JPH07105983B2 - Sound field correction device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound field correction device, and more particularly to a device for correcting a sound field at a predetermined listening point in a sound field created by a direct radiated sound from a speaker and its reflected sound.

BACKGROUND ART As an example of audio equipment, there is a magnetic tape reproducing device. In this device, a reproducing signal from a reproducing head is amplified into a signal having a regular frequency characteristic by a reproducing amplifier having an equalizer function, and the next stage graphic equalizer or the like. Is adjusted to a desired reproduction frequency characteristic by the frequency characteristic variable amplifier and becomes a speaker drive signal.

In such an acoustic system, as the sound radiated from the speaker 5, for example, the route reaching the predetermined listening point 6 in the sound field shown in FIG. There is a reflected sound due to such a wall. In this case, at the listening point 6, a peak or a dip occurs at a certain frequency due to mutual interference of sounds by both sounds, and the frequency characteristic at the listening point 6 is disturbed. Therefore, the disturbance of the frequency characteristic is corrected by a graphic equalizer or the like.
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, when trying to correct this by the graphic equalizer, a large number of circuits are required and its adjustment becomes very difficult.

Therefore, the present applicant has proposed a sound field correction device as shown in FIG. In the figure, an original signal input IN is delayed by a delay device 1 and applied to a level adjuster 2. The level-controlled signal is sent to the adder 4
It becomes an input 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, it is assumed that the reflector is a so-called fixed-end reflection such as a wall (generally, it may be fixed-end reflection), and the original signal IN is S ₁ = Ae ^jwt.
The delay time by _{- (l 2 -l 1) /} c and the adjustment level by the level adjuster 2, KAl ₁ / l _2. In addition, l ₁ is the path length of the direct sound 7 of the speaker 5 up to the listening point 6, l ₂ is also 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, K is the wall, etc. Is the reflectance of.

The output S _{D of the} inverter 3 is Therefore, the output S ₀ of the adder 4 is Becomes Since this signal S ₀ is applied to the speaker 5,
The sound S _{M at the} listening point 6 includes a direct sound S _S having a signal strength of 1 / l ₁ and a time delay of l ₁ / c, and a signal strength of 1 / l at the reflectance K.
and a l ₂ be synthesized sound and reflected sound S _D having a time delay of l ₂ / c. Therefore, S _M becomes the following equation.

Since 0 ≦ K <1,0 <l ₁ / l ₂ <1 here, (3)
The second term of the equation is sufficiently smaller than the first term, so Therefore, the reflected wave is erased.

However, in the above device, although it is effective for the interference by one reflected sound 8 as shown in FIG. 2, in the actual sound field, as shown in FIG. 3, the listening point 6 is surrounded. Multiple reflected sounds from each wall of the sound field
It is impossible to cancel all these reflected sounds. Reference numeral 30 denotes an audio reproducing system including the device shown in FIG.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a sound field correction device capable of eliminating the influence of reflected sound. .

The sound field correction apparatus according to the present invention, when adjusting the level and phase of the original signal to obtain the correction signal and superimposing the correction signal on the original signal, each of them comprises a series circuit of level adjusting means and phase adjusting means. A plurality of adjusting means for respectively adjusting the level and the phase by the level adjusting means and the phase adjusting means to generate the correction signals having different levels and phases, and the correction signals and the original signal are superposed in a feedforward manner. A means for supplying the sound to a speaker, and cancels a plurality of reflected sounds that reach a predetermined listening point in the sound field through different paths.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a block diagram of an embodiment of the present invention, and the same portions as those in FIG. 1 are designated by the same reference numerals. In the figure,
The original signal IN consists of n (integer of 2 or more) delay devices 1.1 to 1
Each of the delay outputs is applied to n level adjusters 2.1 to 2n. Each level adjustment output is input to the adder 4 via each of the n inverters 3.1 to 3n, and is superimposed on the original signal IN. 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 the same as the path l ₂ of the reflected sound 8 (see FIG. 2) as in the example of FIG. 7 is a function with the path length l ₁ and is set to be τ∝ (l ₂ −l ₁ ) / c and α∝ / l ₁ / l ₂ and cancels the influence of the reflected sound 8.

