JP2003052096A - Noise gate device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent noise gate device in which troublesome opera tion is reduced and the operation is facilitated by varying a noise removal threshold depending on the amplification factor of a head amplifier. SOLUTION: The noise gate device operates to cut off signals lower than a noise expressed in terms of an input when the amplification factor of a head amplifier 11 is large, and to cut off a voice at a preset noise removal threshold or a threshold being provided from a variation setting operation unit 15 when the amplification factor is small by varying the noise removal threshold depending on the value of a gain setting operation unit 13 of the head amplifier 11 passed through a parameter converting means 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise gate device for removing noise in voice processing.

[0002]

2. Description of the Related Art Generally, the volume of a voice signal input to a head amplifier 1 has various values from a microphone of -70 to -40 dB to a line device of -20 to +10 dB.
A small signal such as a microphone needs to be amplified to a reference signal level by a head amplifier so that it can be used in a device in the subsequent stage.

Conventionally, as shown in FIG. 2, a head amplifier 1
Is amplified according to the amplification degree determined by the gain setting operator 2, and at this time, the heat generated by the output resistance of the connected device included in the input signal of the head amplifier 1 is generated. The noise level is also amplified by the head amplifier 1 together with the audio signal.

Further, the noise gate 3 judges a signal below the threshold value determined by the threshold setting operator 4 as noise and cuts off the output to the subsequent stage, but also cuts off the signal component output as an audio signal, which is unnatural. The threshold should be set as small as possible in order not to be heard.

[0005]

However, in such a conventional noise gate device, there is a problem in that it is impossible to reduce the complexity of the operation and to simplify the operation.

Specifically, in a device that outputs a line level of -20 to +10 dB, the noise gate operates so as to cut off a signal below a set threshold value, but -70 to -40 dB.
When a device having an output level of 1 is connected to the head amplifier, the level of input conversion noise may exceed the threshold set in the noise gate.

The input conversion noise does not fall below the thermal noise uniquely determined by the output resistance value of the device connected to the head amplifier 1 and the ambient temperature. For example, when the output resistance value of the device is 150Ω and the ambient temperature is When the temperature is 20 ° C, -132dB thermal noise is generated, and the input conversion noise is at least -132dB or more. In such a case, according to the conventional technique, the noise gate 3
Since the noise removal threshold of is determined by the threshold setting operator 4, the noise removal threshold does not change even if the input signal amplification degree to the noise gate 3 changes due to the operation of the gain setting operator 2, and the threshold setting operator does not change. It is necessary to reset the noise removal threshold according to 4.

When the noise removal threshold value is set to -90 dB and the line amplifier having an output level of +4 dB is connected to the head amplifier 1 and is reconnected to the microphone having an output level of -50 dB, the reference level is set. It is necessary to increase the amplification of the head amplifier by 54 dB to make it uniform.

At this time, thermal noise generated by the output resistance of the microphone is also amplified by 54 dB. When the output resistance value of the microphone is 150Ω, the thermal noise generated by the resistance component has a value of −132 dB, and is amplified to −78 dB by the head amplifier. Since the noise gate has a noise removal threshold value of -90 dB, thermal noise cannot be removed.

In order to remove this thermal noise, it is necessary to re-operate the threshold setting operator 4 so that the noise removal threshold becomes -78 dB or more. These operations occur every time the amplification degree of the head amplifier is changed, and become extremely complicated operations.

The present invention is to solve the above-mentioned conventional problems, and the noise removal threshold value is changed according to the amplification degree of the head amplifier to reduce the complexity during operation.
An object of the present invention is to provide an excellent noise gate device that can realize simplification of operation.

[0012]

A noise gate device according to the present invention is defined by a head amplifier for amplifying an audio signal, a gain setting operator for determining the amplification degree of the head amplifier, and the gain setting operator. A parameter conversion unit that converts a set value into a threshold value and a noise gate that removes a signal component having an amplitude equal to or less than the threshold value are provided, and the noise gate It is configured to change the threshold.

