CA2404863C - Method for providing the transmission characteristics of a microphone arrangement and microphone arrangement - Google Patents
Method for providing the transmission characteristics of a microphone arrangement and microphone arrangement Download PDFInfo
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- CA2404863C CA2404863C CA002404863A CA2404863A CA2404863C CA 2404863 C CA2404863 C CA 2404863C CA 002404863 A CA002404863 A CA 002404863A CA 2404863 A CA2404863 A CA 2404863A CA 2404863 C CA2404863 C CA 2404863C
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/005—Circuits for transducers, loudspeakers or microphones for combining the signals of two or more microphones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
- H04R25/40—Arrangements for obtaining a desired directivity characteristic
- H04R25/407—Circuits for combining signals of a plurality of transducers
Abstract
Two output signals (A1a and A1b) of a microphone arrangement (1) are divided (7), whereby said signals are dif-ferently dependent on the direction of incidence (.PHI.) of acoustic signals. A product from the division result (A7) and the weighting factor (.alpha.) is saturated (12) and subtracted from a signal value (A) which can be inputted. The subtraction result is multiplied with the output signal of the microphone arrangement (1) which is the denominator signal for the division (7). A desired directivity is produced between the result signal (S out) of the multiplication and the direction of incidence (.PHI.) on the microphone arrangement (1) of incident acoustic signals according to the weighting factor (.alpha.) of the saturation value (B) and of the subtraction value (A).
Description
METHOD FOR PROVIDING THE TRANSMISION CHARACTERISTICS OF A
MICROPHONE ARRANGEMENT AND MICROPHONE ARRANGEMENT
The present invention relates to a microphone arrangement and to a method for establishing a desired transfer characteristic which converts an acoustical input signal impinging on the microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement.
There is frequently a need in the technology for the reception and processing of acoustic signals to implement microphone arrangements having a transmission characteristic that generate the electric output signal as a prescribed or prescribable function of the direction of incidence of the acoustic signals. In particular, there is a need in,this case to implement microphone arrangements having a characteristic directed in a prescribed or prescribable fashion, in the case of which arrangements acoustic signals from prescribed directional ranges act more strongly, while those from other directional ranges act less strongly on the output signal, up to arrangements with a reception characteristic focused virtually in one direction.
Multifarious modes of procedure are known for implementing such transmission characteristics. Purely by way of example, reference may be made in this regard to PCT application published under publication number W099/04598 (cp multiplication), or to PCT
application published under publication number W099/09786 (cp filtering) of the same applicant, in accordance with which desired transmission characteristics of microphone arrangements are obtained in principle from the phase shift of acoustic signals arriving at microphone arrangements and their specific processing.
It is an object of the present invention to propose a further procedure in order to implement a desired transmission characteristic in the above sense.
According to the present invention, there is provided a method for establishing a desired transfer characteristic which converts an acoustical input signal impinging on a microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement, said method comprising the steps of:
providing at said microphone arrangement a first microphone sub-arrangement and a second microphone sub-arrangement, each microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said microphone sub-arrangements into an electric output signal of the respective sub-arrangement, said transfer characteristics of said first microphone sub-arrangements being different from said transfer characteristic of said second microphone sub-arrangement with respect to said acoustical input signal;
forming a ratio of said output signals of said first and second microphone sub-arrangements, thereby generating a ratio result;
-2a-forming a saturated product with said ratio result as one factor, thereby clipping said product at a predetermined or predeterminable value and generating a saturated product result; and generating said electric output signal as a function of said saturated product result.
According to the present invention, there is also provided a method for establishing a desired transfer characteristic which converts acoustical input signals impinging on a microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement, said method comprising the steps of:
providing at said microphone arrangement at least two microphone sub-arrangements, each microphone sub-arrangement having a transfer characteristic which converts said acoustical input signals impinging on said microphone sub-arrangements into an electric output signal of a respective sub-arrangement, said transfer characteristics of said at least two microphone sub-arrangements being different;
forming a ratio of said output signals of said at least two sub-arrangements, thereby generating a ratio result;
forming a saturated product with said ratio result as one factor, thereby performing saturating said product at a predetermined or predeterminable value and generating a saturated product result;
generating said electric output signal as a function of said saturated product result.
According to the present invention, there is also provided a method for establishing a desired transfer characteristic which converts an acoustical input signal impinging on a microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement, said method comprising the steps of:
at said microphone arrangement providing:
- 2b -a first microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said first microphone into an output signal represented by c,,; and a second microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said second microphone into an output signal represented by cZ; and generating said electric output signal according to the equation:
l s -l (A -la f- ICz1 1 cJ n I satB
wherein:
S is said electric output signal, A is a predetermined or adjusted value, ICn I is the amplitude value of the output signal c,,, ICZI is the amplitude value of the output signal cZ, satB is the saturation of the product [] to a predetermined or adjusted minimum or maximum value B, and a is a predetermined or adjustable factor.
When "saturation" is spoken of within the scope of the present application, this means that the value of a mathematical function under consideration is clipped starting from when a prescribed value is reached, so that, as against the course of a mathematical function, it remains constant starting from when this value is reached.
Although a saturation of the product mentioned, that is to say the weighted quotient, to a minimum value can by all means be sensible, it is preferably proposed that the product in any event also be saturated to a maximum value.
In what follows, the second factor of the saturated product can assume an arbitrary non-vanishing value, and thus certainly also the value 1.
In a further preferred embodiment, it is proposed that the function mentioned comprises a difference between a constant - settable, if appropriate - and the saturated product, the value of the constant preferably being selected to be at least approximately equal to the saturation value.
Furthermore, the quotient mentioned is preferably determined from the amplitude values of the output signals without taking account of their phase angle.
In a particularly preferred embodiment of the method according to the invention, the quotient mentioned is used within the scope of the following function:
S=cn, A- a =IcZI
I~ N ~ satB
in which S signifies the output signal of the microphone arrangement A signifies a prescribed or prescribable signal value ICN I signifies the amplitude value of the output signal of a first microphone sub-arrangement whose transmission characteristic exhibits maximum gain for one angle of incidence where the characteristic to be formed is also to exhibit maximum gain IcZ1 signifies the amplitude value of the output signal of the second microphone sub-arrangement satB signifies a saturation of the quotient to a prescribed or prescribable maximum signal value B
a signifies a prescribable or prescribed factor.
In a particularly preferred embodiment, in particular within the scope of the use of the method according to the invention for hearing devices, the transmission characteristics of the microphone sub-arrangements are selected such that they respectively exhibit maximum signal gains for acoustic signals incident from substantiallv inverse directions...
