CN102163426A - Fixed point transmission system - Google Patents

Fixed point transmission system Download PDF

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CN102163426A
CN102163426A CN2010106170864A CN201010617086A CN102163426A CN 102163426 A CN102163426 A CN 102163426A CN 2010106170864 A CN2010106170864 A CN 2010106170864A CN 201010617086 A CN201010617086 A CN 201010617086A CN 102163426 A CN102163426 A CN 102163426A
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voice
module
frequency domain
voice signal
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CN102163426B (en
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吴鸣
黄晨曦
武帅兵
叶超
杨军
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Institute of Acoustics CAS
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Abstract

The invention relates to a fixed-point transmission system. The fixed-point transmission system is characterized in that an input voice is divided into a plurality of divided voices, and certain noise is added to each divided voice, thus each independent divided voice has no intelligibility; and then the divided voices are transmitted by a directional acoustical generator, and focusing, combining and restoring are carried out on a target point to obtain the original voice so as to realize fixed-point transmission of a sound. In the invention, the input voice is divided into the plurality of divided voices, and certain noise is added to each divided voice, thus the independent divided voice has no intelligibility; and the divided voices are transmitted by the directional acoustical generator, and focusing, combining and restoring are carried out on the target point, thus the original voice is obtained, thus, the fixed-point transmission of the sound is realized, a voice signal with intelligibility is produced only at a specific point in space, and the system provided by the invention can be used in an occasion requiring confidential sound communication.

Description

A kind of fixed point transmission system
Technical field
The present invention relates to sound field control technology field, particularly a kind of fixed point acoustic transmission system.
Background technology
Common acoustic transmission system is made up of 3 parts: microphone, sound reinforcement system and sound source.The microphone received signal is amplified via sound reinforcement system, and the sound source of feeding again is as input signal, and the signal that sound source is sent is passed to the attentive listener of target location, a distant place via acoustic path.Yet, this sound transmission equipment, sound is normally outwards propagated with the spherical wave form.Therefore, voice also can be by other people hear do not possess confidentiality on every side when being transferred to attentive listener.
One of solution to this problem is to adopt directive property sound.Usually the mode that realizes directive property sound has two kinds, and a kind of is the form that adopts loudspeaker array, and the amplitude and the phase place of regulating each loudspeaker in the loudspeaker array make its direction at needs produce very big acoustic pressure; Another kind is to adopt parametric array loudspeaker, different with ventional loudspeakers by mechanical vibration excitation air sounding, parametric array loudspeaker is that the non-linear interaction of utilizing ultrasound wave to propagate in air produces the sub-audible sound with high directivity, different frequency is all had roughly the same directive property, and its directive property is also good than loudspeaker array.Adopt loudspeaker array or parametric array loudspeaker only can realize the directional transmissions of sound, voice do not possess confidentiality to being in the unidirectional people of attentive listener in transmission course yet.
Summary of the invention
The objective of the invention is to, a kind of fixed point transmission system is provided, realize the fixed point transmission of sound, only produce the voice signal that possesses intelligibility, be used for to carry out the occasion of secret acoustic communication at the space specified point.
