• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:

    公开号:BE1019734A3
    申请号:E201000185
    申请日:2010-03-23
    公开日:2012-12-04
    发明作者:Schuymer Bart De；Henk Brouckxon
    申请人:Televic Conference Nv；
    IPC主号:
    专利说明:

    STEERABLE MICROPHONE SERIES SYSTEM WITH A FIRST ORDER
    DIRECTION PATTERN
    Technical field of the invention
    The present invention relates essentially to the technical field of microphone series as they are used, for example, in conference systems.
    BACKGROUND OF THE INVENTION
    Within the art, it is well known how a so-called first-order polar pattern can be approximated by using a series of two or more microphones. The microphones are pressure sensitive microphones that each perceive the acoustic pressure at a single point. The polar pattern is formed as the pressure difference between two points in the space. It is an indication of the sensitivity to sounds that arrive at different angles around its central axis. Polar patterns represent the location of points that produce the same signal level output in the microphone if a given sound pressure level is generated from that point. A polar pattern is an indication of the directionality of the microphone.
    A first-order differential microphone typically has a polar pattern given by R (9) = A + (1 - A) cos Θ, with 0 <A <1 and Θ as the slope (azimuth), so that the response is normalized to have a maximum value of 1 at Θ = 0. The expression for R (6) is the parametric expression of the 'limaçon of Pascal' algebraic curve that is well known to those skilled in the art. The two terms in the above equation can be seen as the sum of a multi-directional sensor (i.e., the first term) and a first-order bipolar sensor (i.e., the second term). This is the general form of the first-order series. Figure 1 is a representation of polar curves of three well-known members of the limaçon family, namely the dipole (A = 0), the cardioid (A = 0.5) and the hypercardioid (A = 0.25). It should be noted that these polar curves always apply the absolute value of R (9).
    Patent document EP 0869697 B1 relates to a controllable and variable first-order differential microphone series. The invention is also described in the document "A controllable and variable first-order differential microphone series" (G. 1/1 /. Elko et al., ICASSP'97, pp. 223-226). In the proposed method, a polar pattern of type A + B cos Θ is approximated (with A = 1-B). This pattern can be seen as the sum of a multi-directional microphone (A) and a double-directional (or eight-shaped) microphone (B cos9). The first commercial cardioid and multi-directional microphones were even made by adding the signals from these two types of microphones together. To achieve the desired polar pattern, an approach to slowing down and addition is used. An applied microphone array arrangement is shown in FIG. 2 shown. When the input from the second microphone is simply subtracted from the input from the first microphone, the following polar pattern is obtained (where k indicates the acoustic wave number): or equivalent
    Note that s / nx * x for small values of x is obtained
    for kd «π. The above equation is easily recognized as a 90 ° phase-shifted eight-shaped polar pattern. The scaled addition of a multi-directional 90 ° phase-shifted polar pattern with the aforementioned approach to a two-pole polar pattern allows the construction of an approximation of any first-order (limaçon) polar pattern. This phase-shifted multi-directional pattern is achieved by adding the scaled output of two oppositely-oriented phase-shifted cardioid approaches. A cardioid polar pattern can be approximated by adding the output of the first microphone to a delayed (with kd seconds) output of the second microphone. The opposite polar pattern is obtained by delaying the first microphone instead of the second. Adding these opposite approaches to cardioid polar patterns (scaled by 1/2) gives:
    simplified up to and including
    For kd «77, the above equation approximates a multi-directional polar pattern, with the same phase shift as the resulting approximation of the eight-shaped polar pattern. All polar patterns can be obtained with the delay and addition technique since the filter coefficients are frequency independent. The proposed solution relies on the application of analogue filters. When drawing the magnitude response of Θ = 0, a highly permeable characteristic is easily observed for the applied delay and addition. Undoing this high-transmissive behavior requires an extra filter and also amplifies the low-frequency sound. Another disadvantage of the delay and addition method is that unless the filter is implemented in an analog circuit, a fractional delay is required, e.g., about 2,09913 samples for d = 0.015 m and a sampling frequency of 48 kHz. The accuracy of the fractional delay depends on the filter length used. Obtaining good accuracy of the fractional delay therefore implies the addition of additional delay. Yet another disadvantage of the delay and addition method is the undesirable effect of attenuating the signal when the microphone distance d is reduced. This is illustrated in FIG. 3. On the left side the polar patterns are shown for the method of deceleration and addition at d = 0.015 m, on the right side the result is shown for d = 0.005 m. It can be easily verified that although the shape of the polar pattern improves, the gain decreases when d decreases.
