
The invention relates to audio signals (in particular sound transducer signals) and devices or methods for their extraction, transmission, transformation and reproduction.

In general, such systems attempt to map or suggest spatial information to be clipped to the human ear. This can be achieved either by the reproduction of two or more differently designed end signals, by the addition of artificial first reflections or artificial diffuse sounds or by the simulation of human acoustic head related acoustic conditions by means of HRTF. These approaches are used, in particular, to convert monophonic audio signals into those which give the ear an actual or fictitious spatiality. Such methods are referred to as "pseudostereophon".

Pseudostereophonic signals generally show deficits compared to conventional stereo signals. In particular, for psychoacoustic reasons, the localizability of the sound sources, such as in methods that distribute the frequency spectrum differently phaseshifted distributed on the final signals, limited. The use of runtime differences also usually leads to contradictory localization for the same reasons. The artificial reverberation, also for psychoacoustic reasons, causes the listener to fatigue. A number of proposals have been made, in particular by Gerzon (see below), to eliminate such inconsistencies in the stereophonic imaging of sound sources. A representation of the original spatial conditions, how they are able to image conventional stereo signals, however, does not usually occur even in complex applications.

In particular, a pseudostereophony based on the simulation of intensitystereophonic methods has the particular problem that a monophonic audio signal based on achterricht characteristic can not be stereophonised, this due to the nonimaging of laterally incident sound.

The prior art form the following documents:
 US 5173944 observes at constant azimuth of 90 degrees, 120 degrees, 240 degrees and 270 degrees using HRTF from the differently delayed, but uniformly amplified fundamental signal obtained signals that are superimposed on the fundamental signal. Level and time corrections remain independent of the original recording situation.
 US 6636608 Depending on the frequency, it proposes certain phase shifts of the mono signal to be stereophonic, which are also different in their different  more independent from the recording situation!  Gain in both the left and right channels superimposed on the original monophonic audio signal.

Already mentioned document
US 5671287 (Gerzon) improves a method proposed by Orban (which obtains a sum and a difference signal from a monophonic audio signal, which have frequencydependent phase shifts  regardless of the recording situation!), These improvements also on frequencydependent phase shifts or on a  independent of the recording situation !  Reinforcement based on slight change in the formation of the sum or difference signal.

Own European application no.
06008455.5 proposes a methodical consideration of the manually or metrologically determined angle Phi, including the main axis and sound source, using timeofflight and level differences dependent on the angle Phi. If the angle Phi is equal to zero, however, a stereophonic mapping is not possible.

The invention explained below is intended to represent a significant improvement in the stereophonic reproduction of a monophonic imaged sound source, taking into account the recording situation. In addition, for the aforementioned, so far for intensity stereophonic simulations problematic Achtersrichtcharakteristik a reliable method of stereophonic be offered. Furthermore, a stereophonic image should also be made possible in the event that the angle Phi, the main axis and the sound source are equal to zero.

The subject invention can be represented as follows:
 The (in its own European application no. 06008455.5 proposed) technical solution of a methodological consideration of the angle Phi, the main axis and sound source include, using using the Phi dependent timeandlevel differences includes an MS matrixing, wherein for input signals M and S and resulting signals L and R the following relationships apply: $$L=\left(M+S\right)*\frac{1}{\sqrt{2}}$$ $$R=\left(MS\right)*\frac{1}{\sqrt{\mathrm{2}}}$$

The classic S signal, which is specific to the MS technique, has aftdirection characteristic, which is offset 90 degrees to the left of the M signal. If the level of the S signal is increased compared to the M signal, the socalled opening angle 2α (which results from the intersections of the overlapping polar diagrams of the M system or S system) decreases and, like the aft direction characteristic of the S signal, Systems  always symmetrical to the main axis of the M signal is) increasingly.

In a first step, a fictitious opening angle 2α can also be parameterized in an arrangement or a method which takes into account the angle Phi which the main axis of the monophonic signal and the sound source include. The calculated simulated side signal then depends on both the angle Phi and the half fictitious opening angle alpha.

In a second step, gain factors are applied only to the signals that, summed, give the side signal.

In a third step, the angledependent pole spacing f describing the directional characteristic of the M signals is parameterized. Thus, it is now possible to stereophonise monophonic signals of any directional characteristic, taking into account a fictitious opening angle 2α.
Disclosure of the invention

The invention consists in the parameterization of a fictitious opening angle α + β. Alpha represents here the fictitious left opening angle (lying left of the main axis of the stereophonic monophonic audio signal), Beta the notional right opening angle (right of the main axis of the stereophonizing monophonic audio signal), where α ≠ β. Thus, consideration is given to the case of possible unbalanced fictitious aperture angles α + β, which does not occur in classical MSmatrixing, with respect to the main axis of the monophonic audio signal to be stereophoned.

Accordingly, the trigonometrically determined level and transit time differences for the simulated side signal in addition to Phi and f are also made dependent on the fictitious left opening angle alpha or the fictitious right opening angle beta, where  if the sound source is to be classified left of the main axis  the relationship φ≤α or  if the sound source is to be placed to the right of the main axis  the relationship φ≤β. Exclude for alpha and beta is in any case zero or an environment of zero, since the calculated under parametrization of alpha or beta level or time differences converge to infinity, so are not technically feasible.

By a suitable choice of alpha and beta, a stereophonic mapping of a monophonic audio signal can thus be achieved, which offers generally more favorable conditions than methods which neglect a parameterization of a fictitious aperture angle α + β. In particular, a stereophonic resolution for the case of Phi equal to zero is possible. Alpha and Beta can be chosen freely under the above conditions or determined accordingly by a suitable algorithm.

