JPS61108294

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DESCRIPTION JPS61108294
[0001]
The present invention relates to an automatic sound field correction apparatus that automatically
corrects frequency characteristics of a listening space to desired characteristics. BACKGROUND
ART A conventional example of an automatic sound field correction apparatus is shown in FIG. In
the present apparatus, an audio signal output from a signal source 1 such as a tape decoder is
supplied to an adder 2. A test signal generator 3 is connected to the adder 2 and the test signal
generator 3 generates a test signal with an apparent characteristic such as pink noise. A graphic
equalizer 4 having a plurality of adjustment bands is connected to the output end of the adder 2,
and the output end of the graphic equalizer 4 is the output end of the present apparatus. The
power amplifier 5 of the sound reproducing apparatus is connected to the output terminal, and
the speaker 6 is driven by the power amplifier 5. The sound emitted from the speaker 6 is
detected by the microphone 7, and the frequency characteristic detection circuit 8 is connected
to the output end of the microphone 7. The frequency characteristic detection circuit 8 has a
plurality of BPFs having mutually different characteristics, and detects the frequency
characteristic of the sound field in accordance with the output signal of the microphone 7. A
control circuit 10 is connected to the frequency characteristic detection circuit 8 via an A / D
converter 9. The control circuit 10 preferably comprises a microcomputer and controls the
operation of the test signal generator 3 and the gain level of each adjustment band of the graphic
equalizer 4. In such a configuration, the control circuit 10 activates the test signal generator 3 in
response to an automatic sound field correction command from a keyboard (not shown). Thus,
the test signal is supplied to the graphic equalizer 4 via the adder 2. At this time, the supply of
the audio signal from the signal source 1 to the adder 2 is stopped, and the frequency
characteristics of the graphic equalizer 4 are all flat with the level 19 of each adjustment band
made the same level. . The test signal output from the graphic equalizer 4 is amplified by the
power amplifier 5 and supplied to the speaker 6, and the test signal reproduction sound is
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emitted from the speaker 6 to the listening space. The sound pressure of the test signal
reproduction sound is detected by the microphone 7 at the listening point, and the detected
sound pressure signal is supplied to the frequency characteristic detection circuit 8. The
frequency characteristic detection circuit 8 detects the sound pressure signal level corresponding
to each adjustment band of the graphic equalizer 4, and the respective detection levels are
converted into digital data by the A / D converter 9 and the control circuit 10 Supplied to The
control circuit 10 determines the frequency characteristics of the detected sound pressure signal
according to the digital data, that is, the frequency characteristics of the sound field, and the
frequency characteristics of the sound field become flat characteristics. By controlling the gain
level and stopping the operation of the test signal generator 3, the automatic sound field
correction operation ends.
By the way, usually, when a person listens to the audio reproduction sound in the listening space,
it is naturally affected by the head, face, pinnacle, etc., and the sound field is particularly
important for the listening space, the signal source, the power amplifier, the speaker etc. It is
determined that the frequency characteristic of the sound field is aurally flat if there is no
element that disturbs the frequency characteristic of. Also, it is clear that it is better to perform
sound field correction in a practical state where human beings listen. Therefore, as shown in FIG.
