AU2000234142B2 - Method for providing the transmission characteristics of a microphone arrangement and microphone arrangement - Google Patents

Description

PCT

WORLD INTELLECTUAL PROPERTY ORGANIZATION International Bureau INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International patent classification: (11) International publication number: WO 00/33634 Not lassfiedA2 (43) International publication date: June 2000 (15.06.2000) (21) International application number: PCT/CHOO/00190 (81) Designated states: AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, DZ, (22) International filing date: 31 March 2000 (3 1.03.00) EE, ES, Fl, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, (71) Applicant (for all designated States except US): LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PHONAK AG [CICH]; Laubisrujtistraisse 28, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, CH-8712 Stafa UA, UG, US, UZ, VN, YU, ZW, ARIPO Patent (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), (72) Inventor; and Eurasian Patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, Inventor/Applicant (US only): ROECK, Hans-Uell TM), European Patent (AT, BE, CH, CY, DE, DK, ES, [CICH]; Heusserstrasse 27, CH-8634 FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OAPI Hombrechtjkon Patent (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG).

(74) Attorney: TROESCH SCHEIDEGGER WERNER AG; Siewerdtstrasse 95, CH-8050 Zfirich (CH).

Published On request of the Applicant, before expiry of the stipulated period allowed in accordance withi Article 21 paragraph 2(a).

Withtout the International Search Report and to be republished once the report has been received.

Wit/hout classification; description and abstract not examined by the International Searching Authority.

As printed (54) Title. METHOD FOR PROVIDING THE TRANSMISSION CHARACTERISTICS OF A MICROPHONE ARRANGEMENT AND MICROPHONE ARRAN(WMENT (54) Bezeiching: VERFAHREN ZLJR VORGADEDER CJBERTRAGUNCTSCHARAKTERISTIK EWER MIKROPHONANORDNUNG UND MtKROPHONANORI)NUNG (S7) Abstract Two outpu signals sr ndF A b) of a microphone arrangemnt (1) are divided wheirby said signals A ane differenty dependent on dhe direction or incidenc~e of acmfsic A signals. A product from the division result (A7) and the weighiting facor7 F7 is saturated (12) anid sutnacd 1 L1 from a signal value whicb can hI be inputted. MThe subtraction insult3 5b 11 is multiplied with the output signial l of the microphone arangement s which is the denominator signal for n E the division A desired directivity"aA is produced batwee the result signal (Sout) of te rultiplicatie nd S~d~ the direction of incidence on the microphone amagmtent of incident acoustic signals accoidinS to the weighting factor of fth saturation value and -of the1 subrmccion vali (57) 7aamnasn Zwei Ausgagssignalac (At& wid Aitb) elier Mikrophonamordnung welche urnezchiedlich abiklgg vont der Einfailsrichng (pgr) akustiscbe Signaic sind, werden dividiet Ein Produlct aus dem Divisioasreultat Und cinem Gu~~hngSfakror (a) wirti 31101it (12) iund von cirten cingcbbarcn Signiwert subtrihiert. Das Subu~aktionmsuli wiW i t demjcnigen Ausgangssigllal der Mu phIonanoranung multipliziest welches auh das Nae~nal fOr die Division bildet. In At4nigkit des Gewichtugsfaktors des Sateungswatcs sawis des Subrrskzomswertes wlrd zwischen fxtstlsipnit (Swj) der Mulciplikation und Eaft1isichwimg (phgr,) adf die Milcrophnanonlang einfallander akustischer Signale cine erwarschte Richtcharalktistik realisieri.

Codes used to identi under the PCT -are published.

