JPH0728466B2 - Sound reproduction device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound reproducing device for improving sound characteristics.

2. Description of the Related Art In recent years, the widespread use of passenger cars has been remarkable, and along with this, the sound quality of car audio has changed from the previous good times to better sounds and hi-fi era. However, in the extension of the conventional idea of home audio, it is not possible to cope with the bad condition of the acoustic characteristics in the vehicle interior, and it is not possible to obtain a good sound quality under the present circumstances.

An example of the above-mentioned conventional method will be described below with reference to the drawings.

FIG. 9 shows an example of a conventional on-vehicle reproducing apparatus. Reference numeral 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, and a generator 1 The signal from is amplified by the amplifier 2 and then reproduced from the speakers 3 to 6 into the passenger compartment.
However, if the sound is reproduced as it is, due to the poor acoustic characteristics of the passenger compartment, the frequency characteristics will have peaks and valleys due to the effect of standing waves due to the small volume of the room. Reference numeral 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.

Figure 10 shows an example of actual measurement, about 200Hz, about 1KHz.
It can be seen that there is a large peak in.

Therefore, if mountains and valleys are formed, on the other hand, the frequency characteristics of the opposite characteristics are made electrically, and the mountains and valleys will be canceled by reproducing. This is a fixed equalizer having a mountain-valley 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 when correction is made by the circuit configuration of FIG. 9 using the fixed equalizer 7. But electrically 10
It can be seen that the effect is acoustically up to 3 dB regardless of the correction of more than dB. A is a characteristic diagram before correction and B is a characteristic diagram after correction. That is, with respect to acoustically generated peaks and valleys, there is a problem that the electrical amplitude correction by the fixed equalizer 7 has a limited effect and cannot be sufficiently corrected by such a conventional method. Furthermore, the reproduction by the conventional sound reproducing device is not realistic and unsatisfactory for the driver.

The present invention provides a sound reproducing device that can solve the above problems.

Means for Solving the Problems The sound reproducing device of the present invention reproduces using a phase shifter for changing the phase of an original signal from a generator whose frequency band is limited through a bandpass filter, and an original signal from the generator. A high frequency band control unit for taking out a high frequency band component of a sound to be taken and performing a phase shift is provided, and the outputs of the phase shifter and the high frequency band control unit are mixed with the original signal.

Action The present invention adds a phase change signal to the original signal so as to obtain a correction effect by limiting each band of the standing wave,
The frequency characteristics of the original signal can be changed to correct the acoustic frequency characteristics due to standing waves in the passenger compartment, and the phase of the high frequency band component can be shifted to enhance the reverberation and enhance the realism.

Embodiment Hereinafter, a sound reproducing device according to an embodiment of the present invention will be described with reference to FIG. Although the left and right front seat speakers of the vehicle-mounted speaker are described in the present embodiment, the present embodiment can be applied to the left and right rear seat speakers.

The signal of the generator 11 that generates an electric signal corresponding to the sound to be reproduced is limited to an arbitrary frequency band by the bandpass filter 12. In this embodiment, the correction frequencies are 200 Hz and 1.0 KH
In the case of z, the center frequencies of the filters 12a and 12b of the two correction chains are ₁ = 200 Hz and ₂ = 1.0 KHz, respectively. The outputs of the filters 12a, 12b are mixed with the original signal by the mixing section 14 after the phase shifters 13a, 13b provide the optimum shift amounts at the respective center frequencies. The signal is then amplified by amplifier 15 and front speaker 16
The sound is reproduced by. Also, the original signal is high-pass filter 17
The high frequency band component of the signal containing a lot of reverberation components is taken out, and then the phase shift is performed by the phase shifter 18, so that a pseudo shift effect due to reflection of reverberation sounds can be produced. By adding this processed signal to the original signal in the mixing unit 14, the high-frequency reverberation sound becomes rich, and the sound image such as the audibility and the spread feeling can be improved.

Further, as shown in FIG. 2, the difference between the original signal at the input of the high frequency control unit and the other channel signal (the left channel signal when the signal applied to the generator 1 is the right channel) is calculated by the difference amplifying unit. By taking the value of 19, it is possible to obtain a signal with more reverberation components in a stereo source. That is, generally, the channel difference signal of the stereo signal contains a lot of reverberation components, so that the reverberation sound in the high frequency range is increased and the sense of presence is strengthened.

Further, 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 whose phase is shifted by the phase shifter 20, even in the monaural source,
You can create an effect signal.

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. As shown in FIG. 4, for example, if the lateral direction of the passenger compartment is about 1.6 m, Of this
A standing wave is generated at a wavelength of n / 2 (n = 1.2 ...) Multiples, and 200 Hz in this embodiment can be considered to be n = 2.

