CN102638740A - Difference double-microphone noise reducing method for breathing mask - Google Patents
Difference double-microphone noise reducing method for breathing mask Download PDFInfo
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- CN102638740A CN102638740A CN2012100356303A CN201210035630A CN102638740A CN 102638740 A CN102638740 A CN 102638740A CN 2012100356303 A CN2012100356303 A CN 2012100356303A CN 201210035630 A CN201210035630 A CN 201210035630A CN 102638740 A CN102638740 A CN 102638740A
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Abstract
The invention relates to a difference double-microphone noise reducing method for a breathing mask. The method comprises the following steps in turn: connecting two same single microphones in a difference connecting manner; deducing a relation of a distance between the two single microphones and a difference of phase angles of two-way audio signals output by the microphones; giving a critical value of the difference of the phase angles; determining a main frequency range needing the breathing mask to perform noise suppression; deducing the distance between the two single microphones; coaxially, symmetrically and equidistantly mounting the two single microphones on two sides of the inner cavity wall of the breathing mask by taking a point acoustic source in the cavity as a center, wherein the distance between the two single microphones is the deduced distance; and returning to the second step and adjusting the distance between the two single microphones when the to-be-suppressed noise frequency range of the breathing mask is changed. According to the method provided by the invention, the noise suppression capacity is greatly increased; the microphone jetting phenomenon is obviously eliminated; the existing single microphones are replaced by the double microphone in difference connection; the structure change is slight; and the original oxygen supply protecting property is maintained.
Description
Technical field
The present invention relates to the breathing mask field, especially a kind of difference diamylose gram noise-reduction method of breathing mask.
Background technology
In fields such as aviation and fire-fighting, breathing mask is mainly users such as pilot and fireman and when work, the filtration oxygen supply is provided, and is the crucial individual protection harness of user, and breathing mask is equipped with Mike, can be users such as pilot and fireman and when conversation, uses.
The Mike that existing breathing mask is installed is single Mike, and under the environment for use condition of very noisy, single Mike is when picking up user's signal that speak in the front in the face shield body cavity, and ambient noise signals such as very noisy are also picked up into through mask body.So just make user's ambient noise signal such as positive signal of speaking and very noisy in the face shield body cavity mix the sound quality variation that causes single Mike to pick up.In addition, single Mike in the process of using since its with very near apart from the lip of forward in the face of the user, the air-flow that the user speaks can directly be sprayed onto on single Mike, and comparatively serious spray wheat phenomenon will take place.It is thus clear that above-mentioned two kinds of phenomenons all can seriously influence user's speech quality.
Summary of the invention
The object of the present invention is to provide a kind of effectively filtering very noisy to disturb, eliminate spray wheat phenomenon, improve the difference diamylose gram noise-reduction method of the breathing mask of speech quality greatly.
For realizing above-mentioned purpose, the present invention has adopted following technical scheme: a kind of difference diamylose gram noise-reduction method of breathing mask, and this method comprises the step of following order:
(1) two identical single Mikes is connected with the difference connected mode; Form diamylose gram noise reduction unit; Derive the relational expression of two distances between single Mike and the difference at its output two-way audio signal phase angle, analyze the stack of two-way audio signal, provide the critical value of the difference at phase angle;
(2) the main frequency part of the background very noisy in the analysis breathing mask institute applied environment need to confirm breathing mask to carry out the main frequency range of noise suppressed;
(3) difference at two-way audio signal phase angle is in the critical value; And in the noise frequency range of the required inhibition of breathing mask; Derive two distances between single Mike; With two single Mikes with point sound source in the chamber be the center with the equidistant both sides that are installed in the breathing mask internal chamber wall of axial symmetry, the distance between two single Mikes is the distance that above-mentioned derivation is come out;
(4) when the noise frequency range of the required inhibition of breathing mask changes, return step (2), adjust the distance between two single Mikes.
Can know that by technique scheme when the user put on breathing mask among the present invention and speaks, the air-flow that the user speaks no longer directly was sprayed onto two symmetries and is installed on the single Mike on the breathing mask internal chamber wall, has avoided spray wheat phenomenon; Two single Mikes adopt differential mode to connect, and the output differential signal can carry out noise suppressed well in the subsequent transmission process.In a word, the present invention has greatly improved noise inhibiting ability, has obviously eliminated spray wheat phenomenon, only existing single Mike is replaced with the diamylose gram that difference connects, and structural change is little, and has kept original oxygen supply barrier propterty.
