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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
sound reproducing apparatus for improving acoustic characteristics. Prior Art In recent years,
the popularity of 16 passenger cars has been remarkable, and along with this, with regard to the
sound quality of car audio, it has become an era of better sound, noise reduction from the good
old days of sounding. There is. However, the extension of the conventional idea of home audio
can not cope with the adverse conditions of the acoustic characteristics in the vehicle
compartment, and can not currently obtain good sound quality. Hereinafter, an example of the
above-described conventional method will be described with reference to the drawings. FIG. 9
shows an example of a conventional in-vehicle reproduction apparatus, wherein 1 is a generator
of a music electric signal such as a radio or cassette deck, 2 is an amplifier, 3 to 6 are speakers,
the generator 1 The signal from is amplified by the amplifier 2 and then reproduced from the
speakers 3 to 6 into the vehicle compartment. However, if the sound is reproduced as it is, peaks
and valleys in the frequency characteristic are generated due to the influence of the standing
wave due to the inferiority of the vehicle interior acoustic characteristics, in particular, the small
volume of the chamber. Here, 3 is a front seat right speaker, 4 is a front seat left speaker, 5 is a
rear seat right speaker, and 6 is a rear seat left speaker. FIG. 10 shows an example of actual
measurement, and it can be seen that a large peak occurs at about 200 Hz and about I KHz. So, if
a mountain and valley can be made, the frequency characteristic of the opposite characteristic is
made electrically, and it is an example of Fig. 11 that is constructed from the idea that the
mountain and valley will be canceled if it is regenerated. This is a fixed equalizer having a peakto-peak characteristic opposite to the frequency of the standing wave, and the others are the
same as in FIG. Problems to be solved by the invention FIG. 12 is a characteristic diagram in the
case of correction by the circuit configuration of FIG. 9 using the fixed equalizer 7. However, it
can be seen that there is only an acoustic effect up to sdB, regardless of electrically correcting by
more than 1 odB. Here, a person is a characteristic diagram before correction, and B is a
characteristic diagram after correction. That is, in the case of acoustically generated peaks and
valleys, the electrical amplitude correction by the fixed equalizer 7 has a problem that the effect
is limited and can not be sufficiently corrected by the conventional method. Furthermore, the
reproduction by the conventional sound reproducing apparatus is not realistic and is
unsatisfactory for the driver. The present invention provides a sound reproduction device that
can solve the above-mentioned problems. Means for Solving the Problems The sound
reproducing apparatus according to the present invention uses a phase shifter for changing the
phase of the original signal from the generator, and extracts the high band component of the
sound to be reproduced using the original signal from the generator. And a high-frequency
control unit that performs phase shift, and mixes the output of the phase shifter and the highfrequency control unit with the original signal.
The present invention changes the frequency characteristic of the original signal by adding a
phase change signal to the original signal, can correct the acoustic frequency characteristic due
to the standing wave in the vehicle interior, and shift the phase of the high band component. Can
enhance the reverberation and enhance the sense of reality. Embodiment Hereinafter, a sound
reproducing apparatus according to an embodiment of the present invention will be described
with reference to FIG. Although in the present embodiment the left and right speakers for the
front seat of the in-vehicle speaker are described, the present embodiment can be applied to the
left and right speakers for the rear seat. The signal of the generator 11 that generates an
electrical signal corresponding to the sound to be reproduced is limited by the band pass filter
12 to an arbitrary frequency band. In the present embodiment, the correction frequency is 2 oo
Hz. In the case of □ KHz, the center frequencies of the filters 12eL and 12b of the two correction
chains are respectively f, 200H1, and f2 = 1.0KHz. The outputs of the filters 12 &, 12b are mixed
with the original signal by the mixing unit 14 after the phase shifters 132L, 13b give the
optimum shift amounts at the respective center frequencies. The signal is then amplified by
amplifier 15 and acoustically reproduced by front speaker 16. Further, the high band filter 1γ
extracts the high band component of the signal containing a large amount of reverberation
components, and then the phase shifter 18 shifts the phase, thereby causing a shift due to
reflection of the reverberation in a pseudo manner. Can produce the effects of By adding this
processed signal to the original signal by the mixing unit 14, it is possible to improve the sound
image, such as the sense of spreading, in the sense that the high frequency reverberation is rich.
Also, as shown in FIG. 2, the difference between the original signal of the high band control unit
and the other channel signal (left channel signal when the signal applied to the generator 1 is a
light channel) is a difference amplification unit. In the case of the stereo signal, it is possible to
obtain a signal with more reverberation components by taking it according to (19). That is, in
general, the channel difference signal of the stereo signal contains a large amount of
reverberation components, and the reverberation of the high region is enhanced, and the sense
of realism is enhanced. Also, as shown in FIG. 3, by making the input of the high-frequency
control unit the difference between the original signal and the other channel signal phase-shifted
by the phase shifter 2o, an effect signal is produced even at the monaural source time. Can do.