Trigonometrically the angle Phi, the angledependent pole distance f describing the directional characteristic of the M signal, and the angles alpha and beta result in the following delay times L (alpha), L (beta) and gain factors P (alpha), P (beta) (the, to one to allow unrestricted choice of Phi, f as well as alpha and beta, to which the simulated side signal S resulting signals S (alpha) and S (beta) are to be applied):
$${L}_{\alpha}=\frac{f\left(\mathit{\alpha}\right)}{2\mathrm{sin}\mathit{\alpha}}+\sqrt{\frac{{f}^{2}\left(\mathit{\alpha}\right)}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{f}^{2}\left(\mathit{\phi}\right)\frac{f\left(\mathit{\alpha}\right)}{\mathrm{sin}\mathit{\alpha}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$ $${L}_{\mathit{\beta}}=\frac{f\left(\mathit{\beta}\right)}{2\mathrm{sin}\mathit{\beta}}+\sqrt{\frac{{f}^{2}\left(\mathit{\beta}\right)}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{f}^{2}\left(\mathit{\phi}\right)+\frac{f\left(\mathit{\beta}\right)}{\mathrm{sin}\mathit{\beta}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$ $${P}_{\mathit{\alpha}}=\frac{{f}^{2}\left(\mathit{\alpha}\right)}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{f}^{2}\left(\mathit{\phi}\right)\frac{f\left(\mathit{\alpha}\right)}{\mathrm{sin}\mathit{\alpha}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$ $${P}_{\mathit{\beta}}=\frac{{f}^{2}\left(\mathit{\beta}\right)}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{f}^{2}\left(\mathit{\phi}\right)+\frac{f\left(\mathit{\beta}\right)}{\mathrm{sin}\mathit{\beta}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$

A simplification for devices or methods, which take the subject of the invention as an opportunity, is the indication that the discriminants of L (alpha) and L (beta) are used directly for the determination of P (alpha) and P (beta) to let. Circuit diagrams or algorithms are thereby significantly simplified, which means a miniaturization of the corresponding hardware with maximum efficiency.

The following solution is derived, in particular, for the abovementioned problem of stereophonization of a monophonic audio signal with averaging characteristic, based on the pole spacing
f (ψ) = cosψ which describes the aftdirection characteristic of the M signal and is dependent on the polar angle ψ:
$${L}_{\mathit{\alpha}}=\frac{\mathrm{cos}\mathit{\alpha}}{2\mathrm{sin}\mathit{\alpha}}+\sqrt{\frac{{\mathrm{cos}}^{2}\mathit{\alpha}}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{\mathrm{cos}}^{2}\mathit{\phi}\frac{\mathrm{cos}\mathit{\alpha}}{\mathrm{sin}\mathit{\alpha}}*\mathrm{cos}\mathit{\phi}*\mathrm{sin}\mathit{\phi}}$$ $${L}_{\mathit{\beta}}=\frac{\mathrm{cos}\mathit{\beta}}{2\mathrm{sin}\mathit{\beta}}+\sqrt{\frac{{\mathrm{cos}}^{2}\mathit{\beta}}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{\mathrm{cos}}^{2}\mathit{\phi}+\frac{\mathrm{cos}\mathit{\beta}}{\mathrm{sin}\mathit{\beta}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$ $${P}_{\mathit{\alpha}}=\frac{{\mathrm{cos}}^{2}\mathit{\alpha}}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{\mathrm{cos}}^{2}\mathit{\phi}\frac{\mathrm{cos}\mathit{\alpha}}{\mathrm{sin}\mathit{\alpha}}*\mathrm{cos}\mathit{\phi}*\mathrm{sin}\mathit{\phi}$$ $${P}_{\mathit{\beta}}=\frac{{\mathrm{cos}}^{2}\mathit{\beta}}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{\mathrm{cos}}^{2}\mathit{\phi}+\frac{\mathrm{cos}\mathit{\beta}}{\mathrm{sin}\mathit{\beta}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$

It remains characteristic of the subject of the invention that the resulting MS signals must finally be subjected to a stereo reaction according to formulas (1) and (2). The result is a classic stereo signal.

Incidentally, including prior art apparatuses and methodologies, it is possible to obtain signals using the subject invention to provide stereophonic information through more than two speakers (such as the prior art surround systems).
Brief description of the illustrations