    Objects of the invention
    It is an object of the present invention to provide a microphone array system that is capable of producing an output signal with a first-order direction pattern in which the disadvantages of the prior art are overcome. A further object of the invention is to provide a method for generating an output signal with a first-order direction pattern.
    Summary
    The present invention, from a first aspect, relates to a microphone array system that is capable of producing an output signal with a first-order direction pattern. The microphone array system comprises a first and a second multi-directional microphone. These two microphones are spaced apart by a minimum acoustic wavelength defined by the desired audio frequency operating range. The microphone array system comprises a first filter for filtering a signal received by the first multi-directional microphone and a second filter for filtering a signal received by the second multi-directional microphone. The first filter has a first frequency response. This filter generates a first filtered output signal. The second filter has a second frequency response and produces a second filtered output signal. The first filter and second filter are designed to have a frequency response that takes into account the frequency response of the first and second multi-directional microphone. The microphone array system further comprises an addition means for adding the Output signals of the first and second filter. The resulting combined signal then has the desired first-order direction pattern.
    The proposed solution certainly achieves the goal. With only two microphones, good directional patterns are available within a wide frequency range, making cheap and small solutions possible. The approach followed can be seen as a method of filtering and adding, while solutions of the current state of the art prefer to use a method of delaying and adding. The method of filtering and adding exhibits low permeable behavior, while delaying and adding has rather a high permeable characteristic, as mentioned earlier.
    In a preferred embodiment, the first and second filtering means are implemented as finite impulse response filters. The proposed solution is implemented in a cost-effective manner in digital implementation. An implementation of the delay and addition method would require a fractional delay. The accuracy of the fractional delay depends on the filter length used. Therefore, obtaining a sufficiently accurate fractional delay implies the addition of additional delay. This problem is avoided by applying the filtering and adding approach of the present invention.
    In a digital implementation of the microphone array system, conversion means are preferably provided for converting the respective signals received by the first and second multi-directional microphone into corresponding digital output signals. In an alternative embodiment, digital microphones of sufficient quality can be used, whereby the conversion from analog to digital is canceled.
    In an advantageous embodiment, the microphone array system further comprises means for performing block processing for determining the signal output by the first and second filter means. This makes faster processing possible by applying the technique of overlapping and adding when performing the filtering work.
    In a preferred embodiment, the first and second filtering means are adjustable, so that parameters A and B of the first-order direction pattern of type> A + Scos Θ can be set.
    In an embodiment of the invention, the microphone array system further comprises a third multi-directional microphone and a third filter for filtering the signal received by the third multi-directional microphone. This third microphone is located at a distance from the first or the second microphone that is smaller than the minimum acoustic wavelength defined by the audio frequency operating range. The third microphone is preferably positioned such that the set of three microphones forms the angular points of a substantially straight and isosceles triangle. The third filter has a frequency response which is determined by taking into account the frequency response of the third multi-directional microphone. The adding means is organized such that the filtered signal output through the third filter can be added to the signal output through the first and second filter.
    In a preferred embodiment, the microphone array system comprises a third and a fourth multi-directional microphone. The third and fourth multi-directional microphones are spaced apart by a minimum acoustic wavelength defined by the desired audio frequency operating range. The third and fourth microphone are positioned such that they form a series with an axis that is substantially orthogonal to the axis of the series formed by said first and second microphone. Preferably, the centers of the four microphones form the corners of substantially a square. The third and fourth filter have a third and fourth frequency response, respectively. These frequency responses take into account the frequency responses of the third and fourth multi-directional microphone. The adding means in this embodiment is preferably arranged to add up the signal output of the third and fourth filtering means and to combine the resulting output signal with the resulting output signal of said first and second filtering means. Alternatively, a separate addition means for the signal output of the third and fourth filter means is provided, as well as a suitable combination means for combining the addition signals of the first and second filter and the third and fourth filter, respectively. This configuration makes it possible to control the listening direction in 360 degrees.
    In another preferred embodiment, the microphone array system further comprises storage means for storing filter coefficient values for a plurality of control angles. In an arrangement with two microphones, steering is only possible in the two directions of the microphone axis. With more available microphones, any listening direction in the plane formed by the microphones can be controlled.