ONLY FOR INFORMATION .fy the PCT member States on the flyleaves of the brochures in which international applications made AL Albania ES Spain AM Armenia F1 Finland AT Austria FIR France AU Australia GA Gabon AZ Azerbaidjan GB United Kingdom BA Bosni a- Herzegovina GE Georgia BB Barbados GH Ghana BE Belgium GN Guinea BF Burkina Fasso GR Greece BG Bulgaria 1113 Hungary Bj Benin IE Ireland BR Brazil IL Israel BY Belarus is Iceland CA Canada IT Italy CF Central African Republic ,jp Japan CG Congo KE Kenya CH Switzerland KG, Kyrghyzstan CI Ivory Coast KP Democratic People's CM Cameroon Republic of Korea CN China KR Republic of Korea CU Cuba KZ Kazakhstan CZ Czech Republic LC Saint Lucia DE Germany LI Liechitenstein DK Denmark LK Sri Lanka EE Estonia LR Liberia LS Lesotho SI Slovenia LT Lithuania SK Slovakia LU Luxembourg SN Senegal LV Latvia SZ Swaziland MC Monaco TD Chad MD Republic of Moldova TG Togo MG Madagascar Ti Tajikistan MK Former Yugoslav Republic TM Turkmenistan of Macedonia TR Turkey ML Mali 'IT Trinidad and Tobago MN Mongolia UA Ukraine MR Mauritania UG Uganda MW Malawi us United States of America MX Mexico UZ Uzbekistan NE Niger VN Vietnam NL Netherlands YU Yugoslavia NO Norway ZW Zimbabwe NZ New Zealand PL Poland PT Portugal RO, Romania RU Russian Federation SD Sudan SE Sweden SG Singapore Method for prescribing the transmission characteristics of a microphone arrangement, and microphone arrangement The present invention relates to the reception and processing of acoustic signals incident on microphones.

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 W099/04598 and US 09/146784 (T multiplication), or to H:\mavism\keep\specis\2000234142.doc 29/04/05 2 W099/09786 and US 09/168184 (p 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.

According to one aspect of the present invention there is provided a method for prescribing the transmission characteristic with the aid of which acoustic signals incident on a microphone arrangement are converted into an electric output signal as a function of their direction of incidence, characterized in that provided at the microphone arrangement are at least two microphone subarrangements whose transmission characteristics differ in each case in terms of their electric output signals as a function of said direction, and in that the output signal is formed as a function of a product, saturated to a prescribed or prescribable value, with the quotient of the output signals of the microphone sub-arrangements as factor.

According to another aspect of the present invention there is provided a microphone arrangement having at least two microphone sub-arrangements whose transmission H:\mavism\keep\specis\2000234142.doc 29/04/05 3 characteristics differ with reference to the direction of signals arriving at them, and whose outputs are led to inputs of a processing unit with one output, characterized in that the processing unit comprises a weighted quotient forming unit with a denominator input, a numerator input, as well as a weighting input, numerator and denominator inputs being operationally connected to an input of the processing unit, the weighted quotient forming unit further generating at its output an output signal saturated to a maximum and/or a minimum value, which output is operationally connected to the output of the processing unit.

The preferred embodiment of the present 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 subarrangements used according to embodiments of the present invention; Figure 2 shows, plotted against the angle axis T in accordance with figures la and ib, the formation of a quotient function Q from the characteristics in accordance H:\mavism\keep\specis\2000234142.doc 29/04/05 4 with figures la and ib, 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 Ib a transmission characteristic implemented according to an embodiment of the present invention; Figure 5 shows in a representation similar to figure 4 a further transmission characteristic implemented according to an embodiment of the present invention; and Figure 6 shows the implementation of a microphone arrangement according to an embodiment of the present invention in the form of a simplified signal flow/function block diagram.

H:\mavism\keep\specis\2000234142.doc 29/04/05 5 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 i.

In a 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 H:\mavism\keep\specis\2000234142.doc 29/04/05 6 without taking account of their 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 c I satB in which S signifies the output signal arrangement of the microphone A signifies a prescribed or prescribable signal value ICNI 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 Icz I signifies the amplitude value of the output signal H:\mavism\keep\specis\2000234142.doc 29/04/05 7 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 substantially inverse directions.

A microphone arrangement according to embodiments of the present invention of the type mentioned at the beginning is distinguished in that the processing unit comprises a weighted quotient forming unit with a denominator input, a numerator input, as well as a weighting input, numerator and denominator inputs being operationally connected to an input of the processing unit, the weighted quotient forming unit further generating at its output an output signal saturated to a maximum and/or a minimum value, which output is operationally connected to the output of H:\mavism\keep\specis\2000234142.doc 29/04/05 8 the processing unit.

The method and the microphone arrangement according to embodiments of the present invention are particularly suitable for use on hearing devices.

Although it is certainly possible to implement the described method and microphone arrangement by means of signal processing in the time domain, in a preferred embodiment of the present invention the signal processing is undertaken in the frequency domain with the use of time domain/frequency domain converters and frequency domain/time domain converters.

The procedure according to the preferred embodiment 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 preferred embodiment even when starting from more complex transmission functions.