For achieving the above object, a kind of fixed point transmission system is provided, it is characterized in that, this fixed point transmission system resolves into a plurality of division voice by importing voice, and each is divided voice add certain noise, makes independent division voice not possess intelligibility, then, adopt directed acoustical generator to launch these and divide voice, and focus on, make up, recover raw tone, to realize the fixed point transmission of sound at impact point;
This system comprises: frequency domain modular converter, frequency domain are divided module, are divided voice signal composite module, masking noise generation module and directed generator battle array;
Described frequency domain modular converter, a time domain voice signal x (n) who is used for the handle input are converted to and pre-determine quantity is the individual frequency domain voice signal x_i (n) of M; Wherein, M is a positive integer; I=0,1 ..., M-1;
Described frequency domain is divided module, and all Frequency points that are used for frequency-region signal that described frequency domain modular converter is obtained are divided and produced different frequency point set I_k, and wherein, gathering I_k has
Figure BSA00000405113600011
Frequency, total N Frequency point set, k=0...N-1; Promptly
In the formula (1), N represents the number of the set of described frequency domain division Module Division; Be the most honest integer less than M/N;
Described division voice signal composite module is used for the frequency domain voice signal being reconfigured according to formula (2) according to the Frequency point dividing mode of described frequency domain division module; Be that Frequency point set I_k produces N frequency domain division voice signal y_k_i (n);
y _ k _ i ( n ) = x _ i ( n ) i ∈ I _ k 0 others - - - ( 2 )
Pass through corresponding inverse transformation again, N frequency domain divided voice signal y_k_i (n) be converted to N time domain division voice signal y_k (n);
Described masking noise generation module comprises noise signal generator and shelters the ratio computing unit; Described noise signal generator is used to produce noise u (n), and this noise u (n) obtains its corresponding frequency-region signal u_k_i (n) through described frequency domain modular converter; The described ratio computing unit of sheltering calculates its corresponding masking by noise ratio Q_k_i (n) according to N the frequency domain division voice signal y_k_i (n) that described division voice signal composite module obtains; Thus, described masking noise generation module produces masking noise v_k_i (n) according to formula (3);
v_k_i(n)＝u_k_i(n)×Q_k_i(n) (3)
Through corresponding inverse transformation, N frequency domain divided masking noise signal be converted to N time domain division masking noise signal v_k (n);
Described directed generator battle array, comprise N directed generator, be used for dividing voice signal y_k (n) and time domain and divide masking noise signal v_k (n) and adjust each directed acoustical generator wave beam, make and divide voice signal y_k (n) and synthesize in impact point focusing and restore primary speech signal according to N time domain of feeding.
Described frequency domain modular converter adopts multiphase filter, fast Fourier transform (FFT) or improvement discrete cosine transform (MDCT) that the time domain voice signal x (n) of input is converted to and pre-determines M frequency domain voice signal x_i (n).
The described ratio of sheltering that adopts in the ratio computing unit of sheltering draws according to the auditory psychology Model Calculation or simply is made as 1.
It is that 1 average is 0 white noise signal that noise signal generator in the described masking noise generation module produces variance.
Described directed generator adopts the directed acoustical generator based on loudspeaker array.At this moment, this system also comprises voice signal beam steering module and masking noise beam steering module;
Described voice signal beam steering module is used for obtaining according to formula (4) according to the y_k (n) that described division voice signal composite module obtains the input speech signal p_k_j (n) of each loudspeaker unit;
p_k_j(n)＝y_k(n)*w1_j(n) (4)
In the formula (4), j represents j loudspeaker unit, j=1: J, J represent the loudspeaker unit number; * representation signal convolution; The voice filter function of j loudspeaker correspondence of w1_j (n) expression;
Described masking noise beam steering module is used for obtaining according to formula (5) according to the masking noise signal v_k (n) that described masking noise generation module obtains the input masking noise signal q_k_j (n) of each loudspeaker unit;
q_k_j(n)＝v_k(n)*w2_j(n) (5)
In the formula (5), j represents j loudspeaker unit, j=1: J, J represent the loudspeaker unit number; * representation signal convolution; The masking noise filter function of j loudspeaker correspondence of w2_j (n) expression.
Described voice signal p_k_j (n) and described masking noise signal q_k_j (n) obtain the input signal r_k_j (n) of described directed acoustical generator based on loudspeaker array according to formula (6);
r_k_j(n)＝p_k_j(n)+q_k_j(n) (6)。
Bank of filters in the described voice signal beam steering module adopts classical beam pattern overall approach to obtain; Formed wave beam needs to have maximal value object-oriented some position.
Bank of filters in the described masking noise beam steering module adopts classical beam pattern overall approach to obtain; Formed wave beam needs to have minimum value object-oriented some position.
Described directed generator adopts the directed acoustical generator based on parametric array loudspeaker, comprises J ultrasonic transducer unit; Be used for sound signal is modulated to ultrasonic carrier, by the directed sound of non-linear interaction generation of air.This moment, this system also comprised audio mixing module and beam steering module;
Described audio mixing module is used for described y_k (n) and described v_k (n) obtaining parametric array loudspeaker input signal r_k (n) according to formula (7) linear superposition;
r_k(n)＝y_k(n)+v_k(n) (7)
Described beam steering module, the main beam direction that is used for adjusting the ultrasonic carrier t (n) of described ultrasonic transducer unit based on parametric array loudspeaker comes the definite object position.