    The invention also relates to a speaker unit of a conference system, comprising a microphone array system as previously described.
    With advantageous consequences, the speaker unit is arranged to be built into a table. In this way, the microphone series is completely discreet and practically invisible to the speaker: the flat surface of the table is preserved. This is possible through the use of multi-directional microphones. In another advantageous embodiment, the microphone array system can be built into a table in a foldable manner so that it can be lifted if necessary, thereby reducing the elevation angle.
    The invention also relates to a conference system comprising a plurality of said speaker units.
    In another aspect, the invention relates to a method for generating an output signal from a microphone array with a first-order direction pattern, comprising the steps of: - providing a first and second microphone located on a spacing less than a minimum acoustic wavelength defined by the desired audio frequency operating range, - applying a signal received by the first microphone to a first filtering means and a signal received by the second microphone to a second filtering means, wherein the first and second filtering means respectively have a first and second frequency response, these first and second frequency responses being determined while taking into account the frequency response of the third and fourth multi-directional microphone, - adding the signal output of the first and second filtering means and generating the ou Microphone series output signal with first-order directional pattern.
    In a most preferred embodiment, the first and second microphone are configured as a back-beam series, the listening angle being parallel to the microphone axis.
    The above method can also be applied with minor adjustments when a three or four microphones system is used.
    Brief description of the drawings
    FIG. 1 illustrates some well-known polar patterns.
    FIG. 2 shows an arrangement of a first-order microphone series.
    FIG. 3 illustrates the problem of dependence on the microphone distance in the method of delay and addition.
    FIG. 4 shows an arrangement with two microphones.
    FIG. 5 shows the method of filtering and adding the present invention.
    FIG. 6 illustrates directional patterns obtained with an arrangement with two microphones.
    FIG. 7 shows a controllable configuration of the first-order method.
    FIG. 8 shows a rotated cardioid analysis.
    FIG. 9 shows directional patterns obtained with an arrangement with four microphones.
    FIG. 10 shows improvements by using 4 microphones instead of 2.
    FIG. 11 shows an arrangement of a conference system.
    FIG. 12 shows some two-dimensional polar curves for a pair of elevation angles.
    FIG. 13 shows an arrangement with three microphones.
    FIG. 14 depicts a back-beam sequence with three microphones.
    DETAILED DESCRIPTION OF THE INVENTION
    In a first aspect, the present invention relates to a microphone array system for producing an output signal with a first-order direction pattern. In contrast to EP0869697, an approach is followed in which a method of filtering and adding is applied to obtain an estimate of a first-order polar pattern. Good directional patterns can thus be achieved within a wide frequency range with the help of only two (multi-directional) microphones, making cheap and small solutions possible.
    The arrangement with the first-order microphone array as shown in FIG. 4 is being considered. Note that in the calculations below, the reference point is in the middle between the two microphones. The frequency responses of the first and second multi-directional microphone can be written as
    where d is the distance between the two microphones and ω is the angular frequency. The ω / c can be written as ω / c = 2nf / c = 2π / λ = k, where λ represents the wavelength of the sound signal, ƒ the acoustic frequency, c the speed of sound in the air (approximately 343 m / s ) and k the acoustic wave number. Θ refers to the slope. In the above approximation step, the first two terms of the Taylor polynomial for the exponential function have been omitted. The invention proposes the application of a filter Ηι (ω) on Si (œ, 9) and a filter Η2 (ω) on S2 (co, 9) and adding the filtered signals as follows:
    The resulting values of A and B are therefore:
    For a given value of A and B one gets the following filter design:
    In a case where the reference point is not the center point between the two microphones, the expressions for the filter characteristics can be easily derived in a manner similar to that shown above. FIG. 5 illustrates the approach followed in the method of filtering and addition. It is easy to verify that Ηλ (ώ) and Η2 (ω) depend on the frequency. In contrast to the approach followed in "Directional patterns obtained from two orthree microphones" (Directional patterns obtained from two or three microphones, S. Thompson, Knowles Electronics, September 29, 2000), the solution according to the invention adapts advantageously to this frequency. dependence on.
    In an advantageous embodiment, a digital implementation with finite impulse response filters is used.
