EP0696155A1

EP0696155A1 - Method and acoustic system for sonification of enclosed and open spaces

Info

Publication number: EP0696155A1
Application number: EP92911868A
Authority: EP
Inventors: Alexei Vladimirovich Vinogradov; Vladimir Sergeevich Konischev; Vladimir Vladimirovich Smirnov
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-04-23
Filing date: 1992-05-22
Publication date: 1996-02-07
Also published as: WO1993022889A1; RU2018207C1; EP0696155A4; AU1972992A; KR940701630A; KR0149685B1

Abstract

A method and an acoustic system for sonification of enclosed and open spaces are used for sonification of enclosed and open spaces with the use of acoustic pseudosystems. In a method for sonification of enclosed and open spaces which includes separation of spectral components of the electric signal corresponding to different frequency bands, conversion of the electric signals into acoustic ones by means of pairwise and in-phase connected main and additional electroacoustic radiation heads providing for coherency of the acoustic waves and mounted in parallel and axially-opposite manner so that their front panels face each other at different distances corresponding to their different frequency bands, the main and the additional heads are mounted at the distances from each other correspondingly equal to 0.5-2.0 of the distances at which the irregularity of the frequency response is minimal within each frequency band in the directions which are perpendicular to the axes along which are mounted the radiation heads and which are not limited by their front panels, the characteristic sensibility of each additional radiator being so chosen that it exceeds by 1-12 dB that of each main radiator and the excess sound power fed to the heads of the additional radiations being dampened during the whole sonification process. Besides, the main and additional radiation heads with different frequency bands facing each other by their front panels are mounted in one or different planes in relation to each other.

Description

Field of Technology

This invention relates to the field of acoustic wave physics and may be used for sonification of enclosed and open spaces using acoustic pseudo stereo systems.

Prior Art

It is known in the art the method of omnidirectional sonification of enclosed and open spaces and the device for implementation thereof, comprising the mounting of two transducers one opposite the other and connected in-phase (USA, 395201).
The disadvantage of the above method and device is a redundancy of directed sonification and the lack of its voluminosity.
Another known installation of a single-channel system of a sonic transducer where the method of sonification of enclosed and open spaces is implemented The method is based on in-phase connection of two electroacoustic transducers being mounted horizontally and in pairs so that their radiating panels face each other (SU, A, 936462).
The disadvantage of the installation and the method implemented therein is that it does not provide a natural sounding.
By the results obtained, the closest technical solution is the method of sonification of closed and open spaces including a separation of spectral components to different frequency bands, conversion of electrical signals into acoustic ones by means of paired and in-phase connected main and additional electroacoustic transducers providing coherent acoustic waves and mounted in parallel and coaxially facing each other at various distances in accordance with various frequency bands.
Said method has been implemented in an acoustic system for sonification of enclosed and open spaces comprising paired main and additional electroacoustic transducers mounted, respectively, on the basement and on the holder so that the radiating apertures face each other, connected in parallel and in-phase to the source of sine electric signal, its frequency being equal to that of the acoustic signal (See "Izobretatel i Ratsionalizator" Magazine, No.6. 1985, pp.16-17, USSR).
The disadvantage of said method and the acoustic system is that they do not provide a wide amplitude-frequency characteristic (AFC) with the minimal irregularity which in turn does not provide a high quality and naturalism of sounding of the acoustic system using commercial electroacoustic transducers.

