Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R3/00—Circuits for transducers
  • H04R3/005—Circuits for transducers 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; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
  • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
  • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
  • H04R1/406—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers microphones
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
  • H04R2201/40—Details of arrangements for obtaining desired directional characteristic by combining a number of identical transducers covered by H04R1/40 but not provided for in any of its subgroups
  • H04R2201/401—2D or 3D arrays of transducers

Definitions

• the invention relates to a sound recording device, in particular for a microphone unit according to the preamble of claim 1.
• Sound recorders are known as individual microphones that are available with or without directional characteristics. If sound recording devices are used in connection with microphone units for conference systems or lecterns, a high level of feedback security, good decoupling from ambient noise and extensive independence of the signal level from changing speech directions and positions are desirable.
• Microphones without directional characteristics can be used in changing speech directions and positions, but they offer only a low level of feedback security and poor decoupling from ambient noise.
• a small amplification factor would have to be selected and at the same time a very small speech distance had to be maintained, so that the sound level of the speaker on the microphone is sufficiently large to mask ambient noise.
• Changes in speech directions and positions then cause comparatively larger changes in distance and thus also sound level fluctuations than if a large speaking distance can generally be maintained.
• microphones offer
• the invention has for its object to improve a sound recording device, in particular for microphone units, in such a way that both high feedback security and good decoupling from ambient noise as well as extensive independence of the signal level from changing sound directions and positions as well as security against POP noise is achieved .
• the sound emitted by a sound source is picked up by at least two sound recorders simultaneously.
• the received signals from all sound recorders it is possible to record the sound at a more uniform level even if the direction of propagation or the position of the sound source changes, than would be possible with a single sound pickup.
• the addition of the amplitudes of the individual output signals of the sound recorders leads overall to a level increase of sound signals which have their origin in the reference point, but also to a level reduction of ambient signals. Because of the alignment with the reference point, the useful signals of the sound pickups are correlated, but interference signals and their noise voltages are not correlated.
• the directivity of the entire sound recording device advantageously differs from the directivity of conventional directional microphones, because the directivity does not diverge from the sound sensor to the sound source, but converges at the reference point, similar to the focus of a concave mirror. This also achieves the desired feedback security and decoupling from ambient noise and further improves it compared to the possible directivity of individual sound pickups. At the same time, a greater distance between the sound source and sound recorders is possible, which prevents pop sounds that can arise from explosive sounds caused by air flow. In addition, there is the possibility of accommodating the sound recording device in a compact housing at an increased distance from the speaker, so that the clear view to the front is not obstructed. Changes in the position of the sound source are also compensated for within a limited range around the reference point. This greatly reduces the volume fluctuation problem feared by movements of the speaker.
• the sound recorders are at a uniform distance from the reference position and are arranged on a circular or spherical section, the center of which is formed by the reference position.
• these delay elements can be assigned between the reference position and the sound sensors.
• the transmission dimension is adjustable to uniform signal levels of all sound sensors.
• transmission measure includes amplification, attenuation and unchanged amplitude of the signal.
• the sound recorders can have directional characteristics and be oriented such that the axes of their main reception directions each point to the reference position.
• the restricted sound pick-up angle of the individual sound pickups does not have a disadvantage, since there are several sound pickups whose sound pick-up angles overlap and thus ensure a uniform sound sensitivity within the pick-up area of the sound pick-up device.
• the sound recorders are preferably designed directly as acoustic-electrical transducers.
• the sound recorders can be designed as inlets for acoustic waveguides, which lead to one or more common acoustic-electrical transducers.
• an optical marking for the target position of the sound source can be provided.
• the optical marking is expediently formed by at least two light sources, each of which emits a characteristic light from the sound recording device in the direction of the desired position of the sound source only in the solid angle of the most favorable sound recording.
• This measure automatically signals the speaker deviations from the optimal speaking position so that he can correct his position at any time.
• a further development provides that the arrangement of the sound pickups and / or their main receiving direction and / or the running time of the delay elements can be adapted to a change in the actual position of the sound source in such a way that the reference position of the sound recording device can be tracked with the actual position of the sound source.
• This measure makes it possible to give the speaker more freedom of movement without loss of feedback security and decoupling from ambient noise and to pay less attention to a static speech position. It can also be adapted to speakers of different heights.
• the arrangement of the sound recorders can be moved and / or pivoted individually or in groups, and a drive for moving and / or pivoting can be controlled manually or by automatic position detection of the sound source.
• the duration of the delay elements can also be controlled manually or by automatic position detection of the sound source.
• the change in the transit time is also possible in combination with a change in the arrangement of the sound pickups and / or their main reception direction.
