JPS60223294A - Sound field corrector - Google Patents

Abstract

PURPOSE:To correct a sound field by obtaining plural correction signals set at different levels and phases from an original signal and adding these correction signal to the original signal. CONSTITUTION:An original signal IN is supplied to delay devices 1.1-1.n respectively, and each delay output is impressed to level controllers 2.1-2.n respectively. Each level control output is used as an input of an adder 4 via inverters 3.1-3.n respectively and superposed on the signal IN. This addition output drives a speaker 5 via a power amplifier 9. The delay time of each delay device and the level attenuation of each level controller are equal to the functions of the routes of the reflected sound and the direct sound.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a sound field correction device, and more particularly to a device for correcting a sound field in a predetermined listening atmosphere within a sound field created by direct radiation from a speaker and its reflected sound.

Background Art An example of audio equipment is a magnetic tape playback device. In this device, the playback signal from the playback head is amplified by a playback amplifier with an equalizer function into a signal with regular frequency characteristics, and then the signal is amplified by a next-stage graphic equalizer, etc. The frequency characteristic variable amplifier adjusts the frequency characteristic to a desired reproduction frequency characteristic and becomes a speaker drive signal.

In such a sound system, the route of the sound radiated from the speaker 5 to the predetermined listening point 6 in the sound field shown in FIG. There is also sound reflected from walls etc. as shown. In this case, at the listening point 6, a peak or a dip occurs at a certain frequency due to mutual interference of sounds due to rain sounds, and the frequency characteristics at the listening point 6 are disturbed. Therefore, a graphic equalizer or the like is used to correct this disturbance in frequency characteristics.

However, since the peak and dip frequencies change depending on the installation state of the device and the listening position, the frequency disturbance also changes. Therefore, if an attempt is made to correct this using a graphic equalizer, a large number of circuits will be required and the adjustment will be extremely difficult.

Therefore, the applicant of the present application has proposed a sound field correction device as shown in FIG. In the figure, an original signal input IN is delayed in a delay device 1 and then output to a level adjuster 2. The level-controlled signal is supplied to the adder 4 via the inverter 3, and is added and superimposed with the original signal input IN. This addition output OUT becomes the drive signal for the speaker 5 shown in FIG.

In the sound field shown in Fig. 2, one reflecting object is a so-called fixed-end reflection such as a wall, and in general it can be assumed that it is a fixed-end reflection), and the original signal INtS1=Aej (Dt is the delay time due to delay device l). Let be -(Z2-Zl)/c and the adjustment level l KAL1/12 by the level adjuster 2. Note that tl is the direct sound 7 of the speaker 5 up to the listening point 6.
, t2 is the path length of the reflected sound 8, C is the speed of sound,
A is the signal strength on the vibration surface of the speaker, and A is the reflectance of walls, etc.

The output SD of Impark 3 is Sn”-(KAZ1/12)'eJ(IJ(t-(1z
-lt)/c) ・,・,= (1°), therefore, the output S of the accelerator 4. is 5o=S□10SD “A”ωt CKAt1/12 )ejωCt-(12
-'t)/c) , , (2 degrees. Since this signal S is applied to the speaker 5, the sound S at the listening point 6 is
M is a direct sound S8 with a signal strength of 17'Z 1 and a time delay of t□/C, and a signal strength of 1,4 with a reflectance of
It becomes a synthesized sound with the reflected sound SD which is □ and has a time delay of 12/C. Therefore, SM becomes the following formula.

SM=88+5D = (A/L1)'ノ(c)(t-'y')(KA/Zz
)'ノω(t-(12-11)7cm1v'c)ten(K
A/12)gノω(t-lz/C)-CI<n”2)C
KAI, /12) eノω(t-CLz-Ll)/c-
1,/c)"(A/1i)eノω(t-'1/C)-C
KAI□/12 houses (1) (t-(21', -Z・)''
) ......(3) Ko\te, 0≦Niku1,0kuz1
/12 times 1.

The second term in equation (3) is sufficiently smaller than the first term, so SM=+=(A/A,)e+(t-l't/')・
, , , , , , (4) The reflected waves are eliminated.

However, although the above device is effective against interference caused by a single reflected sound 8 as shown in FIG. 2, in an actual sound field, as shown in FIG. Since a plurality of reflected sounds from each wall surface of the sound field arrive at the listening point 6, it is impossible to cancel out all of these reflected sounds. Note that 30 indicates an audio reproduction system including the device shown in FIG.

