CN113329288A - Bluetooth headset noise reduction method based on notch technology - Google Patents
Bluetooth headset noise reduction method based on notch technology Download PDFInfo
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- CN113329288A CN113329288A CN202110477342.2A CN202110477342A CN113329288A CN 113329288 A CN113329288 A CN 113329288A CN 202110477342 A CN202110477342 A CN 202110477342A CN 113329288 A CN113329288 A CN 113329288A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/10—Earpieces; Attachments therefor ; Earphones; Monophonic headphones
- H04R1/1083—Reduction of ambient noise
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10L—SPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
- G10L21/00—Processing of the speech or voice signal to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
- G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
- G10L21/0208—Noise filtering
- G10L21/0216—Noise filtering characterised by the method used for estimating noise
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10L—SPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
- G10L21/00—Processing of the speech or voice signal to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
- G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
- G10L21/0208—Noise filtering
- G10L21/0216—Noise filtering characterised by the method used for estimating noise
- G10L2021/02161—Number of inputs available containing the signal or the noise to be suppressed
- G10L2021/02166—Microphone arrays; Beamforming
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2460/00—Details of hearing devices, i.e. of ear- or headphones covered by H04R1/10 or H04R5/033 but not provided for in any of their subgroups, or of hearing aids covered by H04R25/00 but not provided for in any of its subgroups
- H04R2460/01—Hearing devices using active noise cancellation
Abstract
The invention relates to a noise reduction method of a Bluetooth headset based on a notch technology, which comprises the steps of forming a microphone array with two non-directional microphones which are linearly arranged on the Bluetooth headset, dividing the space into a target space sub-band for obtaining a target sound signal and a plurality of interference space sub-bands based on the microphone array, and obtaining a noise power spectrum of an input signal of a current frame according to the power spectrum of the input signal and the noise power spectrum of each interference space sub-band; and taking the noise power spectrum of the input signal and the power spectrum of the input signal as input, and performing voice enhancement on the input signal by adopting a preset voice enhancement algorithm. And a better noise reduction effect is achieved under the condition that hardware resources are not increased much.
Description
Technical Field
The invention relates to the technical field of voice signal processing, in particular to a noise reduction method of a Bluetooth headset based on a notch technology.
Background
When people hold communication equipment for communication, if the surrounding environment is too noisy, the communication quality can be seriously influenced by larger background noise, especially when the Bluetooth headset is used, because the microphone is far away from a speaker, the influence of the background noise on the communication quality is more serious, and therefore, the noise reduction scheme of the Bluetooth headset is always paid attention.
With respect to noise reduction schemes for bluetooth headsets, there are many types of noise reduction schemes, including single microphone, dual microphone, and triple microphone, and some of them are added with bone conduction microphones. The two microphones commonly adopt a beam forming method, one is a noise reduction scheme based on adaptive beam forming, and the other is a noise reduction scheme based on fixed beam forming. Although the noise reduction scheme based on the adaptive beamforming has a good noise reduction effect, hardware resources need to be added, so that the cost is high, the space is increased, a user can easily cause large voice loss due to incorrect posture when wearing the bluetooth headset, and although the noise reduction scheme based on the fixed beamforming has low requirements on the hardware resources and higher robustness to the deviation of the speaking direction of a wearer, the noise reduction scheme based on the fixed beamforming has limited interference noise suppression capability and has poorer noise reduction effect as the distance from the speaking direction of the wearer is closer.
Disclosure of Invention
The invention provides a noise reduction method of a Bluetooth headset based on a notch technology, and aims to solve the technical problem that in the noise reduction scheme of the Bluetooth headset in the prior art, either the requirement on hardware resources is high or the noise reduction effect is poor.