'S τ and α delayer 1, 2 and level adjuster 2.2, a function of the path length l ₁ of the direct sound and the path length l ₃ of the other reflections, τα (l ₃ -l ₁₎ / c and α∝l ₁ / l ₃ . Similarly, a path length of each reflected sound and a path length of a direct sound are similarly set, and each reflected sound is set to be canceled.

FIG. 5 is a block diagram of another embodiment of the present invention, in which n delay devices 1.1-1.n are connected in cascade, and the delay output from each cascade connection point is adjusted by n level adjusters 2.・ Input to 1 ~ 2 ・ n. Then, each level adjustment output is input to each adder 4 through the n inverters 3.1 to 3n. Other configurations are the same as those in the example of FIG.

Here, the delay time of the delay output of each of the delay devices 1.1 to 1 · n is the sum of all the delay times of the preceding-stage delay devices because each delay device is connected in series. That is, the reflected sound of the shortest reflection distance is canceled by the output signal of the delay device 1.1, and the reflected sound of the next long reflection distance and the output signal of the delay devices 1 and 2 respectively. Is also the same. Level adjusters 2.1-2.n and inverters 3.1-3.
Each action of n is the same as in the example of FIG.

FIG. 6 is a block diagram of still another embodiment of the present invention,
A single inverter 3 is used instead of the inverters 3.1 to 3 in the example of FIG. Therefore, the output of each level adjuster 2.1-2.n is added by an adder.
The addition is made at 10 and is supplied to the adder 4 via the 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 3.1 to 3 in the example shown in the figure, and the output of each level adjuster 2.1 to 2 · n is input to the adder 10 The addition output is applied to the adder 4 via the inverter 3.

Effect According to the present invention, each is composed of a series circuit of the level adjusting means and the phase adjusting means, and the level and the phase of the original signal are adjusted by the level adjusting means and the phase adjusting means to have the different level and phase. A plurality of adjusting means for respectively generating a signal are provided, and each of the correction signals and the original signal are superposed in a feedforward manner and supplied to the speaker, and a plurality of arriving at a predetermined listening point in the sound field through different paths. It is designed to cancel the reflected sound. As described above, the sound field correction device of the present invention is of the feed-forward type in which the number of correction signals for one original signal is limited, and since the correction signal output from the adjusting means does not include a feedback component, The plurality of correction signals can almost cancel the reflected sound component, and furthermore, even if the listening point deviates from the predetermined position, it is possible to prevent the generation of a sharp peak component which is sensitive to hearing. Therefore, for example, it is possible to prevent the listening sound from becoming an unnatural sound in a space where it is difficult to be located at a good listening point such as a vehicle interior.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a sound field correction device proposed by the applicant of the present application, FIGS. 2 and 3 are diagrams showing examples of a sound field space, and FIGS. 4 to 7 are present inventions. It is a block diagram of each embodiment of. Explanation of symbols of main parts 1.1-1.n ... delay device 2.1-2.n ... level adjuster 3,3. 1-3.n ... inverter 4 ... adder 5 ... speaker

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshikazu Yoshimi 1-25-25 Nishimachi Yamada, Kawagoe, Saitama Prefecture Pioneer Co., Ltd. Kawagoe Factory (72) Yoshio Sasaki 1-25-25 Nishimachi, Yamada, Kawagoe, Saitama Pioneer Co., Ltd. Kawagoe Factory (56) References JP-A-55-121793 (JP, A) JP-B-57-22443 (JP, B2)

Claims (1)

[Claims] 1. A sound field correction device for correcting a sound field created by a direct radiated sound from a speaker and a reflected sound thereof, each of which comprises a series circuit of a level adjusting means and a phase adjusting means, A plurality of adjusting means for adjusting the level and the phase by the level adjusting means and the phase adjusting means to respectively generate correction signals having different levels and phases; And a means for supplying the speaker to the speaker in a superimposed manner, and canceling a plurality of reflected sounds arriving at predetermined listening points in the sound field through different paths.