H:\mavism\keep\specis\2000234142.doc 29/04/05 9 Let a first microphone sub-arrangement have the threedimensional 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 p. 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 subarrangement. The transmission characteristic in accordance with figure la may be denoted by cN, and that in accordance with Ib 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 p 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 subarrangements considered.

H:\mavism\keep\specis\2000234142.doc 29/04/05 10 According to the preferred embodiment, a quotient, for example, Q= IZ1 is now formed 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 have a pole at p t. In the case of real quotient formation, the pole resulting for the zero of the denominator function ICNI 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, is for the H:\mavism\keep\specis\2000234142.doc 29/04/05 10a transmission characteristic result to be achieved, that is to say be a transmission characteristic that has a high signal gain in an angular range in 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 embodiment can be seen. 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 that the possibility now exists of intervening H:\mavism\keep\specis\2000234142.doc 29/04/05 WO 00/33634 11 PCT/CH00/00190 simply, specifically by saturation to a prescribable or prescribed constant value of the quotient function.

For reasons of clarity, the quotient function Qsat1 saturated to is now introduced into figure 3 with linear gain scaling. It may now be seen further from this that the saturated quotient function Qsati exhibits the profile of a directed transmission characteristic in the non-saturated angular ranges, in the present case between 0 and R/2, as well as between 37/2 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, 12 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 S3x 0 p and p 2 t.

2 2 The following can now be set forth with reference to the procedure according to the preferred embodiment: Fundamentally, the transmission characteristics to be implemented is implemented on the output side of the microphone arrangement 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 H:\mavism\keep\specis\2000234142.doc 29/04/05 WO 00/33634 13 PCT/CH00/00190 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 another function, that is to say as F F[(x -Q)satB], in general, it is much preferred to implement a directed characteristic 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.

WO 00/33634 14 PCT/CH00/00190 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 p of acoustic signals that strike.

SIn 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.

SThe implementation of such microphone 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.

0 It goes without saying that it is possible to WO 00/33634 15 PCT/CHOO/00190 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* l ScN 1satB Figure 4 illustrates the transmission function that was formed according to the invention from inversely directed, identical cardoid transmission characteristics Ca, corresponding to the transmission function

S'C

N

I

The resulting transmission characteristic is illustrated in figure 5 when the following is true: CN 1- NI4-cZ, NI satl 16 A microphone arrangement operating using the method according to the preferred embodiment 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. Output signals appear at their outputs Ala and AIb as a function of the acoustic signals incident at the microphones on the input side [lacuna] direction p. As illustrated in figure 6, the two microphone sub-arrangements can well be implemented 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 p 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 H:\mavism\keep\specis\2000234142.doc 29/04/05 wo 00/33634 17 PCT/CHOO/00190 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 S 9 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 illustrated by way of example in figure 6 and capable of being set at the weighting unit 9 can assume arbitrary non-vanishing values.

As further illustrated schematically in figure 6, the signal at the output A 9 of the weighted quotient forming unit 10 is fed to a saturation unit 12 whose output is firstly fed to the input E1a,. 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 18 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 A 11 of the subtraction unit 11 is operationally connected to one input E13a of a multiplication unit 13 to whose second input E13b the output signal of that microphone subarrangement la is operationally connected that is also operationally connected to the denominator input N of the division unit 7. 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 for the denominator signal, and if appropriate 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 S,,t of the microphone arrangement on the output side of the multiplication unit 13. It has the desired transmission characteristic as a function of the solid angle p 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 H:\mavism\keep\specis\2000234142.doc 29/04/05 19 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 Sout by setting the weighting factor c, the saturation value B, the fixed value A, and further weighting factors such as P, if appropriate.

The method according to embodiments of the invention and the microphone arrangement according to embodiments of 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 possibility 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 subarrangements with cardoid characteristics Ca, it is rather those with hypercardoid characteristics Hca (figure 5) that are preferably used for hearing devices.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, H:\mavism\keep\specis\2000234142.doc 29/04/05 20 i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

H:\mavism\keep\specis\2000234142.doc 29/04/05

Claims (16)

