JP2953923B2 - Sound field control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital audio system which uses an electronic time delay network to generate a reflected sound or a reverberant sound so as to execute a control that sounds as if it were in a different sound field. Field control system.

[0002]

2. Description of the Related Art Digital audio systems include:
FIG. 6 is a block diagram showing an example of a hardware configuration of such a digital audio system, which can be realized by enabling high-speed arithmetic processing of digital signals with the advance of semiconductor technology. As shown in this figure,
An analog audio signal from an analog audio signal source 1 such as a tape deck or a tuner is converted into a digital signal via an A / D (analog / digital) converter 3 and then converted into a digital audio signal source such as a CD player. The digital audio signals from the digital signal processor 2 are directly input to a digital signal processor (DSP) 4. The DSP 4 executes various audio controls on the input digital signal while being controlled by the control microcomputer (microcomputer) 5. And the output is D / A
The (digital / analog) converter 6 converts the audio signal into an analog signal. Further, the analog signal is amplified by the amplifier 7 and finally converted into sound by the speaker 8.

In the audio control performed by the DSP 4 and the control microcomputer 5 in the form of software in cooperation with each other, a reflected sound or a reverberant sound is generated, and a sound for executing a control that sounds as if it is in a different sound field is performed. There is field control. This sound field control is performed by a FIR filter (Finite Impulse Response Fi
lter) and IIR filter (Infinite Impulse ResponseF)
This is realized by constructing a time delay network by ilter) or the like.

[0004]

However, at present, due to the limitation of the computing capability of the computing device (DSP, etc.), compared to the reflected sound and reverberant sound that normally occur in the natural world,
Only very low density sounds can be created. for that reason,
When a sound that rises steeply around 1 kHz to 10 kHz (for example, a rim shot of a drum or a sound of a drum synthesizer) is input to the sound field control system, an unusual sound is generated because the spaces between the reflected sounds are not filled. Will occur. FIG. 7 is a diagram for explaining this state. The reflected sound generated by the DSP is shown in FIG. 7A as an impulse response. However, for a sound field control system having such an impulse response, a mid-high sound as shown in FIG. When a steeply rising sound is input, a waveform as shown in FIG. 7 (c), which is the result of convolution and integration (Convolution) operation, is output, and the portion indicated in the figure is heard as an abnormal sound.

In view of such circumstances, an object of the present invention is to provide a sound field control system capable of generating a sound effect without generating an abnormal sound even when a sound in which a mid-high sound rises steeply is input. It is in.

[0006]

SUMMARY OF THE INVENTION The present invention achieves the above object by detecting a sound in which a mid-high sound rises sharply and, when the sound is detected, blocking the input of the sound. That is, the sound field control system according to the present invention includes a sound effect generating unit that generates a reflected sound or a reverberant sound using an electronic time delay network, and executes control that makes it sound as if it were in a different sound field. And 1 kHz
detecting means for detecting that the input energy of some or all of the frequency bands from z to 10 kHz increases sharply, and depending on the output of the detecting means, between several ms and several tens ms, And control means for cutting or attenuating the input to the sound effect generating means.

Further, a further sound field control system according to the present invention provides a sound field control system according to the detection means,
Control means for cutting or attenuating at least a part of the frequency band from 1 kHz to 10 kHz of the input to the sound effect generating means for several ms to several tens ms.

Further, according to the present invention, in the above-mentioned sound field control system, the sound field control system further comprises second detection means for detecting input energy in all frequency bands, wherein the control means outputs an output of the second detection means. There is provided a sound field control system, wherein the sound field control system is configured to change an operation condition according to the operation condition.

[0009]

In the sound field control system configured as described above, a sound in which a middle and high frequency rises steeply can be detected by the detection means, and when the sound is detected, the control means detects the sound of the sound. Since the input to the sound effect generating means is blocked, generation of abnormal noise is prevented. Further, the provision of the second detection means improves the accuracy of such detection. The more detailed structure of the present invention will become more apparent from the following description of the embodiments.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing the configuration of an embodiment of a sound field control system according to the present invention. In this figure, reference numeral 10 denotes a band-pass filter, reference numeral 20 denotes a level detection circuit (integration circuit), reference numeral 30 denotes a level difference detection circuit (differential circuit), reference numeral 40 denotes a control unit, reference numeral 50 denotes a delay unit, and reference numeral 60 denotes a control unit. Denotes a gain (multiplier), reference numeral 70 denotes a sound effect generator, and reference numeral 80 denotes a level detection circuit (integration circuit). Then, the band pass filter 10, the level detection circuit 20, and the level difference detection circuit 30 constitute the detection means, and the control unit 40 constitutes the control means. Further, the level detection circuit 80 constitutes the second detection means. Hereinafter, the operation will be described.

When a sound having a steep rising of a middle and high frequency as shown in FIG. 2A is input as the input signal S,
A part or all of the signal S around 1 kHz to 10 kHz is extracted by band cut of the band-pass filter 10, and becomes an output signal A as shown in FIG. This signal A is integrated by the level detection circuit 20 to become an output signal B as shown in FIG. Next, the signal B is differentiated by the level difference detection circuit 30 to become an output signal C as shown in FIG. Further, the signal C is input to the control unit 40.

