound signal in an external environment, and obtaining a plurality of samples from the continuous sound signal, where the sample may be a complete sound signal within the preset time period, or a sound signal of a certain time period of the preset time period, and determining a noise reduction construction signal based on the plurality of samples. In this embodiment, determining the noise reduction construction signal based on the plurality of samples includes:

[0049] According to a number of samples, the fundamental frequency and harmonic frequency are obtained, a constructed sound signal is determined by the fundamental frequency, harmonic frequency and generation function, and a noise reduction constructed signal is determined according to the constructed sound signal.

[0050] Specifically, if the noise reduction construction signal corresponding to the sound signal during this period is obtained through the generating function, the fundamental wave and the harmonic wave in this continuous sound signal are obtained, and the fundamental wave frequency and the harmonic wave frequency are determined; then the frequency of the constructed sound signal is obtained through the fundamental wave frequency. Since the constructed sound signal refers to the subharmonic wave of the fundamental wave in the continuous sound signal, the frequency of the constructed sound signal is n / m of the fundamental wave frequency, where n and m are natural numbers, and n is less than m. Finally, the noise reduction construction signal is calculated and obtained using the generating function according to the constructed sound signal, the harmonic coefficient, etc.

[0051] Among them, the expression of the generating function is M=Kv+w, and v=a*sin(2*π*A*f*t); M represents the noise reduction construction signal, K is the rate of change of the collected sound signal (that is, the ratio of the frequencies of two consecutive sound signals), a is the amplitude of the constructed sound signal, A is the harmonic coefficient, f is the frequency of the constructed sound signal, t is time, and w is a constant.

[0052] Among them, the harmonic coefficient can be determined by the harmonics and the fundamental wave.

[0053] In another embodiment, determining the noise reduction construction signal according to the plurality of samples includes:

[0054] According to a number of samples, a noise signal of a standard noise frequency corresponding to the frequency is obtained from a preset noise database and determined as a noise reduction construction signal.

[0055] S400, quantizing the noise reduction structure signal to obtain a quantization result; in this embodiment, quantizing the noise reduction structure signal to obtain a quantization result includes:

[0056] The continuous noise reduction structured signal is sampled at equal intervals on the time axis to obtain a series of signal values ​​at specific time points, and the amplitude of each obtained signal value is quantized. By setting a certain quantization level and quantization rule, the continuous amplitude value is mapped to a finite number of discrete values, which are the quantization levels, and the quantization levels are the quantization processing results.

[0057] Specifically, "quantization level" refers to the finite number of discrete values ​​corresponding to the amplitude of discrete sample values ​​after quantization processing.

[0058] Quantization processing helps reduce the amount of data and facilitates digital storage, transmission and calculation. Quantization will introduce certain errors, but with reasonable quantization accuracy, the signal can be effectively represented within an acceptable error range.

[0059] S500, performing audio encoding on the quantization processing result to obtain an audio encoding result; in this embodiment, performing audio encoding on the quantization processing result to obtain an audio encoding result includes:

[0060] The quantization processing result is binary-encoded to obtain a number of binary digits. Each binary digit is arranged to obtain a digital information stream composed of a binary pulse string. The frequency of the binary pulse is equal to the product of the sampling frequency and the number of quantization bits. The digital rate of the digital signal is obtained from this. The digital rate of the digital signal is the audio encoding result.

[0061] Specifically, after encoding, each binary digit corresponds to a quantization level, and these quantization levels are arranged to obtain a digital information stream composed of a binary pulse string, where the frequency of the composed binary pulse is equal to the product of the sampling frequency and the number of quantization bits, and this frequency is the digital rate. Among them, the sampling frequency refers to the number of times a continuous signal is sampled per unit time, and the number of quantization bits refers to the number of binary bits used to represent each sampling point, which determines the number of quantization levels, that is, how many different levels the sampled value can be divided into; and the digital rate refers to the number of binary bits transmitted or processed per unit time, usually in bits per second (bps), which determines the speed of data transmission.