Embodiments and application examples of the present invention will be explained by way of example with reference to the following figures:
 FIG. 1 represents the operating principle of the European application no. 06008455.5 , dar.
 FIG. 2 represents a circuit according to European application no. 06008455.5 a monophonic audio signal is converted into MS signals that are stereophonize.
 FIG. 3 forms the internal signals of in FIG. 2 shown circuit.
 FIG. 4 represents a classic MS arrangement for half the opening angle alpha equal to 135 degrees, consisting of an Msystem with kidney characteristics and an Ssystem with Achtersrichtcharakteristik.
 FIG. 5 represents a classic MS arrangement for the half opening angle alpha equal to 90 degrees, consisting of an Msystem with ballshaped characteristic and an Ssystem with Achtersrichtcharakteristik.
 FIG. 6 represents a classic MS arrangement for half the opening angle Alpha equal to 53 degrees, consisting of an Msystem with kidney characteristics and an Ssystem with Achtersrichtcharakteristik.
 FIG. 7 represents a classic MS arrangement for the half opening angle Alpha equal to 45 degrees, consisting of an Msystem with Achterrichtcharakteristik and an Ssystem with Achterrichtcharakteristik.
 FIG. 8 represents a classic MS arrangement for the half opening angle Alpha equal to 33.5 degrees, also consisting of an Msystem with Achtersrichtcharakteristik and an Ssystem with Achterrichtcharakteristik.
 FIG. 9 represents an extension of the functional principle of European application no. 06008455.5 , in which a fictitious half opening angle alpha is taken into account.
 FIG. 10 represents a circuit under Considering a fictitious halfopening angle alpha, a monophonic audio signal is converted into MS signals that can be stereophonised.
 FIG. 11 exemplifies the principle of operation of the invention for a signal with omnidirectional characteristic, which includes a left fictitious opening angle alpha and a right fictitious opening angle beta, in a classical MS arrangement due to the use of a 90 degrees to the left symmetric to the main axis system Achtrichtcharakteristik for the S signal can not occur.
 FIG. 12 exemplifies the principle of operation of the invention for a cardioid signal.
 FIG. 13 exemplifies the principle of operation of the invention for a signal with hypercardioid characteristic.
 FIG. 14 exemplifies the principle of operation of the invention for a signal with Achtersrichtcharakteristik.
 FIG. 15 illustrates a circuit according to the subject invention, which, taking into account the acceptance angle Phi, a left fictitious opening angle alpha, a right fictitious Öffungswinkels beta and one, the directional characteristic of the M signal descriptive angledependent pole distance f a monophonic audio signal into MS signals that are stereophonize.
 FIG. 16 represents a variant to the circuit of FIG. 15 wherein, for the pickup angle Phi, the left fictitious opening angle alpha and the, the directional characteristic of the M signal descriptive angledependent pole distance f must apply to the expression $$\frac{{f}^{2}\left(\mathit{\alpha}\right)}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{f}^{2}\left(\mathit{\phi}\right)\frac{f\left(\mathit{\alpha}\right)}{\mathrm{sin}\mathit{\alpha}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$
not equal to zero or element of a zero environment.  FIG. 17 represents a further variant to the circuit of FIG. 15 in which the angle .delta. to the angle β must be the angle of acceptance Phi, the right fictitious aperture angle .beta., and the angledependent pole distance f describing the directional characteristic of the M signal must have the expression $$\frac{{f}^{2}\left(\mathit{\beta}\right)}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{f}^{2}\left(\mathit{\phi}\right)+\frac{f\left(\mathit{\beta}\right)}{\mathrm{sin}\mathit{\beta}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$
not equal to zero or element of a zero environment.  FIG. 18 represents the parameters t _{i} , P _{i} ( _{t} i) of FIG. 19 represents.
 FIG. 19 FIG. 3 illustrates the flowchart of a method according to the subject invention, taking into account the pickup angle Phi, a left fictitious opening angle alpha, a right fictitious opening angle beta and an angledependent pole spacing f describing the directional characteristic of the M signal at sufficiently small intervals [ t _{i} , t _{ i +1} ] converts a monophonic audio signal into MS signals that can be stereophonised.
Embodiments and application examples of the invention in detail

Outlined the state of the art in terms of the principle of operation of a device or a method for stereophoning a monophonic signal with omnidirectional characteristic FIG. 1 A sound source 101 is received at position 102 by a omnidirectional microphone, with major axis 103 and sounding axis 104 of the sound source including angle Phi (105). Figures 108 and 109 illustrate the geometric positioning of those two simulated signals that, when summed, yield the simulated side signal. The propagation time difference from the main signal for the simulated left signal represents 110, the level of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 101 and 112 (level correction taking into account the square of the distance decreasing sound intensity) , The transit time difference from the main signal for the simulated right signal represents 111, the level of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 101 and 113.

In a reweighting of the levels at which the input signal is directly assigned to the simulated left signal, the circuit diagram for the circuit which converts a monophonic input signal into MS signals which can be stereophonised results
FIG. 2 , Determined trigonometrically, this results in the transit time differences L
_{A} and L
_{B} and the gain factors P
_{A} and P
_{M} :
$${L}_{A}=\sqrt{\frac{5}{4}\mathrm{sin}\mathit{\phi}}\frac{1}{2}$$ $${L}_{B}=\sqrt{\frac{5}{4}+\mathrm{sin}\mathit{\phi}}\frac{1}{2}$$ $${P}_{M}=\frac{1}{\frac{5}{4}\mathrm{sin}\mathit{\phi}}$$ $${P}_{B}=\frac{\frac{5}{4}+\mathrm{sin}\mathit{\phi}}{\frac{5}{4}\mathrm{sin}\mathit{\phi}}$$

The nature of the internally processed signals FIG. 3 The main signal 316 is juxtaposed with two simulated signals 317 (with the delay time 310) and 318 (with the delay time 311) (where 314 represents the time axis and 315 represents the level axis). The maximum level point 302 is calculated from the maximum level point 312 according to the formula (15), the maximum level point 313 according to the formula (16).

To derive angledependent devices or methodologies for obtaining a pseudostereophonic audio signal, first of all the classical MSmatrixing for different halfaperture angles 2α and different directional characteristics of the Msystem is considered. Due to the symmetry of the S system rotated to the left by 90 degrees to the main axis of the M system, all methodologies have an opening angle 2α which is also symmetrical to the main axis and which is formed by the intersections of the overlapping polar diagrams of the M system or S system calculated.