Described beam steering module adopts and postpones structure; Described carrier signal t (n) obtains the input carrier signal t_j (n) of each ultrasonic transducer unit through described beam steering module;
t_j(n)＝t(n-jΔ) (8)
In the formula (8), Δ is represented retardation, changes Δ and can change directed sound sensing.
The invention has the advantages that the present invention is resolved into a plurality of division voice to the input voice, each is divided voice add certain noise, makes independent division voice not possess intelligibility.Adopt directed acoustical generator to launch these and divide voice, and focus on, make up, recover raw tone at impact point.Realize the fixed point transmission of sound like this, only produce the voice signal that possesses intelligibility, be used for to carry out the occasion of secret acoustic communication at the space specified point.
Description of drawings
Fig. 1 is the schematic block diagram of fixed point acoustic transmission system of the present invention;
Fig. 2 is the processing flow chart of fixed point acoustic transmission system of the present invention;
Fig. 3 is the schematic block diagram of the masking noise generation module of fixed point acoustic transmission system of the present invention;
Fig. 4 is the directed acoustical generator system schematic block diagram based on loudspeaker array of the present invention;
Fig. 5 is the directed acoustical generator system schematic block diagram based on parametric array loudspeaker of the present invention.
Embodiment
The present invention is further described below in conjunction with drawings and Examples.
The present invention is resolved into a plurality of division voice to the input voice, each is divided voice add certain noise, makes independent division voice not possess intelligibility.Adopt directed acoustical generator to launch these and divide voice, and focus on, make up, recover raw tone at impact point.
The structure that a kind of acoustic transmission system of fixing a point that the present invention proposes has adopted comprises: the frequency domain modular converter transfers the time domain input speech signal to the frequency domain input speech signal; Frequency domain is divided module, and all Frequency points of frequency-region signal are divided, and produces the set of different frequency point; Divide the voice signal composite module, divide the Frequency point dividing mode that module determines, the frequency domain voice signal is reconfigured, produce a plurality of division voice signals, make single division voice signal not possess intelligibility according to frequency domain; The masking noise generation module produces corresponding masking noise according to dividing voice signal; Directed acoustical generator array module is made up of a plurality of directed acoustical generators.According to sound transmission impact point position, adjust directed acoustical generator, the division sound signal is focused at impact point, synthesize again and restore primary speech signal.
The schematic block diagram of fixed point acoustic transmission system of the present invention, as shown in Figure 1.The fixed point sound transmission equipment of present embodiment comprises: input end 1, and the output signal of amplifier of microphone and the output signal of AD converter are input in this input end; Frequency domain modular converter 2 transfers the time domain input speech signal to the frequency domain input speech signal; Frequency domain is divided module 3, and all Frequency points of frequency-region signal are divided; Divide voice signal composite module 4, divide the Frequency point dividing mode of module decision, the frequency domain voice signal is decomposed and reconfigures, produce a plurality of division sound signals, make single division voice signal not possess intelligibility according to frequency domain; Masking noise generation module 5 produces corresponding masking noise according to the frequency domain input speech signal; Directed acoustical generator battle array 8 is made up of a plurality of directed acoustical generators 6.According to sound transmission impact point position, adjust each directed acoustical generator wave beam, make and divide sound signal in impact point 7 focusing, synthesize again and restore primary speech signal.
The processing flow chart of fixed point acoustic transmission system of the present invention, as shown in Figure 2.The operation of such fixed point sound transmission equipment is described below with reference to Fig. 2.
Step S1): frequency domain modular converter 2 provides frame buffering for the signal that is input to input end 1, the about 10ms of frame length is to 100ms, and by as multiphase filter, fast fourier transform (FFT) or to improve discrete cosine transform methods such as (MDCT) be that unit is divided into time signal x (n) and pre-determines quantity such as M frequency-region signal x_i (n) with the frame.Wherein, i comprises 0 to M-1 positive integer, and M is a positive integer.