A noise reduction method of a Bluetooth headset based on a notch technology is characterized in that a first microphone and a second microphone which are linearly arranged are arranged on the Bluetooth headset, and the first microphone and the second microphone form a microphone array; based on a microphone array, the space is divided into a target space sub-band and a plurality of interference space sub-bands of a target sound signal, and the method comprises the following steps:
step a1, receiving an original sound signal using a microphone array;
step A2, dividing the original sound signal received by the first microphone according to a preset time interval and converting the original sound signal into a first frequency domain signal, dividing the original sound signal received by the second microphone according to the preset time interval and converting the original sound signal into a second frequency domain signal, and processing the first frequency domain signal and the second frequency domain signal to obtain a plurality of frame input signals of the microphone array;
step A3, calculating the power spectrum of the input signal based on the input signal;
step A4, adopting a notch wave beam of each interference space sub-band designed in advance to filter an input signal, and obtaining a filtered signal of each interference space sub-band;
step A5, calculating the noise power spectrum of each interference space sub-band based on the power spectrum of the input signal and the filtered signal of the interference space sub-band;
step A6, calculating the noise power spectrum of the current frame input signal based on the input signal power spectrum and the noise power spectrum of the interference space sub-band;
and step A7, taking the power spectrum of the input signal and the noise power spectrum of the input signal as input, and performing voice enhancement processing on the input signal by adopting a preset voice enhancement algorithm.
Step A8, converting the input signal after the speech enhancement of the current frame into a time domain signal and outputting the time domain signal;
and step A9, in the noise reduction method of the Bluetooth headset, circularly executing the steps A3-A8 to respectively perform voice enhancement processing on each frame of input signals and convert the input signals into time domain signals, and then combining all the frame time domain signals to be output as target sound signals after noise reduction so as to realize the noise reduction processing of the Bluetooth headset.
Further, in step a4, the design process of the notch beams of the interference spatial subband includes:
step A41, constructing an expression of a microphone array receiving signal in a frequency domain;
step A42, obtaining the estimated signal through a linear filter, and adopting the following expression:
Z(ω)＝hH(ω)Y(ω)＝hH(ω)d(ω)X(ω)+hH(ω)v(ω)；
step a43, setting a constraint condition to ensure that the target principal direction angle is undistorted, the constraint condition is as follows:
hH(ω)d(ω，θ)＝1；
step a44, involving constraints on the stop band beams to satisfy the constraints to obtain the notch beams for the interference spatial subbands, the constraints are as follows:
wherein the content of the first and second substances,
z (omega) is an estimation signal;
x (ω) is the desired signal;
h (omega) is a trapped wave beam to be solved;
the superscript H is a conjugate transpose operation;
y (omega) is an expression of a microphone array receiving signal in a frequency domain;
d (omega) is a space guide vector when angular frequency omega is used as a variable to participate in calculation;
x (ω) is the desired signal;
v (ω) is a noise signal vector;
d (omega, theta) is a space guide vector when angular frequency omega and incidence angle theta are taken as variables to participate in calculation;
Γα，β(ω) is a uniform sound field noise covariance matrix with sound incidence angles in the range of α to β;
epsilon is the white noise gain controlling the formation of the trapped wave beam;
IMis an identity matrix of order M.
Further, in step a41, the expression of the microphone array received signal in the frequency domain is as follows:
Y(ω)＝[Y1(ω)Y2(ω)]T＝x(ω)+v(ω)＝d(ω)X(ω)+v(ω)；
wherein the content of the first and second substances,
Y1(ω) is an expression designed in the frequency domain for the received signal of the first microphone:
Y2(ω) is an expression designed in the frequency domain for the received signal of the first microphone:
x (ω) is the desired signal;
v (ω) is a noise signal vector.
Further, in step a4, the formula of the notch beam of the interference spatial subband is as follows:
wherein h isα，β(ω, θ) is a processing result of the notch beam of the interference spatial subband;
d (omega, theta) is a space guide vector when angular frequency omega and incidence angle theta are taken as variables to participate in calculation;
epsilon is the white noise gain controlling the formation of the trapped wave beam;
IMan identity matrix of order M;
Γα，β(ω) is a uniform sound field noise covariance matrix within a range of sound incidence angles α to β;
the superscript H is a conjugate transpose operation;
d (ω) is a spatial steering vector when an angular frequency ω is included as a variable to participate in the calculation.
Alpha represents a lower critical value of an incidence angle range in the interference space sub-band;
beta represents the upper critical value of the range of angles of incidence in the interfering spatial sub-bands.
Further, in step a4, the equation of the covariance matrix of the noise of the uniform sound field with the incidence angle ranging from α to β is as follows:
wherein the content of the first and second substances,
Γα，β(ω) is a uniform sound field noise covariance matrix within a range of sound incidence angles α to β;
the superscript H is a conjugate transpose operation;
alpha represents a lower critical value of an incidence angle range in the interference space sub-band;
beta represents the upper critical value of the range of angles of incidence in the interfering spatial sub-bands.