For example FIG. 4 a classic MS arrangement for half the opening angle alpha (406) equal to 135 degrees, consisting of an M system with Kidney characteristics and an Ssystem with Achterrichtcharakteristik. FIG. 5 represents a classic MS arrangement for the half opening angle Alpha (506) equal to 90 degrees, consisting of an Msystem with balldirectional characteristics and an Ssystem with aftdirection characteristic. FIG. 6 represents a classic MS arrangement for the half opening angle Alpha (606) equal to 53 degrees, consisting of an Msystem with kidney characteristics and an Ssystem with Achtersrichtcharakteristik. FIG. 7 represents a classic MS arrangement for the half opening angle Alpha (706) equal to 45 degrees, consisting of an Msystem with Achterrichtcharakteristik and an Ssystem with Achterrichtcharakteristik. FIG. 8 represents a classic MS arrangement for half the opening angle Alpha (806) equal to 33.5 degrees, also consisting of an Msystem with Achterrichtcharakteristik and an Ssystem with Achterrichtcharakteristik.

An extension of the functional principle that is made up of FIG. 1 derives the additional consideration of a fictional halfopening angle alpha, as in FIG. 9 In this case, a sound source 901 is recorded by a monomicrophone 902 with a ballshaped characteristic, with the main axis 903 and the sighting axis 904 of the sound source enclosing the angle Phi (905). The fictitious half opening angle Alpha (906) is taken into account again. From this, the geometric positioning 908 of the simulated left signal S _{A} and the geometric positioning 909 of the simulated right signal S _{B} are directly derived (according to the principle that the distances of 902 and 908 or the distances of 902 and 909 are equal to that of FIG. the directional characteristic of the main signal descriptive pole distance for the angle to be alpha must) which, when summed, give the simulated side signal. The transit time difference from the main signal for the simulated left signal represents 910, the level of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 901 and 912 (level correction taking into account the square of the distance decreasing sound intensity) , The transit time difference from the main signal for the simulated right signal represents 911, the level of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 901 and 913.

The associated, opposite the circuit of the
FIG. 2 slightly modified, circuit delivers
FIG. 10 which converts a monophonic audio signal into MS signals, which can be stereophonised, taking into account the fictitious half opening angle alpha. For the time differences L
_{A} and L
_{B} and the gain factors P
_{A} and P
_{B} the following relationships apply:
$${L}_{A}=\frac{1}{2\mathrm{sin}\mathit{\alpha}}+\sqrt{\frac{1}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+1\frac{\mathrm{sin}\mathit{\phi}}{\mathrm{sin}\mathit{\alpha}}}$$ $${L}_{B}=\frac{1}{2\mathrm{sin}\mathit{\alpha}}+\sqrt{\frac{1}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+1+\frac{\mathrm{sin}\mathit{\phi}}{\mathrm{sin}\mathit{\alpha}}}$$ $${P}_{A}=\frac{1}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+1\frac{\mathrm{sin}\mathit{\phi}}{\mathrm{sin}\mathit{\alpha}}$$ $${P}_{B}=\frac{1}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+1+\frac{\mathrm{sin}\mathit{\phi}}{\mathrm{sin}\mathit{\alpha}}$$

Application of the subject invention to a main signal with omnidirectional characteristic:

A first application example of the invention based on a monophonic audio signal with omnidirectional characteristic shows FIG. 11 , Here, according to the invention, a fictitious opening angle α + β is parameterized, where alpha represents the fictitious left opening angle 1106 (lying to the left of the main axis of the stereophonic monophonic audio signal), Beta the fictitious right opening angle 1107 (right of the main axis of the monophonic to stereophonizing Audio signal)  ie angles that can not occur in a classical MS arrangement due to the use of a 90 degree to the left symmetric, symmetrical to the main axis Ssystem with achrichtcharakteristik.

Accordingly, the subject invention possibly leads to viewing the main axis of the monophonic audio signal to be stereophonised possibly asymmetrical fictitious aperture angle α + β.

In detail, the arrangement consists of a sound source 1101 received by a spherical omnidirectional monomicrophone 1102, with the microphone main axis 1103 and the sounding axis 1104 of the sound source including the angle Phi (1105). Furthermore, a fictitious left opening angle alpha is parametrized (1106) and a fictitious right opening angle beta (1107), whereby  if the sound source is to be classified left of the main axis  the relationship φ≤α or  if the sound source to the right of the main axis is to be classified  the relationship ψ≤β. In addition, for alpha and beta zero or zero environment must be excluded in each case (since the parameterization of Alpha or beta trigonometrically calculated level or time differences converge towards infinity, so are technically not feasible).

Alpha now determines exactly the geometrical positioning 1108 of the simulated left signal S (alpha) (according to the principle that the distance of 1102 and 1108 must be equal to the polar distance for the angle alpha describing the directional characteristic of the main signal) and beta exactly geometric positioning 1109 of the simulated right signal S (beta) (according to the principle that the distance of 1102 and 1109 must be equal to the pole characteristic for the angle beta describing the directional characteristic of the main signal) which, when summed, give the simulated side signal. The transit time difference L (alpha) versus the main signal for the simulated left signal represents 1110, the level P (alpha) of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 1101 and 1112 (level correction taking into account with the square of the distance decreasing sound intensity). The transit time difference L (beta) against the main signal for the simulated right signal represents 1111, the level P (beta) of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 1101 and 1113.