Disclosure of the Invention

The basement of the invention is to widen the AFC and decrease its irregularity which allows, through superimposing radiated waves to form non-directional secondary acoustic field sources providing qualitative and natural voluminous sounding and peak signal levels with minimal frequency non-linear and transitional distortions.
The task is solved by the new method of sonification of enclosed and open spaces and the new acoustic system implementing thereof.
The new method of sonification of enclosed and open spaces comprising isolation of electric signal spectral components that correspond to various frequency bands, conversion of electric signals into acoustic ones by means of paired and in-phase connected electroacoustic transducers providing coherent of acoustic waves and mounted parallel and coaxially facing each other at various distances corresponding various frequency bands, the main and additional transducers are mounted at distances equal 0.5-2.0 times of that where the irregularity of the characteristic is minimal within each frequency band in directions normal too the axes of transducer mounting and not restricted by their face panels, with characteristic sensitivity of each additional radiator being 1-2 dB higher than that of each main radiator, whereas the excessive acoustic power fed to the additional transducers is being extinguished throughout an entire stage of sonification.
Besides, transducers with different frequency bands and face panels facing each other are mounted in single or several planes relative each other.
The new acoustic system for sonification of enclosed and open spaces comprising paired main and additional electroacoustic transducer heads mounted on the basement and on the holder, respectively, with face panels mounted in parallel and coaxially, connected in pairs and in-phase with the sine electric signal source, uses as the main and additional electroacoustic radiator cased low-frequency, middle-frequency, and high-frequency cone transducers mounted in pairs, with face panels facing each other; cases of the low-frequency loudspeakers are mounted and secured to the basement, middle-frequency transducers are mounted on the holders mounted on the cases of low-frequency transducers, high-frequency transducers are provided with a frame attached thereto, whereas the frame on the holders is mounted on the middle-frequency transducers with the ratio of distances between the edges of face panels of the low-frequency transducers to that of middle-frequency and high-frequency is adopted as $S_{lf} {: S}_{mf} {: S}_{hf} = 1 : (0.08 - 12.5) : (0.08 - 12.5)$
, where S_lf -distance between low-frequency transducer face panel edges; S_mf -distance between middle-frequency transducer face panel edges; and S_hf -distance between high-frequency transducer face panel edges; the tolerance of parallelism of mounting of face panels of cones of the main and additional transducers facing each other in vertical and horizontal planes is adopted equal to γ = +/- (0.1-15)°, while the ratio of coaxiality of face cones of transducers mounted in vertical and horizontal planes to the maximum characteristic dimension between face panels of the transducers facing each other equals, respectively, $Δ : D : S = 1 : [+/-(0.002-0.1)] : [+/-(0.0007-0.02)]$
, where:

γ -: tolerance in parallelism of mounting of face panels of cones of main and additional transducers facing each other;
D -: maximum characteristic dimension of transducer cone face panel;
Δ -: coaxiality of mounting of transducers' cones;
S -: distance between face panels of transducers racing each other.

In addition to the above, cases of the low-frequency transducers, the middle-frequency, and high-frequency transducers are mounted with provisions of adjustment of their position in vertical and horizontal planes relative to the basement, low-frequency transducers and middle-frequency transducers, respectively.
The above set of essential features is aimed at achievement of a technological result and stays in a cause-effect relationship with it and, as compared to known solutions, allows to form non-directional acoustic field sources with the frequency characteristics of minimal irregularity thus providing qualitative and natural volume sounding.

Brief Description of the Drawings

The invention is illustrated by the drawings where Fig. 1 shows the acoustic system for sonification of enclosed and open spaces;

Fig. 2 is a view by arrow "A" Fig. 1;
Fig. 3 is a view by arrow "B" Fig. 1;
Fig. 4 is a block "A" Fig. 1;
Fig. 5 is an amplitude-frequency characteristic (AFC) of the system.