    A representation of a transformation domain is made up of two FIR filters and S_lt as follows. For a sample duration of F Hz and a filter length of N ticks (where N is even), the values ^ [w] resp. S ^ ln] for the ne (0 <n <N) frequency box of the N-point FFT of respective filters H1 and H2 given by: and
    where i ^ i [o] = u, D and / [2] [uj = up. a monsierauur from uvv. κπζ. and filter length of e.g. N = 1024 can be used. If time domain filtering is desired, the time domain representation of the filters can be easily obtained using an inverse DFT algorithm.
    As explained, the desired polar pattern response is obtained by filtering the input of microphone m-i and m2 with the FIR filter corresponding to / - / and H2 and by adding the filter outputs. This filtering can, for example, be done in the transformation domain, by means of overlapping and adding to obtain the correct time domain result. To improve performance, block processing can be applied in the transformation domain. Also, to soften the filter response, the FIR filter coefficients can be weighted through a window (e.g., the Flamming window), after which they are transformed back into the transformation domain.
    As also disclosed in EP08696971, an additional short FIR filter can optionally be provided to compensate for non-idealities of the microphones. This makes it possible to use normal, cheaper microphones. This additional filter can in one embodiment be combined in a filter corresponding to a cascade of the short filter and the filter H as described above.
    The distance between the centers of both microphones in an arrangement with two microphones should be at most about 1.5 cm, because the performance for higher frequencies depends on the distance between the microphones. A distance of 1.5 cm allows the use of electret microphones with a diameter of up to 1.5 cm. The microphones are advantageously placed in a back-beam configuration. This means that the listening angle is parallel to the microphone axis. Steering is only possible in the two back-beam directions, as shown in Figs. 6.
    isUf ζυιυ / υι »5
    The polar curve of the ideal first-order polar patterns directed at an angle α can be obtained using the formula
    wherein (#, abs (./ a (#))) are the polar coordinates of the corresponding polar pattern. The well-known cardioid and hypercardioid patterns are obtained by setting A = B = 0.5 and A = 0.25 and 6 = 0.75, respectively. Note that a = 0 results in the limaçon family.
    These first-order polar patterns can be approximated by the combination of two orthogonal back-ray sets with two microphones each, see Figs. 6. The configuration consists of four multi-directional microphones that are placed at the corner points of a square. The length of the diagonal of the square is preferably 1.5 cm or less. The two microphone sets are formed by the two pairs of microphones at the opposite angular points of the square, as indicated by the dashed lines in FIG. 7.
    The rotated cardioid polar pattern can be obtained, for example, by two orthogonal eight-shaped polar patterns and a multi-directional pattern, see Figs. 8. The two eight-shaped patterns are summed so that a rotated eight-shaped pattern is obtained (note that the polar patterns in Fig. 8 only provide magnitude information, not phase information). By adding this pattern to a multi-directional pattern (with magnitude 0.5), the desired rotated (in this case 45 °) cardioid polar pattern is obtained.
    By applying the approach of the invention as described above, a steerable microphone array can be implemented. For a polar pattern in which parameters A and 6 are rotated by a degree, the first microphone series is of the type Rx {ß) = A / 2 + Bcos ar and the second is of the type R2 {ß) = AH + Bsina. Note that unlike the method described in EP0869697, there is no phase shift between the output of both microphone sets. This simplifies the implementation.
    With more mathematical detail, the derivation of the filter characteristic can be described as follows. Four microphones mi, rri2, m3 and m4 are considered (see Fig.7). The center point is taken as the reference point in the calculations below. The microphone pairs (mi, m2) and (m3, m4) can be used respectively to estimate the following
    features:
    By applying the identity cos (# + ^) = cos (#) cos (^) - sin (<9) sin (ç9), a first-order slope characteristic that is rotated φ degrees can be written as a combination of these characteristics :
    Resulting in:
    and
    The filter coefficients for different control angles can be calculated efficiently in real time. Alternatively, the filter coefficients can be calculated offline and, for example, stored in external memory, so that no calculation power is lost for obtaining the filter coefficients.
    In an arrangement with four microphones, the centers of the four microphones are advantageously placed at the corners of substantially a square. As with the setup with two microphones, the diagonal length of the square must not exceed 1.5 cm. The arrangement is illustrated in FIG. 9 where two possible (ideal) polar patterns are given.
