LOUDSPEAKER ARRANGEMENT

Abstract: The invention relates to a loudspeaker arrangement for creating a three-dimensional stereo sound effect. The loudspeaker arrangement is to be located at a suitable distance from sound-reflecting surfaces. The loudspeaker elements (12a, 13a, 14a; 12b, 13b, 14b) of the left-hand channel (2) and the right-hand channel (3) in the loudspeaker arrangement are located within one and the same loudspeaker unit (1), where they are separated from each other by means of a zone (4) which is at least of the same size as the interval (a) between human ears. The loudspeaker elements are arranged to radiate towards different sides (A, B) of the said zone (4), in a similar fashion, within 180 DEG circle sectors, in which case the sounds reflected from the surfaces, together with the sounds coming directly from the loudspeaker unit, create a depthwise expanded, three-dimensional stereo sound effect, mainly within the sector (10) expanding away from the loudspeaker unit.

Description: LOUDSPEAKER ARRANGEMENT The invention relates to a loudspeaker arrange¬ ment defined in the introductory section of the appended patent claim 1. In principle a stereophonic sound effect is nowadays created so that a musical performance or the like is recorded with two microphones that are advan¬ tageously located at a distance from each other, the said distance corresponding to the interval between human ears. The voltage signals from the microphones are amplified in respective amplifiers, and recorded, generally each sound channel separately, to a suitable means such as a record or tape. Correspondingly, the obtained record is played by amplifying the sound signal recorded in each channel in respective amplifiers, and by reproducing the sound via loudspeakers placed at a suitable distance. The problem with the current system is that a stereo effect is generally formed only if the loud¬ speakers of the separate channels together with the listener form an isosceles triangle, so that the lis¬ tener is located at the point of the triangle. Thus the creation of a depthwise expanded stereo effect within a large space is difficult. Another problem is that the current arrange¬ ments require at least two loudspeaker units. In the prior art there is known, from the FI patent publication 35,014, an arrangement where two normal stereo channel signals are electrically trans¬ formed into three different outlet signals, which are amplified and fed out via three loudspeaker units. To a certain degree this type of arrangement creates a ste¬ reophonic impression of depthwise extension within the given space. The problem with the aforementioned arrangement is that it requires three loudspeaker units and a spe- cial amplifier for producing three outlet signals out of two normal stereo channel signals. The biggest drawback with the present-day stereo loudspeaker arrangements is that they are dif- ficult to place within the given space so that the listeners on different sides of the space could get a clear stereophonic impression of the record being played. On the other hand, if the arrangement according to the above described Finnish patent publication is applied, special equipment is required. A further drawback with current stereo loud¬ speaker arrangements is that the created stereophonic sound effect hardly gives an impression of a depthwise expanded sound. The sound field seems to come flat out of the wall. In a system of two loudspeakers, it is true, it is to some degree possible to create a depth¬ wise extension of the sound field, particularly within the medium level of the loudspeakers, but the impression of the space of the performance remains, however, inade- quate, and greatly dependent on the imagination of the listener. The object of the present invention is to eliminate the above mentioned drawbacks. The loudspeaker arrangement of the invention means a substantial im- provement in the creation of a threedimensional stereo sound effect within a given space. The loudspeaker arrangement of the invention characterized by the features enlisted in the patent claim 1. The loudspeaker arrangement of the invention for creating a three-dimensional stereo sound effect is to be placed at a suitable distance from sound-reflect¬ ing surfaces. According to the invention, the loud¬ speaker elements of the left and right channels in the loudspeaker arrangement are located within one and the same loudspeaker unit, where they are separated from each other by means of a zone corresponding at least to the size of the interval between human ears, and where they are arranged to radiate towards different sides of the said zone, in a similar fashion, within 180" circle sectors, so that the sounds reflected from the surfaces, together with the sounds coming directly from the loud¬ speaker unit, create a depthwise expanded, threedimen¬ sional stereo sound effect, mainly within the sector expanding away from the loudspeaker unit. In a preferred embodiment of the invention, the bass elements of the left and right channels are placed vertically with the cones towards opposite direc¬ tions, so that in between them there is placed a sound reflection plate. The most important advantage of the invention is that by employing only one loudspeaker unit, there is created a stereophonic, depthwise expanded impres¬ sion of the original space of performance. Thus the impression that the listener receives of a musical performance or the like comes close to the real impres- sion experienced by the listeners present at the ori¬ ginal performance. Another advantage of the present invention is that the loudspeaker arrangement renders a three-dimen¬ sional stereo effect within a radiation sector of ad- vantageously 45 - 50 degrees. Thus the position of the listener with respect to the loudspeaker arrangement is fairly free. Hence the listener obtains a depthwise expanded, stereophonic sound impression in the biggest part of the given space. Yet another advantage of the invention is that the loudspeaker arrangement is compatible with all regular stereo systems. In the ■ following the invention is explained in more detail with reference to the appended drawings, where figure 1 is an illustration of a loudspeaker arrangement of the invention, seen from the side in partial cross-rsection; figure 2 in an illustration of the loudspeaker arrangement of figure 1, seen from the top in partial cross-section; and figure 3 is an illustration of the operation of the loudspeaker arrangement of the invention within a given space with sound-reflecting walls. Figures 1 and 2 represent a sche atical il¬ lustration of a loudspeaker arrangement of the inven- tion. The loudspeaker elements 12a, 13a, 14a and respec¬ tively 12b, 13b and 14b, of the left 2 and right 3 channels are placed within one and the same loudspeaker unit 1. The loudspeaker elements of the left 2 and right 3 channels are separated from each other by means of a vertical zone 4. In this case the zone 4 is a sound- penetrating space, which is arranged particularly in between the medium sound elements 13a, 13b and the treble sound elements 14a, 14b. The width a of the zone 4 is within the range of 15...25 cm, which corresponds to the interval of human ears from each other. The loudspeaker elements of both channels 2, 3, particularly the medium and treble elements 13a, 14a; 13b, 14b, are located in the form of a semicircle within the loudspeaker unit l, so that they radiate towards their respective 180° circle sectors A, B. The bass elements 12a, 12b are located in the bottom part of the loudspeaker unit 1. They are placed vertically, with the loudspeaker cones towards opposite directions, and installed in the support plates 16a, 16b. In between the bass elements 12a, 12b there is placed the sound reflection plate 11. Thus the low sounds are directed from the bass elements 12, through the spaces in between the sound reflection plate 11 and the support plates 16a, 16b, via the openings 15a, 15b, each to their respective sectors A, B to different sides of the zone 4. In the loudspeaker arrangement of figures 1 away from the loudspeaker unit, which sector is advant¬ ageously about 50°. The dotted lines in figure 1 desig¬ nate the radiation sector 10. In the above described preferred embodiments of the loudspeaker arrangement of the invention, the feedback between the loudspeaker elements of the se¬ parate channels of the loudspeaker arrangement is acous¬ tic. The feedback can alternatively be carried out at least partly electrically, by feeding a small part of the sound signals from the channels crosswise to op¬ posite channels. Thus the zone 4 can be a suitably wide, sound-proof space a in between the loudspeaker elements of the separate channels.