Trigonometrically, therefore, the following delay times L (alpha), L (beta) and gain factors P (alpha), P (beta) (which, to allow unrestricted choice of phi, alpha and beta, result in the simulated side signal S, signals S (alpha) and S (beta) are to be applied):
$${L}_{\mathit{\alpha}}=\frac{1}{2\mathrm{sin}\mathit{\alpha}}+\sqrt{\frac{1}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+1\frac{\mathrm{sin}\mathit{\phi}}{\mathrm{sin}\mathit{\alpha}}}$$ $${L}_{\mathit{\beta}}=\frac{1}{2\mathrm{sin}\mathit{\beta}}+\sqrt{\frac{1}{{4\mathrm{sin}}^{2}\mathit{\beta}}+1+\frac{\mathrm{sin}\mathit{\phi}}{\mathrm{sin}\mathit{\beta}}}$$ $${P}_{\mathit{\alpha}}=\frac{1}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+1\frac{\mathrm{sin}\mathit{\phi}}{\mathrm{sin}\mathit{\alpha}}$$ $${P}_{\mathit{\beta}}=\frac{1}{{4\mathrm{sin}}^{2}\mathit{\beta}}+1+\frac{\mathrm{sin}\mathit{\phi}}{\mathrm{sin}\mathit{\beta}}$$

Application of the subject invention to a main signal with renal directivity ( FIG. 12 ):

The arrangement under consideration here consists of a sound source 1201 which is picked up by a cardiogramshaped monomicrophone 1202, with the main microphone axis 1203 and the sounding axis 1204 of the sound source enclosing the angle Phi (1205). Furthermore, a fictitious left opening angle alpha is parameterized (1206) and a fictitious right opening angle beta (1207), whereby  if the sound source is to be arranged on the left of the main axis  the relation φ≤α must apply or  if the sound source to the right of the Main axis is  the relationship φ≤β. In addition, in each case zero or an environment of zero is to be excluded for alpha and beta (since the level or transit time differences calculated by parameterization of alpha or beta also converge towards infinity, ie are technically not feasible).

Alpha determines together with the nowdirectional characteristic for the main signal exactly the geometric positioning 1208 of the simulated left signal S (alpha) (according to the principle that the distance of 1202 and 1208 must be equal to the pole characteristic for the angle alpha describing the directional characteristic of the main signal) and beta also together with the directional characteristic considered here exactly the geometric positioning 1209 of the simulated right signal S (beta) (according to the principle that the distance of 1202 and 1209 must be equal to the pole spacing for the angle beta describing the directional characteristic of the main signal) which, when summed, give the simulated side signal. The transit time difference L (alpha) versus the main signal for the simulated left signal represents 1210, the level P (alpha) of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 1201 and 1212 (level correction taking into account with the square of the distance decreasing sound intensity). The transit time difference L (beta) against the main signal for the simulated right signal represents 1211, the level P (beta) of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 1201 and 1213.

Again, the following delay times L (alpha), L (beta) and gain factors P (alpha), P (beta), respectively, can be considered taking into account the polarangle ψdependent polar distance, which describes the renal direction characteristic of the M signal
$$f\left(\mathit{\psi}\right)=\frac{1}{2}\left(1+\mathrm{cos}\mathit{\psi}\right)$$ trigonometrically (with the gain factors  to allow unrestricted choice of phi, alpha, and beta with respect to the directional characteristic) to the, simulated side signal S, signals S (alpha) and S (beta) are to be applied):
$$\begin{array}{l}{L}_{\mathit{\alpha}}=\frac{\left(1+\mathrm{cos}\mathit{\alpha}\right)}{4\mathrm{sin}\mathit{\alpha}}+\sqrt{\frac{{\left(1+\mathrm{cos}\mathit{\alpha}\right)}^{2}}{{16\mathrm{sin}}^{2}\mathit{\alpha}}+\frac{1}{4}{\left(1+\mathrm{cos}\mathit{\phi}\right)}^{2}\frac{\left(1+\mathrm{cos}\mathit{\alpha}\right)}{4\mathrm{sin}\mathit{\alpha}}*\left(1+\mathrm{cos}\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}\\ {L}_{\mathit{\beta}}=\frac{\left(1+\mathrm{cos}\mathit{\beta}\right)}{4\mathrm{sin}\mathit{\beta}}\end{array}$$ $$+\sqrt{\frac{{\left(1+\mathrm{cos}\mathit{\beta}\right)}^{2}}{{16\mathrm{sin}}^{2}\mathit{\beta}}+\frac{1}{4}{\left(1+\mathrm{cos}\mathit{\phi}\right)}^{2}+\frac{\left(1+\mathrm{cos}\mathit{\beta}\right)}{4\mathrm{sin}\mathit{\beta}}*\left(1+\mathrm{cos}\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$ $${P}_{\mathit{\alpha}}=\frac{{\left(1+\mathrm{cos}\mathit{\alpha}\right)}^{2}}{{16\mathrm{sin}}^{2}\mathit{\alpha}}+\frac{1}{4}{\left(1+\mathrm{cos}\mathit{\phi}\right)}^{2}\frac{\left(1+\mathrm{cos}\mathit{\alpha}\right)}{4\mathrm{sin}\mathit{\alpha}}*\left(1+\mathrm{cos}\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$ $${P}_{\mathit{\beta}}=\frac{{\left(1+\mathrm{cos}\mathit{\beta}\right)}^{2}}{{16\mathrm{sin}}^{2}\mathit{\beta}}+\frac{1}{4}{\left(1+\mathrm{cos}\mathit{\phi}\right)}^{2}+\frac{\left(1+\mathrm{cos}\mathit{\beta}\right)}{4\mathrm{sin}\mathit{\beta}}*\left(1+\mathrm{cos}\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$

Application of the subject invention to a signal with hypercardioid characteristic ( FIG. 13 ):

The arrangement consists of a sound source 1301, which is picked up by a monomicrophone 1302 with hypercardioid polar pattern, with the microphone main axis 1303 and the sighting axis 1304 of the sound source enclosing the angle Phi (1305). Furthermore, a fictitious left opening angle alpha is parametrized (1306) and a fictitious right opening angle beta (1307), again  if the sound source is to be classified left of the main axis  the relation φ≤α must apply or  if the sound source to the right of the main axis is  the relationship φ≤β. Again, zero or an environment of zero can be excluded for alpha and beta in any case (since the levels or runtime differences calculated by parameterization of alpha or beta are trigonometrically calculated) Converge infinitely, that is technically not feasible).