Further, in step a5, the step of calculating the noise power spectrum of each interference space subband based on the power spectrum of the input signal and the filtered signal of the interference space subband includes the following steps:
step A51, calculating the power spectrum of the filtering signal of each interference space sub-band based on the filtered signal of the interference space sub-band;
step A52, calculating the noise power spectrum of each interference space sub-band based on the input signal power spectrum and the filtering signal power spectrum.
Further, in step a6, the step of calculating the noise power spectrum of the current frame input signal includes:
step A61, calculating the signal-to-noise ratio of each interference space sub-band based on the power spectrum of the input signal and the noise power spectrum of the interference space sub-band;
step A62, calculating the noise existence probability of each interference space sub-band according to the signal-to-noise ratio of each interference space sub-band;
step A63, calculating a steady-state noise power spectrum according to an input signal;
and step A64, estimating the noise power spectrum of the input signal of the current frame according to the steady-state noise power spectrum and the noise power spectrum of each interference space sub-band by combining the noise existence probability of each interference space sub-band.
Further, in step a61, the snr of the interference spatial subband is calculated as follows:
wherein the content of the first and second substances,
Girepresenting the signal-to-noise ratio of the ith interfering spatial subband;
nfft is the frequency point number of the single frame input signal;
Ni(ωn) The noise power spectrum of the ith interference space sub-band when the number of the frequency points is n;
P(ωn) Representing the power spectrum of the input signal with the number of frequency points n.
Further, in step a62, the calculation formula of the noise existence probability of the interference spatial subband is as follows:
wherein the content of the first and second substances,
Peithe noise existence probability of the ith interference space sub-band;
Githe signal-to-noise ratio for the ith interfering spatial subband.
Further, the space is divided into a target space sub-band and three interference space sub-bands;
the angle range of the target space sub-band is 0-45 degrees, and the angle of the target main direction is 0 degree;
the angle ranges of each interference spatial sub-band are 45-90 degrees, 90-135 degrees and 135-180 degrees respectively.
The beneficial technical effects of the invention are as follows: the invention discloses a Bluetooth headset double-microphone noise reduction method based on a trapped wave technology, which is used for noise power spectrum estimation by combining a method of noise power spectrum estimation of each spatial sub-band, can realize directional noise source tracking, obtains better noise reduction effect and increases little hardware resources.
Drawings
FIG. 1 is a schematic diagram of the arrangement of two microphones on the Bluetooth headset of the present invention;
FIG. 2 is a schematic diagram of the main direction angles of sound signals received by the two microphones of the present invention;
FIG. 3 is a schematic diagram of a notch beam with an interference spatial subband angle range of 90-135 in accordance with the present invention;
FIGS. 4-5 are schematic flow charts of a method for reducing noise of a Bluetooth headset based on a notch technique according to the present invention;
fig. 6-9 are flowcharts illustrating steps of a method for reducing noise of a bluetooth headset according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.
Referring to fig. 1-9, the present invention provides a noise reduction method for a bluetooth headset based on a notch technology, wherein a first microphone and a second microphone are arranged on the bluetooth headset in a linear arrangement, and the first microphone and the second microphone form a microphone array; based on a microphone array, the space is divided into a target space sub-band and a plurality of interference space sub-bands of a target sound signal, and the method comprises the following steps:
step a1, receiving an original sound signal using a microphone array;
step A2, dividing the original sound signal received by the first microphone according to a preset time interval and converting the original sound signal into a first frequency domain signal, dividing the original sound signal received by the second microphone according to the preset time interval and converting the original sound signal into a second frequency domain signal, and processing the first frequency domain signal and the second frequency domain signal to obtain a plurality of frame input signals of the microphone array;
step A3, calculating the power spectrum of the input signal based on the input signal;
step A4, adopting a notch wave beam of each interference space sub-band designed in advance to filter an input signal, and obtaining a filtered signal of each interference space sub-band;
step A5, calculating the noise power spectrum of each interference space sub-band based on the power spectrum of the input signal and the filtered signal of the interference space sub-band;
step A6, calculating the noise power spectrum of the current frame input signal based on the input signal power spectrum and the noise power spectrum of the interference space sub-band;
and step A7, taking the power spectrum of the input signal and the noise power spectrum of the input signal as input, and performing voice enhancement processing on the input signal by adopting a preset voice enhancement algorithm.
