JPH02214400A - Microphone device - Google Patents

Abstract

PURPOSE:To eliminate wind noise automatically by providing a low pass filter and an automatic level control circuit and controlling the level of a low frequency component from the low pass filter in response to the level of the wind noise automatically. CONSTITUTION:An output of a microphone 1 is fed respectively to a high pass filter 8 and a low pass filter 9 via a preamplifier circuit 2. The high pass filter 8 passes a frequency signal over 150Hz and the low pass filter 9 passes the low frequency signal including the wind noise component below 150Hz. The output signal of the high pass filter 8 is fed to one input terminal of the adder circuit 11 and the output signal of the low pass filter 9 is fed to the other input terminal of the adder circuit 11 via an automatic level control circuit 10. In this case, the automatic level control circuit 10 consists of a variable gain amplifier circuit 10a and a level detection circuit 10b and the level is not attenuated when no wind noise exists and the attenuation is increased as the level of the wind noise is increased. An audio signal output terminal 7 is led from the output side of the adder circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microphone device suitable for use in recording outdoors.

[Summary of the invention]

The present invention relates to a microphone device suitable for use in outdoor recording, etc., which includes a microphone that converts audio into an electrical signal, and a high-pass filter to which the electrical signal from the microphone is supplied and which passes signals of a predetermined frequency or higher. , a low-pass filter to which the electric signal from this microphone is supplied and passes signals below a predetermined frequency, and an automatic level to which the output signal of this low-pass filter is supplied and the output signal level is controlled according to the level of this output signal. It has a control circuit and an addition circuit that adds the output signal of this high-pass filter and the output signal of this automatic level control circuit, and by deriving the output signal from this addition circuit, it automatically improves wind noise. It is made so that it can be removed.

[Conventional technology]

Wind noise is generally a problem when using a microphone outdoors for recording. A large windscreen is installed as a countermeasure against this wind noise, but normally this windscreen alone is not sufficient. Also, JP-A No. 57-15597, JP-A No. 62-
It has also been proposed to remove this wind noise by combining a high-pass filter and a low-pass filter, as shown in Japanese Patent No. 24999, but this combination of high-pass filter and low-pass filter does not solve this problem well. Wind noise could not be removed.

Therefore, conventionally, an external changeover switch as shown in FIG. 4 is used to electrically attenuate the low frequency characteristic, which is the main component of wind noise, in several stages, for example, four stages.

That is, in Fig. 4, (1) shows a microphone that converts audio into an electrical signal, and the electrical signal from this microphone (1) is sent to the external selector switch (3) via a preamplifier circuit (2). so as to supply the first fixed contact (3,),
Also, the output signal of this preamplifier circuit (2) has a low frequency attenuation of 3
The second fixed contact (3z) and the third fixed contact ( 3,) and the fourth fixed contact (34), respectively. In this case, the magnitude of low-frequency attenuation is set such that low-frequency cut filter (4)<low-frequency cut filter (5)<low-frequency cut filter (6). An audio signal is derived from the movable contact (3a) of this external changeover switch (3). (7) is an audio signal output terminal.

In the conventional microphone device as shown in FIG. 4, the operator monitors the sound by using the movable contact (3a) of the external changeover switch (3) and selects the desired one with greater low-frequency attenuation when wind noise is large. fixed contact (fourth fixed contact (34)
) side), and when there is no wind noise, connect the desired fixed contact (first fixed contact (31
) side) to obtain a good audio signal with little wind noise at the audio signal output terminal (7).

[Problem to be solved by the invention]

However, in the microphone device shown in FIG.
There is an inconvenience in that the movable contact (3a) of 3) must be switched each time depending on the wind noise.

In view of this point, the present invention aims to automatically and effectively remove wind noise.

[Means to solve the problem]

The microphone device of the present invention includes, for example, a microphone (1) that converts sound into an electrical signal as shown in FIG. ), a low-pass filter (9) to which the electrical signal from the microphone (1) is supplied and which passes signals below a predetermined frequency;
An automatic level control circuit (10) to which the output signal of this low-pass filter (9) is supplied and whose output signal level is controlled according to the level of this output signal, and an automatic level control circuit (10) that controls the output signal of this high-pass filter (8) and It has an adder circuit (11) that adds the output signal of the circuit (10), and the output signal is derived from the adder circuit (11).