Here, 21 is a speaker, 22 is an occupant, 23 and 24 are standing wave amplitudes, 25 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 on the frequency characteristic. That is, at this point, as shown in FIG. 5, the direct wave a and the reflected wave b exactly overlap with each other in time, causing resonance and enhancing the listening wave c. That is, the peak A of the direct wave a and the peak RA of the reflected wave b corresponding to this peak _A.
And and resonate, and the peak B + R _A appears in the listening wave c. Therefore, even if the amplitude of the direct wave is increased by an electric signal simply by equalizing, the increase due to resonance is large because the positive feedback is caused by the reflectance, and it is difficult to sufficiently correct it. However, as shown in FIG. 6, it is possible to correct the increase of the listening wave c due to the resonance by adding the correction wave having the opposite phase to the reflected wave b to the direct wave a. In other words, if the peak A of the direct wave a is 360 ° phase-corrected to become the peak C _A , the peak C _A and the peak R _A resonate, and the listening wave C becomes B + C _A + R _A , as in the case of FIG. Unnecessary peaks do not occur.

Therefore, in the band of 200 Hz and 1 KHz in which a large peak in the vehicle interior acoustic frequency characteristic is generated as in this embodiment,
The phase is adjusted by the phase shifters 13a and 13b to create a correction wave, which is added to the mixing unit 14.

By the way, actually, the listening point is not limited to the size of the belly or the node.
Also, since the harmonic order n of the standing wave can take various values,
The phase shift amount of the correction wave needs to be changed accordingly.

Regarding the structure of the phase shifter, as shown in FIG. 7a, by using the secondary shifter 51 as a base and connecting n in series, a shift amount of n × 90 ° can be obtained at the center frequency ₀ . Also, by changing the resistance R, it is 0 in one stage.
It is possible to obtain shifts of up to 180 °. A characteristic diagram of one stage of the secondary shifter 51 is shown in FIG.

FIG. 8 shows the results of the vehicle interior characteristics of this embodiment, where A is before correction and B is after correction. As is clear from the figure,
It can be seen that the effect amount is improved and the characteristic of the peak sock is improved in comparison with the fixed equalizer method. The effect amount is variable depending on the mixing amount of the correction unit to the original signal, and in this example, the mixing amount is −3 dB of the original signal.
It is the result of time.

EFFECTS OF THE INVENTION As described above, according to the present invention, the corrected frequency limited to each band of the standing wave is mixed with the original signal and reproduced to correct the acoustic frequency characteristic of the standing wave. However, it is possible to realize uniform acoustic frequency characteristics, and by shifting the phase of the high band component, it is possible to enhance the reverberant sound and provide a realistic sensation.

[Brief description of drawings]

1 to 3 are block diagrams of a sound reproducing device according to an embodiment of the present invention, FIG. 4 is an explanatory diagram of a standing wave in a vehicle compartment, and FIG. 5 is an explanation of standing waves, direct waves, and reflected waves. 6 and 6 are explanatory diagrams of a standing wave, a direct wave, a reflected wave, and a correction wave, FIG. 7 is a diagram showing a shifter configuration diagram and a characteristic diagram, and FIG. 8 is an acoustic frequency characteristic diagram according to the present embodiment. FIG. 9 is a block diagram of a conventional sound reproducing device,
FIG. 10 is a sound frequency characteristic diagram of a vehicle interior, FIG. 11 is a block diagram of a sound reproducing device using an equalizer system, and FIG. 12 is a sound characteristic diagram after correction by a conventional correction reproducing device. 11 ... Generator, 12a, 12b ... Filter, 13a, 13b ... Phase shifter, 14 ... Mixing section, 15 ... Amplifier, 16 ... Speaker, 17 ... High-pass filter, 18, 20 ... Phase shifter , 19 …… Differential amplifier.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Hiroshi Yagi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Takahiro Nakama 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP-A-60-214193 (JP, A) JP-A-63-204897 (JP, A) Actual development Sho-60-193776 (JP, U)

Claims (1)

[Claims] 1. An electric signal generator for generating an electric signal corresponding to a sound to be reproduced, a bandpass filter for limiting a frequency band of an original signal from the generator, and a phase change of an output of the bandpass filter. Phase shifter, a high frequency control section for extracting the high frequency band component of the sound to be reproduced by using the original signal from the generator and phase shifting, and outputs of the phase shifter and the high frequency control section for the original frequency. A sound reproducing device having a mixing section for mixing with a signal, an amplifying section for amplifying a signal from the mixing section, and a speaker for acoustically reproducing an electric signal output from the amplifying section.