Step S2) frequency domain is divided module 3 all Frequency points is divided into the set that pre-determines quantity, and I_k has as set
Figure BSA00000405113600051
Frequency, total N set, k comprises 0 to N-1 positive integer.
Figure BSA00000405113600052
In the following formula
Figure BSA00000405113600053
Be maximum integer less than M/N.Each N of the purpose of following formula Frequency point extracts one, forms N Frequency point set, and each Frequency point set is divided voice signal corresponding to one.
Step S3): divide voice generation module 4 and produce N frequency domain division voice signal according to Frequency point set I_k.
y _ k _ i ( n ) = x _ i ( n ) i ∈ I _ k 0 others
Pass through corresponding inverse transformation again, N frequency domain divided voice signal be converted to N time domain division voice signal y_k (n).
Step S4): masking noise generation module 5 produces masking noise by the mode of Fig. 3.The schematic block diagram of the masking noise generation module of fixed point acoustic transmission system of the present invention, as shown in Figure 3.It is that 1 average is 0 white noise u (n) that white noise signal generator 9 produces variance, obtains its corresponding frequency-region signal u_k_i (n) through frequency domain modular converter 2.Shelter ratio computing module 10 and calculate its corresponding masking by noise ratio Q_k_i (n) according to frequency-region signal y_k_i (n).The ratio of sheltering can draw according to the auditory psychology Model Calculation, also can simply be made as 1.It is the product of u_k_i (n) and Q_k_i (n) that masking noise generation module 5 produces masking noise v_k_i (n):
v_k_i(n)＝u_k_i(n)×Q_k_i(n)
Through corresponding inverse transformation, N frequency domain divided masking noise signal be converted to N time domain division masking noise signal v_k (n).
At last N time domain divided voice signal and time domain and divide masking noise signal v_k (n) N the different directed acoustical generator of feeding respectively, adjust each directed acoustical generator wave beam, make and divide voice signal, synthesize again and restore primary speech signal specifying acceptance point focusing.
According to one embodiment of the present of invention, directed acoustical generator has adopted the structure that realizes based on loudspeaker array.The voice filter pack module carries out filtering to input speech signal, forms the voice wave beam of expectation.Masking noise bank of filters module is carried out filtering to the input masking noise, forms the noise wave beam of expectation.Filtered voice signal of process and masking noise signal addition are as the input signal of loudspeaker unit.
Directed acoustical generator system schematic block diagram based on loudspeaker array of the present invention, as shown in Figure 4.Directed acoustical generator system based on loudspeaker array among the embodiment comprises: input speech signal y_k (n) obtains the input speech signal of each loudspeaker unit through voice signal beam steering module 11;
p_k_j(n)＝y_k(n)*w1_j(n)
Wherein, j represents j loudspeaker unit, j=1: J, J represent the loudspeaker unit number, * representation signal convolution.Voice signal beam steering module 11 is a bank of filters, feed the respectively loudspeaker unit of J of filtering output signal.The voice filter of j loudspeaker correspondence of w1_j (n) expression.Voice signal beam steering module 11 median filter groups can adopt classical beam pattern overall approach to obtain, and formed wave beam needs to have maximal value object-oriented some position.Input masking noise signal v_k (n) obtains the input masking noise signal of each loudspeaker unit through masking noise beam steering module 12;
q_k_j(n)＝v_k(n)*w2_j(n)
Masking noise beam steering module 12 is similarly one group of wave filter, and j represents j loudspeaker unit, j=1: J, J represent the loudspeaker unit number, * representation signal convolution, the masking noise wave filter of j loudspeaker correspondence of w2_j (n) expression.The beam pattern method of the adopted classics of masking noise beam steering module 12 etc. obtains, and formed wave beam needs to have minimum value object-oriented some position.Preferably filtered voice signal and masking noise signal addition input signal as loudspeaker unit.
r_k_j(n)＝p_k_j(n)+q_k_j(n)
According to an alternative embodiment of the invention, directed acoustical generator has adopted the structure that realizes based on parametric array loudspeaker.The audio mixing module is input voice and masking noise linear superposition, as the parametric array loudspeaker input signal.Beam steering module is adjusted transducer unit carrier phase in the parametric array loudspeaker, makes its definite object point orientation.