According to the present invention, there is also provided a microphone arrangement comprising:
two microphone sub-arrangements each having an output, each of said microphone sub-arrangements also having a respective transfer characteristic with which acoustical input signal impinging on said microphone sub-arrangements are converted into respective electrical output signals at said outputs as a function of the angle at which said acoustical input signals impinge on said microphone sub-arrangements, said transfer characteristics of said microphone sub-arrangements being different with respect to said acoustical input signal;
a computing unit having at least two inputs and an output, said outputs of said microphone sub-arrangements being respectively operationally connected to said inputs of said computing unit, said computing unit including:
a ratio forming and weighing unit having an output, a denominator input, a numerator input and a weighing input, wherein - 5a -one of said inputs of said computing unit is operationally connected to said denominator input, and wherein the other of said inputs of said computing unit is operationally connected with said numerator input, and further wherein said ratio forming and weighing unit generates at said output an output signal saturated at a maximum or minimum value, the output of said ratio forming and weighing unit being operationally connected to the output of said microphone arrangement.
According to the present invention, there is also provided a microphone arrangement comprising:
a first microphone sub-arrangement having a first output in the time domain having a first transfer characteristic with respect to an impinging acoustic signal;
a second microphone sub-arrangement having a second output in the time domain having a second transfer characteristic with respect to an impinging acoustic signal, wherein said first transfer characteristic and said second transfer characteristic are different;
a first time to frequency converter unit for converting said first output into a first frequency domain signal;
a second time to frequency converter unit for converting said second output into a second frequency domain signal;
a computing unit having a first input, a second input, and an output, wherein said frequency domain signals of said time to frequency converter units are connected to said inputs of said computing unit, respectively, wherein said computing unit generates a ratio signal that is proportional to an amplitude or an absolute value of one of said first and second frequency domain signals, and further wherein - 5b -said ratio signal is inversely proportional to an amplitude or an absolute value of the other of said first and second frequency domain signals, and still further wherein said ratio forming and weighing unit multiplies said ratio signal by a non-zero value to create a weighted ratio; and wherein said ratio forming and weighing unit generates a saturated signal by clipping said weighted ratio at a maximum or minimum value.
MICROPHONE ARRANGEMENT AND MICROPHONE ARRANGEMENT
The present invention relates to a microphone arrangement and to a method for establishing a desired transfer characteristic which converts an acoustical input signal impinging on the microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement.
There is frequently a need in the technology for the reception and processing of acoustic signals to implement microphone arrangements having a transmission characteristic that generate the electric output signal as a prescribed or prescribable function of the direction of incidence of the acoustic signals. In particular, there is a need in,this case to implement microphone arrangements having a characteristic directed in a prescribed or prescribable fashion, in the case of which arrangements acoustic signals from prescribed directional ranges act more strongly, while those from other directional ranges act less strongly on the output signal, up to arrangements with a reception characteristic focused virtually in one direction.
Multifarious modes of procedure are known for implementing such transmission characteristics. Purely by way of example, reference may be made in this regard to PCT application published under publication number W099/04598 (cp multiplication), or to PCT
application published under publication number W099/09786 (cp filtering) of the same applicant, in accordance with which desired transmission characteristics of microphone arrangements are obtained in principle from the phase shift of acoustic signals arriving at microphone arrangements and their specific processing.
It is an object of the present invention to propose a further procedure in order to implement a desired transmission characteristic in the above sense.
According to the present invention, there is provided a method for establishing a desired transfer characteristic which converts an acoustical input signal impinging on a microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement, said method comprising the steps of:
providing at said microphone arrangement a first microphone sub-arrangement and a second microphone sub-arrangement, each microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said microphone sub-arrangements into an electric output signal of the respective sub-arrangement, said transfer characteristics of said first microphone sub-arrangements being different from said transfer characteristic of said second microphone sub-arrangement with respect to said acoustical input signal;
forming a ratio of said output signals of said first and second microphone sub-arrangements, thereby generating a ratio result;
-2a-forming a saturated product with said ratio result as one factor, thereby clipping said product at a predetermined or predeterminable value and generating a saturated product result; and generating said electric output signal as a function of said saturated product result.
According to the present invention, there is also provided a method for establishing a desired transfer characteristic which converts acoustical input signals impinging on a microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement, said method comprising the steps of:
providing at said microphone arrangement at least two microphone sub-arrangements, each microphone sub-arrangement having a transfer characteristic which converts said acoustical input signals impinging on said microphone sub-arrangements into an electric output signal of a respective sub-arrangement, said transfer characteristics of said at least two microphone sub-arrangements being different;
forming a ratio of said output signals of said at least two sub-arrangements, thereby generating a ratio result;
forming a saturated product with said ratio result as one factor, thereby performing saturating said product at a predetermined or predeterminable value and generating a saturated product result;
generating said electric output signal as a function of said saturated product result.
According to the present invention, there is also provided a method for establishing a desired transfer characteristic which converts an acoustical input signal impinging on a microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement, said method comprising the steps of:
at said microphone arrangement providing:
- 2b -a first microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said first microphone into an output signal represented by c,,; and a second microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said second microphone into an output signal represented by cZ; and generating said electric output signal according to the equation:
l s -l (A -la f- ICz1 1 cJ n I satB
wherein:
S is said electric output signal, A is a predetermined or adjusted value, ICn I is the amplitude value of the output signal c,,, ICZI is the amplitude value of the output signal cZ, satB is the saturation of the product [] to a predetermined or adjusted minimum or maximum value B, and a is a predetermined or adjustable factor.
When "saturation" is spoken of within the scope of the present application, this means that the value of a mathematical function under consideration is clipped starting from when a prescribed value is reached, so that, as against the course of a mathematical function, it remains constant starting from when this value is reached.
Although a saturation of the product mentioned, that is to say the weighted quotient, to a minimum value can by all means be sensible, it is preferably proposed that the product in any event also be saturated to a maximum value.
In what follows, the second factor of the saturated product can assume an arbitrary non-vanishing value, and thus certainly also the value 1.
In a further preferred embodiment, it is proposed that the function mentioned comprises a difference between a constant - settable, if appropriate - and the saturated product, the value of the constant preferably being selected to be at least approximately equal to the saturation value.
Furthermore, the quotient mentioned is preferably determined from the amplitude values of the output signals without taking account of their phase angle.
In a particularly preferred embodiment of the method according to the invention, the quotient mentioned is used within the scope of the following function:
S=cn, A- a =IcZI
I~ N ~ satB
in which S signifies the output signal of the microphone arrangement A signifies a prescribed or prescribable signal value ICN I signifies the amplitude value of the output signal of a first microphone sub-arrangement whose transmission characteristic exhibits maximum gain for one angle of incidence where the characteristic to be formed is also to exhibit maximum gain IcZ1 signifies the amplitude value of the output signal of the second microphone sub-arrangement satB signifies a saturation of the quotient to a prescribed or prescribable maximum signal value B
a signifies a prescribable or prescribed factor.
In a particularly preferred embodiment, in particular within the scope of the use of the method according to the invention for hearing devices, the transmission characteristics of the microphone sub-arrangements are selected such that they respectively exhibit maximum signal gains for acoustic signals incident from substantiallv inverse directions...
