Directional-microphone and method for signal processing in same

1. A directional-microphone system, comprising:

a first figure-of-eight microphone and a second figure-of-eight microphone particularly arranged such that a major axis of the first figure-of-eight microphone and a major axis of the second figure-of-eight microphone extend in parallel with a first axis;

a third figure-of-eight microphone and a fourth figure-of-eight microphone particularly arranged such that a major axis of the third figure-of-eight microphone and a major axis of the fourth figure-of-eight microphone extend in parallel with a second axis, the first axis and the second axis being orthogonal to one another;

a fifth figure-of-eight microphone particularly arranged such that a major axis of the fifth figure-of-eight microphone extends orthogonal to the major axis of the first figure-of-eight microphone; and

a device for phase shifting connected downstream of two of the figure-of-eight microphones whose respective major axes extend orthogonal to one another.

2. A directional-microphone system as claimed in claim 1 , further comprising a control device connected to at least one of the arrangement of the first figure-of-eight microphone and the second figure-of-eight microphone, the arrangement of the third figure-of-eight microphone and the fourth figure-of-eight microphone, and the fifth figure-of-eight microphone, such that a respective major lobe orientation of the directional-microphone system can be varied.

3. A directional-microphone system as claimed in claim 1 , wherein the first figure-of-eight microphone and the fifth figure-of-eight microphone are particularly arranged such that the first figure-of-eight microphone and the fifth figure-of-eight microphone are adjacent to one another.

4. A directional-microphone system as claimed in claim 1 , wherein the first figure-of-eight microphone and the fifth figure-of-eight microphone are particularly arranged such that a center of the first figure-of-eight microphone and a center of the fifth figure-of-eight microphone are substantially coincident.

5. A directional-microphone system as claimed in claim 1 , wherein the second figure-of-eight microphone and the fifth figure-of-eight microphone are particularly arranged such that the second figure-of-eight microphone and the third figure-of-eight microphone are substantially coincident.

6. A directional-microphone system as claimed in claim 1 , wherein the second figure-of-eight microphone and the fifth figure-of-eight microphone are particularly arranged such that a center of the second figure-of-eight microphone and a center of the third figure-of-eight microphone are substantially coincident.

7. A directional-microphone system as claimed in claim 1 , wherein at least some of the figure-of-eight microphones are designed as pressure-gradient transducers.

8. A directional-microphone system as claimed in claim 7 , wherein at least some of the figure-of-eight microphones are respectively implemented by two spherical microphones arranged offset to one another.

9. A method for signal processing in a directional-microphone system, the method comprising the steps of:

driving a first arrangement of two figure-of-eight microphones with mutually parallel major axes such that a first received signal proportional to A*cos2(α) is obtained;

driving a second arrangement of two figure-of-eight microphones with mutually parallel major axes such that a second received signal proportional to B*sin 2 (α) is obtained;

driving a fifth figure-of-eight microphone with a major axis orthogonal to a figure-of-eight microphone of one of the first arrangement and the second arrangement such that a third received signal proportional to C*cos(α)*sin(α) is obtained;

driving a figure-of-eight microphone of the first arrangement and a figure-of-eight microphone of the second arrangement, the major axes of which extend orthogonal to one another, such that a fourth received signal proportional to D*cos(α)+E*sin(α) is obtained; and

phase-shifting the fourth received signal by 90° and linearly combining it with a sum of the first received signal, the second received signal and the third received signal, in each case weighted with factors, setting

A:=cos 2 (φ)

B:=sin 2 (φ)

C:=−2 cos(φ)*sin(φ)

D:=cos(φ)

E:=−sin(φ), and where

α:=a direction from which a sound wave is coming

φ:=desired direction of a major lobe of the directional-microphone system.

10. A method for signal processing in a directional-microphone system as claimed in claim 9 , the method further comprising the steps of:

linearly combining the first received signal and the second received signal such that a fifth received signal having a spherical directional-microphone pattern is formed; and

linearly combining the first received signal, the second received signal, the third received signal, the fourth received signal and the fifth received signal, weighted with factors.