With such a configuration, when the head amplifier has a large amplification degree, it operates so as to cut off a signal equal to or less than the input conversion noise, and when the amplification degree is small, a noise gate that cuts off sound with a preset noise removal threshold value. It can be operated as a device, complexity of operation can be reduced, and operation can be simplified.

Further, in the noise gate device of the present invention, the parameter converting means includes a change amount setting operator.

With such a structure, when the amplification of the head amplifier is large, it operates so as to cut off a signal below the input conversion noise, and when the amplification is small, it cuts off the sound at the threshold value given by the change amount setting operator. It can be operated as a noise gate device, and the complexity of the operation can be reduced and the operation can be simplified.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a noise gate device according to the present invention.

First, the structure will be described. In FIG. 1, the noise gate device includes a head amplifier 11, a noise gate 12,
It is composed of a gain setting operator 13, a parameter converting means 14, and a variation setting operator 15.

The head amplifier 11 is for amplifying a voice signal, and the gain setting operator 13 is for determining the amplification degree of the head amplifier 11. The parameter conversion means 14 converts the set value determined by the gain setting operator 13 into a threshold value, and the noise gate 12 removes a signal component having an amplitude equal to or less than the threshold value.

The change amount setting operator 15 sets the change amount of the threshold value of the parameter converting means 14.

Next, the operation will be described.

+4 dB as a device connected to the head amplifier 11
When the line device having the output level of is reconnected to the microphone having the output level of −50 dB, the gain of the head amplifier 11 needs to be increased by 54 dB by the gain setting operator 13.

At this time, the thermal noise generated by the output resistance of the microphone is also amplified by 54 dB. When the output resistance value of the microphone is 150Ω, the thermal noise generated from the resistance component has a value of −132 dB, and is amplified to −78 dB by the head amplifier 11. On the other hand, the gain setting operator 13
Is connected to the noise gate 12 via the parameter conversion means 14, and the parameter conversion means 14 comprises the conversion table shown in Expression 1.

[Equation 1] However, TRIN: Trim set value by the gain setting operator 13 TROUT: Noise removal threshold value of the noise gate 12 output from the parameter converting means GTH: Preset value LUN: Reference signal level EIN: Input conversion noise

By providing the parameter conversion means 14 with the parameter conversion table given by the equation 1, a noise removal threshold value corresponding to the set value of the gain setting operator 13 is set in the noise gate 12. As a result, when a line device with a high output level is connected to the head amplifier 11, the noise gate 12 cuts off signals with a level below the preset GTH and outputs a very small signal to the head amplifier 11. Gain control to connect to
When the amplification degree is increased by 13, the operation is performed so as to cut off a signal equal to or less than the input conversion noise, and the complexity during the operation can be reduced.

Further, by setting the value of the change amount setting operator 15 connected to the parameter converting means 14 as GTH, the change amount setting operator 15 is operated and is always independent of the amplification degree of the head amplifier 11. A threshold for removing the input conversion noise can be set, and the operation can be simplified.

The noise gate device of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0027]

According to the present invention, when the amplification degree of the head amplifier is large, it operates so as to cut off a signal equal to or less than the input conversion noise, and when the amplification degree is small, the sound is cut off by a preset noise removal threshold value. It is possible to provide a noise gate device which can be operated as a noise gate device, which can reduce complexity during operation and simplify operation.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a noise gate device according to the present invention.

FIG. 2 is a block diagram of a conventional noise gate device.

[Explanation of symbols]

11 head amplifier 12 noise gate 13 Gain setting control 14 Parameter conversion means 15 Conversion amount setting operator

Claims (2)

[Claims] 1. A head amplifier that amplifies an audio signal, a gain setting operator that determines an amplification degree of the head amplifier, and a parameter conversion unit that converts a set value determined by the gain setting operator into a threshold value. A noise gate for removing a signal component having an amplitude equal to or less than the threshold value, and the threshold value of the noise gate is changed according to a change in the amplification degree of the head amplifier by the gain setting operator. Noise gate device. 2. The noise gate device according to claim 1, wherein the parameter conversion means includes a change amount setting operator.