According to the present invention, there is also provided a microphone arrangement comprising:
two microphone sub-arrangements each having an output, each of said microphone sub-arrangements also having a respective transfer characteristic with which acoustical input signal impinging on said microphone sub-arrangements are converted into respective electrical output signals at said outputs as a function of the angle at which said acoustical input signals impinge on said microphone sub-arrangements, said transfer characteristics of said microphone sub-arrangements being different with respect to said acoustical input signal;
a computing unit having at least two inputs and an output, said outputs of said microphone sub-arrangements being respectively operationally connected to said inputs of said computing unit, said computing unit including:
a ratio forming and weighing unit having an output, a denominator input, a numerator input and a weighing input, wherein - 5a -one of said inputs of said computing unit is operationally connected to said denominator input, and wherein the other of said inputs of said computing unit is operationally connected with said numerator input, and further wherein said ratio forming and weighing unit generates at said output an output signal saturated at a maximum or minimum value, the output of said ratio forming and weighing unit being operationally connected to the output of said microphone arrangement.
According to the present invention, there is also provided a microphone arrangement comprising:
a first microphone sub-arrangement having a first output in the time domain having a first transfer characteristic with respect to an impinging acoustic signal;
a second microphone sub-arrangement having a second output in the time domain having a second transfer characteristic with respect to an impinging acoustic signal, wherein said first transfer characteristic and said second transfer characteristic are different;
a first time to frequency converter unit for converting said first output into a first frequency domain signal;
a second time to frequency converter unit for converting said second output into a second frequency domain signal;
a computing unit having a first input, a second input, and an output, wherein said frequency domain signals of said time to frequency converter units are connected to said inputs of said computing unit, respectively, wherein said computing unit generates a ratio signal that is proportional to an amplitude or an absolute value of one of said first and second frequency domain signals, and further wherein - 5b -said ratio signal is inversely proportional to an amplitude or an absolute value of the other of said first and second frequency domain signals, and still further wherein said ratio forming and weighing unit multiplies said ratio signal by a non-zero value to create a weighted ratio; and wherein said ratio forming and weighing unit generates a saturated signal by clipping said weighted ratio at a maximum or minimum value.
Preferred design variants of the microphone arrangement according to the invention are specified in claims 10 to 18.
The method according to the invention and the microphone arrangement according to the invention are particularly suitable for use on hearing devices.
Although it is certainly possible to implement the method according to the invention and the microphone arrangement according to the invention by means of signal processing in the time domain, in a preferred embodiment the signal processing is undertaken in the the frequency domain with t.the use of time domain/frequency domain converters and frequency domain/time domain converters.
The invention is explained below by way of example with the aid of figures, in which:
Figures la and b show, by way of example, the transmission characteristics of two (a and b) microphone sub-arrangements used according to the invention;
The method according to the invention and the microphone arrangement according to the invention are particularly suitable for use on hearing devices.
Although it is certainly possible to implement the method according to the invention and the microphone arrangement according to the invention by means of signal processing in the time domain, in a preferred embodiment the signal processing is undertaken in the the frequency domain with t.the use of time domain/frequency domain converters and frequency domain/time domain converters.
The invention is explained below by way of example with the aid of figures, in which:
Figures la and b show, by way of example, the transmission characteristics of two (a and b) microphone sub-arrangements used according to the invention;
Figure 2 shows, plotted against the angle axis cp in accordance with figures la and lb, the formation of a quotient function Q from the characteristics in accordance with figures la and lb, as well as the saturation of this quotient function to the maximum value 0 dB;
Figure 3 shows, starting from the saturated quotient function explained with the aid of figure 2, the same saturated quotient function with linear gain scaling, and the formation of a function F from the difference between said saturated quotient function and a fixed value;
Figure 4 shows in a shaded fashion in a representation similar to figures la and lb a transmission characteristic implemented according to the invention;
Figure 5 shows in a representation similar to figure 4 a further transmission characteristic implemented according to the invention; and Figure 6 shows the implementation of a microphone arrangement according to the invention in the form of a simplified signal flow/function block diagram.
The procedure according to the invention is to be illustrated with the aid of figures 1 to 3 without pretension to scientific exactitude with the aid of simple transmission characteristics corresponding in each case to first-order cardoids. This comprehensible and simple procedure provides the person skilled in the art with the instructions as to how a desired transmission characteristic can be implemented according to the invention even when starting from more complex transmission functions.
Let a first microphone sub-arrangement have the three-dimensional transmission characteristic, illustrated in two dimensions in figure la, with reference to its transmission or gain characteristic with reference to acoustic signals incident on it from the direction T.
In a representation similar to figure la, there is illustrated in figure lb the transmission characteristic of a second microphone sub-arrangement which may be a mirror image with reference to the axis n/2; 3n/2 of the transmission characteristic of the first microphone sub-arrangement. The transmission characteristic in accordance with figure la may be denoted by CN, and that in accordance with lb by cZ.
The magnitude of the transmission characteristics CN and cZ, respectively, is illustrated qualitatively and in dB
in figure 2 against the angle axis cp in accordance with figures la and lb.
In the case of acoustic standard signals incident on the two microphone sub-arrangements, the transmission characteristics illustrated in figures la and lb correspond at the same time to the respective signal values on the output side of the microphone sub-arrangements considered.
According to the invention, a quotient, for example, ICN I
is now formed according to the invention from these two output signal values, which are likewise denoted by CN
and cz, respectively. This quotient formation results in the function Q, represented qualitatively with a dash-dotted line in figure 2 and having a pole at cp =n. In the case of real quotient formation, the pole resulting for the zero of the denominator function IcN I is captured in any case, that is to say the quotient function Q is saturated. The quotient function is preferably saturated at a prescribed or prescribable value B, in accordance with figure 1 preferably at the value "one", in the case of a maximum value of the transmission functions in accordance with figures la, b of "one".
If it is now assumed that the denominator transmission characteristic, in the present case cN, be that which is to be the dominant one for the transmission characteristic result to be achieved, that is to say be a transmission characteristic that has a high signal gain in an angular range iq which the desired characteristic to be implemented is also to have a high signal gain, then the advantage of the quotient formation according to the invention is already to be seen now. A pole of the quotient results in the zero angular range from this transmission characteristic dominant for the result to be targeted. The zero angular range of the dominant transmission characteristic or of those angular ranges with reduced signal gain will, however, be those that are to be changed, that is to say can be "improved" in order to obtain the desired characteristic. It is precisely there that the possibility now exists of intervening simply, specifically by saturation to a prescribable or prescribed constant value of the quotient function.
For reasons of clarity, the quotient function Qsati saturated to "1" is now introduced into figure 3 with linear gain scaling. It may now be seen further from this that the saturated quotient function Qsatl exhibits the profile of a directed transmission characteristic in the non-saturated angular ranges, in the present case between 0 and n/2, as well as between 3n/2 and 2n.
