JPS6343413A - Sound field controller - Google Patents

Abstract

PURPOSE:To realize the presence equivalent to a real sound field by dividing a pseudo initial reflected sound group into plural groups in response to plural propagation paths of sound in the real sound field and number of times of reflection on a wall face and deciding the delay time and the frequency characteristic for each split sound group. CONSTITUTION:In reproducing the sound field for a concert hall or the like whose music sound is recorded, to divide sound groups in response to the sound groups with much and the less number of times of reflection on the wall faces of the hall, digital delay circuits 11-14 are connected in series. Delay data group outputted from digital delay circuits 11-14 is inputted to multiplier circuits 21-24, where a constant for each delay data is multiplied and the result is fed to adder circuits 31-34. The adder circuits 31-34 add the delay data groups and supply the result to filters 41-44. Then the outputs of the filters 41-44 are added by an adder circuit 35. Through the constitution above, the frequency characteristic is varied by changing a multiplicand (coefficient) set to the multiplier circuits 21-24. a, input data signal b, output data signal.

Description

[Detailed Description of the Invention] Flame Hole Light 1 The present invention provides a method for adding holes, etc. to audio signals! The present invention relates to a sound field control device that provides a listener with a so-called sense of being in a concert hall, for example, by adding a group of eight tones.

1. In an indoor acoustic space, one of the conditions for obtaining a sense of presence is the reflected sound characteristics of the acoustic space. A conventional example of a sound field control device that sets such characteristics will be explained with reference to FIG. In FIG. 5, an input data signal, which is a series of sample values of an audio signal, is applied to a digital delay circuit 10. In FIG. The digital delay circuit 10 is constituted by a memory group that stores the memory contents of the previous stage in response to a clock signal (not shown), and uses the output of each memory of this memory group to sequentially delay an input data signal by a predetermined period of time. Obtain data group. Each delay data is multiplier 2 for each delay data.
0+ to 2On (n is an integer), respectively. Multipliers 20+ to 20. constitutes the multiplication circuit 20. A predetermined caulking multiplier is set in advance in each multiplier, and each multiplier obtains the product of the delay data and this multiplier and supplies it to the addition circuit 30. The adder circuit 30 obtains the sum of each level-adjusted delay data and supplies the sum to the digital filter 40. The digital filter 40 is, for example, a low-pass filter, in which case it attenuates high-frequency components. The output of the digital filter 40 is supplied to the next stage digital audio circuit (not shown) as an output data signal.

Next, the operation of the circuit will be explained. Delay time for each delay signal of digital delay circuit 10 and multipliers 20+ to 2O
The multiplier of n is usually determined by sound field simulation of the listening acoustic space using calculations, and each corresponds to 1 of the parameters that define the impulse response characteristics from the sound source (the sound source) to the sound receiving point. do. FIG. 4 shows the addition circuit 3 when an impulse is supplied to the digital delay circuit 10.
The pseudo early reflection sound group shown in FIG. 4 corresponds to the early reflection sound group in a concert hall or the like. The early reflection group is l! Expanding the sound field,
Since this has a large effect on the sound, etc., the sense of realism can be maximized by appropriately setting the pseudo early reflection sound signal group added to the audio signal.

In such conventional devices, the frequency characteristics and phase characteristics of the reflected sound are not taken into account, and various musical tones cannot necessarily be reproduced appropriately with the reverberation characteristics of the actual sound field.

Therefore, it is an object of the present invention to provide a sound field control device that makes it possible to bring various reproduced musical sounds closer to the actual sound field.

In order to achieve the above object, the sound field control device of the present invention divides the pseudo early reflection sound δY into a plurality of parts corresponding to the plurality of propagation paths of the sound in the actual sound field and the number of reflections on the wall surface. The configuration is such that the level, delay time, and frequency characteristics are determined for each pseudo early reflection sound group.

Embodiments of the present invention will be described below with reference to FIG. 1.

In FIG. 1, the input data signal is input to the digital delay circuit 1.
1 and the adder circuit 35. The digital delay circuit 11 is configured similarly to the digital delay circuit 10 and supplies the obtained delayed data group to a multiplication circuit 21 configured similarly to the multiplication circuit 20. The final delay data is sent to a digital delay circuit 12 configured similarly to the digital delay circuit 10.
supplied to The multiplication circuit 21 multiplies each delay data by a constant for each delay data, and then adds the data group to the addition circuit 31.
supply to. The adder circuit 31 adds the above data group and supplies it to the filter 41.

The filter 41 is composed of a digital filter with variable frequency characteristics. Here, the filter 41 corresponds to a basic filter. Digital delay circuit 11, multiplication circuit 21,
Adder circuit 31 and filter 41 constitute a first signal processing circuit.

Similarly to this first signal processing circuit, a second signal processing circuit is constructed by a digital delay circuit 12, a multiplication circuit 22, an addition circuit 32, and a filter 42; Third
The signal processing circuit includes a digital delay circuit 14 and a multiplication circuit 2.
4. The adder circuit 34 and the filter 44 constitute a fourth signal processing circuit. Here, each digital delay circuit serves as a delay means, each multiplication circuit serves as a level a adjusting means, and a filter 42
．． 43 and 44 correspond to additional filters.