    Even in the case where the steering only takes place in one fixed direction parallel to an axis of a microfocus array, it may be advantageous to use the four-microphone arrangement instead of the two-microphone arrangement. This is illustrated in FIG. 10, where the three-dimensional polar pattern is plotted from two angles of view for a frequency of 8 kHz and a microphone distance of 1.5 cm. The lower two curves correspond to the case where all four microphones are used, while the lower two curves correspond to the case where only two microphones are used. In the figures above, a backward lob is visible which is undesirable when approaching a cardioid pattern. It can be concluded that the addition of two microphones on a perpendicular axis is advantageous since the polar pattern for the arrangement with four microphones is clearly more similar to the ideal cardioid pattern.
    With the arrangement with four microphones, it is possible to control the listening direction 360 degrees (without physically changing the arrangement of the microphone array). In the setup with two microphones, it is only possible to steer to the front or rear of the microphone array.
    Ideally, the plane in which the microphones are placed points (vertically) towards the direction of the speaker, because the directionality in this plane is maximized. However, this is not essential and any deviation from this optimum is permitted. The angle of inclination φ must be kept as small as possible. For example, an arrangement in which the microphones are placed in the horizontal plane must already have sufficient directional sensitivity in some situations. This is the case, for example, when the microphones are integrated in a table and the speaker is seated at the same table (conference system setup). FIG. 11 illustrates this arrangement in which the angle of inclination φ is clearly indicated. The two-dimensional polar curves for a pair of elevation angles are shown in FIG. 12 given. The figures indicate that a target angle of 0 ° to 45 ° is acceptable.
    In one embodiment, the microphone array system comprises three microphones. See FIG. 13. Such a microphone array can be separated into two subset pairs (m *, m2) and where and mi physically correspond to microphone m:
    and
    As shown in FIG. 13, the three microphones are preferably positioned such that they (i.e., their centers) substantially form the vertices of a straight and isosceles triangle. The adder is arranged to also add the signal output from the third filter. The three-microphone solution can advantageously be used as a backup solution in the case where a microphone of a four-microphone system no longer works.
    The invention also relates to a speaker unit of a conference system, comprising a microphone array system as described. The participants sit at tables in a conference system. The preferred placement of the microphone array system of this invention is therefore either on the table or mounted in the table. The selection of the desired steering direction can be done automatically or manually. Automatic steering can be achieved by determining the direction of the speaker. This can be done, for example, by applying a voice activity detector and measuring the average quadratic amplitude of the output signal for different control angles. Another possibility is to apply a mechanism that is started by a participant or director. This can be done, for example, by pressing a button. Each button then corresponds to a fixed and a priori known steering angle. Some advantageous possible arrangements are discussed in the following paragraphs.
    In a parallel arrangement, one or two participants can use the microphone array. Both the setup with two and the setup with four microphones can be used. Each participant is positioned in such a way that the microphone axis points in his or her direction. In the case of two participants, they are located on opposite sides of the microphone array. When only one participant speaks, a cardioid or hyper-cardioid pattern is applied to send to the participant. When both participants speak, a two-pole pattern can be applied to send to both participants.
    Four microphones are required in a parallel and perpendicular arrangement. This arrangement requires the arrangement with four microphones. The possibility of up to four participants exists, but their possible positions are limited so that all listening angles are parallel to the axis formed by one of the two microphone pairs. The polar patterns are optimized in this way. The participants can each sit on one side of a square table or alternatively at a round table in 90 ° angles. Again a bipolar pattern or a combination of a cardioid and bipolar pattern can be used if more than one participant speaks.
    An arrangement with a round table also requires the arrangement with four microphones. The participants are ideally placed at a round table, although other arrangements with, for example, a rectangular table are also possible. Now the ideal situation in which each steering direction is parallel to an axis formed by a microphone pair is no longer necessary. Although the obtained polar patterns will essentially degenerate somewhat, more flexibility in the placement of the participants is obtained.
    The above description explains how a signal with a first-order direction pattern can be derived by applying a filtering and addition approach. This approach can be applied to achieve a higher-order directional pattern. For example, if one wants to generate a signal with a second-order pattern, the filters can be determined by taking into account an additional term (i.e., the second-order term) of the Taylor polynomial for the exponential function. The second-order polar pattern that is approximated is then given by met

    In this case, a back-beam sequence with three microphones at the same distance is required (see Fig. 14). The filter design is then characterized by
    Please note that this microphone series can only be steered in a direction parallel to the microphone axis.