If the aim is now the directional characteristic expressed for the desired transmission characteristic to be implemented, the region of the quotient function set according to the invention to the prescribed saturation value, "one" in the example described, is utilized for the purpose of achieving a defined minimum gain of the desired transmission characteristic there, that is to say in this angular range. This is achieved in the example presented by virtue of the fact that the saturated quotient function is subtracted from a prescribed or prescribable fixed value A, for example, and preferably in the example presented, having the value "one". The result is the function F = A - QsatB, represented once again with a continuous line in figure 3, or, as a special and preferred case, the function F = 1 - Qsati =
It may be seen from this that a transmission function, F, must be achieved that exhibits a non-vanishing signal gain exclusively in the angular range 05 tp < 2 and 32 < cp <_ 2~.
The following can now be set forth with reference to the procedure according to the invention:
~ Fundamentally, the transmissioft characteristic to be implemented is implemented on the output side of the microphone arrangement according to the invention as a function of the quotient, saturated to a prescribed or prescribable maximum value, of the output signals of two microphone sub-arrangements having a different transmission characteristic.
It is preferred in this case, as is to be shown later, to multiply the quotient function Q, as factor, by a further permanently prescribed or settable weighting factor before saturation takes place at the resulting product. The weighting factor mentioned is 1 in the example presented with the aid of figures 1 to 3.
Furthermore, it can well be advantageous to undertake the saturation at the product of the factor mentioned and the quotient at least also when the prescribed minimum values are reached.
== The quotient formation can be performed in this case directly by quotient formation of the signal amplitude values, without taking account of phase.
== Although the saturated product can be used, if appropriate, in the form of 4nother function, that is to say as F = F[(a = Q) sats], in general, it is much preferred to implement a directed charac-teristic by subtracting the saturated product mentioned from a prescribed or prescribable fixed value.
As will be shown later the possibility of varying the targeted directional characteristic results in a very simple way from varying the fixed value mentioned and/or the multiplicative factor a of the saturated product.
Figure 3 shows, starting from the saturated quotient function explained with the aid of figure 2, the same saturated quotient function with linear gain scaling, and the formation of a function F from the difference between said saturated quotient function and a fixed value;
Figure 4 shows in a shaded fashion in a representation similar to figures la and lb a transmission characteristic implemented according to the invention;
Figure 5 shows in a representation similar to figure 4 a further transmission characteristic implemented according to the invention; and Figure 6 shows the implementation of a microphone arrangement according to the invention in the form of a simplified signal flow/function block diagram.
The procedure according to the invention is to be illustrated with the aid of figures 1 to 3 without pretension to scientific exactitude with the aid of simple transmission characteristics corresponding in each case to first-order cardoids. This comprehensible and simple procedure provides the person skilled in the art with the instructions as to how a desired transmission characteristic can be implemented according to the invention even when starting from more complex transmission functions.
Let a first microphone sub-arrangement have the three-dimensional transmission characteristic, illustrated in two dimensions in figure la, with reference to its transmission or gain characteristic with reference to acoustic signals incident on it from the direction T.
In a representation similar to figure la, there is illustrated in figure lb the transmission characteristic of a second microphone sub-arrangement which may be a mirror image with reference to the axis n/2; 3n/2 of the transmission characteristic of the first microphone sub-arrangement. The transmission characteristic in accordance with figure la may be denoted by CN, and that in accordance with lb by cZ.
The magnitude of the transmission characteristics CN and cZ, respectively, is illustrated qualitatively and in dB
in figure 2 against the angle axis cp in accordance with figures la and lb.
In the case of acoustic standard signals incident on the two microphone sub-arrangements, the transmission characteristics illustrated in figures la and lb correspond at the same time to the respective signal values on the output side of the microphone sub-arrangements considered.
According to the invention, a quotient, for example, ICN I
is now formed according to the invention from these two output signal values, which are likewise denoted by CN
and cz, respectively. This quotient formation results in the function Q, represented qualitatively with a dash-dotted line in figure 2 and having a pole at cp =n. In the case of real quotient formation, the pole resulting for the zero of the denominator function IcN I is captured in any case, that is to say the quotient function Q is saturated. The quotient function is preferably saturated at a prescribed or prescribable value B, in accordance with figure 1 preferably at the value "one", in the case of a maximum value of the transmission functions in accordance with figures la, b of "one".
If it is now assumed that the denominator transmission characteristic, in the present case cN, be that which is to be the dominant one for the transmission characteristic result to be achieved, that is to say be a transmission characteristic that has a high signal gain in an angular range iq which the desired characteristic to be implemented is also to have a high signal gain, then the advantage of the quotient formation according to the invention is already to be seen now. A pole of the quotient results in the zero angular range from this transmission characteristic dominant for the result to be targeted. The zero angular range of the dominant transmission characteristic or of those angular ranges with reduced signal gain will, however, be those that are to be changed, that is to say can be "improved" in order to obtain the desired characteristic. It is precisely there that the possibility now exists of intervening simply, specifically by saturation to a prescribable or prescribed constant value of the quotient function.
For reasons of clarity, the quotient function Qsati saturated to "1" is now introduced into figure 3 with linear gain scaling. It may now be seen further from this that the saturated quotient function Qsatl exhibits the profile of a directed transmission characteristic in the non-saturated angular ranges, in the present case between 0 and n/2, as well as between 3n/2 and 2n.
If the aim is now the directional characteristic expressed for the desired transmission characteristic to be implemented, the region of the quotient function set according to the invention to the prescribed saturation value, "one" in the example described, is utilized for the purpose of achieving a defined minimum gain of the desired transmission characteristic there, that is to say in this angular range. This is achieved in the example presented by virtue of the fact that the saturated quotient function is subtracted from a prescribed or prescribable fixed value A, for example, and preferably in the example presented, having the value "one". The result is the function F = A - QsatB, represented once again with a continuous line in figure 3, or, as a special and preferred case, the function F = 1 - Qsati =
It may be seen from this that a transmission function, F, must be achieved that exhibits a non-vanishing signal gain exclusively in the angular range 05 tp < 2 and 32 < cp <_ 2~.
The following can now be set forth with reference to the procedure according to the invention:
~ Fundamentally, the transmissioft characteristic to be implemented is implemented on the output side of the microphone arrangement according to the invention as a function of the quotient, saturated to a prescribed or prescribable maximum value, of the output signals of two microphone sub-arrangements having a different transmission characteristic.
It is preferred in this case, as is to be shown later, to multiply the quotient function Q, as factor, by a further permanently prescribed or settable weighting factor before saturation takes place at the resulting product. The weighting factor mentioned is 1 in the example presented with the aid of figures 1 to 3.
Furthermore, it can well be advantageous to undertake the saturation at the product of the factor mentioned and the quotient at least also when the prescribed minimum values are reached.
== The quotient formation can be performed in this case directly by quotient formation of the signal amplitude values, without taking account of phase.