• Suitable methods for position detection can be based on the reception of heat radiation from the speaker's face, radar, ultrasound or video image processing.
• the activity and / or the position of the sound source can be determined by a correlator to which the signals of the sound pickups are fed.
• the position of the sound source can be determined by measuring the time difference between the zero crossings of the signals from different sound pickups.
• the correlator can determine activity by means of the criterion of simultaneous or largely simultaneous arrival of Determine gnale on the sound pickups. This criterion indicates that a sound source is in the reference position or close to the reference position.
• the detection of activity can be used, for example, to connect the sound recording device to a loudspeaker system.
• the correlator can determine the position of the sound source by evaluating the phase shifts in the amplitude values arriving from the individual sound pickups, since these phase shifts are a measure of the distance of the sound source from the reference position.
• the electrical signals of the acoustic-electrical transducers after digitization are fed to a digital signal processor which emulates an addition device, delay elements, transmission elements and / or a correlator.
• the sound recorders can also be designed as segments of an acoustic-electrical transducer extended in one, two or three-dimensional direction, the surface of which corresponds at least approximately or in sections to a circular or spherical section.
• This embodiment represents an alternative to an embodiment in which a large number of individual acoustic-electrical transducers are arranged directly next to one another on a circular or spherical section.
• FIG. 1 is a schematic representation of the sound recording device according to the invention with acoustic-electrical transducers on a circular section,
• Fig. 8 is a sound recording device with waveguides
• a reference position 1 corresponds to the ideal or target position of a sound source.
• the sound pickups 2 are arranged such that direction vectors 4 point in different directions between the reference position 1 and the sound pickups 2.
• the sound pickups 2, which are designed directly as acoustic-electrical transducers, are directional microphones whose axes of their main reception directions 3 intersect in the reference position 1.
• the amplitudes of the output signals of the individual sound recorders 2 are added in a downstream addition device 6 and passed to a discharging signal path 7. Due to the identical spacing of all sound pickups 2 to reference position 1, the output signals when the sound source is arranged in or in the vicinity of reference position 1 are essentially in phase and of the same strength and are therefore added to the maximum possible output signal strength.
• the output signal strength decreases with increasing steepness.
• the output signal strength remains largely independent of the position of the sound source when it is in a region between the reference position 1 and the sound pickups 2. This is explained by the fact that the sound source approaches individual sound pickups 2 on or adjacent to their axis of the main receiving direction 3 and their signal level then rises, while the sound source simultaneously emerges from the main receiving direction 3 of other sound pickups 2 and the signal level thereupon drops. The addition of all output signals largely compensates for these two effects.
• FIG. 2 shows an embodiment in which the arrangement of the sound pickups 2 also extends into the third dimension.
• the sound pickups 2 are arranged on a spherical section 5. This arrangement results in a further improved concentration of the recording on the reference position 1, because height deviations are also taken into account.
• Fig. 3 shows a sound recording device with sound sensors 2 in a straight line.
• the sound recorders 2 are at different distances from the reference position 1, namely the intersection of the main reception directions 3 Sound sensor 2 arranged.
• This arrangement leads to a more compact design of the call station. It can be seen that the transit time of the sound from the reference position 1 to the sound transducers 2 is different due to the different distances. The recording volume is also lower for the more distant sound recorders 2.
• the transmission dimensions of the transmission elements 18 correspond to an attenuation.
• the middle four sound sensors 2 can be arranged virtually as if they were at the same distance from the reference position 1 as the outer sound sensors 2.
• Fig. 4 shows an optical device for marking the optimal speech position.
• This device comprises two light sources 9, each emitting light in a limited solid angle. The solid angles are aligned so that the zones of light propagation overlap and the reference position 1 lies in the center of this overlap area 10. Only in this overlap area 10 does a speaker see both light sources 9, which signals to him that he is in the area of the cheapest sound recording. If he sees only one of the light sources 9, then he is outside the most favorable recording area and he can correct his position.
• the outputs of all sound sensors 2 are connected to a correlator 11.
• An output of the correlator 11 is connected via a threshold value detector 12 to a control input of a switch 13 at the output of the addition device 6.
• the correlator 11 checks the output signals of the sound pickups 2 for the correspondence of their amplitudes and phases. Only when a sound source is arranged at the reference position 1, all amplitudes and phases agree, which corresponds to a high correlation factor. As the distance of the sound source from the reference position 1 increases, individual or more amplitude and phase values deviate more and more from others, as a result of which the correlation factor is reduced.
• the absolute value of the amplitude remains largely without influence on the determined correlation factor. This makes it possible to automatically recognize whether a sound source is in the vicinity of reference position 1 or not.