Description of drawings
Fig. 1,2 is respectively the principle of noise reduction figure that the present invention adopts direct differential connected mode, indirect difference connected mode;
Fig. 3,6 is respectively noise reduction vector analysis figure of the present invention and noise-reduction method flow chart;
Fig. 4,5 is noise reduction analysis chart of the present invention.
Embodiment
A kind of difference diamylose gram noise-reduction method of breathing mask; This method comprises the step of following order: (1) connects two identical single Mikes with the difference connected mode; Form diamylose gram noise reduction unit; Derive the relational expression of two distances between single Mike and the difference at its output two-way audio signal phase angle, analyze the stack of two-way audio signal, provide the critical value of the difference at phase angle; (2) the main frequency part of the background very noisy 4 in the analysis breathing mask institute applied environment need to confirm breathing mask to carry out the main frequency range of noise suppressed; (3) difference at two-way audio signal phase angle is in the critical value; And in the noise frequency range of the required inhibition of breathing mask; Derive two distances between single Mike; With two single Mikes with point sound source in the chamber 3 be the center with the equidistant both sides that are installed in the breathing mask internal chamber wall of axial symmetry, the distance between two single Mikes is the distance that above-mentioned derivation is come out; (4) when the noise frequency range of the required inhibition of breathing mask changes, return step (2), adjust the distance between two single Mikes.As shown in Figure 6.
Like Fig. 1, shown in 2, described two single Mikes are first and second single Mike 1,2, and first and second single Mike 1,2 all fits tightly on the internal chamber wall of breathing mask.Described two single Mikes are moving-coil Mike; First and second single Mike's 1,2 difference connect and distribute along both center line A-A bilateral symmetry; Point sound source 3 is user's voice, and point sound source 3 is positioned at that center line A-A goes up and is coaxial with first and second single Mike 1,2, has avoided the air-flow of user's voice directly to be sprayed onto on the microphone; Effectively avoided spray wheat phenomenon, and point sound source 3 is with non-direction spherical wave overseas publicity.First and second single Mike 1,2 is directive property Mike, and the forced vibration through its vibrating diaphragm separately realizes picking up the sound wave of point sound source 3.
As shown in Figure 1, described difference connected mode adopts the direct differential connected mode, and said direct differential connected mode is with point sound source 3 as a reference, the directly series connection difference output of two single Mikes' audio signal output in-phase end head and the tail.When having very noisy 4 in the breathing mask surrounding environment, as far as adopting the breathing mask of direct differential connected mode, the phase angle difference of the low frequency signal in two very noisies that single Mike picked up 4 is smaller or equal to 60
o, the low frequency signal in the very noisy 4 can be suppressed well, and the part of the high-frequency signal in the very noisy 4 can effectively be suppressed by the cover body of breathing mask.
As shown in Figure 2, described difference connected mode adopts indirect difference connected mode, and said indirect difference connected mode is with point sound source 3 as a reference, and two single Mikes' audio signal output in-phase end is successively through difference channel 5, the output of filter network 6 difference.As far as adopting the breathing mask of indirect difference connected mode, filter network 6 can effectively suppress the high-frequency signal in the very noisy 4 with difference channel 5.
As shown in Figure 3; There is the poor of phase angle in two identical single Mikes based on the coaxial symmetrical distribution of certain distance to picking up of coaxial same point sound source 3 signals; And the difference principle inequality at the phase angle of different frequency signals part, the relational expression of deriving distance
between poor
at the phase angle of the two-way audio signal of exporting behind the frequency
of point sound source 3 signals, two single Mike's pickup point sound source 3 signals, two the single Mikes is following:
(
,
is velocity of sound) formula (1);
The principle of representing according to the available polar plot of the stack of audio signal; Make the vector analysis figure of the superposition of two-way audio signal; Draw
absolute value and have critical value
; That is: when
absolute value is in
; Mould length after the stack of two-way audio signal is long smaller or equal to the mould of its single audio signal; And
absolute value is when exceeding
, and the mould of the stack calculated value of two-way audio signal is grown up long in the mould of single audio signal.