== Although the saturated product can be used, if appropriate, in the form of 4nother function, that is to say as F = F[(a = Q) sats], in general, it is much preferred to implement a directed charac-teristic by subtracting the saturated product mentioned from a prescribed or prescribable fixed value.
As will be shown later the possibility of varying the targeted directional characteristic results in a very simple way from varying the fixed value mentioned and/or the multiplicative factor a of the saturated product.
= In principle, it is possible to use as microphone sub-arrangements all known microphones and their combinations that have different transmission characteristics as required in the position of use and as required with reference to the direction of incidence tp of acoustic signals that strike.
== In order, in particular, to implement directed characteristics, it is preferred to use microphone sub-arrangements whose transmission characteristics are identical, but inversely directed with reference to the direction of incidence of acoustic signals.
== The implementation of such macrophone arrangements can be performed, in particular, by using the known "delay and add" principle.
Particularly in the case of this form of implementation, as well, the inversely acting microphone arrangements just named can be implemented with two microphones whose outputs, as still to be shown, are time delayed and appropriately added in each case in order to form the two microphone sub-arrangements.
= It goes without saying that it is possible to implement very highly complex transmission functions and transmission function combinations by developing the procedure according to the invention with three and more microphone sub-arrangements.
The transmission function preferably used according to the invention may be reproduced once again in summary, specifically:
S=cN A- a= IcZI
IcN) atB
Figure 4 illustrates the transmission function that was formed according to the invention from inversely directed, identical cardoid transmission charac-teristics Ca, corresponding to the transmission function S'=cN I- 1. ZI
I ccNI atl The resulting transmission characteristic is illustrated in figure 5 when the following is true:
c S"=cN I- 4= Z
cN
I I satl A microphone arrangement operating using the method according to the invention is illustrated by way of example, in particular for use in a hearing device, as well, in figure 6 with the aid of a simplified signal flow/functional block diagram.
In accordance with figure 6, an arrangement 1 having at least two microphone sub-arrangements la and lb is provided at the microphone arrangement according to the invention. Output signals appear at their outputs Ala and Alb as a function of the acoustic signals incident at the microphones on the input side as a function of the direction cp. As illustrated in figure 6, the two microphone sub-arrangements can well be impleipented by means of a single pair of microphones whose outputs are coupled to one another using the "delay and add" technique. What is essential is that basically signals having different transmission characteristics with reference to the direction cp of arriving acoustic signals are generated at the outputs Ala and Alb.
The outputs Ala and Alb are preferably led to time domain/frequency domain converter units FFT 3a and 3b, respectively, if, as preferred, the subsequent signal processing is to be performed in the frequency domain.
The outputs mentioned are operationally connected to inputs E5a and E5b, respectively, of magnitude forming units 5a and 5b. The outputs of the magnitude forming units mentioned are, as illustrated, led to the denominator and numerator inputs N and Z of a division unit 7. The output A7 is operationally connected to one input Ella of a subtraction unit 11 in a fashion multiplied by a weighting unit 9 by a weighting factor a that can be prescribed at a control input S9.
As boxed in a dashed manner in figure 6, the division unit 7 and weighting unit 9 form a weighted quotient forming unit 10. The factor a illustrated by way of example in figure 6 and capable of being set at the weighting unit 9 can assume a3;bitrary non-vanishing values.
As further illustrated schematically in figure 6, the signal at the output Ay of the weighted quotient forming unit 10 is fed to a saturation unit 12 whose output is firstly fed to the input E11a= At the saturation unit 12, which can, of course, be integrally combined with the weighted quotient forming unit 10, the output signal of the weighted quotient forming unit 10 is saturated downward (indicated by dashes in block 12 of figure 6) and/or upward to a prescribed or prescribable value B - as set in a way illustrated schematically at =
== In order, in particular, to implement directed characteristics, it is preferred to use microphone sub-arrangements whose transmission characteristics are identical, but inversely directed with reference to the direction of incidence of acoustic signals.
== The implementation of such macrophone arrangements can be performed, in particular, by using the known "delay and add" principle.
Particularly in the case of this form of implementation, as well, the inversely acting microphone arrangements just named can be implemented with two microphones whose outputs, as still to be shown, are time delayed and appropriately added in each case in order to form the two microphone sub-arrangements.
= It goes without saying that it is possible to implement very highly complex transmission functions and transmission function combinations by developing the procedure according to the invention with three and more microphone sub-arrangements.
The transmission function preferably used according to the invention may be reproduced once again in summary, specifically:
S=cN A- a= IcZI
IcN) atB
Figure 4 illustrates the transmission function that was formed according to the invention from inversely directed, identical cardoid transmission charac-teristics Ca, corresponding to the transmission function S'=cN I- 1. ZI
I ccNI atl The resulting transmission characteristic is illustrated in figure 5 when the following is true:
c S"=cN I- 4= Z
cN
I I satl A microphone arrangement operating using the method according to the invention is illustrated by way of example, in particular for use in a hearing device, as well, in figure 6 with the aid of a simplified signal flow/functional block diagram.
In accordance with figure 6, an arrangement 1 having at least two microphone sub-arrangements la and lb is provided at the microphone arrangement according to the invention. Output signals appear at their outputs Ala and Alb as a function of the acoustic signals incident at the microphones on the input side as a function of the direction cp. As illustrated in figure 6, the two microphone sub-arrangements can well be impleipented by means of a single pair of microphones whose outputs are coupled to one another using the "delay and add" technique. What is essential is that basically signals having different transmission characteristics with reference to the direction cp of arriving acoustic signals are generated at the outputs Ala and Alb.
The outputs Ala and Alb are preferably led to time domain/frequency domain converter units FFT 3a and 3b, respectively, if, as preferred, the subsequent signal processing is to be performed in the frequency domain.
The outputs mentioned are operationally connected to inputs E5a and E5b, respectively, of magnitude forming units 5a and 5b. The outputs of the magnitude forming units mentioned are, as illustrated, led to the denominator and numerator inputs N and Z of a division unit 7. The output A7 is operationally connected to one input Ella of a subtraction unit 11 in a fashion multiplied by a weighting unit 9 by a weighting factor a that can be prescribed at a control input S9.
As boxed in a dashed manner in figure 6, the division unit 7 and weighting unit 9 form a weighted quotient forming unit 10. The factor a illustrated by way of example in figure 6 and capable of being set at the weighting unit 9 can assume a3;bitrary non-vanishing values.