2, when the microphones 7 are respectively disposed at the entrance of the ear canal of both ears
and automatic sound field correction similar to the above is performed in an ideal listening space,
the head, face, pinnacle etc. Under the influence, the frequency characteristic of the sound field
obtained from the output signal of the frequency characteristic detection circuit 8 becomes a
characteristic different from that in the case of a single microphone, for example, as shown by
the solid line a in FIG. It becomes the characteristic which is not flat. If the graphic equalizer 4 is
adjusted so as to be opposite to the frequency characteristic, the frequency characteristic of the
sound field becomes theoretically flat during audio reproduction. However, there was a problem
that the hearing was rather unnatural. The purpose of the present invention is to provide an
automatic sound field correction apparatus capable of correcting the frequency characteristic of
a sound field so as to give a natural hearing sensation when microphones are provided to the
listeners' ears. . The automatic sound field correction apparatus according to the present
invention is provided on a supply line to an electroacoustic conversion means such as a speaker
of a test signal or any one of processing lines of output signals of two microphones to listen to
the sense of frequency characteristics of sound field. It is characterized by including
compensation means for compensating for the deviation. Embodiment Hereinafter, an
embodiment of the present invention will be described with reference to FIG. In the automatic
sound field correction apparatus according to one embodiment of the present invention shown in
FIG. 4, the same parts as those of the apparatus shown in FIG. 11 are connected. The
compensation circuit 11 is an amplifier or attenuator having an inverse characteristic (for
example, a characteristic indicated by a broken line I in FIG. 3) of the frequency characteristic of
the sound field obtained in advance from the output signal of the frequency characteristic
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detection circuit 8 in an ideal listening space. And the like, and the output signal of the
compensation circuit 11 is supplied to the A / D converter 9. Also, two microphones 7 are
provided to the listener's ears as shown in FIG. The rest of the configuration of the automatic
sound field correction apparatus according to the present invention is the same as the apparatus
shown in FIG. In such a configuration, the output level of the frequency characteristic detection
circuit 8 is compensated by the compensation circuit 11, and so-called weighting is performed.
Therefore, the influence of the head, face, pinnacle, etc. of the listener contained in the output
signal of the frequency characteristic detection circuit 8 is canceled and supplied to the control
circuit 10 through the A / D converter 9, The gain level of each adjustment band of the graphic
equalizer 4 is not controlled so that the frequency characteristic of the sound field at the time of
audio reproduction becomes flat, and only the deviation in auditory sense, that is, the disturbance
characteristic of only the compensation valve by the compensation circuit 11 To be controlled. In
the above-described embodiment of the present invention, when the frequency characteristic
detection circuit 8 is a system having a plurality of BPFs having different characteristics and
selectively using the BPFs, the output of each BPF is set to the center frequency thereof.
Attenuator or the like corresponding to the compensation amount may be added as the
compensation means. When a wobble tone is used as the test signal tone, the compensation
circuit 11 compensates for the compensation amount according to the frequency of the wobble
tone. In this case, a plurality of attenuators or amplifiers having different compensation amounts
may be used to switch the attenuators or amplifiers according to the frequency of the wobble
tone. Further, in the above-described embodiment of the present invention, the compensation
circuit 11 is provided between the frequency characteristic detection circuit 8 and the A / D
converter 9, but the present invention is not limited to this, as shown in FIG. Even if the
compensation circuit 12 is provided between the signal generator 3 and the adder 2, similar
effects can be obtained. As described above, according to the automatic sound field correction
device of the present invention, the compensation means for compensating the auditory
deviation of the frequency characteristic of the sound field is a supply line or two of the test
signal to the electroacoustic transducing means. Since it is provided in one of the processing lines
of the output signal of the microphone, the sound field in a practical state can be determined by
determining the frequency characteristics of the sound field from the output signals of the two
microbons provided in both ears. It is possible to perform audio reproduction with characteristics
that can be corrected and that are audibly good.
[0002]
Brief description of the drawings
[0003]
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FIG. 1 is a block diagram showing a conventional example of the automatic sound field correction
apparatus, FIG. 2 is a diagram showing the arrangement of microphones, and FIG. 3 is a diagram
showing the sound field detected by the two microphones shown in FIG. FIG. 4 is a diagram
showing a frequency characteristic and its inverse characteristic, FIG. 4 is a block diagram
showing an embodiment of the present invention, and FIG. 5 is a block diagram showing another
embodiment of the present invention.
Explanation of the Signs of the Main Parts 1 ..... Signal Source 3 ..... Test Signal Generator 4 .....
Graphic Equalizer 0-5 .... Power Amplifier 7 ..... ... Microphone 8 ..... Frequency characteristic
detection circuit 10 ..... Control circuit
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