CN1851804B - Active soft boundary acoustic shielding - Google Patents

Abstract

This invention discloses an active soft border sound screen including: a passive sound screen, a secondary sound source array, an error sensor array and a controller, in which, the secondary sound source array is mounted at the top of the passive sound screen, the error sensor array is distributed near the secondary sound source. The optimum position for placing the error sensor is got by changing the placing position of the error sensor in digit simulation and experiment. The placing position of error sensor in the invention can make active soft border sound screen has good noise-reducing effect.

Description

Active Soft Boundary Sound Barrier

1. Technical field

The present invention relates to a noise barrier, in particular to an active noise barrier.

2. Background technology

To eliminate noise in a noisy environment and obtain a quiet area, a sound barrier made of sound-insulating material is usually used for noise reduction. However, the traditional sound barrier, that is, the passive sound barrier has certain limitations in practical use, and its noise reduction effect in the low frequency band is not good. Active noise control technology is mainly used in the low frequency range, and it is applied to passive sound barriers to become active sound barriers. In the existing active sound barrier technology, the error microphone is generally placed near the top boundary of the barrier, and the output of the secondary speaker array is controlled by the controller to minimize the square sum of the sound pressure amplitude at the error microphone array, thereby achieving noise reduction. Purpose, this kind of active sound barrier that minimizes the boundary sound pressure is called active soft boundary sound barrier. There is a problem of how to optimize the placement of the error sensor near the secondary sound source. By optimizing the position of the error sensor near the secondary sound source, the noise reduction effect of the active soft boundary sound barrier can be improved. How to arrange the position of the error sensor in the active soft-boundary sound barrier has not been introduced in other literatures so far.

3. Contents of the invention

1. Purpose of the invention: The purpose of the present invention is to provide an active soft boundary noise that improves the noise reduction effect of the active soft boundary sound barrier at the far field by optimizing the layout position of the error sensor in the active soft boundary sound barrier barrier.

2. Technical solution: In order to achieve the above-mentioned purpose of the invention, the active soft boundary sound barrier of the present invention includes: a passive sound barrier, a secondary sound source array, an error sensor array and a controller, and the secondary sound source array is installed on a passive sound barrier. On the top of the sound barrier, the error sensor array is distributed in the vicinity of the secondary sound source. Generally, the distance between the error sensor and the secondary sound source is within 20 cm, and the best distance obtained through experiments is 8 cm; in the secondary sound source array The secondary sound sources are evenly distributed on the top of the passive sound barrier; the position of each error sensor in the error sensor array corresponds to the position of each secondary sound source in the secondary sound source array, and the acoustic centers of the two respectively on two parallel lines; the error sensor uses an error microphone; the secondary sound source uses a loudspeaker; the controller uses an adaptive algorithm to adjust the output of the secondary speaker array so that the sum of the squares of the sound pressure amplitudes at the error sensor array minimum.

In the present invention, the placement position of the error sensor is different from that of the existing active soft-boundary sound barrier, and its optimal position is obtained by changing the placement position of the error sensor in numerical simulation and experiment, and the evaluation standard is to make the far-field noise can be minimized. For the active soft boundary sound barrier with the secondary placed on the top of the sound barrier, when the error sensor is placed near the secondary sound source, the noise reduction effect obtained directly above is the best; at the same time, when the error sensor is placed on the secondary sound source When the primary sound source is directly above, the distance between the error sensor and the secondary sound source has an optimal value so that the noise reduction effect of the active soft boundary sound barrier in the far field is the best.

3. Beneficial effects: the placement position of the error sensor of the present invention can make the active soft boundary sound barrier have a good noise reduction effect in the noise far field.

4. Description of drawings

Fig. 1 is a schematic diagram of the array structure of the present invention;

Fig. 2 is a schematic block diagram of the present invention;

Fig. 3 is a schematic diagram of positions between three secondary sound sources and error sensors;

Figure 4 is a schematic diagram of the comparison of the new insertion loss of the active sound barrier in the far field at three positions of the error sensor;

Fig. 5 is a diagram of numerical simulation and experimental results of new insertion loss changes in the far field when the distance between the error sensor and the secondary sound source changes.