On the other hand, the input signal S is delayed by the delay unit 50, multiplied by a gain 60, and then input to the sound effect generation unit 70. The control unit 40 changes the gain 60 according to the signal C. Control. The delay unit 50 delays the time from when the input signal S is input to the band-pass filter 10 to when the output signal of the control unit 40 corresponding to the input signal S is generated.

Next, the processing of the control unit 40 will be described with reference to FIG.
This will be described with reference to the flowchart of FIG. First, it is determined whether the signal C is larger than a predetermined threshold Thr (step 102). If it is larger, the gain is reduced (step 104). If not, it is determined whether the gain is larger than 1.0 (step 106). as a result,
If the gain is greater than 1.0, the gain is set to 1.0 (step 108); otherwise, the gain is multiplied by a constant greater than 1.0. Thus, the control unit 4
0 controls the gain 60 in accordance with the input C. As shown in FIGS. 2D and 2E, when the signal C exceeds a predetermined threshold, the gain is reduced to less than 1.0. It has become. As described above, 1 kHz to 10
When it is detected that the input energy of some or all of the frequency bands up to kHz is sharply increased, the input to the sound effect generator is cut or cut for several ms to several tens ms. By attenuating the noise, generation of abnormal noise can be prevented.

In addition, since the level and the slope of the output signals B and C change between the case where the input signal S is small and the case where the input signal S is large, erroneous detection may occur unless the threshold Thr is also changed. Could lead to Therefore, it is preferable to further provide the level detection circuit 80 of FIG. 1 to detect the input energy of the entire band and change the threshold in accordance with the input energy. That is,
The control unit 40 further executes a process of appropriately switching the threshold, as shown in FIG. 4, according to the output signal F of the level detection circuit 80.

In FIG. 1, a filter is provided in place of the gain 60 so as to cut or attenuate all or a part of the band (1 kHz to 10 kHz) relating to the abnormal sound in the input of the sound effect generator. Thus, occurrence of abnormal noise may be prevented. That is, instead of performing control to change the gain over time to t ₀ , t ₁ , t ₂ , and t ₃ as shown in FIG. 2 (e), a filter is provided and its frequency characteristic is changed as shown in FIG. From the characteristics at time t ₀ , t ₁ , t ₂ , t ₃
The object of the present invention can also be achieved by gradually changing the characteristics to the point in time.

The embodiment of the present invention has been described above. From the block diagram of a digital system including a delay unit, a multiplier and an adder as basic elements as shown in FIG.
Since it is easy for a person skilled in digital signal processing technology to create an actual DSP program, further description for implementing the present invention will not be particularly necessary. It should be noted that the present invention is of course not limited to these embodiments, and it will be easy for those skilled in the art to devise various embodiments without departing from the scope of the claims.

[0018]

As described above, according to the present invention,
Provided is a sound field control system capable of generating a sound effect without generating abnormal noise even when a sound in which a mid-high sound rises steeply is input. In an audio system incorporating such a sound field control system, generation of abnormal noise is prevented even when the sound field control is applied to a fu- jun or a rock music with a steep rise of middle and high frequency sounds, and the quality as a product (sound quality) is prevented. Improvement and claim reduction are achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a sound field control system according to the present invention.

FIG. 2 is a waveform chart of each part in FIG.

FIG. 3 is a flowchart for explaining processing contents in a control unit of FIG. 1;

FIG. 4 is a flowchart for explaining further processing contents in a control unit in FIG. 1;

FIG. 5 is a frequency characteristic diagram of a filter provided in another embodiment of the sound field control system according to the present invention.

FIG. 6 is a block diagram illustrating an example of a hardware configuration of a digital audio system.

FIG. 7 is a characteristic diagram illustrating how abnormal noise is generated in a conventional sound field control system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Analog sound signal source 2 ... Digital sound signal source 3 ... A / D converter 4 ... DSP 5 ... Control microcomputer 6 ... D / A converter 7 ... Amplifier 8 ... Speaker 10 ... Band pass filter 20 ... Level detection circuit (integration circuit) 30 ... Level difference detection circuit (differentiation circuit) 40 ... Control unit 50 ... Delay unit 60 ... Gain (multiplier) 70 ... Sound effect generation unit 80 ... Level detection circuit (integration circuit)

Claims (3)

(57) [Claims] 1. A digital audio system comprising: a sound effect generating means for generating a reflected sound or a reverberant sound using an electronic time delay network; and performing control as if the sound were in different sound fields. In the sound field control system, detecting means for detecting that the input energy of part or all of the frequency band from 1 kHz to 10 kHz sharply increases, and from several ms depending on the output of the detecting means Control means for cutting or attenuating the input to the sound effect generating means for several tens of milliseconds. 2. A digital audio system, comprising: a sound effect generating means for generating a reflected sound or a reverberant sound using an electronic time delay network; and performing control as if it were in a different sound field. In the sound field control system, detecting means for detecting that the input energy of part or all of the frequency band from 1 kHz to 10 kHz sharply increases, and from several ms depending on the output of the detecting means Control means for cutting or attenuating at least a part of the frequency band from 1 kHz to 10 kHz of the input to the sound effect generating means for several tens of ms. Control system. 3. The apparatus according to claim 2, further comprising: a second detection unit configured to detect input energy in all frequency bands, wherein the control unit is configured to change an operation condition according to an output of the second detection unit. The sound field control system according to claim 1 or 2, wherein: