JPH0560594A - Howling simulation device - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to provide a howling simulation device capable of predicting a howling phenomenon in a loudspeaker on a desk. [Structure] A reflected sound from a speaker in a sound field to a microphone is calculated by a reflected sound calculating means 2 for each direction of a sound line by a virtual image method, and the calculated reflected sound is divided by an angle by a reflected sound dividing means 3. To do. The impulse response to the divided reflected sound is selected from the impulse responses for each angle measured and stored in advance in the impulse response storage means 1, the convolution operation means 5 calculates the response for each angle, and the Fourier transform unit 6 Find the frequency characteristics of the response. The frequency corresponding to the maximum value of the response is set to a frequency that facilitates howling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound field simulation device for analyzing a sound field in a room.

[0002]

2. Description of the Related Art In recent years, there have been a great number of music and theater events, but complete installation of audio equipment in stage equipment is an important issue.

Conventionally, when a speaker (hereinafter, referred to as a microphone) and a speaker are used for loudspeaking in a room or the like, there is a problem that a howling group is generated in the loudspeaking system and howling occurs depending on the arrangement state of the speaker and the microphone. Conventionally, the state of howling has been confirmed by actually increasing the gain of a system including a speaker and a microphone and measuring the howling limit. Moreover, whether or not howling is likely to occur was comprehensively predicted by the reverberation time of the reproduction place, the directivity of the speaker and the microphone used, and the installation position and direction.

[0004]

In such a conventional predicting means, the howling margin cannot be obtained unless the speaker and the microphone are actually placed in the room to make the sound loud, and it is difficult to predict howling in advance. ..

The present invention solves the above problems, and provides a howling simulation device capable of easily obtaining a frequency at which howling is easy by assuming the position and direction of a speaker or a microphone on a desk. The purpose is to

[0006]

In order to achieve the above object, the present invention provides an impulse storage means for storing impulse responses of a speaker and a microphone for each angle, and a reflected sound operation for calculating a reflection path from the speaker to the microphone. Means, reflected sound selection means for dividing the reflected sound input to the microphone by angle, impulse response selecting means for selecting impulse response for each angle from the impulse storage means, selected impulse response and reflection for each angle A howling simulation apparatus is provided with a convolution calculation unit that convolves a sound and a Fourier transform unit that performs a Fourier transform on the impulse response obtained by the convolution calculation unit.

[0007]

According to the present invention, in the above configuration, the impulse response for each angle of the speaker or the microphone is convoluted with the impulse response obtained by the reflected sound calculation method such as the virtual image method, so that a frequency that is easy to howl on a desk is easily obtained. It is possible to dramatically improve the efficiency of acoustic design for howling.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A howling simulation apparatus according to an embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of a howling simulation apparatus according to an embodiment of the present invention. In the figure, 1 is an impulse response storage means for storing the impulse response of a speaker and the impulse response of a microphone for each angle measured in advance, and 2 is a reflected sound for calculating a reflection path from a sound source to a sound receiving point by the virtual image method. Calculating means 3 is a reflected sound dividing means for selecting the reflected sound obtained by the reflected sound calculating means 2 for each angle with respect to both the sound source and the sound receiving point and collecting the reflected sound. 4 is obtained by the reflected sound selecting means 3. An impulse response selecting means for selecting an impulse response corresponding to a reflected sound for each angle from the impulse response storage means 1, a convolution calculating means for convolving the selected impulse and the reflected sound, and a Fourier transform 6 for the obtained impulse response. It is a Fourier transform unit.

The mutual relationship and operation of the above components will be described below. First, the impulse response at each angle of the speaker and the microphone used for the howling simulation is measured. FIG. 2 is a plan view showing the structure of an impulse response measuring device for a microphone and a speaker. In the figure, 7 is a speaker for a sound source, and 8 is a microphone for collecting sound. As shown in the figure, the impulse response for each angle between the speaker 7 and the microphone 8 is measured. FIG. 2 shows a case where the impulse response is measured every 30 degrees. The measured impulse response between the speaker 7 and the microphone 8 for each angle is stored in the impulse response storage means 1 as a number 49 obtained by multiplying the speaker division number 7 and the microphone division number 7.

FIG. 3 is a schematic diagram showing the shape of a hall and the speaker and microphone for actually performing a howling simulation. In the figure, 10 is a hole for performing howling simulation, and 11 is one of the reflected sounds obtained by the reflected sound calculation means 2. The reflection path between the speaker 7 and the microphone 8 arranged as shown in FIG. 3 is obtained by the virtual image method. At the sound receiving point of the microphone 8, the size, direction, time, and the like of the sound ray entering the microphone 8 are calculated.

FIG. 4 is a schematic diagram showing the process of signal processing according to the present invention. The obtained impulse response a of the sound receiving point is obtained by the reflected sound dividing means 3 from which direction of the speaker 7 which is the sound source is emitted and which direction of the sound receiving point is incident on each reflected sound. It is divided for each angle as shown in b. For example, since the reflected sound 11 in FIG. 3 is a sound emitted from the speaker in the direction of 30 degrees and incident from the direction of the microphone in the direction of 45 degrees, the impulse response corresponding to the angle of the impulse response storage means 1 is selected. The above operation is performed for each angle as shown in FIG.

Next, the convolution calculation is performed on the impulse response of the speaker and the microphone selected from the impulse response storage means 1 stored in advance by the impulse response selection means 4 and the reflected sound divided by the reflected sound dividing means 3. I do.

The impulse response of the reflected sound group selected by the reflected sound classification means 3 is hhn (t), and the impulse response of the impulse response storage means 1 corresponding to the angle is hsn.
Assuming that (t), the convolution operation result hn (t) is
It is expressed by the equation (1).

[0014]

[Equation 1]

These processes are performed for each reflected sound group,
The result of the addition is expressed by the equation (2).

[0016]

[Equation 2]

An impulse response h (t) considering the directivity of the speaker and the microphone is obtained. FIG. 4D corresponds to the result.

The Fourier transform unit 6 performs a Fourier transform on the impulse response thus obtained, and transforms it into data on the frequency axis.

FIG. 5 shows the result of Fourier transform of the impulse response obtained by the convolution operation unit 5 by the Fourier transform unit. Here, the frequency at which howling is most likely is the frequency with the largest gain, so that in FIG. 5, it becomes (A), and the howling frequency can be predicted by looking at the frequency characteristics.

Further, it is possible to obtain the positions of the speaker and the microphone in which howling is unlikely to occur by repeating these series of simulations by assuming various directions of the speaker and the position of the microphone.

As described above, according to the howling simulation apparatus of the embodiment of the present invention, the impulse storage means for storing the impulse response for each angle of the speaker and the microphone, and the reflected sound operation for calculating the reflection path from the speaker to the microphone. Means, reflected sound selection means for dividing the reflected sound input to the microphone by angle, impulse response selecting means for selecting impulse response for each angle from the impulse storage means, selected impulse response and reflection for each angle By using a howling simulation apparatus that includes a convolution operation unit that convolves a sound and a Fourier transform unit that performs a Fourier transform on the impulse response obtained by the convolution operation unit, it is possible to accurately predict the frequency at which howling easily occurs. ..

In the present embodiment, the case of one speaker and one microphone has been described as an example, but it is also possible to perform simulation for a plurality of speakers.

[0023]

As is apparent from the above embodiments, the impulse storage means for storing the impulse response for each angle of the speaker and the microphone, the reflected sound operation means for calculating the reflection path from the speaker to the microphone, and the microphone Reflected sound selection means for dividing the input reflected sound by angle, impulse response selection means for selecting impulse response for each angle from the impulse storage means, and convolution operation for convoluting the selected impulse response and the reflected sound for each angle By using the howling simulation apparatus including the means and the Fourier transform unit that performs the Fourier transform on the impulse response obtained by the convolution operation means, it is possible to accurately predict the frequency at which howling is likely to occur.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a howling simulation apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an impulse response measuring device for a speaker and a microphone.

FIG. 3 is a schematic diagram showing an arrangement of a speaker and a microphone in a howling simulation apparatus according to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing a process of convolution of reflected sound in the howling simulation apparatus according to an embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a result of Fourier transform of impulse response.

[Explanation of symbols]

 1 Impulse Response Storage Means 2 Reflected Sound Calculating Means 3 Reflected Sound Dividing Means 4 Impulse Response Selecting Means 5 Convolution Calculating Means 6 Fourier Transform Unit 7 Speaker 8 Microphone

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroko Numazu 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. An impulse storage unit for storing impulse responses of a speaker and a microphone for each angle, a reflected sound calculation unit for calculating a reflection path from the speaker to the microphone, and a reflected sound input to the microphone for each angle. The reflected sound selection means, the impulse response selection means for selecting the impulse response for each angle from the impulse storage means, the convolution operation means for convoluting the selected impulse response and the reflected sound for each angle, and the convolution operation means A howling simulation apparatus including a Fourier transform unit that performs a Fourier transform on an impulse response.