5. Specific implementation

As shown in Figure 1, the active soft boundary sound barrier of the present embodiment includes a passive sound barrier, a secondary sound source array, an error sensor array and a controller, the secondary sound source array includes 16 secondary loudspeakers, and the error sensor array Including 16 error sensors, the secondary speakers are evenly distributed on the top of the passive sound barrier, the error sensor array is distributed in the vicinity above the secondary sound source and the position of each error sensor is one by one with each secondary sound source Correspondingly; the controller employs an adaptive algorithm to adjust the output of the secondary loudspeaker array to minimize the sum of the absolute values of the sound intensities at the error sensor array. 16 secondary speakers are arranged at the top of the passive sound barrier at equal intervals r _c , where r _c must be less than one-half wavelength of the highest control frequency; 16 error sensors are arranged at equal intervals r _e at the secondary speakers (acoustic near the top of the barrier), and the acoustic centers of the two are on two parallel lines, where _rc = r _e . As shown in Figure 2, the sound pressure _pe at the error sensor array includes two parts, one is the sound pressure p _p generated by the noise source, and the other is the sound pressure HV _S generated by the secondary sound source, where V _S is the secondary speaker , H is the sound pressure transfer function from the secondary sound source to the error sensor, so _pe =p _p +HV _S ; in order to minimize the sum of the squares of the amplitude _{of pe} , that is, _pe ^H pe _is the smallest, it can be simplified as follows:

$\mathrm{<span\; class="notranslate">\; J</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; HV</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; HV</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}\mathrm{<span\; class="notranslate">\; A</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

in

A=H ^H H, b=H ^H p _p , $c=p_p^h{p}_p$

The parameter to measure the performance of the present invention is ΔIL, that is, the ratio of the square of the sound pressure of the observation point in the controlled area before and after the control

ΔIL＝10log ₁₀ [|p ₀ (r _i )| ² /|p _f (r _i )| ² ] (2)

Where r _i is the coordinate position of the observation point, the controlled area is the far field of the sound barrier, p ₀ and p _f are the sound pressures at the far field observation points before and after control, respectively.

The comparison between the active soft-boundary sound barrier with error sensor position optimization described in this embodiment and the existing active soft-boundary sound barrier with the error sensor at other positions, for example, the error sensor is placed directly in front of the secondary sound source Compared with the front and back, the result is shown in Figure 3. In this embodiment, the height of the barrier is 1.22m, and the secondary sound source is placed on the top of the barrier, which is also 1.22m. The distance between the error sensor and the secondary sound source in the three positions is 0.08m. The three positions are: the error sensor is located directly above the secondary speaker, the error sensor is located directly in front of the secondary speaker, and the error sensor is located directly behind the secondary speaker. Error sensor placement is found at 125Hz, 160Hz, 200Hz and 250Hz Active soft-boundary barriers are best at reducing noise in the far field when directly above the secondary sound source. The observation points are selected from three points on the central axis of the two barriers at a height of 0.1m and 0.5m from the ground, and the coordinates are respectively measuring point 1 (4, 0, 0.1), measuring point 2 (5, 0, 0.1), Measuring point 3 (6, 0, 0.1), measuring point 4 (4, 0, 0.5), measuring point 5 (5, 0, 0.5) and measuring point 6 (6, 0, 0.5). Figure 4 shows the comparison of the newly added insertion loss of the active soft-boundary sound barrier in the far field at three placement positions of the error sensor at 160Hz. It can be concluded that the noise reduction effect of the error sensor is directly above the secondary sound source most.

After obtaining the optimal position of the error sensor, changing the distance between the error sensor and the secondary sound source, it is found that there is an optimal value between the error sensor and the secondary sound source so that the active soft boundary sound barrier is in the far field The maximum amount of noise reduction can be obtained.

Figure 5 shows the experimental and numerical simulation results of the new insertion loss introduced by the active noise control system in the active soft-boundary sound barrier when the error sensor is directly above the secondary sound source observed at six observation points at 160 Hz From the comparison, we can find the existence of this optimal distance, where in this example the value of this optimal distance is 0.08m.

Claims (2)

1. active soft boundary acoustic shielding, comprise passive sound barrier, secondary sound source array, error pick-up array and controller, it is characterized in that, the secondary sound source array is installed in the top of passive sound barrier, the zone of error pick-up array distribution directly over secondary sound source, and the distance between error pick-up array and the secondary sound source array is 0-20 centimetre; Secondary sound source in the secondary sound source array is installed in the top of passive sound barrier equably, and secondary sound source is a loudspeaker; Corresponding with the position of each secondary sound source in the secondary sound source array respectively and both acoustic centre of source, the position of each error pick-up is respectively on two parallel lines in the error pick-up array; Controller is used to adjust the output of sub loudspeaker.

2. active soft boundary acoustic shielding as claimed in claim 1 is characterized in that, error pick-up is an error microphone.

Images