Critical value
by formula (1) and
absolute value; Derive
in its critical value
time that be in two-way output audio signal in the required noise suppressed frequency range of breathing mask, the distance
between two single Mikes.
Be further described below in conjunction with Fig. 3,4,5,6 couples of the present invention.
Single Mike representes all available sinusoidal type signal of the signal of telecommunication of acoustic signals institute output audios such as user's voice in the chamber of picking up and chamber external environment very noisy 4, and can express with the vector expression of sinusoidal class signal, and it is following to embody formula:
And this is represented that with vector expression formula is:
.
Very noisy 4 is a chamber external environment very noisy; Coverlet Mike picks up and the signal of telecommunication of output audio is reduced to a sinusoidal type signal:
; And this is represented that with vector expression formula is:
.
When calculating the two paths of signals stack that two single Mikes pick up point sound source 3 and very noisy 4 one by one; Vector expression
and
of all available two sinusoidal type signals represent two values that single Mike picked up; Stack to
and
is calculated; Can express with vector analysis figure, as shown in Figure 3.
As shown in Figure 3;
and
mould appearance etc. have poor
at phase angle between the two.When
Absolute value smaller or equal to 60
oThe time,
With
Difference
Mould length smaller or equal to
With
Mould long; When
With
Between phase angle poor
Absolute value greater than 60
oThe time,
With
Difference
Mould grow up in
Mould long; When
With
Between phase angle poor
Absolute value equal 180
oThe time,
With
Difference
Mould length equal
With
The long sum of mould.
Promptly pick up phase angle poor of signal as first and second 1,2 of single Mike
Absolute value smaller or equal to 60
oThe time, the differential signal of diamylose gram noise reduction unit output is long smaller or equal to the mould of the signal that picks up with a single Mike, realizes the inhibition to signal; Pick up phase angle poor of signal as first and second 1,2 of single Mike
Absolute value greater than 60
oThe time, the differential signal of diamylose gram noise reduction unit output is long greater than the mould of the signal that picks up with a single Mike, especially poor at the phase angle
Absolute value equal 180
oThe time, the twice mould of the signal that the differential signal of diamylose gram noise reduction unit output equals to pick up with a single Mike is long, and realization is to the enhancing of signal.
Thereby need make the poor of signal phase angle that diamylose gram noise reduction unit picked up point sound source 3
Absolute value equals 180
o, and then diamylose gram noise reduction unit effectively strengthens point sound source 3; Make the poor of signal phase angle that diamylose gram noise reduction list picked up very noisy outside the chamber 4
Absolute value is smaller or equal to 60
o, and then diamylose gram noise reduction unit effectively suppresses the very noisy chamber outside 4, the basic derivation of its mathematical theory as follows:
The gain G of diamylose gram noise reduction unit is expressed as its pickup processing effect to acoustic signals, and mathematic(al) representation is:
，
During as
;
;
,
;
During as
,
.
Thereby can know and work as
The time, the gain G of the acoustic signals that diamylose gram noise reduction unit is picked up has inhibitory action smaller or equal to 0 to acoustic signals; When
Value 60
oWith 300
oBetween the time,
, acoustic signals is had humidification.
This shows; The realization key of diamylose gram noise-reduction method is the difference satisfied
of diamylose gram noise reduction unit to the phase angle of 4 pickoff signals of very noisy outside the chamber; And this key is the distance
between two single Mikes of adjustment rationally; Make diamylose restrain the difference satisfied
of noise reduction unit to the phase angle of the institute of the low frequency signal in the very noisy outside the chamber 4 pickoff signals, its mathematical theory is derived as follows:
When the sound wave of only considering point sound source 3 acts on 1,2 last times of first and second single Mike separately; As shown in Figure 1; The both sides and the distance that are symmetrically distributed in point sound source 3 because of first and second single Mike 1,2 are very near; Assert the not decay of signal of point sound source 3, the phase angle of the signal that first and second single Mike 1,2 picks up poor
Equal
, what promptly first and second single Mike 1,2 picked up is exactly signal equivalent, anti-phase, thereby diamylose gram noise reduction unit output differential signal, and its amplitude size is the twice of single Mike's signal, promptly realizes the postiive gain G of the 3dB of point sound source 3 signals
00
Be positioned at the left side of the coaxial line of diamylose gram noise reduction unit when very noisy 4; As shown in Figure 1; First and second single Mike 1, distance is near between 2; Assert the not decay between two single Mikes of very noisy 4 signals; The mould of the signal that two single Mikes pick up equates, only has poor
at phase angle.
