JPH1021047A - Noise-suppressing sound collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress not only a noise coming in the horizontal direction but also a noise coming in the vertical direction, by composing a sound collector of plural microphones attached to the frame part of a display and respectively parallelly arranged in the vertical and horizontal directions and a noise suppressing part, to which the outputs of plural microphones are inputted, for extracting the sound in the target direction. SOLUTION: The noise-suppressing sound collector 15 is composed of a display filter 16, microphone array 17 as a sound collecting part, noise suppressing circuit 18 as a noise suppressing part, and connector part 19 for outputting to an external sound recognizing device or the like. The display filter 16 is composed of an outer frame part 16a and a glass part 16b held on that outer frame part 16a so as to close this outer frame part. Then, the microphone array 17 is arranged in the horizontal direction/vertical direction while being embedded in the outer frame part 16a of the display filter 16. Therefore, not only the noise coming in the horizontal direction but also the noise coming in the vertical direction can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for voice communication or voice recognition performed by a user toward a display of a computer or the like. In particular, the present invention relates to noise suppression for suppressing noise and appropriately collecting user's voice. The present invention relates to a sound pickup device.

[0002]

2. Description of the Related Art In recent years, with the advancement of multimedia technology, it has become possible to perform voice communication and voice recognition by connecting a microphone and a speaker to a computer. In such a case, there is a demand for a sound collection device that collects only a target sound such as a voice without collecting unnecessary sounds such as an air-conditioning sound and a keyboard tapping sound. Also, in a loudspeaker call using a speaker and a microphone, the voice of the other party (the other party) radiated from the speaker is picked up by the microphone and often becomes an obstacle. There is a need for a sound pickup device that picks up only voice.

[0003] As an example of such a sound pickup device, there is a sound pickup device in which a plurality of microphones (microphone arrays) are installed and their outputs are subjected to signal processing to extract a target sound. Signal processing methods for suppressing noise and extracting a target sound using such a microphone array include a delay-and-sum method and an A-type signal processing method.
There are many known MNORs. For example, in the delay-and-sum method, a target sound is extracted as follows.

FIG. 3A is a diagram for explaining the principle of target sound extraction by the delay-and-sum method. Sound pickup unit (microphone array)
1 is composed of microphones 2 ₁ , 2 ₂ ,..., 2 _M (M is the number of microphones) arranged in a straight line at equal intervals d, and sound waves s (t) (t represents time) It is assumed that the microphones arrive at the microphones arranged in a straight line at an angle θ.
The distance the sound wave reaching the microphone 2 ₁ propagates before reaching the microphone 2 ₂ is expressed by dsinθ from the arrival angle θ microphone spacing d. Similarly, sound waves reach the microphone 2 ₁ i-th microphone 2 _i (i = 2, ..., M) the distance that propagates before reaching the is represented by (i-1) dsin. Therefore, the sound wave arriving at the microphone 2 _1
i (i = 2,..., M) delay time τ
_i is expressed by the following equation (1) by dividing this propagation distance by the sound speed c.

Τ _i = (i−1) dsin θ / c (1) Here, when an output signal from each microphone 2 _i (i = 1,..., M) is represented by x _i (t), this is a sound wave. s (t)
Is delayed by τ _i , so that the following equation (2) is obtained. x _i (t) = s (t−τ _i ) (2) Here, the output signals x _i (t) of the microphones 2 _i are added by the adder 4 through the delay units 3 _i , respectively.
_{i (i = 1,2, ...,} M) when appropriately setting the delay amount D _i, it is possible to obtain an output signal 5 which emphasizes a sound wave only coming from θ direction to the output of the adder 4. This is shown below.

The delay amount D _i of the delay unit 3 _i (i = 1, 2,..., M) is set as in the following equation (3). D _i = D _o −τ _i (3) D _o is a fixed delay amount added to prevent a decrease in accuracy in realizing delay characteristics with a digital filter when the value of τ _i is too small.