    Although the present invention has been illustrated by reference to specific embodiments, it is obvious to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be practiced with various modifications and modifications. without deviating from its range. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated rather by the appended claims than by the foregoing description, and all changes falling within the meaning and the equivalence range of the claims, therefore be included as such. In other words, it is contemplated that the invention encompasses any and all modifications, variations, or equivalents that fall within the scope of the basic underlying principles and the main features of which are claimed in this patent application. It is further understood by the reader of this patent application that the words "comprising" or "includes" do not exclude other elements or steps, that the word "a" does not exclude a plural and that a single element, such as a computer system, a processor or a other integrated unit can fulfill the functions of different resources listed in the claims. All reference marks in the claims should not be construed as limiting the respective claims concerned. The terms "first", "second", "third", "a", "b", "c" and the like are introduced in use in the description or in the claims to distinguish between similar elements or steps and do not necessarily describe a sequential or chronological order. Similarly, the terms "top", "bottom", "top", "bottom" and the like are introduced for descriptive purposes and not necessarily to indicate relative positions. It is to be understood that the terms used in this way are interchangeable under suitable conditions and that embodiments of the invention are capable of operating according to the present invention in sequences or orientations other than those described or illustrated above.
    权利要求:
    Claims (14)
    [1]
    A microphone set system (1) for producing an output signal with a first-order direction pattern, comprising - a first (2) and second (4) multi-directional microphone spaced apart by a minimum acoustic wavelength which is defined by the desired audio frequency operating range, - a first filtering means (6) for filtering a signal received by said first multi-directional microphone and a second filtering means (8) for filtering a signal received by said first a second multi-directional microphone, wherein said first filtering means has a first frequency response that produces a first filtered output signal and said second filtering means has a second frequency response that produces a second filtered output signal, wherein said first and said second frequency response take into account the frequency responses of said first and second multiv digitally directed microphones, - an adding means (9) for adding said first and said second filtered output signal, so that the resulting added signal has said first-order direction pattern.
    [2]
    A microphone set system as in claim 1, wherein said first and second filtering means are implemented as finite impulse response filters.
    [3]
    A microphone set system as in claim 2, comprising conversion means for converting the respective signals received by said first and second microphone into corresponding digital output signals,
    [4]
    A microphone set system as in claim 2 or 3, further comprising means for performing block processing for determining said signal output by said first and second filtering means.
    [5]
    A microphone set system as in any of the preceding claims, wherein said first and second filtering means are adaptable.
    [6]
    A microphone set system as in any of the preceding claims, further comprising: - a third multi-directional microphone located at a distance from said first or said second microphone that is smaller than a minimum acoustic wavelength defined by the desired audio frequency operating range, - a third filtering means for filtering a signal received by said third multi-directional microphone, said third filtering means having a third frequency response that produces a third filtered output signal, wherein said third frequency response takes into account the frequency response of said third multiple directed microphone, and wherein said adding means is also adapted to add said third filtered output signal.
    [7]
    A microphone set system as in any of claims 1 to 5, further comprising - a third and a fourth multi-directional microphone located at a distance from each other that is smaller than said minimum acoustic wavelength defined by said given audio frequency operating range, wherein said third and fourth multi-directional microphone are arranged to form a series with an axis substantially orthogonal to the axis of the series formed by said first and second multi-directional microphone, - a third filtering means for filtering a signal received by said third multi-directional microphone and a fourth filtering means for filtering a signal received by said fourth multi-directional microphone, said third filtering means having a third frequency response producing and displaying a third filtered output signal fourth filter medium 1 has a fourth frequency response which produces a fourth filtered output signal, wherein said third and said fourth frequency response take into account the frequency responses of said third and fourth multiply-directed microphones, - wherein said adding means is arranged to add up said third and fourth Output signals and to combine the resulting output signal with said resulting output signal produced by said first and second filtering means.
    [8]
    A microphone array system as in any of the preceding claims, further comprising storage means for storing filter coefficient values for a plurality of control angles.
    [9]
    A speaker unit of a conference system comprising a microphone array system as in any of the preceding claims.
    [10]
    10. Speaker unit as in claim 9, arranged to be built into a table.
    [11]
    11. Speaker unit as in claim 10, arranged to be foldable.
    [12]
    A conference system comprising a plurality of speaker units as in any one of claims 9 to 11.