SUMMARY OF THE INVENTION The present invention was made to eliminate the above-mentioned drawbacks, and its purpose is to provide a sound field correction device that makes it possible to eliminate the influence of reflected sound. .

The sound field correction device according to the present invention, when adjusting the level and phase of the original signal and superimposing it on the original signal, cancels a plurality of reflected sounds that arrive at a predetermined listening point in the sound field through different routes. Embodiment The present invention will be described in detail with reference to one drawing below.FIG. 1 is a block diagram of an embodiment of the present invention, and parts equivalent to those in FIG. 1 are designated by the same reference numerals.

In the figure, the original signal IN is input to n (an integer greater than or equal to 2) delay devices 1.1 to 1Φn, respectively, and each delayed output is input to n level adjusters 2.1 to 2.n. are applied respectively. Each level adjustment output has n imparks 3.1 to 3.
It is superimposed on the input of the adder 4 and the original signal IN via each of the input signals IN and NI. This added output drives the speaker 5 via the power amplifier 9.

Here, the delay time τ and the level attenuation amount α of the delay device 1.1 and the level adjuster 2.1 are determined by the path No. 2 of the reflected sound 8 (see FIG. 2) and the direct sound. It is a function of path length no □ of
It is set to be 2, which cancels out the influence of reflected sound 8.

τ and α of delay devices 1 and 2 and level adjusters 2 and 2 are the path length of other reflected sounds and the path length of direct sound! , τ-, ()3-11)/C and α=, , /ノ3. Similarly, it is a function of the path length of each reflected sound and the path length of the direct sound, and is set so that each reflected sound is canceled out.

FIG. 5 is a block diagram of another embodiment of the present invention, in which n delay devices 1.1 to 1.xf are connected in cascade, and fn level adjusters 2.1 are provided with delayed outputs from each cascade connection point. ~2・n is being input. Each level adjustment output is input to the adder 4 via n inverters 3.1 to 3.n.

The other configurations are the same as the example shown in FIG.

Here, since each delay device is connected in series, the delay time of the delayed output of each delay device 1.1 to l.n is the sum of all the delay times of the preceding delay devices. In other words, the reflected sound with the shortest reflection distance is canceled by the output signal of delay devices 1 and 1, and the reflected sound with the next longest reflection distance is canceled by the output signals of delay devices 1 and 2, respectively. The same applies to other reflected sounds. Level adjuster 2.1~2en and inverter 3.1~3.
Each effect of n is equivalent to the example of FIG.

FIG. 6 is a block diagram of still another embodiment of the present invention, in which a single inverter 3 is used in place of the inverters 3.1 to 3.3 in the example of FIG. For that purpose, each level adjuster 2.1 to 211? The outputs of L are added by an adder 10 and supplied to an adder 4 via an inverter 3.

FIG. 7 is a block diagram of another embodiment of the present invention;
A single inverter 3 is used instead of the inverters 301 to 3-3 in the example shown in the figure, and the outputs of each level adjuster 2.1 to 2.n are input to the adder 10, and the addition output is applied to the adder 4 via the inverter 3.

Effects According to the present invention, it is possible to effectively correct disturbances in frequency characteristics due to complex reflections in a complex sound field space.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a sound field correction device being proposed by the applicant, FIGS. 2 and 3 are diagrams showing examples of sound field spaces, and FIGS. 4 to 7 are diagrams showing the present invention. FIG. 2 is a block diagram of each embodiment of FIG. Explanation of symbols of main parts 1・l~1・n...Delay unit 2・1~2・
n・・・・・・Level adjuster 3.3.1~3.n
・・・Inverter 4・・・・・・・・・・・・・・・・・・・・・
・・・Adder 5・・・・・・・・・・・・・・・・・・
・・・・・・・・・Speaker Applicant Pioneer Co., Ltd. Agent Patent Attorney Motohiko Fujimura

Claims (1)

[Claims] A sound field correction device that corrects a sound field created by direct radiation sound from a speaker and its reflected sound, the device comprising: adjustment means for adjusting the level and phase of an original signal; and an output signal of the adjustment means and the original signal. and means for superimposing and supplying the same to the speaker, and the adjusting means adjusts the level and phase to be different in order to cancel out a plurality of reflected sounds that arrive at a predetermined listening point in the sound field through different routes. A sound field correction device characterized in that it is configured to obtain a plurality of correction signals set to from the original signal.