The Best Mode for Carrying Out the Invention

The method for sonification of enclosed and open spaces is accomplished as follows.
An acoustic system is assembled from a set of paired electroacoustic transducers with various frequency bands and distances between transducers' heads facing each other and connected in-phase (at the moment of switching on the current the cones of heads are pushed out and pulled in a similar manner) which convert electric signals into acoustic ones providing coherence of acoustic waves. Heads of radiators of the same type are placed at distances corresponding a homogeneous AFC within each band in directions perpendicular to axes of radiator heads mounting and not restricted with face panels. The ranges of distances between radiator heads of the same type are determined experimentally to obtain a minimum irregularity of the AFC with characteristic sensitivity of each radiator determined by ratio of acoustic pressure to the power consumed. Superimposition of acoustic waves propagated in the space between the radiator heads in directions perpendicular to the axes of heads mounting and not restricted by their face panels results in formation of secondary acoustic field sources which possesses voluminosity on non-directional sonification with a maximum naturality of sound. In the process of formation of the secondary acoustic sources an excessive acoustic power fed primarily to the additional radiator heads is damped by passive elements. The set of paired radiators may comprise from one to three radiators and, in an ideal case, may comprise a radiator for each extracted note. Paired radiator heads with different frequency bands with the panels facing each other are mounted in a single or in different planes relative to each other.
The claimed method has been implemented in an acoustic system for sonification of enclosed and open spaces.
An acoustic system for sonification of enclosed and open spaces comprises basement 1 on which cases 2 of low-frequency loudspeaker are mounted. Each of low-frequency loudspeakers possesses the head of loudspeaker comprising cone 4 with sound coil 5 and magnet core 6. On the top side of cases 2 plates 7 are installed to which brackets 8 are fastened, to the top plates of which supporting rings 9 are attached where middle-frequency loudspeakers 10 are mounted. Each loudspeaker 10 comprises a head including cone 11 with coil 12, magnet core 13 and a device for damping excessive sound power due to passive elements which are not included in the acoustic system (not shown in the drawings). On supporting rings 9 of middle-frequency loudspeaker 10 brackets 14 are mounted to the top plates of which frame 15 is attached along the axis of which in vertical plane at the center of horizontal crossbar of frame 15 high-frequency loudspeakers 16 are mounted and fixed. Each loudspeaker 16 has a head including cone 17 comprising sound coil 18 and magnet core 19. Each pair of cones 4, 11, and 17 of low-frequency, middle-frequency, and high- frequency loudspeakers 3, 10, and 16, respectively, is mounted so that they face each other and the front panels of cones 4, 11, 17 are parallel and coaxially opposite in vertical and horizontal planes. The heads of loudspeakers 3, 10, 16 are mounted at distances from each other corresponding to equalized frequency response in the limits of each frequency band in directions perpendicular to the axis along which the heads of loudspeakers 3, 10, and 16 are mounted and which are not limited by their front panels. Ratio of distance between the edges of cone front panels 4 of low-frequency loudspeakers 3 to distances between edges of front panels of cones 11 and 17 of middle-frequency and high- frequency loudspeakers 10 and 16, respectively, is adopted as $S_{lf} {: S}_{mf} {: S}_{hf} = 1 : (0.08 - 12.5) : (0.08 - 12.5)$
.
It has been established experimentally that the characteristic sensitivity determined by the ratio of sonic pressure to the power consumed by each middle-frequency and high-frequency loudspeaker (10 and 16, respectively) must be higher by 1-12 dB that the characteristic sensitivity of each low-frequency loudspeaker 3. To ensure a minimal irregularity of the frequency response, the tolerance for parallelism of front panels of cones 4, 11, and 17 of low-frequency, middle-frequency, and high- frequency loudspeakers 3, 10, and 16, respectively, facing each other in vertical and horizontal planes must be equal to γ = +/-(0.1-15)°,, while the ratio of coaxiality in vertical and horizontal planes of mounting of cones 3, 10 and 16 front panels facing each other to the maximum characteristic dimension (D) of the front panel of cones 4, 11, and 17 of loudspeakers 3, 10, and 16 to the distance (S) between face panels of cones 4, 11, and 17 of loudspeakers 3, 10, and 16 facing each other is adopted to be equal $Δ : D : S = 1 : [+/-(0.002-0.1)] : [+/-(0.0007-0.02)]$
(see Figs. 1, 3). The total frequency response (see Fig. 4) of all three pairs of loudspeakers 3, 10, and 16, provided the above conditions are adhered to, must demonstrate a minimum of irregularities and approach the trapeze form, with no splashes and gaps both in the zone of characteristic junction of separate loudspeakers 3, 10, and 16 and in general during operation of the acoustic system.
Adjustment and mounting of the acoustic system is carried out as follows.