Step A8, converting the input signal after the speech enhancement of the current frame into a time domain signal and outputting the time domain signal;
and step A9, in the noise reduction method of the Bluetooth headset, circularly executing the steps A3-A8 to respectively perform voice enhancement processing on each frame of input signals and convert the input signals into time domain signals, and then combining all the frame time domain signals to be output as target sound signals after noise reduction so as to realize the noise reduction processing of the Bluetooth headset.
Specifically, the first microphone and the second microphone are both non-directional microphones.
Specifically, the method carries out environmental noise suppression through four steps of notch beam former design, space subband noise power spectrum estimation, noise estimation and voice enhancement.
Specifically, the speech enhancement algorithm may employ MMSE, spectral subtraction, and the like.
Further, in step a4, the design process of the notch beams of the interference spatial subband includes:
step A41, constructing an expression of a microphone array receiving signal in a frequency domain;
further, the expression of the microphone array receiving signal in the frequency domain is as follows:
Y(ω)＝[Y1(ω)Y2(ω)]T＝x(ω)+v(ω)＝d(ω)X(ω)+v(ω)；
wherein the content of the first and second substances,
Y1(ω) is an expression designed in the frequency domain for the received signal of the first microphone:
Y2(ω) is an expression designed in the frequency domain for the received signal of the first microphone:
x (ω) is the desired signal;
v (ω) is a noise signal vector.
Step A42, obtaining the estimated signal through a linear filter, and adopting the following expression:
Z(ω)＝hH(ω)Y(ω)＝hH(ω)d(ω)X(ω)+hH(ω)v(ω)；
step a43, setting a constraint condition to ensure that the target principal direction angle is undistorted, the constraint condition is as follows:
hH(ω)d(ω，θ)＝1；
step a44, involving constraints on the stop band beams to satisfy constraints so as to obtain the above-mentioned notch beams h for the interfering spatial subbandsα，β(ω, θ), the constraints are as follows:
wherein the content of the first and second substances,
z (omega) is an estimation signal;
x (ω) is the desired signal;
h (omega) is a trapped wave beam to be solved;
the superscript H is a conjugate transpose operation;
y (omega) is an expression of a microphone array receiving signal in a frequency domain;
d (omega) is a space guide vector when angular frequency omega is used as a variable to participate in calculation;
x (ω) is the desired signal;
v (ω) is a noise signal vector;
d (omega, theta) is a space guide vector when angular frequency omega and incidence angle theta are taken as variables to participate in calculation;
Γα，β(ω) is a uniform sound field noise covariance matrix with sound incidence angles in the range of α to β;
epsilon is the white noise gain controlling the formation of the trapped wave beam;
IMis an identity matrix of order M.
Further, in step a4, the formula of the notch beam of the interference spatial subband is as follows:
wherein h isα，β(ω, θ) is a processing result of the notch beam of the interference spatial subband;
d (omega, theta) is a space guide vector when angular frequency omega and incidence angle theta are taken as variables to participate in calculation;
epsilon is the white noise gain controlling the formation of the trapped wave beam;
IMan identity matrix of order M;
Γα，β(ω) is a uniform sound field noise covariance matrix within a range of sound incidence angles α to β;
the superscript H is a conjugate transpose operation;
d (ω) is a spatial steering vector when an angular frequency ω is included as a variable to participate in the calculation.
Alpha represents a lower critical value of an incidence angle range in the interference space sub-band;
beta represents the upper critical value of the range of angles of incidence in the interfering spatial sub-bands.
Specifically, the expression of the spatial steering vector d (ω, θ) is as follows:
wherein the content of the first and second substances,
d (ω, θ) is used to represent the steering vector at the angle of incidence θ;
superscript T denotes transpose operation;
ω 2 pi f is the angular frequency;
f is the frequency;
t0＝d/c；
theta is an incident angle;
d is the spacing between the first microphone and the second microphone;
c is the speed of sound;
c＝340m/s。
further, in step a4, the equation of the covariance matrix of the noise of the uniform sound field with the incidence angle ranging from α to β is as follows:
wherein the content of the first and second substances,
Γα，β(ω) is a uniform sound field noise covariance matrix within a range of sound incidence angles α to β;
the superscript H is a conjugate transpose operation;
alpha represents a lower critical value of an incidence angle range in the interference space sub-band;
beta represents the upper critical value of the range of angles of incidence in the interfering spatial sub-bands.