Alpha in turn together with the hypercardioid characteristic of the main signal exactly determines the geometrical positioning 1308 of the simulated left signal S (alpha) (according to the principle that the distance of 1302 and 1108 must be equal to the pole distance for the angle alpha describing the directional characteristic of the main signal ), Beta together with the hypercardioid characteristic exactly the geometrical positioning 1309 of the simulated left signal S (beta) (according to the principle that the distance of 1302 and 1309 must be equal to the pole distance for the angle beta describing the directional characteristic of the main signal), which adds up to the simulated page signal. The transit time difference L (alpha) versus the main signal for the simulated left signal represents 1310, the level P (alpha) of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 1301 and 1312 (level correction taking into account with the square of the distance decreasing sound intensity). The transit time difference L (beta) against the main signal for the simulated right signal represents 1311, the level P (beta) of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 1301 and 1313.

The delay times L (alpha), L (beta) and amplification factors P (alpha), P (beta) are (taking into account the polar spacing, which is dependent on the polar angle ψ, describing the hyperemission characteristic of the M signal
$$f\left(\mathit{\psi}\right)=1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\psi}.$$ (where n is 1.5) to be trigonometrically calculated (where the amplification factors  to allow unrestricted choice of Phi, Alpha and Beta with respect to the directional characteristic  are applied to the signals S (alpha ) and S (beta)):
$${L}_{\mathit{\alpha}}=\frac{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\alpha}\right)}{2\mathrm{sin}\mathit{\alpha}}+\sqrt{\frac{{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\alpha}\right)}^{2}}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\phi}\right)}^{2}\frac{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\alpha}\right)}{\mathrm{sin}\mathit{\alpha}}*\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$ $${L}_{\mathit{\beta}}=\frac{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\beta}\right)}{2\mathrm{sin}\mathit{\beta}}+\sqrt{\frac{{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\beta}\right)}^{2}}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\phi}\right)}^{2}+\frac{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\beta}\right)}{\mathrm{sin}\mathit{\beta}}*\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$ $${P}_{\mathit{\alpha}}=\frac{{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\alpha}\right)}^{2}}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\phi}\right)}^{2}\frac{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\alpha}\right)}{\mathrm{sin}\mathit{\alpha}}*\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$ $${P}_{\mathit{\beta}}=\frac{{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\beta}\right)}^{2}}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\phi}\right)}^{2}+\frac{\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\beta}\right)}{\mathrm{sin}\mathit{\beta}}*\left(1\frac{n}{2}+\frac{n}{2}*\mathrm{cos}\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$

Application of the subject invention to signals with other special forms of a cardioid characteristic:

If the input signal to be stereophonised has special forms of the cardioid characteristic, the corresponding transit time differences L (alpha) and L (beta) or amplification factors P (alpha) and P (beta) from the formulas (29) to (32) can be easily calculated. 0≤ n ≤2: this is true for n.

If n is 1, the gain factors or propagation time differences result for an input signal with a classical refractive index characteristic, for the value 0 those for an input signal with a ballshaped characteristic, for the value 2 those for an input signal with a conventional aftereffect characteristic. If n is 1.25, the propagation time differences or gain factors for a supercardioid input signal result.

The application of the formula (28a) to the polar distance f, which leads to the formula apparatus (29) to (32), proves to be particularly favorable. All that remains to be determined is the parameter n to describe almost all possible directional characteristics for the M signal, expressed in polar coordinates (except for the lobe characteristic, which has increasingly different polar coordinates with increasing frequency than it is able to represent (28a)).

Application of the subject invention to a signal with Achterrichtcharakteristik:

FIG. 14 illustrates in detail the application for an input signal with Achrichtrichtcharakteristik, which has already been discussed several times above. The arrangement consists of a sound source 1401, which is recorded by a monomicrophone 1402 with achterrichtcharakteristik, the main microphone axis 1403 and the bearing axis 1404 of the sound source the Include angle Phi (1405). A fictitious left opening angle alpha is parametrised (1406) and a fictitious right opening angle beta (1407), whereby  if the sound source is to be arranged on the left of the main axis  the relation φ≤α must apply or  if the sound source is to the right of the main axis is to be classified  the relationship φ≤β. Furthermore, zero or an environment of zero is to be excluded in any case for alpha and beta (since the levels or time differences calculated trigonometrically under parameterization of alpha or beta also converge towards infinity, ie are technically not feasible).

Alpha, together with the achterrichtcharakteristik the main signal exactly the geometric positioning 1408 of the simulated left signal S (alpha) (according to the principle that the distance of 1402 and 1408 must be equal to the, the directional characteristic of the main signal, pole distance for the angle alpha) Beta together with the Achtersrichtcharakteristik exactly the geometric positioning 1409 of the simulated right signal S (beta) (according to the principle that the distance of 1402 and 1409 must be equal to the directional characteristic of the main signal, pole distance for the angle beta), which sums up the simulated page signal. The Runtime difference L (alpha) versus the main signal for the simulated left signal represents 1410, the level P (alpha) of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 1401 and 1412 (level correction in consideration of FIG the square of the distance decreasing sound intensity). The transit time difference L (beta) against the main signal for the simulated right signal represents 1411, the level P (beta) of the simulated signal is determined from the level of the main signal multiplied by the square of the distance of 1401 and 1413. The associated formula apparatus for The delay times L (alpha), L (beta) and the gain factors P (alpha), P (beta) can be found in equations (7) to (10), or equations (29) to (32), if n equals 2 (the gains  to allow unrestricted choice of Phi, Alpha, and Beta with respect to the directional characteristic  apply to the simulated side signal S, S (alpha) and S (beta) signals) ,