At the adjusting of an acoustic system the low-frequency loudspeakers 3 in cases 2 are mounted on a special stand (not shown in the drawings) by front panels of cones 4 so that their face each other in keeping of strict parallelism and coaxiality of front panels both in vertical and horizontal planes, the distance S_lf between cones 4 is fixed. Sound cone 5 of cones 4 connected by magnet cores 6 pair-wise and in-phase are inserted to the source of sound signal (not shown in the drawings). The selection of distances between front panels of cones 4 in general depends on operating frequency range of loudspeaker 3, frequency response of pair of loudspeakers 3, and also on parallelism and coaxiality of front panels of cones 4. An adjustment of the acoustic system is carried out by displacement of loudspeakers 3 toward each other or by disjoining one with respect to the other with measuring of frequency response when the pair of cones 4 is in operation with sound coil 5 and measuring the spectrum of the radiated frequency in direction perpendicular to the axis along which the heads of loudspeakers 3 are installed and which are not limited by their front panels, for example, by means of the Clark Technic frequency spectrum analyzer. By means of displacement of loudspeakers 3 one with respect to the other, an optimal distance between them is found, where the frequency response of radiating sound field is closed to equalized without splashes and gaps in it. At a determined distance, body 2 of loudspeakers 3 is fixed and fastened by means of special fixing elements of the stand. Adjustment of an installation of bodies 2 with loudspeakers 3 in the stand both in vertical and horizontal position is carried out. As it was pointed out above, to remove splashes and gaps in the frequency response, parallelism of front panels of cones 4 in vertical and horizontal planes is checked to meet the tolerance of parallelism within γ = +/- (0.1-15)°. To keep parallelism between the planes less than 0.1° is practically unfeasible, while a decrease of inclination angle of the front panel of cone 4 in vertical and horizontal planes for more than 15° results to a significant gap in frequency response and the pair of loudspeakers 3 actually operate in an independent mode. As experiments have demonstrated, the above ration of coaxiality (Δ) to maximum characteristic dimension of radiating aperture (D) of cone 4 and to the distance between front panels of cones (S_lf) is optimal for different types of loudspeakers.
In a similar manner adjustment of the middle-frequency and high- frequency loudspeakers 10 and 16, respectively, in the section of the stand arranged above the section for adjustment of low-frequency loudspeakers 3 is carried out (not shown in the drawings).
After conducting of separate adjustment of loudspeakers 3, 10, and 16 at the stand the total adjustment of acoustic system us carried out which results from the necessity of checking out the summary frequency response (see Fig. 4) at the simultaneous operation of all three pairs of loudspeakers 3, 10, 16. The total adjustment of all three pairs of loudspeakers consists in the measurement of spectrum of the radiating frequency response in directions perpendicular to the axis along which the head of loudspeakers 3, 10, and 16 are mounted and which are not limited by their front panels, by means of the Clark Technic frequency spectrum analyzer. In the case of break down of the equalization (linearity) in the summary frequency response of the acoustic system which means the presence of splashes and gaps in it, the additional adjustment of separate pairs of operating heads of loudspeakers is carried out, after which the irregularity of the frequency response of the acoustic system will be minimal. The additional adjustment of the acoustic system brings about in the same manner as the adjustment of the separate different frequency loudspeaker. During the assembly of the acoustic system in dependence of chosen kind of heads of loudspeakers 3, 10, and 16 preliminary the brackets 8 and 14 are manufactured, and also frame 15 of the suitable dimensions. Then at distances fixed during adjustment on the stand the low-frequency loudspeakers 3 are mounted so that their front panels of cones 4 face each other, and disposed inside bodies 2 fastened to basement 1. After this on plates 7 of bodies 2 in a required place the bottom plates of brackets 8 are mounted and fastened, and the top plates of brackets 8 are connected to the down part of supporting ring 9 of middle-frequency loudspeakers 10, strictly following the distance between front panels of cones 11 of loudspeakers 10, as determined during adjustment. In frame 15 the high-frequency loudspeakers are mounted and fastened, strictly following the distance between front panels of cones 17 of loudspeakers 16, as determined during adjustment. Frame 15 with high-frequency loudspeakers 16 is mounted and fastened in the upper part of supporting ring 9 of middle-frequency loudspeakers 10. After the acoustic system has been assembled and checked for parallelism and coaxiality of the front panels of cones 4, 11, and 17, and also the distance between them, the checking of the system operation ability is carried out. In case the deviation of the frequency response from the required standard, a correction is carried out by means of displacement and fastening heads of loudspeakers in places, where the irregularity of summary frequency response of the acoustic system is minimal.
The acoustic system for sonification of enclosed and open spaces operates in the following manner.
To sound coils 5, 12, and 18 of cones 4, 11, and 17 of loudspeakers 3, 10, and 16 a sonic signal is supplied which can be produced directly from a microphone or any other carrier of record of any kind (not shown in the drawings). The sonic signal produces mechanical vibrations of sound coils 5, 12, and 18 of cones 4, 11, and 17, which is proportional, in an ideal case, to the sonic signal. In that ideal case all cones 4, 11, and 17 are vibrating in opposite directions along their own axis. Mechanical vibrations are converted to sonic oscillations of air particles which are spreading out in directions of pairwise opposite cones respectively. In the space between the cones facing each other the interference (superimposition) of the acoustic waves excited by them occurs, which leads to formation of secondary sound sources. These secondary sound sources lead in the environment to formation of sonic field acting in directions perpendicular to the axis along which the heads of loudspeakers 3, 10, and 16 are mounted and which are not limited by their front panels, possessing of a high naturalism and voluminosity of sounding. However, the latter could be achieved only in the case if the distances between front panels of cones 4, 11, and 17 are chosen so that the summary characteristics of formed secondary sound source has a minimal irregularity and also if the required parameters of parallelism and coaxiality of the front panels of cones 4, 11, and 17 are observed.