As further illustrated schematically in figure 6, the signal at the output Ay of the weighted quotient forming unit 10 is fed to a saturation unit 12 whose output is firstly fed to the input E11a= At the saturation unit 12, which can, of course, be integrally combined with the weighted quotient forming unit 10, the output signal of the weighted quotient forming unit 10 is saturated downward (indicated by dashes in block 12 of figure 6) and/or upward to a prescribed or prescribable value B - as set in a way illustrated schematically at =
the input satB. This preferably at least also in this case to a maximum value. At the subtraction unit 11, the signal present there is subtracted from a fixed value A set, or settable, at the second input Ellb. The output A11 of the subtraction unit 11 is operationally connected to one input E13a of a multiplication unit 13. The output signal Ala of the microphone sub-arrangement la is operationally connected to the second input E13b of the multiplication unit 13 via the converter unit FFT 3a, and is also operationally connected to the denominator input N of the division unit 7 via the magnitude forming unit 5a. If appropriate for changing the saturation angular range explained with the aid of figures 1 to 3, it is possible, as illustrated by dashes at 15, for the denominator signal, and if cippropriate also the numerator signal, which is fed to the input N or the input Z of the division input 7, to be weighted.
The output signal Sout of the microphone arrangement according to the invention appears on the output side of the multiplication unit 13. It has the desired transmission characteristic as a function of the solid angle tp with which acoustic signals are incident on the microphone arrangement 1 on the input side.
As has already been mentioned, it is preferred to select identical characteristics that act in inverse directions relative to one another for the transmission characteristics of the microphone sub-arrangements la and lb. The desired transmission characteristic is set at the output signal Soõt by setting the weighting factor a, the saturation value B, the fixed value A, and further weighting factors such as (3, if appropriate.
The method according to the invention and the microphone arrangement according to the invention are excellently suited to use with hearing devices, particularly also because of the low outlay on signal processing and, as was shown with the aid of figures 3 and 4, the pronounced possibil#y of suppressing the signal transmission from undesired directions of incidence such as from behind with reference to a hearing device that is worn. Instead of microphone sub-arrangements with cardoid characteristics Ca, it is rather those with hypercardoid characteristics Hca (figure 5) that are preferably used for hearing devices.
The output signal Sout of the microphone arrangement according to the invention appears on the output side of the multiplication unit 13. It has the desired transmission characteristic as a function of the solid angle tp with which acoustic signals are incident on the microphone arrangement 1 on the input side.
As has already been mentioned, it is preferred to select identical characteristics that act in inverse directions relative to one another for the transmission characteristics of the microphone sub-arrangements la and lb. The desired transmission characteristic is set at the output signal Soõt by setting the weighting factor a, the saturation value B, the fixed value A, and further weighting factors such as (3, if appropriate.
The method according to the invention and the microphone arrangement according to the invention are excellently suited to use with hearing devices, particularly also because of the low outlay on signal processing and, as was shown with the aid of figures 3 and 4, the pronounced possibil#y of suppressing the signal transmission from undesired directions of incidence such as from behind with reference to a hearing device that is worn. Instead of microphone sub-arrangements with cardoid characteristics Ca, it is rather those with hypercardoid characteristics Hca (figure 5) that are preferably used for hearing devices.
Claims (36)
1. A method for establishing a desired transfer characteristic which converts an acoustical input signal impinging on a microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement, said method comprising the steps of:
providing at said microphone arrangement a first microphone sub-arrangement and a second microphone sub-arrangement, each microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said microphone sub-arrangements into an electric output signal of the respective sub-arrangement, said transfer characteristics of said first microphone sub-arrangements being different from said transfer characteristic of said second microphone sub-arrangement with respect to said acoustical input signal;
forming a ratio of said output signals of said first and second microphone sub-arrangements, thereby generating a ratio result;
forming a saturated product with said ratio result as one factor, thereby clipping said product at a predetermined or predeterminable value and generating a saturated product result; and generating said electric output signal as a function of said saturated product result.
providing at said microphone arrangement a first microphone sub-arrangement and a second microphone sub-arrangement, each microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said microphone sub-arrangements into an electric output signal of the respective sub-arrangement, said transfer characteristics of said first microphone sub-arrangements being different from said transfer characteristic of said second microphone sub-arrangement with respect to said acoustical input signal;
forming a ratio of said output signals of said first and second microphone sub-arrangements, thereby generating a ratio result;
forming a saturated product with said ratio result as one factor, thereby clipping said product at a predetermined or predeterminable value and generating a saturated product result; and generating said electric output signal as a function of said saturated product result.
2. The method of claim 1, further comprising the step of saturating said product on a maximum value.
3. The method of claim 1, further comprising the step of forming said saturated product with a second factor having an arbitrary value different from 0.
4. The method of claim 1, wherein said function of said saturated product result comprises a difference function of a constant value and said saturated product result.
5. The method of claim 4, wherein said constant value is selected to be adjustable.
6. The method of claim 4, further comprising the step of saturating said saturated product on a saturation value and selecting said constant to be at least equal with said saturation value.
7. The method of claim 1, further comprising the step of forming said ratio from the amplitude values of said output signals of said sub-arrangements.
8. The method of claim 1, further comprising generating said electric output signal according to the equation:
wherein:
S is said electric output signal, A is a predetermined or adjusted value, ¦C n¦ is the amplitude value of the output signal of one of said sub-microphone arrangements, the transfer characteristic of which has maximum gain for a value of said angle at which said desired transfer characteristic shall have maximum gain as well,.
¦C z¦ is the amplitude value of the other of said at least two sub-microphone arrangements, satB is the saturation of the product [] to a predetermined or adjusted minimum or maximum value B, and .
.alpha. is a predetermined or adjustable factor.
wherein:
S is said electric output signal, A is a predetermined or adjusted value, ¦C n¦ is the amplitude value of the output signal of one of said sub-microphone arrangements, the transfer characteristic of which has maximum gain for a value of said angle at which said desired transfer characteristic shall have maximum gain as well,.
¦C z¦ is the amplitude value of the other of said at least two sub-microphone arrangements, satB is the saturation of the product [] to a predetermined or adjusted minimum or maximum value B, and .
.alpha. is a predetermined or adjustable factor.
9. The method of claim 1 further comprising the step of selecting said transfer characteristics of said microphone sub-arrangements to have respectively a maximum gain for acoustical signal impinging on opposite directions.
10. The method of claim 1, further comprising selecting said transfer characteristics of said microphone sub-arrangements to be generally of cardioid shape in polar diagram representation.
11. The method of claim 1, further comprising selecting said transfer characteristics of said microphone sub-arrangements to be generally of hyper-cardioid shape in polar diagram representation.