The relation that exists for the wavelength
of given
value, distance
and signal is:
; According to the computing formula
between sound frequency
and wavelength
and the velocity of sound
:
.
When n=0; Frequency
; Gain
; Can know
one regularly;
and
is inversely proportional to; Thereby when
; Diamylose gram noise reduction unit is to 4 inhibitory action of chamber external environment very noisy;
is more little;
is big more for institute's blanketing frequency, and its gain
and the relational expression of frequency are:
.And very noisy 4 signals are mainly mixed by low frequency signal and form and most of signal concentrate on below the 500Hz; And speaker's lip has certain width in the chamber; Therefore getting
=6cm earlier analyzes; Can draw
, can make Reduction Analysis Fig. 4.
Can know Fig. 4 analysis, get
=180
oThe time:
,
, therefore
During=6cm,
=2.8333KHz, gain
DB.And can know by Fig. 1,
=180
oThe time, what first and second single Mike 1,2 picked up is exactly signal equivalent, anti-phase.
Get
=60
oThe time:
,
, therefore
During=6cm,
=0.9444KHz, gain
DB.And can know by Fig. 1,
=60
oThe time, the modulus of the signal that first and second single Mike 1,2 picks up equates.
Get
=300
oThe time:
,
, therefore
During=6cm,
=4.722KHz, gain
DB.And can know by Fig. 1,
=300
oThe time, the modulus of the signal that first and second single Mike 1,2 picks up equates.
Analysis can be known; During
=6cm; The diamylose gram low frequency signal that noise reduction unit suppressed can reach 0.9444KHz, satisfies the demand that low frequency signal part in very noisy 4 signals mainly concentrates on 500Hz.To different noise reduction demands; Can pass through the next distance
reasonable in design of formula frequency
and gain
, to reach best noise suppression effect.
As shown in Figure 5, be example during equally with L=6cm, when the frequency of very noisy 4 signals during at 0.9444KHz, the gain that diamylose gram noise reduction unit is picked up noise is 0dB, relatively G
00Be 0dB-3dB=-3dB; When the frequency of very noisy 4 signals during at 4.722KHz, the gain that diamylose gram noise reduction unit is picked up noise is 0dB, relatively G
00For-3dB-3dB=-6dB; When the frequency of very noisy 4 signals during at 2.8333KHz, it is maximum that diamylose gram noise reduction unit is picked up the gain of noise, is 3dB, relatively G
00Be 3dB-3dB=0dB.It is thus clear that in the full range scope of voice, the poorest noise reduction also has 0dB, see very noisy 4 signals that diamylose gram noise reduction unit picks up frequency response figure with respect to sound-source signal in the chamber.
In a word, the present invention can suppress the main low frequency signal that exists in the environment very noisy 4 very effectively; The frequency range that is suppressed for the high-frequency signal part that distributes less in the environment very noisy 4 is periodic distribution, and comparing maximum gain with the gain of the sound wave of speaking in the chamber is 0dB, and deadens and can be suppressed well through mask body.
The difference diamylose gram noise-reduction method of breathing mask.
Claims (7)
1. the difference diamylose of a breathing mask restrains noise-reduction method, and this method comprises the step of following order:
(1) two identical single Mikes is connected with the difference connected mode; Form diamylose gram noise reduction unit; Derive the relational expression of two distances between single Mike and the difference at its output two-way audio signal phase angle, analyze the stack of two-way audio signal, provide the critical value of the difference at phase angle;
(2) the main frequency part of the background very noisy in the analysis breathing mask institute applied environment need to confirm breathing mask to carry out the main frequency range of noise suppressed;
(3) difference at two-way audio signal phase angle is in the critical value; And in the noise frequency range of the required inhibition of breathing mask; Derive two distances between single Mike; With two single Mikes with point sound source in the chamber be the center with the equidistant both sides that are installed in the breathing mask internal chamber wall of axial symmetry, the distance between two single Mikes is the distance that above-mentioned derivation is come out;
(4) when the noise frequency range of the required inhibition of breathing mask changes, return step (2), adjust the distance between two single Mikes.