At this time, the delay units 3 _i (i = 1, 2,...,
Output of M) is, so that the delay D _i of equation (3) to the signal of equation (2) occurs, so that the following equation (4). x _i (t−D _i ) = s (t−τ _i −D _i ) = s (t−τ _i − (D _o −τ _i )) = s (t−D _o ) (4) That is, the microphone 2 _i regardless of the number i, s
(T) is the same signal delayed by D _o.

After the phases are aligned in this manner, the signals are added by the adder 4, and the sound waves arriving from the θ direction are emphasized by the added amount. On the other hand, sound waves and theta directions coming from another theta _N direction, since it is sound receiving with different delay times tau _N and tau _i, the phase is not aligned in the delay amount of a compound of formula (3), by the adder 4 Addition of the signals does not add emphasis.

As described above, in the delay-and-sum method, the sound wave coming from the target direction θ is emphasized, and the noise coming from the other direction θ _N is relatively suppressed. That is, the delay unit 3 _i and the adder 4 constitute the noise suppression unit 6. Conventionally, it has been proposed that a microphone array used in the delay-and-sum method be arranged linearly as shown in FIG.

[0010]

This conventional microphone array suppresses noise and the like generated from a cooling fan of a device arranged around a display such as a printer when sound is collected. There was an effect. However, a sufficient noise suppression effect has not been obtained with respect to noise such as air-conditioning noise blown from the ceiling and keying noise generated from a computer keyboard. As a result of examining the reason why the sufficient noise suppression effect was not obtained, the following causes were found.

Now, as shown in FIG.
Microphone 1 parallel to x-axis among coordinate axes x, y, z
_i(I = 1, 2,..., M) are installed,
It comes from the yz plane. That is, the purpose
Microphone array 1 with both sound and noise parallel to x-axis
_iAnd the state of arrival from the yz plane perpendicular to this
It is. This means that in FIG. 3A, both the target sound and the noise
This corresponds to a situation where the light arrives from the same θ = 0 ° direction.
At this time, from equation (1), θ_sThe target sound coming from the direction
Also for θ_NNoise coming from the direction
Each microphone 2 _iArrival delay time τ_sand
τ_NAre both zero. In other words, both the target sound and the noise
Icrophone 2_iAt the same time. Thus the purpose
Delay time τ for sound and noise respectively_sAnd τ_NAre equal
Therefore, even if signals having the same phase are added by the noise suppression unit 6,
Noise is emphasized along with the typical sound, so noise can be suppressed.
Absent.

In the linear microphone array in which microphones are arranged horizontally as described above, when the target sound and noise enter from a plane perpendicular to the microphone array, noise cannot be suppressed. It became clear from.

[0013]

According to the present invention, a frame provided externally to a display is provided, and a plurality of microphones are attached to the frame in a vertical and horizontal direction, respectively. Is input to the noise suppression unit, and only the sound in the target direction is strengthened or the noise component is weakened, and the sound in the target direction is extracted.

The outer frame of the display filter is used as the frame. For example, as shown in FIG. 1A, the microphones 12 ₁ , 12 ₂ ,..., 12 are displayed on the display 11 against noise arriving from the same vertical plane as the target signal.
_M are arranged horizontally and the microphone 1
_{3 1, 13 2, ...,} 13 N are arranged (the direction along the y-axis) vertical. For simplicity of explanation, the microphone intervals of both microphone arrays are all equally spaced d, the target sound arrives along the z-axis (θ _s = 0 °), and the noise is y−
An example is given in which the light _comes from the angle θ _N in the z plane and the angle φ _N in the xz plane. The target sounds arriving along the z-axis are the horizontal microphones 12 ₁ , 12 ₂ ,.
12 _M and vertical microphones 13 ₁ , 13 ₂ ,
.., 13 _N at the same time, when the delay-and-sum method described with reference to FIG. 3A is used for the noise suppression unit 14, the delay amounts of the delay units are all set to zero, so that the target sound having the same phase is obtained. The target sound can be emphasized by adding them together. Meanwhile, the noise coming from the angle phi _N in the x-z plane (horizontal plane), the microphone 12 ₁ horizontal, 12 _2, ..., 1
When reaching the 2 _M, microphone 12 ₁ relative to the _{(i-1) dsinφ N (} i = 2, ..., M) since the arrival time difference occurs, the phase in the noise suppressor 14 of the delay-and-sum method They will be added together in a state where they do not match. Therefore, the noise is not emphasized like the target sound, and the noise is relatively suppressed. Also, the noise coming from the angle theta _N in the y-z plane (vertical plane), when it reaches the microphone _{13 1, 13 2, ...,} 13 N, as a reference microphone 13 ₁ (i-1) dsin θ _N (i =
2,..., N), the delay-sum type noise suppression unit 14 also adds the signals in a state where the phases are not aligned. Accordingly, also in this case, the noise is not emphasized like the target sound, and the noise is relatively suppressed.