12. The method of claim 1 for establishing a desired transfer characteristic of a hearing device.
13. The method of claim 1 for establishing a desired transfer characteristic for a hearing aid device.
14. A microphone arrangement comprising:
two microphone sub-arrangements each having an output, each of said microphone sub-arrangements also having a respective transfer characteristic with which acoustical input signal impinging on said microphone sub-arrangements are converted into respective electrical output signals at said outputs as a function of the angle at which said acoustical input signals impinge on said microphone sub-arrangements, said transfer characteristics of said microphone sub-arrangements being different with respect to said acoustical input signal;
a computing unit having at least two inputs and an output, said outputs of said microphone sub-arrangements being respectively operationally connected to said inputs of said computing unit, said computing unit including:
a ratio forming and weighing unit having an output, a denominator input, a numerator input and a weighing input, wherein one of said inputs of said computing unit is operationally connected to said denominator input, and wherein the other of said inputs of said computing unit is operationally connected with said numerator input, and further wherein said ratio forming and weighing unit generates at said output an output signal saturated at a maximum or minimum value, the output of said ratio forming and weighing unit being operationally connected to the output of said microphone arrangement.
two microphone sub-arrangements each having an output, each of said microphone sub-arrangements also having a respective transfer characteristic with which acoustical input signal impinging on said microphone sub-arrangements are converted into respective electrical output signals at said outputs as a function of the angle at which said acoustical input signals impinge on said microphone sub-arrangements, said transfer characteristics of said microphone sub-arrangements being different with respect to said acoustical input signal;
a computing unit having at least two inputs and an output, said outputs of said microphone sub-arrangements being respectively operationally connected to said inputs of said computing unit, said computing unit including:
a ratio forming and weighing unit having an output, a denominator input, a numerator input and a weighing input, wherein one of said inputs of said computing unit is operationally connected to said denominator input, and wherein the other of said inputs of said computing unit is operationally connected with said numerator input, and further wherein said ratio forming and weighing unit generates at said output an output signal saturated at a maximum or minimum value, the output of said ratio forming and weighing unit being operationally connected to the output of said microphone arrangement.
15. The arrangement of claim 14, wherein the output signal of said ratio forming and weighing unit is saturated on a maximum signal value.
16. The arrangement of claim 14, wherein said weighing input of said ratio forming and weighing unit is set with a signal representing a weighing factor different from zero which is predetermined or adjustable.
17. The arrangement of claim 14, wherein the output of said ratio forming and weighing unit is operationally connected to said output of said computing unit via a difference forming unit.
18. The arrangement of claim 17, wherein said difference forming unit has a first input operationally connected to the output of said ratio forming and weighing unit and has a second input for a predetermined or adjustable signal.
19. The arrangement of claim 18, wherein the value of said predetermined or adjustable signal is at least equal to a value at which the output signal of said ratio forming and weighing unit is saturated.
20. The arrangement of claim 17, wherein the output of said difference forming unit is operationally connected to an input of a multiplication unit having two inputs and an output, the second input being operationally connected to the output of the microphone sub-arrangement, the output of which is operationally connected to said denominator input, the output of said multiplication unit being operationally connected to the output of said computing unit.
21. The arrangement of claim 14, wherein said inputs of said computing unit are operationally connected respectively to said denominator and numerator inputs of said ratio forming and weighing unit via magnitude forming units.
22. The arrangement of claim 14, wherein said output of said ratio forming and weighing unit is operationally connected to one input of a multiplication unit having at least two inputs and an output, the second input of said multiplication unit being operationally connected to the output of the microphone sub-arrangement, the output of which is operationally connected to said denominator input, said output of said multiplication unit being operationally connected to said output of said computing unit.
23. The arrangement of claim 14 further comprising time to frequency converter units interconnected between said outputs of said microphone sub-arrangements and said inputs of said computing unit.
24. The arrangement of claim 14, wherein said microphone sub-arrangements have respective transfer characteristics with a cardioid shape in polar representation.
25. The arrangement of claim 14, wherein said microphone sub-arrangements have respective transfer characteristics with a hyper-cardioid shape in polar representation.
26. The arrangement of claim 14 being part of a hearing device.
27. The arrangement of claim 14 being part of a hearing aid device.
28. A method for establishing a desired transfer characteristic which converts acoustical input signals impinging on a microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement, said method comprising the steps of:
providing at said microphone arrangement at least two microphone sub-arrangements, each microphone sub-arrangement having a transfer characteristic which converts said acoustical input signals impinging on said microphone sub-arrangements into an electric output signal of a respective sub-arrangement, said transfer characteristics of said at least two microphone sub-arrangements being different;
forming a ratio of said output signals of said at least two sub-arrangements, thereby generating a ratio result;
forming a saturated product with said ratio result as one factor, thereby performing saturating said product at a predetermined or predeterminable value and generating a saturated product result;
generating said electric output signal as a function of said saturated product result.
providing at said microphone arrangement at least two microphone sub-arrangements, each microphone sub-arrangement having a transfer characteristic which converts said acoustical input signals impinging on said microphone sub-arrangements into an electric output signal of a respective sub-arrangement, said transfer characteristics of said at least two microphone sub-arrangements being different;
forming a ratio of said output signals of said at least two sub-arrangements, thereby generating a ratio result;
forming a saturated product with said ratio result as one factor, thereby performing saturating said product at a predetermined or predeterminable value and generating a saturated product result;
generating said electric output signal as a function of said saturated product result.
29. A microphone arrangement comprising:
a first microphone sub-arrangement having a first output in the time domain having a first transfer characteristic with respect to an impinging acoustic signal;
a second microphone sub-arrangement having a second output in the time domain having a second transfer characteristic with respect to an impinging acoustic signal, wherein said first transfer characteristic and said second transfer characteristic are different;
a first time to frequency converter unit for converting said first output into a first frequency domain signal;
a second time to frequency converter unit for converting said second output into a second frequency domain signal;
a computing unit having a first input, a second input, and an output, wherein said frequency domain signals of said time to frequency converter units are connected to said inputs of said computing unit, respectively, wherein said computing unit generates a ratio signal that is proportional to an amplitude or an absolute value of one of said first and second frequency domain signals, and further wherein said ratio signal is inversely proportional to an amplitude or an absolute value of the other of said first and second frequency domain signals, and still further wherein said ratio forming and weighing unit multiplies said ratio signal by a non-zero value to create a weighted ratio; and wherein said ratio forming and weighing unit generates a saturated signal by clipping said weighted ratio at a maximum or minimum value.
a first microphone sub-arrangement having a first output in the time domain having a first transfer characteristic with respect to an impinging acoustic signal;
a second microphone sub-arrangement having a second output in the time domain having a second transfer characteristic with respect to an impinging acoustic signal, wherein said first transfer characteristic and said second transfer characteristic are different;
a first time to frequency converter unit for converting said first output into a first frequency domain signal;
a second time to frequency converter unit for converting said second output into a second frequency domain signal;
a computing unit having a first input, a second input, and an output, wherein said frequency domain signals of said time to frequency converter units are connected to said inputs of said computing unit, respectively, wherein said computing unit generates a ratio signal that is proportional to an amplitude or an absolute value of one of said first and second frequency domain signals, and further wherein said ratio signal is inversely proportional to an amplitude or an absolute value of the other of said first and second frequency domain signals, and still further wherein said ratio forming and weighing unit multiplies said ratio signal by a non-zero value to create a weighted ratio; and wherein said ratio forming and weighing unit generates a saturated signal by clipping said weighted ratio at a maximum or minimum value.