Application of the subject of the invention to a stereophononization circuit of a mono signal:

FIG. 15 represents a, the directional characteristic of the input signal generalized circuit according to the subject invention, taking into account the acceptance angle Phi, a left fictitious opening angle alpha, a right fictitious Öffungswinkels beta and the directional characteristic of the M signal descriptive angledependent pole spacing f a monophonic audio signal in MS signals that can be stereophonized. For the time differences L (alpha) and L (beta) or the gain factors P (alpha) and P (beta), the formulas (3) to (6) are to be used. The input signal is used directly as an M signal. The S signal is added from the one around the Delay time L (alpha) delayed input signal, which is subsequently amplified by the amplification factor P (alpha), and another signal representing the delayed by the delay time L (beta) input signal, then amplified by the gain P (beta). Again  if φ≻0  the relation φ≤α or  if φ ◁ 0  the relation φ≤β. Likewise, zero or an environment of zero must be excluded for alpha or beta in any case (since the levels or time differences calculated trigonometrically under parameterization of alpha or beta converge towards infinity, ie are technically not feasible).

Derivatives of circuits that provide equivalent signals with slight restrictions:

Out
FIG. 15 If the gain factors are rebalanced, a slightly restricted circuit of the form can be used
FIG. 16 derived. The restriction consists in the condition that for the acceptance angle Phi, the left fictitious aperture angle alpha and the angledependent pole distance f describing the directional characteristic of the M signal, the expression
$$\frac{{f}^{2}\left(\mathit{\alpha}\right)}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{f}^{2}\left(\mathit{\phi}\right)\frac{f\left(\mathit{\alpha}\right)}{\mathrm{sin}\mathit{\alpha}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$ not equal to zero or element of a zero environment. In the
FIG. 16 mentioned time differences L (alpha) and L (beta) represent directly equations (3) and (4); for the amplification factors P
_{M} 'and P (Beta)', the relationships apply
$${P}_{M}\text{'}=\frac{1}{\frac{{f}^{2}\left(\mathit{\alpha}\right)}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{f}^{2}\left(\mathit{\phi}\right)\frac{f\left(\mathit{\alpha}\right)}{\mathrm{sin}\mathit{\alpha}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$ $${P}_{\mathit{\beta}}\text{'}=\frac{\frac{{f}^{2}\left(\mathit{\beta}\right)}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{f}^{2}\left(\mathit{\phi}\right)+\frac{f\left(\mathit{\beta}\right)}{\mathrm{sin}\mathit{\beta}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}{\frac{{f}^{2}\left(\mathit{\alpha}\right)}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{f}^{2}\left(\mathit{\phi}\right)\frac{f\left(\mathit{\alpha}\right)}{\mathrm{sin}\mathit{\alpha}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$

In addition  if ψ≻0  the relation φ≤α must apply, or  if φ≺0  the relation φ≤β. Again, zero or an environment of zero can be excluded for each alpha or beta (since the levels or runtime differences calculated trigonometrically under parameterization of alpha or beta partly converge towards infinity, ie are technically unrealizable).

A second derivative
FIG. 15 if the reweighting of the gain factors is changed, a circuit which also operates in a slightly restricted manner results in the shape
FIG. 17 , wherein for the acceptance angle Phi, the right fictitious aperture angle beta and the, the directional characteristic of the M signal descriptive angledependent pole distance f must apply that the expression
$$\frac{{f}^{2}\left(\mathit{\beta}\right)}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{f}^{2}\left(\mathit{\phi}\right)+\frac{f\left(\mathit{\beta}\right)}{\mathrm{sin}\mathit{\beta}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}$$ not equal to zero or element of a zero environment. In the
FIG. 17 In this case, time differences L (alpha) and L (beta) again represent the equations (3) and (4); for the amplification factors P
_{M} '' and P (alpha) ', however, the relationships now apply
$${P}_{M}\mathrm{\text{'}\text{'}}=\frac{1}{\frac{{f}^{2}\left(\mathit{\beta}\right)}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{f}^{2}\left(\mathit{\phi}\right)+\frac{f\left(\mathit{\beta}\right)}{\mathrm{sin}\mathit{\beta}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$ $${P}_{\mathit{\alpha}}\text{'}=\frac{\frac{{f}^{2}\left(\mathit{\alpha}\right)}{{4\mathrm{sin}}^{2}\mathit{\alpha}}+{f}^{2}\left(\mathit{\phi}\right)\frac{f\left(\mathit{\alpha}\right)}{\mathrm{sin}\mathit{\alpha}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}{\frac{{f}^{2}\left(\mathit{\beta}\right)}{{4\mathrm{sin}}^{2}\mathit{\beta}}+{f}^{2}\left(\mathit{\phi}\right)+\frac{f\left(\mathit{\beta}\right)}{\mathrm{sin}\mathit{\beta}}*f\left(\mathit{\phi}\right)*\mathrm{sin}\mathit{\phi}}$$ Again, if φ≻0  the relation φ≤α, or  if φ≺0  the relation φ≤β. In the same way, zero or an environment of zero must be excluded for each alpha or beta (since the levels or runtime differences calculated trigonometrically under parameterization of alpha or beta partly converge towards infinity, ie are technically unrealizable).