[Effect]

According to the present invention, since the automatic level control circuit (10) automatically controls the level of the low frequency component from the low-pass filter (9) according to the level of wind noise, wind noise can be automatically removed.

〔Example〕

An embodiment of the microphone device of the present invention will be described below with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 4 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this example, an audio signal obtained by converting audio from a microphone (1) into an electrical signal is supplied to a high-pass filter (8) and a low-pass filter (9), respectively, via a preamplifier circuit (2). This high-pass filter (8) is designed to pass signals with a frequency of 1507 or more (in this example, as shown by the curve F L I in FIG. 2), and this low-pass filter (9) FL.

In this example, a low frequency signal containing the main component of wind noise below 150 Hz is passed through.

The output signal of this high-pass filter (8) is added to the adder circuit (1).
1), and the output signal of this low-pass filter (9) is supplied to one input terminal of the automatic level control circuit (10).
) to the other input terminal of the adder circuit (11). In this case, the automatic level control circuit (10) converts the output signal of the low-pass filter (9) into the variable gain amplifier circuit (10).
a), and this variable gain amplifier circuit (10a
) is supplied to the other input terminal of the adder circuit (11), and the output signal of this variable gain amplifier circuit (LOA) is supplied to the level detection circuit (10b), and the detection of this level detection circuit (10b) is performed. The variable gain amplifier circuit (10a) is configured to reduce the gain depending on the level. In other words, this automatic level control circuit (10) has no level attenuation when there is no wind noise (its output level is, for example, 3rd level).
As the level of this wind noise increases, the attenuation increases as shown by the broken line in Figure 3, for example, as shown by the solid line in Figure 3.
It is constructed as shown by the dotted chain line.

The output side of this adder circuit (11) is connected to the audio signal output terminal (
7) is derived.

Since this example is configured as described above, the level is attenuated according to the magnitude of the signal passing through the low-pass filter (9), that is, the magnitude of wind noise, so that the frequency at the output side of the adder circuit (11) - As shown in FIG. 3, the response characteristics are such that an audio signal whose low frequency components are attenuated according to the magnitude of the wind noise is obtained, and the wind noise can be automatically removed. In this case, the cutoff frequencies of the low-pass filter (9) and high-pass filter (8) are set as low as, for example, 1507, so that the effect on sound quality is extremely small.

As described above, according to this example, wind noise can be effectively removed automatically, so when recording the audio signal from the microphone (1) as in the past, a person monitors the audio and adjusts the level of wind noise accordingly. There is an advantage that there is no need to bother with changing the external changeover switch (3).

It goes without saying that the present invention is not limited to the above-described embodiments, and that various other configurations can be taken without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, there is an advantage that wind noise can be effectively removed automatically.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the microphone device of the present invention, FIGS. 2 and 3 are diagrams for explaining the present invention, and FIG. 4 is a block diagram showing an example of a conventional microphone device. be. (1) is a microphone, (2) is a preamplifier circuit, (7)
is an audio signal output terminal, (8) is a high-pass filter, (9
) is a low-pass filter, (lO) is an automatic level control circuit, and (11) is an adder circuit.

Claims (1)

[Claims] A microphone that converts sound into an electrical signal, a high-pass filter to which the electrical signal from the microphone is supplied and which passes signals of a predetermined frequency or higher, and a high-pass filter to which the electrical signal from the microphone is supplied and which has a predetermined frequency a low-pass filter that passes the following signals; an automatic level control circuit to which an output signal of the low-pass filter is supplied and whose output signal level is controlled according to the level of the output signal; an output signal of the high-pass filter and the automatic level control circuit; What is claimed is: 1. A microphone device comprising: an addition circuit for adding an output signal of a level control circuit; and an output signal is derived from the addition circuit.