Patent Publication Number: US-RE38350-E

Title: Global sound microphone system

Description:
This application is a continuation of application Ser. No. 08/331,918, filed Oct. 31, 1994 abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention relates in general to microphone systems and more particularly to global sound microphone systems which are portable. 
     BACKGROUND OF THE INVENTION 
     There are a number of existing “surround sound” systems which use digital or analogue equipment to record and reproduce sound. The goal of such systems is to recreate the sound environment. To recreate a sound environment, the surround sound system must be designed with an awareness of the human brain&#39;s ability to determine, within all three dimensions, where a given sound originates. The ear has two independent functions, one, to hear (auditory), the other to sense the motion of the listener or of an object in space identified by the listener (vestibular). Realistic sound production must give the listener a sense of vestibular as well as auditory function, thus, the motion of the listener or object in space identified by the listener is important to the perception of reality. The brain is able to recognize small differences in loudness and timing in soundwaves as they reach both the left and right ears so as to exactly localize and follow a sound source in space. 
     Systems are known in the art which exploit this fact. An example is the binaural system which uses two audio channels to record sound. The binaural system is able to achieve excellent results but the listener must wear headphones to experience the surround sound effect. Otherwise the reproduction is the equivalent of a traditional stereo, two-dimensional, recording. 
     Quadraphonic sound systems have also been devised. Such systems employ four audio channels in a “double stereo” pattern to provide a more realistic localization effect for the listener. This format has not achieved universal acceptance due to the fact that while it was meant for consumer use, there was not enough material available that was recorded for four channels. A special microphone, the Caldrec Soundfield, was developed to record quadraphonically by using four microphone diaphragms and four channels. The diaphragms can be electronically “zoomed” in on a specific channel. The limitation of this process is that the microphone must remain stationary in order for the signal levels received at the microphone diaphragms to remain uniform; it also only has four channels. 
     Multi-channel, surround sound audio systems are now widely accepted in the professional audio market. It is virtually a standard in major motion picture theatres worldwide. The technology is also becoming more commonplace in the consumer audio market. The public theatre and the private livingroom are now places where a realistic, natural sound environment can be created. 
     A typical surround sound environment consists of five to ten speakers placed around a room in several different configurations. In a movie theatre, for example, there may be three speakers behind the projection screen (left-centre, centre, and right-centre), two speakers at the sides of the room (left and right) and two speakers at the rear of the room (left and right surround). Each of these speakers is assigned its own specific channel. During the recording of the live sound sources for surround sound applications, the microphones are set up in a stationary position at approximately the site at which the sound will be heard though the coincident monitor speaker of the surround sound system. This technique works well, only if the perspective of the listener/viewer is meant to be stationary in relation to the sound. As a result, the listener&#39;s position, perceived or actual, must remain stationary and cannot move in relation to the sound. An example of this situation occurs when a camera moves or pans on an object which the listener is focusing his attention through a scene such as a jungle or a city street and surround sound is required to accompany it. 
     At the recording studio during final mixdown of the soundtrack, by using special multi-channel signal processors, an audio technician is able to take any recorded signal and sonically move that signal between any number of the channels, or speakers, in the system, thus creating the illusion that the sound is actually moving from one part of the listening environment to the other. Although this appears as an interesting effect it has been manipulated by a processor and though it may appear natural, it is not. 
     Thus a global microphone system which is able to be used to reproduce “surround sound” and which does not require headphones, which does not have to remain stationary, and which is able to create the effect of motion and exact specific auditory localization of the object in motion without using the mixing process, is desirable. 
     SUMMARY OF THE INVENTION 
     An object of one aspect of the present invention is to provide an improved type of microphone system. 
     In accordance with one aspect of the present invention there is provided a microphone system having a portable frame for mounting a plurality of microphones, each microphone of the plurality of microphones having a diaphragm, the plurality of microphones comprising a set of linear pick-up pattern microphones, whereby when mounted, each one of the set of linear pick-up microphones has its diaphragm facing outwards from the frame and the diaphragms of the set of microphones form a generally elliptical pattern. 
     Conveniently, the means for mounting a plurality of microphones further comprises a means for mounting a microphone having a substantially hemispherical pick-up pattern at a location within the generally elliptical pattern of the linear pattern microphones. 
     Preferably, the means for mounting a microphone having a substantially hemispherical pick-up pattern maintains the orientation of the microphone such that the hemispherical pick-up pattern of the microphone is normal to the plane of the elliptical pattern of the linear pattern microphones and the substantially hemispherical pick-up pattern is directed upwards. 