The output data and input data signals of each signal processing circuit are combined by an adder circuit 35 and supplied to the next stage as output data. The addition circuit 35 corresponds to addition means.

A concrete circuit of the digital filter is shown in FIG.

In FIG. 2, the input data signal is supplied to a multiplier 41a and a one-data delay circuit 41b. The output of the multiplication circuit 41a is supplied to one input terminal of the addition circuit 41d, and the output of the delay circuit 41b is supplied to the other input terminal of the addition circuit 41d via the multiplier 41c.

The output of the adder circuit 4god is supplied to one input end of the adder circuit 41e. The output of the adder circuit 41e is delayed by a 1-data delay circuit 41f, passes through a multiplier 419, and then is sent to the adder circuit 41.
It is supplied to the other input terminal of e.

The output of the adder circuit 41e becomes an output data signal.

In such a configuration, the frequency characteristics can be changed by changing the multiplier (coefficient) set in each multiplier circuit.

Next, the operation of the circuit will be explained with reference to FIG. Figure 3 shows an example of a rectangular two-dimensional inner sound field. When a reference sound (for example, a pulse sound) is emitted from sound generation point 1, sound receiving point 2 first receives a direct signal from the sound generation point. The sound arrives. Next, a large number of reflected sounds that have been reflected repeatedly through different propagation paths are received, such as the sound reflected once on the wall surface (indicated by the dashed line in the diagram) and the sound reflected twice (indicated by the dashed line in the diagram). Sound point 2
It will arrive in Generally, the smaller the number of reflections, the shorter the path length, and therefore the sooner the signal reaches the sound receiving point 2. A collection of these reflected sounds becomes the aforementioned early reflected sound group, which affects the perceptual spread of sound or the reverberation of sound. By the way, since the wall surface itself has acoustic impedance, the attenuation received by the frequency components of the reflected sound is generally not uniform. For example, if the wall surface is made of a material that absorbs high-frequency components, the high-frequency components of the sound will be further attenuated each time the reflection is repeated. Therefore, in order to reproduce the actual sound field where musical sounds are recorded or the sound field of a concert ball, etc., we divide the reflected sound group into those with a small number of reflections and those with a large number of reflections, and adjust the frequency characteristics of each. There is. In the present invention, a frequency characteristic changing circuit (with variable characteristics) in which a number of signal processing circuits corresponding to the number of sound reflections is provided, and a frequency component attenuator is determined in each signal processing circuit in accordance with the number of reflections. filter) is provided.

Note that the multiplier of each multiplier circuit, the delay time of the delay circuit, and the characteristics of the filter can be set by computer simulation.

In this way, by obtaining a group of pseudo early reflection sound signals corresponding to the acoustic impedance characteristics of the wall surface, the delay time of reflected sound, and changes in frequency components due to repeated reflections on the wall surface, and adding this to the input signal, or separately By supplying the signal to the drive circuit of the provided speaker, the reproduced sound field is brought closer to the acoustic characteristics in a predetermined sound field.

Note that although the embodiment is a one-manpower one-output type, in a multiple-input multiple-output type, for example, an input data signal as another channel is supplied to the adder circuit 35, and the digital filter 4 is supplied with an input data signal as another channel.
A configuration in which the outputs of signals 1 to 44 are supplied to a circuit corresponding to the adder circuit 35 of another channel via an attenuator or the like can be used to synthesize data signals. filter 4
1 at the subsequent stage of the multiplication circuit 21, similar effects can be obtained.

Although the embodiment uses a digital circuit, it is obvious that it can also be formed using an analog circuit. Further, the multiplier of each multiplier circuit, the delay time of the delay circuit, the characteristics of the filter, etc. may be set according to preference.

As explained above, in the sound field control device of the present invention, delayed signal groups corresponding to each reflected sound of the pseudo early reflection sound group are divided into a plurality of groups, and each group of reflected sound groups is Since the configuration is such that the phase difference, level, and frequency characteristics are appropriately set, it is preferable that a sense of presence similar to that in the actual sound field can be obtained as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, and FIG.
FIG. 5 is a block diagram showing an example of the configuration of a digital filter, FIGS. 3 and 4 are diagrams for explaining the early reflected sound Δ group, and FIG. 5 is a block diagram showing a conventional example. Explanation of symbols of main parts 10.11, 12.13.14...Digital delay circuit 20.21, 22, 23.24...Multiplication circuit 3
0.31.32, 33, 34.35...Addition circuit 40...Low pass filter,

Claims (1)

[Claims] A sound field control device that generates a pseudo reflected sound group signal that approximates an early reflected sound group generated at a reference position in an indoor acoustic space defined by a wall surface and in which a sound source is placed, a delay means for obtaining a group of delayed signals by delaying the group by time; a level adjusting means for individually adjusting the level of each delayed signal of the group of delayed signals; a basic filter that passes only a predetermined component of at least one first delay signal of the group of delayed signals; A sound field control device comprising: at least one additional filter that allows only components to pass; and addition means that adds the outputs of the basic filter and the additional filter.