As described above, by providing the microphone array not only in the horizontal direction but also in the vertical direction, not only the noise coming from the angle φ _{N in the} horizontal direction but also the noise coming from the angle θ _{N in the} vertical direction. Even this enables noise suppression. Therefore, not only the noise generated from the fan of the device arranged on the side of the display 11 but also the air conditioning noise blown from the ceiling and the noise arriving from below the front of the display 11, such as the sound of a keyboard tap. , Noise suppression is possible.

For example, a microphone array is integrated with a mounting frame of a display filter externally provided to the display to protect the eyes from light of the display. In this case, no special means for mounting the microphone array is required, the appearance is good, and the microphone array can be easily mounted on an existing display. In addition, when a keyboard of a computer or the like is touched near the display, it has been found that installing a microphone below the display filter makes it easier to pick up the tapping sound. in case of,
It is effective not to arrange a microphone below the display filter. That is, when it is desired to reduce the mixing of the tap sound, microphones are installed on the upper side, the right side, and the left side of the display filter.

[0017]

According to such a configuration, a frame in which a microphone array in the vertical and horizontal directions is embedded, for example, an outer frame of a display filter is mounted on a hand-held display, and a signal from this microphone array is transmitted to a noise suppression unit. By performing the processing, it is possible to suppress not only the noise coming from the horizontal direction but also the noise coming from the vertical direction. In addition, since the frame in which the microphone array is embedded is simply mounted on a display on hand, a complicated jig is not required, the device is not large, and the appearance is not unsightly. Another advantage is that the user can use the display on hand without replacing it. When a keyboard of a computer or the like is touched, unnecessary microphone sounds are not collected if a microphone is not provided below the display filter. That is, by installing microphones on the upper side of the frame portion and the upper half of each of the right side and the left side, unnecessary keyboard sound is prevented from being collected.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1B shows a first embodiment of the present invention. The noise suppression sound pickup device 15 of this embodiment includes a display filter 16, a microphone array 17 serving as a sound pickup unit, a noise suppression circuit 18 serving as a noise suppression unit, and a device for outputting to an external device such as a speech recognition device. And a connector section 19 to be used. Display filter 1
Reference numeral 6 includes an outer frame portion 16a and a glass portion 16b held by the outer frame portion 16a so as to cover the outer frame portion 16a. The user uses the display filter 16 by attaching it to a display on hand. For this reason, the user can use the present noise suppression sound collecting apparatus without replacing the display on hand. The microphone array 17 collects the user's voice as the target sound together with the ambient noise, and outputs the sound to the noise suppression circuit 18. The noise suppression circuit 18 may use, for example, the delay-and-sum method shown in FIG. 3A. The microphone array 17 is buried in the outer frame 16a of the display filter 16, and is arranged in the horizontal and vertical directions. Therefore, not only noise in the horizontal direction but also noise coming from the vertical direction can be suppressed. When the ambient noise comes from above like an air-conditioning noise or from below like a keyboard tapping sound, and the user's voice, which is the target sound, comes from the front of the display, the noise suppression circuit 18 uses a delay-and-sum method. At this time, the user's voice coming from the front direction of the display is set in phase and added to emphasize the target voice. At this time, the surrounding noise is not emphasized because it is not in phase, and the noise is relatively suppressed.

