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BRIEF DESCRIPTION OF THE DRAWINGS The attached drawing is a schematic circuit diagram of
the present invention. 1, 1 '... microphone. 2.2 'pre-amplifier, 3 switch, 4, 4' variable resistor. 5:
Reference signal source, b, 6 ': Microphone output end, I, 1': Variable resistor, 8, 8 ': Amplifier, 9,
9' ... Level meter , 10 ... terminal, D ... dummy head. −1−
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to stereo sound
collection devices, in particular the balance of the left and right channels. When sound is
collected using a stereo microphone, correct sound collection can not be performed if the left and
right channels are not well balanced. Therefore, it is necessary to check the balance of the
channels of the left and right microphones, i.e., whether the left and right channels are similarly
set, prior to sound collection. Conventionally, this check and level setting were performed while
the sound source was placed at the center of the left and right microphones and the output of the
microphone was viewed with a level meter or the like. The placement of the actual sound source
at the center of the left and right microphones is performed by human vision, so it is not only
time-consuming but can not be accurately performed. Therefore, the purpose of the present
invention is to make it possible to set the balance or level of the left and right microphone
channels easily and accurately. For this purpose, in the present invention, the actual sound
source is not placed at the center between the left and right microphones, and instead, signals
from signal sources of equivalent levels are supplied to the left and right cylindrical channels to
check the balance of both channels or Set the level. In the present invention, in order to have the
same acoustic spatial effect as an actual human being, the stereo microphone is a dummy head,
that is, a pinaural system set in the ears of a false human head (doll). Incidentally, the dummy
head micro-ho / pinora run system is already known. Next, an embodiment of the present
invention will be described with reference to the attached drawings. The changeover switch 3 is
generated by the left and right microphones /, / 'and the signals amplified by the preamplifiers 2
and 2' in the respective channels and by the oscillator S, the variable resistor 41, p ' And the
reference signal adjusted by the control signal is selectively sent to the output terminal 6 '. The
oscillator S generates, for example, a reference signal of / KHz equivalent to that when the
reference sound pressure (for example, 71 IdBs PL) enters the microphone. When the switch 3
falls to the B side, the same reference signal from the reference signal source S is supplied to the
output ends 6, 6 ', which are further balanced 3- or level-adjusted by the variable resistors 7, 7',
The signal is amplified by the power amplifier 9g 'and led to a recorder such as a tape recorder, a
speaker and other terminals / θ.
The left-right balance or level adjustment by the variable resistors 7, 7 'can be achieved by a level
meter connected between the second stage of the variable resistors 7, 7', e.g. The instruction of q
'is made equal. In this way it is possible to perfectly balance the left and right channels. '' 5 '' AV
'tl' '' '' '' '' 1 '' K '' 1 '' '' '' can produce accurate stereo sound collection. Not only the microphones
/, l ', but also preamps, 2. . 2 ', reference signal source! , And the switch 3 etc. can also be
incorporated in the dummy head D. In this way, it is not necessary to install the reference signal
source j etc. elsewhere.