     Preferably, the means for mounting a plurality of microphones further comprises a second means for mounting a second microphone having a substantially hemispherical pick-up pattern at a location within the generally elliptical pattern and the second means for mounting a second microphone having a substantially hemispherical pick-up pattern is adapted to maintain the orientation of the second microphone such that the hemispherical pick-up pattern of the second microphone is normal to the plane of the elliptical pattern and is directed downwards. 
     Preferably, each microphone of the set of linear pick-up pattern microphones has a hypercardioid or other linear pick-up pattern. 
     Preferably there is provided a means for mounting one of the set of microphones at a position at a one end of the generally elliptical shape and means for mounting the set of the microphones in a generally equispaced relationship about the elliptical shape. 
     Conveniently, there is provided a hand grip depending downwards from the frame, alternatively the frame is attached to a camera. 
     Advantageously, there is provided a multi-channel audio mixer, means for electrically connecting each one of the set of the microphones with a one of the channels of the multi-channel mixer and a means for operatively connecting the multi-channel mixer with a digital multi-channel sound recording device or any advance on that technology. 
     Advantageously, there is provided a means for selectively electronically connecting and disconnecting ones of the set of microphones to adapt the system for a predetermined sound playback configuration. 
     Advantages of the present invention are that a portable system to faithfully, reproduce multiple sounds as recorded, and which permits recording while the object/system is in motion, is provided. 
     An advantage of an embodiment of the present invention is that the sound recorded is “rounded out”. 
     A further advantage of an embodiment of the invention is that the microphone system may be hand-held. 
     An advantage of an embodiment of the invention is that the microphone system may be used in conjunction with a camera to achieve holographic sonic results. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A detailed description of the preferred embodiment is provided herein below with reference to the following drawings, in which: 
     FIG. 1, in a schematic plan view, illustrates the global microphone system in accordance with the preferred embodiment of the present invention; 
     FIG. 2, in a schematic elevational view, illustrates the global microphone system of FIG. 1; 
     FIG. 3, in a schematic plan view, illustrates the operation of the global microphone system of FIG. 1; and 
     FIG. 4, in a schematic plan view, illustrates the replaying of a recording made with the global microphone system of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is illustrated in a schematic plan view, a global microphone system in accordance with the preferred embodiment of the present invention. The global microphone system includes a frame  10 . As the plan view of FIG. 1 indicates, frame  10  has a generally oval outer perimeter and has the cross-section of a flattened sphere. Microphones  12 ,  14 ,  16 ,  18 ,  20 ,  22 ,  24 ,  26  are mounted on frame  10  such that their diaphragms are oriented outwards from frame  10 . Microphones  12 - 26  each have a hypercardioid pick-up pattern. In the preferred embodiment of the invention the frame  10  is generally football-shaped and microphones  12 - 26  are mounted on the peripheray of the frame. As will be apparent one skilled in the art, any combination of frame shape and microphone placement which provides a generally elliptical placement of the microphones  12 - 26  will be suitable. 
     The global microphone system of the preferred embodiment illustrated in FIG. 1 has microphone  28  mounted centrally on the top of frame  10 . Microphone  28  has a hemispherical pick-up pattern which is directed upward from frame  10 . 
     In FIG. 2, there is illustrated in a schematic elevational view, the global microphone system of the preferred embodiment. FIG. 2 illustrates the elevational orientation of microphones  12 ,  26 ,  24 ,  22 ,  20  as well as  28 . A second hemispherical pick-up pattern microphone  30  is shown mounted on the central bottom portion of frame  10 . The hemispherical pick-up pattern of microphone  30  is directed downward from frame  10 . Frame  10  has a hand grip  32  which is attached to the bottom rear quadrant of frame  10 . 
     In FIG. 3, the global microphone system of the preferred embodiment is illustrated in a schematic plan view. FIG. 3 shows the operation of the global microphone system. Frame  10  with microphones  12 - 26  is shown. Microphone  12  is shown with associated pick-up pattern  42 , as are microphones  14 ,  16 ,  18 ,  20 ,  22 ,  24 ,  26  with associated pick-up patterns  44 ,  46 ,  48 ,  50 ,  52 ,  54 ,  56  respectively. FIG. 3 shown a bird  58  moving along at line  60 . 
