Global sound microphone system

A microphone system includes a portable frame for mounting linear pick-up microphones such that each of the microphones has its diaphragm facing outwards from the frame and the diaphragms form a generally elliptical pattern. A microphone with a substantially hemispherical pick-up pattern is mounted on the frame such that it is directed upwards and a second substantially hemispherical pick-up pattern microphone is mounted on the frame directed downwards. The linear pick-up pattern microphones are equispaced about the perimeter of the frame. There is a hand or camera grip depending downwards from the frame. The microphones of the frame can be electronically connected to the respective channels of a multi-channel sound system, or to the channels of a multi-channel digital mixer which in turn can be connected to a multi-channel sound recording device. The microphones may be selectively electronically connected and disconnected to adapt the system for a predetermined sound playback configuration.

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'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 world-wide. 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'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.

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 periphery 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.