[0062] In this embodiment, the digital rate is used to indicate the size of the energy threshold or the left-right correlation threshold. After the quantization result is encoded, since the encoded signal is digitized, it is easier and more accurate to determine its energy threshold and left-right correlation threshold. The energy threshold can be used to detect the strength of the signal, so as to determine whether the signal exists or is important. For example, when the digital rate of a certain quantization level is greater than the preset energy threshold, it can be indicated that the quantization level is important, otherwise it is unimportant. The left-right correlation threshold can be used to detect the similarity of the signal, so as to determine whether the signal is repeatable or can be compressed. For example, when performing similarity analysis, the digital rates of two adjacent quantization levels are compared according to a similarity function (such as a Dice function). When the comparison result exceeds the preset similarity threshold, it can be determined that the two quantization levels are similar, otherwise they are not similar.

[0063] S600, determining an energy threshold and a left-right correlation threshold for the noise reduction structure signal according to the audio encoding result;

[0064] S700: If the energy threshold of the noise reduction structure signal is greater than the preset energy threshold, or the left-right correlation threshold is less than the preset left-right correlation threshold, the noise reduction mechanism of the headset is triggered, and a noise reduction signal is generated according to the noise reduction structure signal and the sound signal heard by the user and output from the ear clip type Bluetooth headset, thereby reducing noise. In this embodiment, the formula of the noise reduction signal is:

[0065]

[0066] Among them, SPL is the noise cancellation signal, R is the sound signal collected by the second microphone, and A j is the cross-sectional area of ​​the sound outlet corresponding to the second microphone, r is the synthesis radius, the value of the synthesis radius is determined according to the strength of the noise reduction construction signal, and F(S) is the spectral function, which is a function of the Strouhal number S.

[0067] It is worth noting that the data of the sound holes on the earphone housing have been obtained in advance.

[0068] In this embodiment, the higher the value of the preset energy threshold, the more difficult it is to trigger the noise reduction mechanism; the lower the value of the preset left-right correlation threshold, the more difficult it is to trigger the noise reduction mechanism.

[0069] In summary, the design focus of the present invention is that it mainly uses a shared temperature detection port to achieve input port expansion, so that the temperature detection port can simultaneously have functions such as temperature detection, button, Hall magnetic attraction, etc., which is relatively low in cost and is conducive to promoting the development of enterprises and industries;

[0070] Secondly, multiple function inputs can be received through one input port, and the position of buttons and Hall can be flexibly selected according to actual design requirements, which has good flexibility.

[0071] The key points of the design of the present invention are that, by using the first microphone and the second microphone, sound signals from the external environment and inside the ear are respectively collected, and the noise cancellation signal is determined by these two sound signals, so that sound waves for canceling noise can be generated more accurately, thereby achieving better noise reduction effect. Moreover, by comparing with the preset energy threshold and the preset left and right correlation threshold, the standard for triggering the automatic noise reduction function can be determined according to the actual noise in the environment, and different active noise reduction conditions can be formulated according to different sound pressure levels.

[0072] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An active noise reduction method for an ear clip type Bluetooth headset, implemented based on an ear clip type Bluetooth headset, characterized in that: The ear clip type Bluetooth headset comprises a first earphone housing, a connecting bridge and a second ear clip housing, wherein the first earphone housing and the second earphone housing are connected via the connecting bridge; The second earphone housing is located in the concha cavity, and a first microphone and a second microphone are provided on the second earphone housing, wherein the first microphone is used to collect sound signals in the external environment, and the second microphone is installed in the second earphone housing and corresponds to the sound outlet hole on the second earphone housing, and the second microphone is used to collect sound signals heard by the user; The method comprises the following steps: S100, obtaining a contact area between the ear clip type Bluetooth headset and the concha cavity; S200, determining whether the contact area is greater than a preset area, if so, determining that the ear clip type Bluetooth headset is in contact with the auricle cavity and then determining that the user is wearing the ear clip type Bluetooth headset correctly, and then executing S300; if not, prompting the user to wear the ear clip type Bluetooth headset correctly, and executing S100 after a preset time; S300, obtaining a continuous sound signal within a preset time period from a sound signal in an external environment, and obtaining a plurality of samples from the continuous sound signal, and determining a noise reduction construction signal based on the plurality of samples; S400, performing quantization processing on the noise reduction structure signal to obtain a quantization processing result; S500, performing audio encoding on the quantization processing result to obtain an audio encoding result; S600, determining an energy threshold and a left-right correlation threshold for the noise reduction structure signal according to the audio encoding result; S700. If the energy threshold of the noise reduction construction signal is greater than the preset energy threshold, or the left-right correlation threshold is less than the preset left-right correlation threshold, the noise reduction mechanism of the headset is triggered, and a noise cancellation signal is generated according to the noise reduction construction signal and the sound signal heard by the user, and is output from the ear-clip Bluetooth headset to achieve noise reduction.