• the correlation factor provides a very reliable and interference-proof criterion for the activity of a sound source in or in the vicinity of the reference position 1.
• the output signal of the correlator 11 can thus be used via the threshold value detector 12 and the control input of the switch 13 for the automatic connection of microphone signals in conference systems.
• FIG. 6 shows an arrangement for pivoting the sound pickups 2.
• the sound pickups 2 are fixedly mounted on a carrier 19, which in turn is pivotably mounted.
• a drive element 16 in the form of a pressure cylinder is coupled to the carrier 19, so that the carrier 19 can be pivoted.
• control buttons can be used which are connected to a control device 15. Is at the same time an optical device for marking tion of the optimal speaking position, the setting is made considerably easier for the user.
• an automatic setting can also be carried out in that the position of the speaker's face or head is automatically determined in a position detection device 14 by means of known methods, such as evaluating the thermal radiation of the face, evaluating radar or ultrasonic sensors or evaluating a video image and with the aid of this information, the drive element 16 is controlled via the control device 15 in such a way that the changed reference position 1 'comes as close as possible to the determined position of the head.
• FIG. 7 shows a sound recording device with a device for changing the main receiving direction 3.
• the sound recorders 2 are again directional microphones. These have the special feature that their main receiving directions 3 can be changed by electrical control signals.
• Various solutions are known for this, for example by superimposing the signals of two sound transducers 2 assembled close together.
• the sound pickups 2 are mounted on a straight line.
• Corresponding delay elements 8 and transmission elements 18 are connected downstream of each sound sensor 2 for the delay time and amplitude compensation.
• the delay times of the delay elements 8 and the transmission dimensions of the transmission elements 18 are continuously adjustable from a control device 15.
• the output signals of the sound pickups 2 are fed to a correlator 11 in the control device 15, which correlates the “transit time differences of the sound to the sound pickups 2 calculated.
• the position of the sound source can in turn be determined from these differences in transit time.
• the control device 15 then sends commands for setting the main receiving direction 3 for each of the sound pickups 2 without mechanical movements having to be carried out, and commands for setting the delay 8 and transmission elements 18 in order to correct delay and amplitude differences. In this case, too, there is a changed reference position 1 '.
• the control device 15 can additionally decide whether the sound source is within the desired range and carry out the connection to the signal paths that lead away.
• correlator 11 can also be connected behind the delay elements 8 and 18. Furthermore, it is possible to design correlator 11, transit time 8 and transmission elements 18 as a digital signal processor, that is to say to carry out all evaluations and settings by software.
• FIG. 8 shows a sound recording device with waveguides 17 which lead to a single acoustic-electrical converter.
• sound inlets of acoustic waveguides 17 are provided instead at the locations of the acoustic-electrical transducers previously installed there.
• the sound inlets can be attached in such a way that a distinctive directional effect is produced for sound reception, as is known, for example, in the case of directional tubes for microphones which operate on the interference principle.
• the waveguide 17, the generally consist of simple pipes, all are now performed together on a single acoustic-electrical transducer.
• the lengths of the waveguides 17 can be chosen so skillfully that the transit time of the sound from the reference position 1 to the acoustic-electrical transducer is the same through all the waveguides 17.
• FIG. 9a shows a representation of a one-dimensional
• FIG. 9b shows a representation of a two- or three-dimensionally stretched acoustic-electrical transducer.
• its surface follows at least approximately or in sections of a circular or spherical section.
• This version corresponds to a very large number of acoustic-electrical transducers that are directly adjacent to one another.
• the transducer is designed with a mechanically continuous membrane, the individual sections act as individual acoustic-electric transducers, the signals of which are added integrally here.

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• Health & Medical Sciences (AREA)
• Otolaryngology (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• General Health & Medical Sciences (AREA)
• Circuit For Audible Band Transducer (AREA)
• Interconnected Communication Systems, Intercoms, And Interphones (AREA)
• Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1998
  • 1998-03-27 EP EP98928096A patent/EP1008277B1/fr not_active Expired - Lifetime
  • 1998-03-27 JP JP54223298A patent/JP4117910B2/ja not_active Expired - Lifetime
  • 1998-03-27 WO PCT/DE1998/000912 patent/WO1998046043A2/fr not_active Ceased
  • 1998-03-27 AT AT98928096T patent/ATE203869T1/de not_active IP Right Cessation
  • 1998-03-27 US US09/402,726 patent/US7366308B1/en not_active Expired - Fee Related
  • 1998-03-27 DE DE59801138T patent/DE59801138D1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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