Directed acoustical generator system schematic block diagram based on parametric array loudspeaker of the present invention, as shown in Figure 5.Directed acoustical generator system adopts parametric array loudspeaker to realize comprising among another embodiment: audio mixing module 13, and importing voice and masking noise linear superposition, as the parametric array loudspeaker input signal
r_k(n)＝y_k(n)+v_k(n)
Different by mechanical vibration generation audio sound with ventional loudspeakers, parametric array loudspeaker is that sound signal is modulated on the ultrasonic carrier, by the directed sound of non-linear interaction generation of air.Just can change directed sound direction by the beam direction of adjusting ultrasonic carrier.Ultrasonic carrier changes by beam steering module 14, and the delay structure that its algorithm can employing obtains.Carrier signal t (n) obtains the input carrier signal of each ultrasonic transducer unit through beam steering module 14
t_j(n)＝t(n-jΔ)
Wherein, j represents j loudspeaker unit, j=1: J, J represent the loudspeaker unit number, and Δ is represented retardation, change Δ and can change directed sound sensing.Obtain ultrasonic transducer cell input signal r_k_j (n) through Signal Pretreatment, Signal Pretreatment can adopt double-sideband modulation, parametric array loudspeaker pretreating scheme commonly used such as single-sideband modulation.
The present invention can be used for carrying out the occasion of secret acoustic communication.
It should be noted last that above embodiment is only unrestricted in order to technical scheme of the present invention to be described.Although the present invention is had been described in detail with reference to embodiment, those of ordinary skill in the art is to be understood that, technical scheme of the present invention is made amendment or is equal to replacement, do not break away from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (12)

  1. One kind the fixed point transmission system, it is characterized in that, this fixed point transmission system resolves into a plurality of division voice by importing voice, and each is divided voice add certain noise, make independent division voice not possess intelligibility, then, adopt directed acoustical generator to launch these and divide voice, and focus on, make up, recover raw tone at impact point, to realize the fixed point transmission of sound; This system comprises: frequency domain modular converter, frequency domain are divided module, are divided voice signal composite module, masking noise generation module and directed generator battle array;
    Described frequency domain modular converter, a time domain voice signal x (n) who is used for the handle input are converted to and pre-determine quantity is the individual frequency domain voice signal x_i (n) of M; Wherein, M is a positive integer; I=0,1 ..., M-1;
    Described frequency domain is divided module, and all Frequency points that are used for frequency-region signal that described frequency domain modular converter is obtained are divided and produced different frequency point set I_k, and wherein, gathering I_k has
    Figure FSA00000405113500011
    Frequency, total N Frequency point set, k=0...N-1; Promptly
    Figure FSA00000405113500012
    In the formula (1), N represents the number of the set of described frequency domain division Module Division, is positive integer;
    Figure FSA00000405113500013
    Be the most honest integer less than M/N;
    Described division voice signal composite module is used for the frequency domain voice signal being reconfigured according to formula (2) according to the Frequency point dividing mode of described frequency domain division module; Be that Frequency point set I_k produces N frequency domain division voice signal y_k_i (n);
    y _ k _ i ( n ) = x _ i ( n ) i ∈ I _ k 0 others - - - ( 2 )
    Pass through corresponding inverse transformation again, N frequency domain divided voice signal y_k_i (n) be converted to N time domain division voice signal y_k (n);
    Described masking noise generation module comprises noise signal generator and shelters the ratio computing unit; Described noise signal generator is used to produce noise u (n), and this noise u (n) obtains its corresponding frequency-region signal u_k_i (n) through described frequency domain modular converter; The described ratio computing unit of sheltering calculates its corresponding masking by noise ratio Q_k_i (n) according to N the frequency domain division voice signal y_k_i (n) that described division voice signal composite module obtains; Thus, described masking noise generation module produces masking noise v_k_i (n) according to formula (3);
    v_k_i(n)＝u_k_i(n)×Q_k_i(n) (3)
    Through corresponding inverse transformation, N frequency domain divided masking noise signal be converted to N time domain division masking noise signal v_k (n);
    Described directed generator battle array, comprise N directed generator, be used for dividing voice signal y_k (n) and time domain and divide masking noise signal v_k (n) and adjust each directed acoustical generator wave beam, make and divide voice signal y_k (n) and synthesize in impact point focusing and restore primary speech signal according to N time domain of feeding.
