SU1248079A1 - Acoustic radiator - Google Patents

Abstract

This invention relates to acoustics and. can be used in sound systems, for example, especially echoing rooms. The purpose of the invention is to improve the quality of sound in open spaces and rooms. The device contains radiating elements 1-6 with circular directivity characteristics, phase-shifting elements 7-11 and is acoustic radiation. third order gradient, ti. The introduction of new elements and the formation of new connections between the elements of the device make it possible to reduce the intensity of the rear radiation maxima. Invention. - additional to the main auth. No. 1184110. 3 Il., (L with LJ iLJ -J Y 1C skh about fig. / ISJ

Description

The invention relates to acoustics and can be used in the sound systems of open spaces and rooms, in particular, particularly echoing rooms.

According to the main auth. No. 1184110 is a big-gradient acoustic emitter containing four three radiating elements having circular directivity characteristics in the low-frequency region and located respectively one after the other at equal distances, as well as phase shifting elements having a linear phase-response characteristic and a low-pass filter included sequentially with the third and fourth radiating elements, while the second and third radiating elements have the polarity of switching on opposite to the first and fourth beams the first phase shifting element is connected in series to the second radiating element, and the second phase shifting element is connected in series to the fourth radiating element.

The known radiator is characterized by a lack of intelligibility of the transmitted information in booming,. acoustically untreated rooms due to the presence of rear lobes of the directivity characteristic of a sufficiently high intensity.

The aim of the invention is to improve the sound quality of open spaces and rooms by reducing the intensity of sound emission in the rear direction.

This goal is achieved by the fact that the fifth and sixth radiating elements, one after the fourth radiating element, having a polarity of switching, corresponding to the polarity of switching on of the first and second radiating elements, as well as the phase-shifting element included sequentially with the sixth radiating element having a transmission coefficient corresponding to the transmission coefficient of the phase-shifting elements connected to the second and fourth radiating elements s, the low pass filter and the phase-shifting element

j 35

transmission coefficient K 1 e connected in series to the fifth and sixth radiating elements, and a phase shifting element connected in series to the third and fourth radiating elements, having a transmission coefficient equal to

K 2cos

M

 Hee a. And .- where d is the distance

between two adjacent radiating elements; L - the length of the sound wave.

Figure 1 shows schematically the emitter; figure 2 - characteristic radiation emitter; FIG. 3 shows a variant of the design of the radiator.

The acoustic emitter contains six radiating elements 1-6 with circular directivity characteristics, located one after the other at a distance d. Elements 1, 4, and 5 have positive polarity, and elements 2, 3, and 6 have a negative polarity. Phase-shifting elements 7, 8 and 9 with jnd are connected in series with the sixth and second radiating elements.

transmission ratios K A

The phase-shifting element 10 is connected in series with the third and fourth radiating elements with the coefficient Tt d –j M of the transmission K 2cos –t – f

Phase-shifting element 11 with K-e transfer coefficient is included in series with the fifth and sixth radiating elements. Filters

low frequencies are formed respectively by the elements of R Ts

and RjLjCj.,

Essentially, the proposed emitter is a third-order acoustic emitter of the gradient.

Under the condition that the sound pressure of the radiating elements 3 and 4 is twice the sound pressure of the other radiating elements, the acoustic pressure of the acoustic radiator will look like

fPl 8 / 3in - (1 + cos h)

L

, 2 "d,. r2 (ld, 1, n |

xSin (-: - cos f). (y + CREATIVE) ./

The frequency range of the radiator is limited by the frequency corresponding to

- -h- Sound pressure in this l about

range reaches the maximum value of P „5.7 with y - Haipks

L 4

the radiation pattern of the radiator is determined by the product of the cardioid and cosinusoid and hypercardiid and in the region of small values

t has a simplified view (figure 2)

L

R l. - (1 + COS H) (-T + COS f)

(3 i

The emitter shown in FIG. 3 contains three housings, each of which has loudspeakers on the front panel and the back walls are made with holes closed by acoustically resistive material with friction resistance. The radiating elements are the front sides of the speaker cones and the holes in the rear the walls of the buildings, and the phase-shifting elements are acoustic GS, links, where Su is the flexibility of air in the volume of the box. The distance between each pair of radiating elements is d.

In series with the first loudspeaker, active resistance R is switched on to halve its sound pressure compared to the sound pressure of the second loudspeaker. The same value has the resistance R, which enters the serial branch of the low-pass filter, the transmission coefficient of which provides the necessary level and phase of the sound pressure of the third loudspeaker. The required level and phase of the sound pressure of the second loudspeaker is provided by a low-pass filter Rj Lj € 2.

In the middle frequency range, the second and third loudspeakers are turned off using these filters, and the holes on the back wall of the body of the first loudspeaker are turned off using an acoustic gS filter. In this case, the directivity of the radiator is determined by the directivity of the front side of the first loudspeaker cone, i.e. the directivity of this radiator in the region of low

and mid frequencies are frequency stabilized.

Thus, this acoustic emitter improves the intelligibility of the transmitted information due to a significant decrease in the intensity of the rear radiation maxima.

Claims (1)

Invention Formula five 0 Acoustic emitter auth.St. No. 1184110, which is designed to increase the sound quality of open spaces and rooms by reducing the intensity of sound emitted in the rear direction, it additionally introduces fifth and sixth radiating elements located one after another after the fourth radiating element, having an inclusion polarity corresponding to the polarity of the first and second radiating element, as well as a phase-shifting element connected in series with the sixth radiating element having a transmission coefficient, corresponding to the transmission coefficient of the phase-shifting elements connected to the second and fourth radiating elements, 5 low-pass filter and phase-shifting element with the transmission factor -I ch i-e A connected in series to the fifth and sixth radiating elements Q, and a phase-shifting element connected in series to the third and fourth radiating elements, having a transmission coefficient equal to nd 0 five K 2cos i where d is the distance between two neighboring radiating elements. cops; D - the length of the sound wave. 120  vy thirty Compiled by A. Tregubov Editor M. Bandura Tehred I. Gaidosh Proofreader S. Shekmar Order 4142/59 Circulation 624 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d, 4/5 Production and printing company, Uzhgorod, st. Project, 4 fig.Z