CN1851803A - Sound intensity active acoustic shielding - Google Patents

Abstract

This invention discloses sound-intensity active sound screen including a passive sound screen, error mike flow array, secondary loudspeaker array and controller. In order to ensure noise-reducing effect, the error mike flow array should be arrayed at one side of observation spot and near the top of the passive sound screen. The distance between the error mike flow and the passive sound screen is obtained through defining and computing the coordinate of the secondary loudspeaker array and the sound screen. The sound intensity active sound screen has better noise-reducing effect than traditional active sound screen in low-frequency stage.

Description

Sound intensity active acoustic shielding

One, technical field

The present invention relates to a kind of sound barrier, relate in particular to a kind of active acoustic shielding.

Two, background technology

Eliminate noise in noise circumstance, obtain the No Tooting Area, usual way is that the sound barrier that adopts sound insulating material to make carries out noise reduction.Yet traditional sound barrier, promptly passive sound barrier has certain limitation, and it is not good in the low-frequency range noise reduction.The Active noise control using technology is mainly used in low-frequency range, and it is used on the passive sound barrier, becomes active acoustic shielding.Existing active acoustic shielding technology directly is placed in error microphone the zone that needs noise reduction, it is the far field of sound barrier, output by controller control sub loudspeaker array makes the sound pressure amplitude quadratic sum minimum at error microphone array place, thereby reaches the noise reduction purpose.But this method is also infeasible in actual applications, for example, can not in the other residential block of highway, lay a lot of error microphone, and error microphone and sub loudspeaker distance is excessive in this case, the variation meeting of physical environment produces different influences to them, will cause the instability of noise reduction.The active acoustic shielding technology that also has adopts microphone array to pick up the sound pressure signal in sound barrier near field, output by controller control sub loudspeaker array, make the sound pressure amplitude quadratic sum minimum at place, sound barrier near field, and then reach the purpose of far field noise reduction, as shown in Figure 5, but the noise reduction of this method is still undesirable.

Along with the development of new technology, Mike flows as a kind of new unit that can measure acoustic pressure and particle velocity simultaneously, can more fully pick up sound field information, therefore is being widely used in recent years.

Three, summary of the invention

1, goal of the invention; The purpose of this invention is to provide a kind of in the low-frequency range noise reduction than the better sound intensity active acoustic shielding of traditional active acoustic shielding.

2, technical scheme: in order to reach above-mentioned goal of the invention, sound intensity active acoustic shielding of the present invention comprises that passive sound barrier, error Mike flow array, sub loudspeaker array and controller, in order to guarantee noise reduction, error Mike flows the top arrangement that array should be positioned at observation station one side and close passive sound barrier, and wherein the distance between sub loudspeaker and the passive sound barrier is to calculate by the coordinate that defines sub loudspeaker array and sound barrier; The sub loudspeaker array should be positioned at noise source one side and arrange near the bottom of passive sound barrier; Error Mike flows error Mike stream in the array and the sub loudspeaker in the sub loudspeaker array should evenly distribute; Each is identical with the coordinate of sub loudspeaker on the y axle to error Mike stream.The number of error Mike's stream and sub loudspeaker is determined according to actual needs.

Controller adopts adaptive algorithm to adjust the output of sub loudspeaker array, so that error Mike flows the sound intensity absolute value sum minimum at array place.

Principle of the present invention is: the present invention reduces the acoustic pressure at place, far field by the sound intensity of controlling place, passive sound barrier near field, thereby on the basis of passive sound barrier, reach extra noise reduction, with general comparing as the active acoustic shielding of error signal, can obtain better noise reduction in the low-frequency range of noise based on picking up acoustic pressure information; And the putting position of error Mike's stream and sub loudspeaker array is feasible in actual applications.The performance of sound intensity active acoustic shielding of the present invention is subjected to error Mike to flow number, spacing, the influence of sub loudspeaker number, spacing and noise signal frequencies.Error Mike flows and sub loudspeaker quantity is many more, spacing is more little, and range of control is big more, and noise reduction is good more; Noise frequency is high more, and noise reduction is poor more.

3, beneficial effect: sound intensity active acoustic shielding of the present invention has than the better noise reduction of traditional active acoustic shielding in the low-frequency range of noise.

Four, description of drawings

Fig. 1 is an array structure synoptic diagram of the present invention;

Fig. 2 is a theory diagram of the present invention;

The comparison synoptic diagram of sound intensity active acoustic shielding of the present invention and traditional active acoustic shielding noise reduction when Fig. 3 is 200Hz;

Fig. 4 is the structural representation of traditional active acoustic shielding;

Fig. 5 is the theory diagram of traditional active acoustic shielding.