Claims: PATENT CLAIMS 1. A loudspeaker arrangement for creating a three-dimensional stereo sound effect, which loudspeaker arrangement is to *be located at a suitable distance from sound-reflecting surfaces, c h a r a c t e r¬ i z e d in that the loudspeaker elements (12a, 13a, 14a; 12b, 13b, 14b) of the left and right channels (2, 3) in the loudspeaker arrangement are located within one and the same loudspeaker unit (1) , where they are separated from each other by means of a zone (4) which is at least of the same size as the interval (a) between human ears, and where they are arranged to radiate towards different sides (A, B) of the said zone (4) , in a similar fashion, within 180° circle sectors, in which case the sounds reflected from the surfaces, together with the sounds coming directly from the loudspeaker unit, create a depthwise expanded, three-dimensional stereo sound effect, mainly within the sector (10) expanding away from the loudspeaker unit. 2. The loudspeaker arrangement of claim 1, c h a r a c t e r i z e d in that the bass elements (12a, 12b) of the left and right channels (2, 3) are placed vertically with the cones towards opposite direc- tions, so that a sound reflection plate (11) is placed in between them.

Inventors: TARKKONEN TIMO, TARKKONEN, TIMO
Applicants: TARKKONEN TIMO, TARKKONEN, TIMO
Application year: 1989
Main classification: H04R5
IPC codes: H04R1, H04R5