2. The active noise reduction method for ear clip type Bluetooth headset according to claim 1, characterized in that: The step of determining the noise reduction structure signal according to the plurality of samples comprises: According to a number of samples, a noise signal of a standard noise frequency corresponding to the frequency is obtained from a preset noise database and determined as a noise reduction construction signal.

3. The active noise reduction method for ear clip type Bluetooth headset according to claim 1, characterized in that: The step of determining the noise reduction structure signal according to the plurality of samples comprises: According to a number of samples, the fundamental frequency and harmonic frequency are obtained, a constructed sound signal is determined by the fundamental frequency, harmonic frequency and generation function, and a noise reduction constructed signal is determined according to the constructed sound signal.

4. The active noise reduction method for ear clip type Bluetooth headset according to claim 3, characterized in that: The expression of the generating function is M=Kv+w, and v=a*sin(2*π*A*f*t); wherein M represents the noise reduction construction signal, K is the rate of change of the collected sound signal, a is the amplitude of the constructed sound signal, A is the harmonic coefficient, f is the frequency of the constructed sound signal, t is time, and w is a constant.

5. The active noise reduction method for ear clip type Bluetooth headset according to claim 1, characterized in that: The quantization processing of the noise reduction structure signal to obtain the quantization processing result includes: The continuous noise reduction constructed signal is sampled at equal intervals on the time axis to obtain a series of signal values ​​at specific time points, the amplitude of each signal value obtained is quantized, and the continuous amplitude value is mapped to a finite number of discrete values; the finite number of discrete values ​​is the quantization level, and the quantization level is the quantization processing result.

6. The active noise reduction method for ear clip type Bluetooth headset according to claim 1, characterized in that: The step of performing audio coding on the quantization processing result to obtain the audio coding result includes: The quantization processing result is binary-encoded to obtain a number of binary digits. Each binary digit is arranged to obtain a digital information stream composed of a binary pulse string. The frequency of the binary pulse is equal to the product of the sampling frequency and the number of quantization bits, and the digital rate of the digital signal is obtained thereby. The digital rate is the audio encoding result.

7. The active noise reduction method for ear clip type Bluetooth headset according to claim 1, characterized in that: The formula of the noise elimination signal is: Among them, SPL is the noise cancellation signal, R is the sound signal collected by the second microphone, and A j is the cross-sectional area of ​​the sound outlet corresponding to the second microphone, r is the synthesis radius, the value of the synthesis radius is determined according to the strength of the noise reduction construction signal, and F(S) is the spectral function, which is a function of the Strouhal number S.

8. The active noise reduction method for ear clip type Bluetooth headset according to claim 1, characterized in that: The step S100 further includes: obtaining the temperature at the second microphone; The step S200 includes: determining whether the temperature is within a preset range and determining whether the contact area is greater than a preset area. If both are true, determining that the ear clip-on Bluetooth headset fits the auricle cavity and then determining that the user is wearing the ear clip-on Bluetooth headset correctly, and then executing S300; otherwise, prompting the user to wear the ear clip-on Bluetooth headset correctly, and executing S100 after a preset time.

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