30. The microphone arrangement of claim 29, wherein said computer unit further generates a difference signal by subtracting said saturated signal from a constant.
31. The microphone arrangement of claim 30, wherein said computer unit further generates an output signal by multiplying said difference signal by one or the other of said first and said second frequency signals.
32. The microphone arrangement of claim 30, wherein said computer unit further generates an output signal by multiplying said difference signal by the other of said first and second frequency domain signals.
33. A method for establishing a desired transfer characteristic which converts an acoustical input signal impinging on a microphone arrangement into an electric output signal as a function of the angle at which said acoustical input signals impinge on said microphone arrangement, said method comprising the steps of:
at said microphone arrangement providing:
a first microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said first microphone into an output signal represented by c n; and a second microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said second microphone into an output signal represented by c z; and generating said electric output signal according to the equation:
wherein:
S is said electric output signal, A is a predetermined or adjusted value, ¦C n¦ is the amplitude value of the output signal c n, ¦C z¦ is the amplitude value of the output signal c z, satB is the saturation of the product [] to a predetermined or adjusted minimum or maximum value B, and .alpha. is a predetermined or adjustable factor.
at said microphone arrangement providing:
a first microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said first microphone into an output signal represented by c n; and a second microphone sub-arrangement having a transfer characteristic which converts said acoustical input signal impinging on said second microphone into an output signal represented by c z; and generating said electric output signal according to the equation:
wherein:
S is said electric output signal, A is a predetermined or adjusted value, ¦C n¦ is the amplitude value of the output signal c n, ¦C z¦ is the amplitude value of the output signal c z, satB is the saturation of the product [] to a predetermined or adjusted minimum or maximum value B, and .alpha. is a predetermined or adjustable factor.
34. The method of claim 33 wherein the transfer characteristic of the first microphone sub-arrangement has maximum gain for a value of said angle at which said desired transfer characteristic shall have maximum gain as well.
35. A microphone arrangement implementing the method of claim 34.
36. A microphone arrangement implementing the method of claim 33.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CH2000/000190 WO2000033634A2 (en) | 2000-03-31 | 2000-03-31 | Method for providing the transmission characteristics of a microphone arrangement and microphone arrangement |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2404863A1 CA2404863A1 (en) | 2002-09-24 |
| CA2404863C true CA2404863C (en) | 2009-08-04 |
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|---|---|---|---|
| CA002404863A Expired - Fee Related CA2404863C (en) | 2000-03-31 | 2000-03-31 | Method for providing the transmission characteristics of a microphone arrangement and microphone arrangement |
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| EP (1) | EP1269576B1 (en) |
| JP (1) | JP2003516646A (en) |
| AU (2) | AU3414200A (en) |
| CA (1) | CA2404863C (en) |
| DE (1) | DE50009746D1 (en) |
| DK (1) | DK1269576T3 (en) |
| WO (1) | WO2000033634A2 (en) |
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| US6449216B1 (en) | 2000-08-11 | 2002-09-10 | Phonak Ag | Method for directional location and locating system |
| US6687187B2 (en) | 2000-08-11 | 2004-02-03 | Phonak Ag | Method for directional location and locating system |
| US7274794B1 (en) | 2001-08-10 | 2007-09-25 | Sonic Innovations, Inc. | Sound processing system including forward filter that exhibits arbitrary directivity and gradient response in single wave sound environment |
| US7076072B2 (en) * | 2003-04-09 | 2006-07-11 | Board Of Trustees For The University Of Illinois | Systems and methods for interference-suppression with directional sensing patterns |
| US7324651B2 (en) | 2004-03-15 | 2008-01-29 | Phonak Ag | Feedback suppression |
| DK1469702T3 (en) * | 2004-03-15 | 2017-02-13 | Sonova Ag | Feedback suppression |
| DK2036396T3 (en) * | 2006-06-23 | 2010-04-19 | Gn Resound As | Hearing aid with adaptive, directional signal processing |
| WO2008061534A1 (en) | 2006-11-24 | 2008-05-29 | Rasmussen Digital Aps | Signal processing using spatial filter |
| JP5409786B2 (en) * | 2009-06-17 | 2014-02-05 | パナソニック株式会社 | Hearing aid |
| WO2011107545A2 (en) * | 2010-03-05 | 2011-09-09 | Siemens Medical Instruments Pte. Ltd. | Method for adjusting a directional hearing device |
| EP2699020B1 (en) * | 2012-08-17 | 2016-04-13 | Sivantos Pte. Ltd. | Method and device for determining a gain factor of a hearing aid |
| DE102013201043B4 (en) | 2012-08-17 | 2016-03-17 | Sivantos Pte. Ltd. | Method and device for determining an amplification factor of a hearing aid |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2242790B2 (en) * | 1972-08-31 | 1976-10-21 | Hißen, Helmut, Dr.-Ing., 5481 Nierendorf; Kosel, Georg, Dr.-Ing., 5483 Bad Neuenahr; Krätzig, Gudrun, 5300 Bonn-Bad Godesberg | DIGITAL RECEIVER WITH SPECTRUM EVALUATION |
| DE3017797A1 (en) * | 1980-05-09 | 1981-11-12 | Fried. Krupp Gmbh, 4300 Essen | METHOD FOR DETERMINING THE DIRECTIONS |
| US4752961A (en) * | 1985-09-23 | 1988-06-21 | Northern Telecom Limited | Microphone arrangement |
| US5289544A (en) * | 1991-12-31 | 1994-02-22 | Audiological Engineering Corporation | Method and apparatus for reducing background noise in communication systems and for enhancing binaural hearing systems for the hearing impaired |
| US5473701A (en) * | 1993-11-05 | 1995-12-05 | At&T Corp. | Adaptive microphone array |
| DE19730878B4 (en) * | 1996-07-20 | 2004-07-08 | Technische Universität Dresden | Arrangement for the objective assessment of the functional state of the human hearing organ |
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2000
- 2000-03-31 WO PCT/CH2000/000190 patent/WO2000033634A2/en active IP Right Grant
- 2000-03-31 CA CA002404863A patent/CA2404863C/en not_active Expired - Fee Related
- 2000-03-31 EP EP00912317A patent/EP1269576B1/en not_active Expired - Lifetime
- 2000-03-31 DE DE50009746T patent/DE50009746D1/en not_active Expired - Lifetime
- 2000-03-31 DK DK00912317T patent/DK1269576T3/en active
- 2000-03-31 AU AU3414200A patent/AU3414200A/en active Pending
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| CA2404863A1 (en) | 2002-09-24 |
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| EP1269576A1 (en) | 2003-01-02 |
| EP1269576B1 (en) | 2005-03-09 |
| WO2000033634A2 (en) | 2000-06-15 |
| AU2000234142B2 (en) | 2005-05-19 |
| DK1269576T3 (en) | 2005-05-17 |
| JP2003516646A (en) | 2003-05-13 |
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