Industrial Applicability

The use of claimed method of sonification of enclosed and open spaces and an acoustic system for its embodiment permits to raise the quality of voluminous non-directional sounding with maximum achievement of naturalism of sound when the up-to-date and also morally obsolete heads of loudspeakers are used, to refrain from using any kinds of electric filters because the system itself represents a system of acoustic filters, which will lead to the decrease of acoustic pseudo stereo system costs.

Claims

A method of sonification of enclosed and open spaces including separation of spectral components of the electric signal corresponding to different frequency bands, conversion of the electric signals into acoustic ones by means of pair of in-phase connected main and additional heads of electroacoustic radiators providing coherent sonic waves and mounted in parallel and coaxially, with front panels facing each other and located at distances corresponding to different frequency bands, characterized in that the main and additional heads are mounted at distances correspondingly equal to 0.5-2.0 times of the distances where irregularity of frequency response is minimal within the given frequency band in directions perpendicular to axes of radiator head mounting and not limited by their front panels, while characteristic sensitivity of each additional radiator is selected to be 1-12 dB higher than that of each main radiator, and excessive sonic power supplied to the additional radiator heads is damped throughout an entire sonification stage.
A method of sonification according to (1) characterized in that the main and additional radiator heads with different frequency bands with their front panels facing each other are mounted in a single or in different planes relative to each other.
An acoustic system for sonification of enclosed and open spaces comprising paired main and additional electroacoustic radiator heads mounted on the basement and on the holders, respectively, with their front panels facing each other and positioned in parallel and coaxially, connected in pairs and in-phase to a source of electric signal with the frequency equal to that of the sonic signal, characterized in that the main and additional electroacoustic radiator heads are implemented as cased low-frequency, middle-frequency, and high-frequency cone loudspeakers located in pairs with their front panels facing each other; cases of the low-frequency loudspeakers are secured to the basement, the middle-frequency loudspeakers are secured to the holders fastened to the low-frequency loudspeakers' cases, and high-frequency loudspeakers are provided with a frame attached thereto, while the frame is attached to the middle-frequency loudspeakers by means of holders, and the ratio of distances between edges of front panels of low-frequency cones to that between the edges of front panels of middle-frequency and high-frequency loudspeakers is adopted, respectively, as $S_{lf} {: S}_{mf} {: S}_{hf} = 1 : (0.08 - 12.5) : (0.08 - 12.5)$

where
S_lf - distance between low-frequency transducer face panel edges;

S_mf - distance between middle-frequency transducer face panel edges; and

S_hf - distance between high-frequency transducer face panel edges;
the tolerance of parallelism of mounting of face panels of cones of the main and additional transducers facing each other in vertical and horizontal planes is adopted equal to γ = +/- (0.1-15)°, while the ratio of coaxiality of face cones of transducers mounted in vertical and horizontal planes to the maximum characteristic dimension between face panels of the transducers facing each other equals, respectively, $Δ : D : S = 1 : [+/-(0.002-0.1)] : [+/-(0.0007-0.02)]$
, where:
γ - tolerance in parallelism of mounting of face panels of cones of main and additional transducers facing each other;

D - maximum characteristic dimension of transducer cone face panel;

Δ - coaxiality of mounting of transducers' cones;

S - distance between front panels of transducers racing each other.
An acoustic system according to (3) characterized in that the mounting of cases of low-frequency loudspeakers, middle-frequency loudspeakers and high-frequency loudspeakers allows to adjust and secure their positions in vertical and horizontal planes relative to the basement, the low-frequency loudspeakers and the middle-frequency loudspeakers, respectively.