  2. 2. fixed point transmission system according to claim 1, it is characterized in that described frequency domain modular converter adopts multiphase filter, fast Fourier transform (FFT) or improvement discrete cosine transform (MDCT) that the time domain voice signal x (n) of input is converted to and pre-determines M frequency domain voice signal x_i (n).
  3. 3. fixed point transmission system according to claim 1 is characterized in that, the described ratio of sheltering that adopts in the ratio computing unit of sheltering draws according to the auditory psychology Model Calculation or simply is made as 1.
  4. 4. fixed point transmission system according to claim 1 is characterized in that, it is that 1 average is 0 white noise signal that the noise signal generator in the described masking noise generation module produces variance.
  5. 5. fixed point transmission system according to claim 1 is characterized in that, described directed generator adopts the directed acoustical generator based on loudspeaker array.
  6. 6. fixed point transmission system according to claim 5 is characterized in that, this system also comprises voice signal beam steering module and masking noise beam steering module;
    Described voice signal beam steering module is used for obtaining according to formula (4) according to the y_k (n) that described division voice signal composite module obtains the input speech signal p_k_j (n) of each loudspeaker unit;
    p_k_j(n)＝y_k(n)*w1_j(n) (4)
    In the formula (4), j represents j loudspeaker unit, j=1: J, J represent the loudspeaker unit number; * representation signal convolution; The voice filter function of j loudspeaker correspondence of w1_j (n) expression;
    Described masking noise beam steering module is used for obtaining according to formula (5) according to the masking noise signal v_k (n) that described masking noise generation module obtains the input masking noise signal q_k_j (n) of each loudspeaker unit;
    q_k_j(n)＝v_k(n)*w2_j(n) (5)
    In the formula (5), j represents j loudspeaker unit, j=1: J, J represent the loudspeaker unit number; * representation signal convolution; The masking noise filter function of j loudspeaker correspondence of w2_j (n) expression.
  7. 7. fixed point transmission system according to claim 6, it is characterized in that described voice signal p_k_j (n) and described masking noise signal q_k_j (n) obtain the input signal r_k_j (n) of described directed acoustical generator based on loudspeaker array according to formula (6);
    r_k_j(n)＝p_k_j(n)+q_k_j(n) (6)。
  8. 8. fixed point transmission system according to claim 6 is characterized in that, the bank of filters in the described voice signal beam steering module adopts classical beam pattern overall approach to obtain; Formed wave beam needs to have maximal value object-oriented some position.
  9. 9. fixed point transmission system according to claim 6 is characterized in that, the bank of filters in the described masking noise beam steering module adopts classical beam pattern overall approach to obtain; Formed wave beam needs to have minimum value object-oriented some position.
  10. 10. fixed point transmission system according to claim 1 is characterized in that, described directed generator adopts the directed acoustical generator based on parametric array loudspeaker, comprises J ultrasonic transducer unit; Be used for sound signal is modulated to ultrasonic carrier, by the directed sound of non-linear interaction generation of air.
  11. 11. fixed point transmission system according to claim 10 is characterized in that this system also comprises audio mixing module and beam steering module;
    Described audio mixing module is used for described y_k (n) and described v_k (n) obtaining parametric array loudspeaker input signal r_k (n) according to formula (7) linear superposition;
    r_k(n)＝y_k(n)+v_k(n) (7)
    Described beam steering module, the main beam direction that is used for adjusting the ultrasonic carrier t (n) of described ultrasonic transducer unit based on parametric array loudspeaker comes the definite object position.
  12. 12. fixed point transmission system according to claim 10 is characterized in that, described beam steering module adopts and postpones structure;
    Described carrier signal t (n) obtains the input carrier signal t_j (n) of each ultrasonic transducer unit through described beam steering module;
    t_j(n)＝t(n-jΔ) (8)
    In the formula (8), Δ is represented retardation, changes Δ and can change directed sound sensing.
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WO2018108061A1 (en) * 2016-12-13 2018-06-21 中兴通讯股份有限公司 Signal processing method, apparatus, terminal and computer storage medium

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