    [13]
    A method for generating an output signal from a microphone array with a first-order direction pattern, comprising the steps of: - providing a first and second multi-directional microphone that are spaced apart by less than a minimum acoustic wavelength defined by the desired audio frequency operating range, - applying a signal received by said first microphone to a first filtering means and a signal received by said second microphone to a second filtering means, said first filtering means having a first has a frequency response and said second filter means has a second frequency response, wherein said first and second frequency responses take into account the frequency response of the first and second multi-directional microphones, - adding the signal output of said first and second filter means and generating said The output signal from the microphone series with first-order directional pattern.
    [14]
    A method for generating an output signal from a microphone array as in claim 13, wherein said first and second microphone are placed in a back-beam configuration.
    类似技术:
    公开号 | 公开日 | 专利标题
    BE1019734A3|2012-12-04|STEERABLE MICROPHONE SERIES SYSTEM WITH A FIRST ORDER DIRECTION PATTERN.
    US20210021930A1|2021-01-21|Conference System with a MicrophoneArray System and a Method of Speech Acquisition in a Conference System
    Jarrett et al.2010|3D source localization in the spherical harmonic domain using a pseudointensity vector
    EP2905975B1|2017-08-30|Sound capture system
    JP3522529B2|2004-04-26|Steerable and variable primary differential microphone array
    CN104581477B|2019-06-25|Electronics hearing protectors with the positioning of quadrant sound
    CN104041075B|2017-10-24|Audio source location is estimated
    Quaegebeur et al.2016|Enhancement of time-domain acoustic imaging based on generalized cross-correlation and spatial weighting
    TWI457011B|2014-10-11|Apparatus and method for spatially selective sound acquisition by acoustic triangulation
    KR102009274B1|2019-08-09|Fir filter coefficient calculation for beam forming filters
    Fischer et al.2017|Improving acoustic beamforming maps in a reverberant environment by modifying the cross-correlation matrix
    EP2382802A2|2011-11-02|Method of and apparatus for planar audio source tracking
    US11064291B2|2021-07-13|Microphone array system
    Meyer et al.2006|Position independent close-talking microphone
    WO2019227353A1|2019-12-05|Method and device for estimating a direction of arrival
    JP6182169B2|2017-08-16|Sound collecting apparatus, method and program thereof
    EP3001697A1|2016-03-30|Sound capture system
    NL2007334C2|2013-03-05|Device and method for measuring sound levels and direction or localisation of sound sources.
    Papez et al.2016|Model of Surveillance System Based on Sound Tracking
    JP4787727B2|2011-10-05|Audio recording apparatus, method thereof, program thereof, and recording medium thereof
    JP6253669B2|2017-12-27|Microphone device with improved directional characteristics
    Kurc et al.2013|Sound source localization with DAS beamforming method using small number of microphones
    Moazzen et al.2013|A nested microphone array for broadband audio signal processing
    de Bree et al.2008|A single broad banded 3D beamforming sound probe
    CN109831709B|2020-10-09|Sound source orientation method and device and computer readable storage medium
    同族专利:
    公开号 | 公开日
    EP2360940A1|2011-08-24|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US6041127A|1997-04-03|2000-03-21|Lucent Technologies Inc.|Steerable and variable first-order differential microphone array|
    US6556678B1|1999-09-30|2003-04-29|Boyce Products, Ltd.|Communication system|
    NZ502603A|2000-02-02|2002-09-27|Ind Res Ltd|Multitransducer microphone arrays with signal processing for high resolution sound field recording|
    US20030059061A1|2001-09-14|2003-03-27|Sony Corporation|Audio input unit, audio input method and audio input and output unit|TWI450602B|2012-06-06|2014-08-21|Nat Univ Tsing Hua|A micro-size electronic shotgun microphone|
    EP2747449B1|2012-12-20|2016-03-30|Harman Becker Automotive Systems GmbH|Sound capture system|
    US9565493B2|2015-04-30|2017-02-07|Shure Acquisition Holdings, Inc.|Array microphone system and method of assembling the same|
    US10367948B2|2017-01-13|2019-07-30|Shure Acquisition Holdings, Inc.|Post-mixing acoustic echo cancellation systems and methods|
    CN111711915B|2020-06-30|2021-11-05|深圳市科奈信科技有限公司|Audio part selection method and audio part selection device thereof|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    EP10151106|2010-01-19|
    EP10151106A|EP2360940A1|2010-01-19|2010-01-19|Steerable microphone array system with a first order directional pattern|
    [返回顶部]