Specifically, the notch beam can ensure the target main direction angle, has no response distortion, and suppresses the directional sound field in the range from alpha to beta.
Specifically, in step a3, the power spectrum of the input signal is obtained by using the following formula:
P(ω)＝(pow(Y1(ω))+pow(Y2(ω)))/2，
wherein the content of the first and second substances,
p (ω) is used to represent the input signal power spectrum;
pow is a power spectrum calculation formula;
Y1(ω) is an expression of the received original speech signal of the first microphone in the frequency domain;
Y2and (ω) is an expression of the received original speech signal of the second microphone in the frequency domain.
The power spectrum of the input signal can be obtained through the formula.
Specifically, pow is a power spectrum calculation formula, pow (Y)1(ω))＝Y1(ω)*conj(Y1(ω))，pow(Y2(ω))＝Y2(ω)*conj(Y2(ω))。
Further, in step a5, the step of calculating the noise power spectrum of each interference space subband based on the power spectrum of the input signal and the filtered signal of the interference space subband includes the following steps:
step A51, calculating the power spectrum of the filtering signal of each interference space sub-band based on the filtered signal of the interference space sub-band;
step A52, calculating the noise power spectrum of each interference space sub-band based on the input signal power spectrum and the filtering signal power spectrum.
Specifically, in step a4, the expression of the filtered signal for each interfering spatial subband is as follows:
wherein the content of the first and second substances,
since the already designed notch beam input signal is used to perform filtering processing in each interference space subband, Z is now the casei(ω) represents the filtered signal of the ith interfering spatial subband;
superscript H represents the conjugate transpose operation;
hia notch beam representing an ith interference space subband design;
y (omega) is an input signal.
Specifically, in step a51, the expression of the filtered signal power spectrum of the interference spatial subband is as follows:
Ei(ω)＝pow(Zi(ω))＝Zi(ω)*conj(Zi(ω))；
wherein the content of the first and second substances,
i＝1，2，3，...，m；
m represents the number of interference spatial subbands;
Ei(ω) is the filtered signal power spectrum of the ith interference spatial subband;
pow is a power spectrum calculation formula;
Zi(ω) represents the filtered signal of the ith interfering spatial subband.
Specifically, in step a52, the calculation formula of the noise power spectrum of each interference spatial subband is as follows:
Ni(ω)＝P(ω)-Ei(ω)；
wherein the content of the first and second substances,
Ni(ω) is the noise power spectrum of the ith interfering spatial subband;
Ei(ω) is the filtered signal power spectrum of the ith interference spatial subband;
p (ω) is used to represent the input signal power spectrum.
Specifically, the power spectrum of the filtered signal of each interference spatial subband is expressed in a determinant manner as follows:
E(ω)＝[El(ω) E2(ω) ... Em(ω)]T；
the noise power spectrum of each interfering spatial subband is expressed in a determinant manner as follows:
N(ω)＝[N1(ω)N2(ω)...Nm(ω)]T＝P(ω)-E(ω)；
the superscript T denotes the transpose operation.
Further, in step a6, the step of calculating the noise power spectrum of the current frame input signal includes:
step A61, calculating the signal-to-noise ratio of each interference space sub-band based on the power spectrum of the input signal and the noise power spectrum of the interference space sub-band;
step A62, calculating the noise existence probability of each interference space sub-band according to the signal-to-noise ratio of each interference space sub-band;
step A63, calculating a steady-state noise power spectrum according to an input signal;
and step A64, estimating the noise power spectrum of the input signal of the current frame according to the steady-state noise power spectrum and the noise power spectrum of each interference space sub-band by combining the noise existence probability of each interference space sub-band.
Further, in step a61, the snr of the interference spatial subband is calculated as follows:
wherein the content of the first and second substances,
i＝1，2，3，...，m；
Girepresenting the signal-to-noise ratio of the ith interfering spatial subband;
nfft is the frequency point number of the single frame input signal;
Ni(ωn) The noise power spectrum of the ith interference space sub-band when the number of the frequency points is n;
P(ωn) Representing the power spectrum of the input signal with the number of frequency points n.