1. 2. The method as claimed in claim 1, further characterized in that the product is saturated to a maximum value.
2. 3. The method as claimed in claim 1 or 2, further characterized in that the second factor of the saturated product can assume an arbitrary non-vanishing value.
3. 4. The method as claimed in one of claims 1 to 3, H:\mavism\keep\specis\2000234142.doc 29/04/05 22 further characterized in that the function 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 The method as claimed in any one of claims 1 to 4, further characterized in that the quotient of the amplitude values of the output signals is determined.
4. 6. The method as claimed in any one of claims 1 to further characterized in that the output signal is formed using the following function. S=cN A- a- IC. SN A- CNsatB in which S signifies the output signal of the microphone arrangement H:\mavism\keep\specis\2000234142.doc 29/04/05 23 A signifies a prescribed or prescribable signal value ICNi 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 ICzl signifies the amplitude value of the output signal of the second microphone sub-arrangement satB signifies a saturation of the product to a prescribed or prescribable maximum signal value B a signifies a prescribable or prescribed factor of the product.
5. 7. The method as claimed in any one of claims 1 to 6, further characterized in that the transmission characterisitics of the microphone sub-arrangements exhibit maximum gains for acoustic signals incident from substantially inverse directions.
6. 8. The method as claimed in claim 7, further characterized in that the transmission characteristics are H:\mavism\keep\specis\2000234142.doc 29/04/05 24 of cardoid or, preferably, hypercardoid shape.
7. 9. A microphone arrangement having at least two microphone sub-arrangements whose transmission characteristics differ with reference to the direction of signals arriving at them, and whose outputs are led to inputs of a processing unit with one output, characterized in that the processing unit comprises a weighted quotient forming unit with a denominator input, a numerator input, as well as a weighting input, numerator and denominator inputs being operationally connected to an input of the processing unit, the weighted quotient forming unit further generating at its output an output signal saturated to a maximum and/or a minimum value, which output is operationally connected to the output of the processing unit. The microphone arrangement as claimed in claim 9, further characterized in that the output signal of the weighted quotient forming unit is saturated to a maximum signal value.
8. 11. The microphone arrangement as claimed in claim 9 or claim 10, further characterized in that an arbitrary non- vanishing weighting factor is fed permanently or settably H:\mavism\keep\specis\2000234142.doc 29/04/05 25 to the weighting input.
9. 12. The microphone arrangement as claimed in any one of claims 9 to 11, further characterized in that the output of the weighted quotient forming unit is operationally connected to the output of the processing unit via a difference forming unit.
10. 13. The microphone arrangement as claimed in claim 12, further characterized in that a second input of the difference forming unit is fed a fixed or settable signal whose value is preferably at least approximately equal to a saturation value of the saturated output signal of the weighted quotient forming unit.
11. 14. The microphone arrangement as claimed in any one of claims 9 to 13, further characterized in that the inputs of the processing unit are each led via magnitude forming units before they are operationally connected to the numerator or denominator input of the quotient forming unit. The microphone arrangement as claimed in any one of claims 9 to 14, further characterized in that the output of the weighted quotient forming unit is operationally H:\mavism\keep\specis\2000234142.doc 29/04/05 26 connected to one input of a multiplication unit whose second input is operationally connected to the output of that microphone sub-arrangement which is operationally connected to the denominator input of the quotient forming unit, and in that the output of the multiplication unit is operationally connected to the output of the processing unit.
12. 16. The microphone arrangement as claimed in claim 13, further characterized in that the output of the difference forming unit is operationally connected to one input of the multiplication unit.
13. 17. The microphone arrangement as claimed in claim 16, further characterized in that the output of the weighted quotient forming unit is operationally connected to one input of a multiplication unit whose second input is operationally connected to the output of that microphone sub-arrangement which is operationally connected to the denominator input of the quotient forming unit, and in that the output of the multiplication unit is operationally connected to the output of the processing unit.
14. 18. The microphone arrangement as claimed in any one of H:\mavism\keep\specis\2000234142.doc 29/04/05 27 claims 9 to 17, further characterized in that time domain/frequency domain converters are provided in each case between the outputs of the microphone sub- arrangements and the inputs of the processing unit.
15. 19. The microphone arrangement as claimed in any one of claims 9 to 18, further characterized in that the microphone sub-arrangements have cardoid or hypercardioid characteristics, preferably the latter. A method as claimed in any one of claims 1 to 8, and substantially as herein described with reference to the accompanying drawings.
16. 21. A microphone arrangement as claimed in any one of claims 9 to 19, and substantially as herein described with reference to the accompanying drawings. Dated this 2 9 th day of April 2005 PHONAK AG By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia H:\mavism\keep\specis\2000234142.doc 29/04/05