Next, the standing wave correction according to the above embodiment will be described. A
standing wave is one in which a specific frequency wave resonates or anti-resonates in
correlation with the size of the space, and as shown in FIG. At the wavelength of-(n = 1. 2...) Of
this, a standing wave is generated, and 200 Hz in this embodiment can be considered to be the
case of n = 2.
Here, 21 is a speaker, 22 is a passenger, 23 ° 24 is a standing wave amplitude, 26 is a node,
and 26 is a belly. In this case, since the listening point by the occupant 22 corresponds to the
position of the antinode of the standing wave 24, it appears as a mountain in the frequency
characteristic. That is, at this point, as shown in FIG. 6, the direct wave a and the reflected wave
become just in time in time, causing resonance and enhancing the listening wave C. That is, the
peak person of the direct wave a resonates with the peak R □ of the reflected wave
corresponding to the peak person, and the peak B + R appears in the listening wave C. Therefore,
even if the amplitude of the direct wave is increased in the electric signal simply by the equalizer
method, the increase due to the resonance is large due to the positive feedback due to the
reflectance, and it is difficult to correct sufficiently. However, as shown in FIG. 6, it is possible to
correct the increase due to the resonance of the listening wave C by adding a correction wave
having an opposite phase to the reflected wave to the direct wave a. That is, when the peak
person of the direct wave color is subjected to 3600 phase correction to obtain the peak C6, the
peak C8 and the peak R □ resonate, and the listening wave C becomes B + C, + R, which is
unnecessary as in the case of FIG. There is no peak. Thus, as in the present embodiment, the
phase shifters 13a respectively in the 200 Hz and 1 KHz bands where large peaks occur in the
acoustic frequency characteristics in the passenger compartment. The phase is adjusted by 13 b
to create a correction wave, which is added to the mixing unit 14. Actually, the listening point is
not limited to the size film or node, and the harmonic order n of the standing wave can take
various values, so the phase shift i of the correction wave needs to be changed accordingly There
is. As for the configuration of the phase shifter portion, as shown in FIG. 7 a, by connecting n in
series based on the secondary shifter 51, the center frequency f. It is possible to obtain a shift i of
n × 90 ° in, and by changing the resistance R, it is possible to obtain a shift from 00 to 1800 in
one stage. A characteristic diagram of one stage of the second-order shifter 51 is shown in FIG.
FIG. 8 shows the results of the room characteristic of the present embodiment, where a person is
before correction and B is after correction. As apparent from the figure, it is understood that the
effect amount is improved and the peak characteristic of the peak portion is in a better direction
as compared with the fixed equalizer method. The effect amount is variable according to the
mixing amount of the correction unit to the original signal, and in this example, the mixing
amount is the result at the time of the original signal of -3 dB. As described above, according to
the present invention, by mixing the correction wave with the original signal and reproducing it,
the acoustic frequency characteristic due to the standing wave can be corrected and the uniform
acoustic frequency characteristic can be realized. Furthermore, by shifting the phase of the high
band component, the reverberation can be enhanced to give a sense of presence.
Brief description of the drawings
1 to 3 are block diagrams of an acoustic reproducing apparatus according to an embodiment of
the present invention, FIG. 4 is an explanatory view of a standing wave in a passenger
compartment, and FIG. 5 is an explanation of a standing wave and a direct wave 1 reflected wave.
Fig. 6 is an explanatory view of a standing wave, a direct wave 9 reflection wave, and a correction
wave, Fig. 7 is a diagram showing a shifter configuration and a characteristic diagram, and Fig. 8
is an acoustic frequency characteristic diagram according to this embodiment, Fig. 9 is a block
diagram of the conventional sound reproducing apparatus, Fig. 1 o is a diagram of the acoustic
frequency characteristics in the passenger compartment, Fig. 11 is a block diagram of the sound
reproducing apparatus by the equalizer system, and Fig. 12 is a graph after correction by the
conventional correction reproducing apparatus. FIG.
11 ······· Generator, 12Ia, 12b ····· Filter, 13L, 13b ······· Phase shifter, 14 ······· Mixing unit, 15 ···
Amplifier 16 Speaker: 17 bypass filter 18.20 phase shifter 19 differential amplifier. Name of
Agent Attorney Nakao Toshio and 1 other person! --晋 1-) (Ma g g gq * う に) 12-Band pass filter
Fig. 2 IQ-笈 峠! Fig. 3 ZO-I standing cover + 1 Fig. 5 Fig. 6 Fig. 7 Fig. 7 t4 + tl Fig. 9 Fig. 11
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