Specifically, the snr of each interference spatial subband is expressed as a determinant:
G＝[G1G2...Gm]T；
further, in step a62, the calculation formula of the noise existence probability of the interference spatial subband is as follows:
wherein the content of the first and second substances,
i＝1，2，3，...，m；
Peithe noise existence probability of the ith interference space sub-band;
Githe signal-to-noise ratio for the ith interfering spatial subband.
The noise existence probability of each interference space sub-band is expressed in a determinant mode as follows:
Pe＝[Pe1 Pe2 ... Pem]T；
wherein the content of the first and second substances,
m represents the number of interference spatial subbands;
the superscript T denotes the transpose operation.
Specifically, in step a64, the calculation formula of the noise power spectrum of the input signal is as follows:
wherein the content of the first and second substances,
NS (ω) represents the steady state noise power spectrum;
n (ω) is a determinant expression of the noise power spectrum of the interfering spatial sub-bands;
Ni(ω) is the noise power spectrum of the ith interfering spatial subband;
Peithe noise existence probability of the ith interference space sub-band;
NN (ω) is the noise power spectrum of the input signal.
Further, the space is divided into a target space sub-band and three interference space sub-bands;
the angle range of the target space sub-band is 0-45 degrees, and the angle of the target main direction is 0 degree;
the angle ranges of each interference spatial sub-band are 45-90 degrees, 90-135 degrees and 135-180 degrees respectively.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (10)
1. A noise reduction method of a Bluetooth headset based on a notch technology is characterized in that a first microphone and a second microphone which are linearly arranged are arranged on the Bluetooth headset, and the first microphone and the second microphone form a microphone array; based on the microphone array, the space is divided into a target space sub-band and a plurality of interference space sub-bands of a target sound signal, and the method comprises the following steps:
step a1, receiving a raw sound signal using the microphone array;
step A2, dividing the original sound signal received by the first microphone according to a preset time interval and converting the original sound signal into a first frequency domain signal, dividing the original sound signal received by the second microphone according to a preset time interval and converting the original sound signal into a second frequency domain signal, and processing the first frequency domain signal and the second frequency domain signal to obtain a plurality of frame input signals of the microphone array;
step A3, calculating an input signal power spectrum based on the input signal;
step A4, performing filtering processing on the input signal by using a pre-designed notch beam of each interference space subband to obtain a filtered signal of each interference space subband;
step A5, calculating the noise power spectrum of each interference space sub-band based on the power spectrum of the input signal and the filtered signal of the interference space sub-band;
step A6, calculating the noise power spectrum of the input signal of the current frame based on the power spectrum of the input signal and the noise power spectrum of the interference space sub-band;
step A7, taking the power spectrum of the input signal and the noise power spectrum of the input signal as input, and performing voice enhancement processing on the input signal by adopting a preset voice enhancement algorithm;
step A8, converting the input signal after the speech enhancement of the current frame into a time domain signal and outputting the time domain signal;
and step A9, in the noise reduction method of the Bluetooth headset, circularly executing the steps A3-A8 to respectively perform voice enhancement processing on each frame of input signals and convert the input signals into time domain signals, and then combining all the frame time domain signals to be output as the target sound signals after noise reduction so as to realize the noise reduction processing of the Bluetooth headset.
2. The method as claimed in claim 1, wherein in step a4, the designing process of the notch beam of the interference spatial subband comprises:
step A41, constructing an expression of the microphone array receiving signal in a frequency domain;
step A42, obtaining the estimated signal through a linear filter, and adopting the following expression:
Z(ω)＝hH(ω)Y(ω)＝hH(ω)d(ω)X(ω)+hH(ω)v(ω)；
step a43, setting a constraint condition to ensure that the target principal direction angle is undistorted, the constraint condition is as follows:
hH(ω)d(ω，θ)＝1；
step a44, involving constraints on stop band beams to satisfy the constraints to obtain the notch beams for the interfering spatial subbands, the constraints are as follows:
wherein the content of the first and second substances,
z (omega) is an estimation signal;
x (ω) is the desired signal;
h (omega) is a trapped wave beam to be solved;
the superscript H is a conjugate transpose operation;
y (omega) is an expression of a microphone array receiving signal in a frequency domain;
d (omega) is a space guide vector when angular frequency omega is used as a variable to participate in calculation;
x (ω) is the desired signal;
v (ω) is a noise signal vector;
d (omega, theta) is a space guide vector when angular frequency omega and incidence angle theta are taken as variables to participate in calculation;
Γα，β(ω) is a uniform sound field noise covariance matrix with sound incidence angles in the range of α to β;
epsilon is the white noise gain controlling the formation of the trapped wave beam;
IMis an identity matrix of order M.