FIG. 2A shows a second embodiment of the present invention. This differs from the embodiment shown in FIG. 1B in that speakers 21 are attached to the left and right side surfaces of the outer frame 16a in addition to the sound pickup system, respectively.
Is connected. This speaker input connector section 22
Is connected to a speaker output of a communication device or the like, and is used for a loudspeaker call or the like. That is, the speaker that emits sound toward the user has conventionally been arranged at an appropriate place by the user. Although this type of speaker may be a noise source for the microphone 17, in the embodiment shown in FIG. 2A, since the position of the speaker 21 with respect to the microphone 17 is fixed, the noise from the speaker 21 is reduced by the noise suppression unit. The noise suppression unit 14 can be set in advance so as to be suppressed by the noise suppression unit 14, and the state is always maintained, so that noise suppression can be performed well. Therefore, the speaker 21 may be any part of the outer frame 16a, and the number is not limited to two.

FIG. 2B shows a third embodiment of the present invention. This is to avoid installing a microphone on the lower side of the display filter 16 and to minimize the sound pickup of a keystroke of a computer keyboard. That is, microphones are installed on the upper side of the outer frame 16a of the display filter and the upper half of each of the right side and the left side, so that the sound pickup of the keyboard tapping sound is reduced as much as possible.

The microphone array is not limited to the outer frame portion of the display filter, but may be a frame shape which can be externally attached to the display so that the outer periphery or the front surface surrounds the display surface. As shown in FIG. What extends in the vertical direction may be only the left side or the right side,
What extends in the horizontal direction may be only the lower side. Therefore, the outer frame portion to be attached to the display is not square, but L
It does not have to be a letter shape, that is, a closed one. The noise suppression unit 14 is not limited to the one that matches the phase of the sound in the target direction, and the noise component may be matched to subtract the noise component to suppress the noise and read the signal.

[0022]

As described above, according to the present invention, since the microphone array arranged not only horizontally but also vertically is provided, it is possible to suppress noise coming not only from the horizontal direction but also from the vertical direction. Can be. Moreover, the outer frame portion array is attached, and the outer frame portion can be easily attached by attaching the outer frame portion to the display. In particular, if the outer frame part of the display filter is used as the outer frame part, no special mounting frame is required, it can be simply attached to the display on hand, no complicated jig is required, and it does not become large, The appearance is not unpleasant, and furthermore, the noise suppression sound pickup apparatus has an unprecedented superior effect that the user can use the display on hand without having to buy a new one.

[Brief description of the drawings]

FIG. 1A is a diagram illustrating an example of installation of a sound pickup unit for enabling noise suppression according to the present invention, and FIG. 1B is a diagram illustrating a first embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

3A is a diagram for explaining the principle of noise suppression sound pickup by the conventional delay-and-sum method, FIG. 3B is a diagram for explaining a conventional microphone array, and FIG. 3C is a sound pickup unit that cannot perform noise suppression sound pickup. It is a figure explaining an example of an installation.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoichi Haneda Nippon Telegraph and Telephone Corporation 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo

Claims (4)

[Claims] 1. A noise suppression sound pickup device used for voice communication, voice recognition, and the like, in which a user is directed to a display such as a personal computer, comprising: a frame externally attached to the display; And a plurality of microphones arranged in a vertical direction and a horizontal direction, respectively, and a noise suppression unit to which outputs of the plurality of microphones are input and which extracts sound from a target direction. Noise suppression sound pickup device. 2. The microphones arranged in the horizontal direction are provided on the upper side of the frame portion, and the microphones arranged in the vertical direction are distributed and provided on each of the left side and the right side of the frame portion. The noise suppression sound collection apparatus according to claim 1, wherein: 3. The noise suppressing and sound collecting apparatus according to claim 1, wherein a speaker that emits sound toward the user is fixed to the frame portion. 4. The noise suppression and sound pickup device according to claim 1, wherein the frame portion is an outer frame portion of a display filter.