2. the difference diamylose of breathing mask according to claim 1 restrains noise-reduction method, it is characterized in that: described point sound source is user's voice, and described two single Mikes fit tightly on the internal chamber wall of breathing mask.
3. the difference diamylose of breathing mask according to claim 1 restrains noise-reduction method; It is characterized in that: described difference connected mode adopts the direct differential connected mode; Said direct differential connected mode is with point sound source as a reference, the directly series connection difference output of two single Mikes' audio signal output in-phase end head and the tail.
4. the difference diamylose of breathing mask according to claim 1 restrains noise-reduction method; It is characterized in that: described difference connected mode adopts indirect difference connected mode; Said indirect difference connected mode is with point sound source as a reference, and two single Mikes' audio signal output in-phase end is successively through difference channel, the output of filter network difference.
5. the difference diamylose of breathing mask according to claim 1 restrains noise-reduction method; It is characterized in that: there be the poor of phase angle in two identical single Mikes based on the coaxial symmetrical distribution of certain distance to picking up of coaxial same point sound source signal; And the difference principle inequality at the phase angle of different frequency signals part, the relational expression of deriving distance
between poor
at the phase angle of the two-way audio signal of exporting behind the frequency
of point sound source signal, two the single Mike's pickup point sound-source signals, two the single Mikes is following:
The principle of representing according to the available polar plot of the stack of audio signal; Make the vector analysis figure of the superposition of two-way audio signal; Draw
absolute value and have critical value
; That is: when
absolute value is in
; Mould length after the stack of two-way audio signal is long smaller or equal to the mould of its single audio signal; And
absolute value is when exceeding
, and the mould of the stack calculated value of two-way audio signal is grown up long in the mould of single audio signal.
6. the difference diamylose of breathing mask according to claim 1 restrains noise-reduction method, and it is characterized in that: described two single Mikes are moving-coil Mike.
7. the difference diamylose of breathing mask according to claim 5 restrains noise-reduction method; It is characterized in that: by the critical value
of formula (1) and
absolute value; Derive
in its critical value
time that be in two-way output audio signal in the required noise suppressed frequency range of breathing mask, the distance
between two single Mikes.
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| CN201210035630.3A CN102638740B (en) | 2012-02-17 | 2012-02-17 | Difference double-microphone noise reducing method for breathing mask |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104409081A (en) * | 2014-11-25 | 2015-03-11 | 广州酷狗计算机科技有限公司 | Speech signal processing method and device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003019218A (en) * | 2001-07-09 | 2003-01-21 | Kajima Corp | Protective mask |
| US20050063561A1 (en) * | 2003-09-22 | 2005-03-24 | Joseph Birli | Dual microphone assembly for mask |
| CN101543089A (en) * | 2006-11-22 | 2009-09-23 | 株式会社船井电机新应用技术研究所 | Voice input device, its manufacturing method and information processing system |
| CN101827298A (en) * | 2009-03-03 | 2010-09-08 | 船井电机株式会社 | Microphone unit |
-
2012
- 2012-02-17 CN CN201210035630.3A patent/CN102638740B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003019218A (en) * | 2001-07-09 | 2003-01-21 | Kajima Corp | Protective mask |
| US20050063561A1 (en) * | 2003-09-22 | 2005-03-24 | Joseph Birli | Dual microphone assembly for mask |
| CN101543089A (en) * | 2006-11-22 | 2009-09-23 | 株式会社船井电机新应用技术研究所 | Voice input device, its manufacturing method and information processing system |
| CN101827298A (en) * | 2009-03-03 | 2010-09-08 | 船井电机株式会社 | Microphone unit |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104409081A (en) * | 2014-11-25 | 2015-03-11 | 广州酷狗计算机科技有限公司 | Speech signal processing method and device |
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