     In FIG. 4, the operation of replaying a recording made with the global microphone system of the preferred embodiment is illustrated in a schematic plan view. A listening chamber or theatre  70  contains a listener  72 . Speakers  82 ,  84 ,  86 ,  88 ,  90 ,  92 ,  94 ,  96  are located about the periphery of the theatre  70 . Each of speakers  82 ,  84 ,  86 ,  88 ,  90 ,  92 ,  94 ,  96  have respective auditory patterns  102 ,  104 ,  106 ,  108 ,  110 ,  112 ,  114 ,  116 . 
     In operation, the global microphone system of FIG. 1 may be hand-held using hand grip  32  shown on FIG.  2  and placed in the vicinity of a sound be recorded. 
     FIGS. 3 and 4 shown how the global microphone system of the preferred embodiment may be used to record a moving object such as a bird. 
     In FIG. 3 bird  58  admits a sound  62 . The sound  62  is within the linear pick-up pattern  56  of microphone  26  and therefore registers on microphone  26 . Because sound  62  is not within the linear pick-up patterns of microphones  12 - 24 , the sound  62  is not recorded to any appreciable degree by these other microphones. Assuming the bird is above the level of the frame  10 , microphone  28  will record sound  62  as well as microphone  26 , due to the hemispherical pick-up pattern of microphones  28 . As the bird flys along line  60 , other sounds made by the bird will be able to be picked by microphones  24 ,  22 ,  20 ,  18 ,  16 ,  14 ,  12 , in sequence. 
     In one option, each of the microphones mounted on frame  10  is connected to single channel of a multi-channel digital mixer, which is in turn connected to a channel of a multi-channel digital recording device. 
     In playing back the sound recorded as described above with respect to FIG. 3, in the theatre  70  of FIG. 4, each of the channels of the sound recording corresponding to microphones  12 - 26  are individually played back through speakers  82 - 96 , respectively. In the example of FIG. 4, there are no separate speakers corresponding to channels of recorded sound originating from microphones  28  or  30 . These channels may either be ignored in the sound reproduction of FIG. 4 or may be mixed with other channels recorded from microphones  12 - 26 . 
     With respect to FIG. 4, the flight of bird  28  shown in FIG. 3 is reproduced for listener  72 . Sound  62  is shown reproduced by speaker  96  as sound  118  contained within the auditory pattern  116  of speaker  96 . Speaker  96  replays the input to microphone  26  as recorded on the individual channel of the multi-channel recording device corresponding to microphone  26 . As shown in FIG. 4, the listener will experience the sounds corresponding to the flight of the bird along path  60  shown in FIG. 3 as represented by line  120  in FIG.  4 . Each of microphone pick-up patterns  42 - 56  are recreated by speaker auditory patterns  102 - 116 . As is apparent, the surround sound recording made as shown and described above with respect to FIG. 3 will provide listener  72  with a natural recreation of the original sound source to provide a natural sound environment in real time accuracy. 
     As will also be apparent from the above description, the fact that the global sound microphone system is capable of being hand held using hand grip  32  shown in FIG. 2, or capable of being mounted on a camera, permits the effect of motion of the microphone system to be created for the listener in, for example, theatre  70  as shown in FIG.  4 . 
     This creates the auditory and vestibular effect of the listener “moving” with the point of view of a camera as a camera moves through a scene. This serves to heighten the realistic effect for the listener  72 . 
     In the preferred embodiment of the invention, the effect of the system is strongest where the pick-up patterns  42 - 56  of microphones  12 - 26  are each a very linear hypercardioid pick-up pattern. This provides good separation between each microphone and hence, each channel in a multi-channel recording device. 
     Multi-channel surround sound systems in use have different speaker placement configurations within the listening environment. A switchable pattern between the different microphone diaphragms  12 - 26  and  28 ,  30  is provided in order to accommodate the different audio systems. Any number of microphones can be turned on and off. For example, two microphones may be utilized to achieve a stereo effect, 4 for quadraphonic, more for THX and soforth. 
     Other variations and modifications of the invention are possible. For example, the frame of the microphone system may be a star-shaped arrangement of struts to maintain the microphones in the desired relationship. All such modifications or variations are believed to be within the sphere and scope of the invention as defined by the claims appended hereto. 
     Also, the scope of the invention includes any number of channels in the above configuration to allow an infinite pick-up with corresponding numbers of attachments to the channels of the multi-track recording device to receive a corresponding plurality of signals.