3. The method as claimed in claim 2, wherein in step a41, the expression of the microphone array received signal in the frequency domain is as follows:
Y(ω)＝[Y1(ω) Y2(ω)]T＝x(ω)+v(ω)＝d(ω)X(ω)+v(ω)；
wherein the content of the first and second substances,
Y1(ω) is an expression designed in the frequency domain for the received signal of the first microphone:
Y2(ω) is an expression designed in the frequency domain for the received signal of the first microphone:
x (ω) is the desired signal;
v (ω) is a noise signal vector.
4. The method of claim 1, wherein in the step a4, the formula of the notch beam of the interference space sub-band is as follows:
wherein h isα，β(ω, θ) is a processing result of the notch beam of the interference spatial subband;
d (omega, theta) is a space guide vector when angular frequency omega and incidence angle theta are taken as variables to participate in calculation;
epsilon is the white noise gain controlling the formation of the trapped wave beam;
IMan identity matrix of order M;
Γα，β(ω) is a uniform sound field noise covariance matrix within a range of sound incidence angles α to β;
the superscript H is a conjugate transpose operation;
d (omega) is a space guide vector when angular frequency omega is used as a variable to participate in calculation;
a represents a lower critical value of the incidence angle range in the interference space sub-band;
β represents an upper critical value of the range of angles of incidence in the interfering spatial sub-bands.
5. The method of claim 4, wherein in the step A4, the equation of the covariance matrix of the noise in the uniform sound field with the incidence angle from α to β is as follows:
wherein the content of the first and second substances,
Γα，β(ω) is a uniform sound field noise covariance matrix within a range of sound incidence angles α to β;
the superscript H is a conjugate transpose operation;
a represents a lower critical value of the incidence angle range in the interference space sub-band;
β represents an upper critical value of the range of angles of incidence in the interfering spatial sub-bands.
6. The method of claim 1, wherein the step a5 of calculating the noise power spectrum of each of the interference spatial sub-bands based on the power spectrum of the input signal and the filtered signal of the interference spatial sub-band comprises the steps of:
step A51, calculating the power spectrum of the filtering signal of each interference space sub-band based on the filtered signal of the interference space sub-band;
step a52, calculating the noise power spectrum of each interference space sub-band based on the input signal power spectrum and the filtered signal power spectrum.
7. The method as claimed in claim 1, wherein the step of calculating the noise power spectrum of the input signal of the current frame in step a6 comprises:
step A61, calculating the signal-to-noise ratio of each interference space sub-band based on the power spectrum of the input signal and the noise power spectrum of the interference space sub-band;
step A62, calculating the noise existence probability of each interference space sub-band according to the signal-to-noise ratio of each interference space sub-band;
step A63, calculating a steady-state noise power spectrum according to the input signal;
step a64, estimating the noise power spectrum of the input signal of the current frame according to the steady-state noise power spectrum and the noise power spectrum of each interference spatial sub-band by combining the noise existence probability of each interference spatial sub-band.
8. The method of claim 7, wherein in the step A61, the SNR of the interference spatial subband is calculated as follows:
wherein the content of the first and second substances,
Girepresenting the signal-to-noise ratio of the ith interfering spatial subband;
nfft is the frequency point number of the input signal of a single frame;
Ni(ωn) The noise power spectrum of the ith interference space sub-band when the number of the frequency points is n;
P(ωn) Representing the power spectrum of the input signal with the number of frequency points n.
9. The method of claim 8, wherein in the step a62, the noise existence probability of the interference spatial sub-band is calculated as follows:
wherein the content of the first and second substances,
Peithe noise existence probability of the ith interference space sub-band;
Githe signal-to-noise ratio for the ith interfering spatial subband.
10. The method of claim 1, wherein the space is divided into one target spatial sub-band and three interfering spatial sub-bands;
the angle range of the target space sub-band is 0-45 degrees, and the angle of the target main direction is 0 degree;
the angle ranges of each interference spatial sub-band are 45 DEG-90 DEG, 90 DEG-135 DEG and 135 DEG-180 deg respectively.
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