Application of the Subject of the Invention to a Computational Method for the Stereophonization of a Mono Signal:

A monophonic input signal can be obtained with the aid of a coordinate system of the form FIG. 18 arithmetically, where 1814 is the time axis, and 1815 the level axis. 1819 represents the time t _{i} , 1820 the level point P _{i} (t _{i} ) which correlates with t _{i} . For sufficiently small intervals [ t _{i} , t _{ i +1} ], ie a sufficient sampling rate, the sound event can now be mapped with sufficient accuracy.

FIG. 19 FIG. 4 illustrates the associated flow chart of a method according to the subject invention, taking into account the pickup angle Phi, a left fictitious opening angle alpha, a right fictitious opening angle beta and one, the Directional characteristic of the Msignal descriptive angledependent pole spacing f at sufficiently small intervals [ t _{i} , t _{ i +1} ] a monophonic audio signal into MS signals that can be stereophonized.

For the time differences L (alpha) and L (beta) or the gain factors P (alpha) and P (beta), the equations (3) to (6) apply in turn.

An Msignal (of the array [ M _{i} ( t _{i} )]) and an Ssignal (of the array [ S _{i} ( t _{i} )]) which is in fact calculated from the input signal delayed by the delay time L (alpha) are calculated , which is subsequently amplified by the amplification factor P (alpha), and a further signal which represents the input signal which is actually delayed by the delay time L (beta), and then amplified by the amplification factor P (beta). The algorithm excludes inadmissible values of alpha and beta. Again  if φ≻0  the relation φ≤α or  if φ≺0  the relation φ≤β. Likewise, zero or an environment of zero must be excluded for alpha or beta in any case (since the levels or time differences calculated trigonometrically under parameterization of alpha or beta converge towards infinity, ie are technically not feasible).

Derivatives of two computational methods that provide equivalent signals with slight restrictions:

Method 1: Provided that the algorithm (33) does not equal zero or an element of a zero environment, a monophonic input signal can be provided for sufficiently small ones Intervals [ t _{i} , t _{ i +1} ] FIG. 19 analogous calculation method based on FIG. 16 however, now the M signal (the array [ M _{i} ( t _{i} )]) appears to be amplified by the factor (34). The S signal (the array [ S _{i} ( t _{i} )]) represents the result of the addition of the input signal (the array [ P _{i} ( t _{i} )] actually delayed by the delay time L (alpha) (see formula (3)). ) with the input signal actually delayed by the delay time L (beta) (see formula (4) and subsequently amplified by the factor P (beta) '(see formula (35)) (again the array [ P _{i} ( t _{i} )]) The algorithm must exclude impermissible values of alpha and beta: If φ≻0, then the relation φ≤α or  if φ≺0  the relation φ≤β must apply, and in any case for alpha or beta Zero or an environment of zero excluded (since the parameterized by parameterization of alpha or beta trigonometrically calculated level or runtime differences partially converge to infinity, so technically not feasible).

Method 2: If it remains algoritmically ensured that (36) is not equal to zero or an element of an environment of zero, a monophonic input signal for sufficiently small intervals [ t _{i} , t _{ i +1} ] can also be added FIG. 19 analogous calculation method in £ based on FIG. 17 now the Msignal (the array [ M _{i} ( t _{i} )]) appears to be amplified by the factor (37). The S signal (of the array [ S _{i} ( t _{i} )]) represents the result of the addition of the actual delayed by the delay time L (alpha) (see formula (3)) and then by the gain P (alpha) '(see Formula (38) of amplified input signal (the array [ P _{i} ( t _{i} )]) with the input signal actually delayed by the delay time L (Beta) (see formula (4) (again the Array [ P _{i} ( t _{i} )]). The algorithm must exclude impermissible values of alpha and beta: If φ≻0, the relation φ≤α must apply or  if ψ≺0  the relation φ≤β. In the same way, zero or an environment of zero can be excluded for alpha and beta in any case (since the levels or runtime differences calculated trigonometrically under parameterization of alpha or beta sometimes converge towards infinity, ie remain technically unrealizable).

Overall, the devices and methods described, of course, also allow the gain of the respective input signal before a subsequent delay is executed.
Examples of applications for the invention

The spatial breakdown of a sound source recorded at a certain angle Phi has great practical significance, in particular for telephone signals. In handsfree devices, such as those used in automobiles or in Internet telephony, the radiated monophonic signal as the real conversation situation is not felt accordingly, the opposite appears "omnipresent". However, if the angle Phi is determined using stateoftheart metrological methods, or the polar coordinates are functionally interpolated (possible by algoritmic consideration of the maxima and minima of the polar diagram of the input signal), the fictitious left aperture angle alpha and the fictitious right aperture angle are subsequently determined Beta algoritmisch or manually adapted to the recording and listening situation, can be about using a (miniaturizable!) Circuit of the form FIG. 15 conclude with MS matrixing to achieve a stereophonic signal that takes a conversation situation under natural conditions much higher wearing.

A similar procedure can be used for monophonic sound recordings in which a single sound source is to be stereophonically reproduced or one sound source monophonic and another stereophone (this is possible if the angle Phi equals zero for a sound source).

Likewise, if the imaging direction of a signal source insulated sound source within a stereo image is perceived as being too sharp, the imaging direction can be gradually dispersed using the subject invention.

The shaping of the directional characteristic of the input signal (selectively possible by varying the polar coordinates describing the directional characteristic of the input signal, comprising, for example, the application of comb filters in connection with Fast Fourier Transformation (FFT) based methods, which belongs to the prior art) Going through an arrangement or a method according to the subject invention may possibly improve the result or to provide for a normalization of the directional characteristic of the input signal.

Overall, the invention is able to make a decisive contribution to the subsequent multidimensional consideration of signal paths. Your application therefore does not remain limited to the above examples.