Five, embodiment

As shown in Figure 1 and Figure 2, the sound intensity active acoustic shielding of present embodiment comprises that passive sound barrier, error Mike flow array, sub loudspeaker array and controller; Error Mike flows array, the sub loudspeaker array is fixed on the passive sound barrier, error Mike flows the near-field region of array distribution at passive sound barrier, promptly be positioned at the top of observation station one side and close passive sound barrier, it comprises 3 error Mike streams, and the distance between every two adjacent error Mikes flow is r _e, and all in the horizontal direction apart from sound barrier d _e, height h _eEqual the height h of sound barrier, wherein, r _eMust be less than 1/2nd wavelength of high controlled frequency; The sub loudspeaker array distribution is in the bottom of noise source one side and close passive sound barrier, and it comprises 3 sub loudspeaker, and the distance between two whenever adjacent sub loudspeaker is r _c, and all in the horizontal direction apart from sound barrier d _c, height h _cMuch smaller than the height h of sound barrier, wherein r _c=r _e, and each is identical with the coordinate of sub loudspeaker on the y axle to error Mike stream.

Error Mike flows the acoustic pressure p at array place _eComprise two parts, the one, the acoustic pressure p that noise source produces _p, the 2nd, the acoustic pressure H that sub loudspeaker produces _pV, wherein V is the driving of sub loudspeaker, H _pBe the acoustic pressure transport function of sub loudspeaker to error Mike stream, so p _e=p _p+ H _pV; Error Mike flows the particle velocity v at array place _eComprise two parts, the one, the particle velocity v that noise source produces _p, the 2nd, the particle velocity H that sub loudspeaker produces _vV, H _vBe the particle velocity transport function of sub loudspeaker to error Mike stream, so v _e=v _p+ H _vV.The effect of active control is to make error Mike flow the array place sound intensity $I=\frac{1}{2}\mathrm{Re}(p_e\×v_e^{*})$ Absolute value sum minimum, just make

$J=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\left|\frac{1}{2}\mathrm{Re}\right\{[p_p\left(n\right)+\underset{m=1}{\overset{N}{\mathrm{\Σ}}}{H}_p(m,n)V\left(m\right)]\×{[v_p\left(n\right)+\underset{m=1}{\overset{N}{\mathrm{\Σ}}}{H}_v(m,n)V\left(m\right)]}^{*}\left\}\right|---\left(1\right)$

Minimum.Above-mentioned N is the number of error Mike stream and sub loudspeaker, p _p(n) and v _p(n) be acoustic pressure and the particle velocity of noise source, H at n error Mike stream place _p(m, n) and H _v(m, n) be m sub loudspeaker in the acoustic pressure at n error Mike stream place and the transport function of particle velocity, V (m) is the driving of m sub loudspeaker.

By acoustic pressure and the particle velocity of real-time measurement noise source at error Mike stream place, and the acoustic pressure that flows from sub loudspeaker to error Mike and the transport function of particle velocity, calculate through controller, can obtain the output V (m) of sub loudspeaker array, so that error Mike flows the sound intensity absolute value sum minimum at array place.

The parameter of weighing performance of the present invention is NR, promptly in Be Controlled the zone in observation station at the ratio of control front and back acoustic pressure square

NR=10log ₁₀[| p ₀(r _i) | ²/ | p _f(r _i) | ²] (2) r wherein _iBe the observation station coordinate position, the Be Controlled zone is the far field of sound barrier, p ₀With p _fBe respectively the acoustic pressure at observation station place, far field, control front and back.

The sound intensity active acoustic shielding that contains 3 error Mike streams, 3 sub loudspeaker in the present embodiment is at d _e=0.1m, h _e=h=1.22m, and d _c=0.15m, h _c=0.15m, r _c=r _eDuring=0.5m, under 125Hz, 160Hz, 200Hz and 250Hz, obtained than the better noise reduction of traditional active acoustic shielding.The comparison of sound intensity active acoustic shielding and traditional active acoustic shielding noise reduction when Fig. 3 is 200Hz, observation station are all on the y=0 plane, and z=0.8m.3 traditional active acoustic shielding noise reduction curves are arranged among the figure, be respectively error microphone and be in sound barrier top, the above 0.1m in top, noise source one side and close sound barrier top; Error microphone is in observation station one side and when the sound barrier top, the control poor effect of traditional active acoustic shielding, even NR is negative value, so do not provide in the drawings.

In addition, according to actual needs, error Mike stream and sub loudspeaker can be a plurality of except that 3, also within protection scope of the present invention.

Claims (5)

1, a kind of sound intensity active acoustic shielding, comprise that passive sound barrier, error Mike flow array, sub loudspeaker array and controller, it is characterized in that, error Mike flows the top arrangement that array is positioned at observation station one side and close passive sound barrier, and the sub loudspeaker array is positioned at noise source one side and arranges near the bottom of passive sound barrier.

2, sound intensity active acoustic shielding as claimed in claim 1 is characterized in that, error Mike flows that error Mike's stream in the array is evenly distributed in observation station one side and near the top of passive sound barrier.

3, sound intensity active acoustic shielding as claimed in claim 1 is characterized in that, the sub loudspeaker in the sub loudspeaker array is evenly distributed in the bottom of noise source one side and close passive sound barrier.

As claim 1,2 or 3 described sound intensity active acoustic shieldings, it is characterized in that 4, each is identical with the coordinate of sub loudspeaker on the y axle to error Mike stream.

5, active acoustic shielding as claimed in claim 1 is characterized in that, controller is used to control the output of sub loudspeaker array, so that error Mike flows the sound intensity absolute value sum minimum at array place.

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