JPH0443799

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DESCRIPTION JPH0443799
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
noise control apparatus for controlling noise at a listening position when a plurality of noise
sources are present in a trial room, a general room or a room of a car. In the prior art test room
and room in general, it is practiced to equip the wall surface with a sound insulating material and
a sound absorbing material as a method of reducing the ambient noise. In addition, damping
materials and strong sound insulation materials are used in and around the noise source in order
to cut off the noise source. Recently, with the advance of digital technology, control using a
digital filter is performed. As shown in FIG. 3, as components, (21) is a noise source, (22) is a
noise detection microphone, (23) is an A / D converter, (24) is a noise control filter, and (25) is D
/ A converter; (26) is a noise control speaker; (27) is an error detector microphone. Next, related
operations of these components will be described. Now, assuming that the transfer function from
the noise source to the evaluation point which is the error place of the error detection
microphone (27) is GM, it is as follows. G (goods) = Ns (goods) + M1 (ro) · H (ro) · Sl network ... (1)
Here, Ns (goods) is the transmission from the noise source (21) to the evaluation point The
function M164 is the transfer function H (b) of the noise detection microphone (22) from the
noise source (21), the transfer function 31 (good) of the noise control filter (24) is the noise
control speaker (26) In order to set G (goods) = 0 at this evaluation point, which is a transfer
function up to the evaluation point, HH = -N s H / M 1 fv /) s I M-"-(2) The transfer function of
the noise control filter (24) should be determined. SUMMARY OF THE INVENTION However, in
the conventional configuration as described above, the constant of the number H (b) of
transmission intervals of the noise control filter (24) set to -degree is a noise detection
microphone (22) or an evaluation If the positional relationship between the error detection
microphone (27) and the noise control speaker (26) located at a point changes, it is necessary to
calculate from the beginning again, and setting in real time is difficult. SUMMARY OF THE
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INVENTION The present invention provides a noise control apparatus which controls the noise in
real time and also controls the noise from a plurality of noise sources, in consideration of the
above problems. Means for Solving the Problem In order to achieve the above object of the
present invention, a plurality of noise detectors, an adaptive filter for adaptively controlling a
detected noise signal, a power amplifier for amplifying an output signal of the adaptive filter, and
power A noise control speaker for reproducing the output from the amplifier, an error detector
for detecting an error at the listening point, an arithmetic circuit for separating the signal from
the error detector into noise signals of independent systems, and It comprises an extractor for
extracting a signal and a signal processing circuit for processing so as to minimize the signal
from the extractor.
Operation The noise control apparatus of the present invention having the above-described
configuration has the error detector installed at the listening point where the noise is to be
controlled, so that the noise signal at this listening point is detected. The noise signal finally
controls the coefficient of the adaptive filter by the signal processing circuit, and the first noise
signal reproduced by the noise control speaker via the adaptive filter and the second noise signal
transmitted directly from the noise source Because the number of transmissions of each
transmission system with the noise signal is far, the relationship that minimizes the noise is
required. That is, by changing the coefficients of the adaptive filter in real time and changing the
transfer function, it is possible to set an environment in which the noise at the listening point is
minimized. Also, although the above operation can be performed for a plurality of noise sources,
it is possible to detect a plurality of spatial noise signals together in a signal detected by one
error detector. Are separated into noise signals for each noise source by an arithmetic circuit. In
this separation, since transfer function information of each noise source is input by a signal for
controlling a plurality of adaptive filters which is an output of a signal processing circuit input to
an arithmetic circuit, one noise signal is one by one by the subtraction processing method. It
separates in order. This separated noise signal is extracted by each extractor and input to each
signal processing circuit, and an independent arithmetic processing is performed for each noise
source, and the environment where the noise at the listening point is minimum is obtained. Can
be achieved. That is, it is possible to control the noise at the position of the error detector as a
whole by setting an adaptive filter so as to control the noise from a plurality of noise sources as if
it were an independent noise at one position. Embodiments Hereinafter, one embodiment of the
present invention will be described with reference to the drawings. FIG. 1 is a block diagram
showing the construction of a noise control system according to an embodiment of the present
invention. As shown in FIG. 1, (1a) to (In) are different noise sources as components, (2a) to (2n)
are noise detectors as noise detectors, (3a) to (3n) are noise sources. 1 A / D converter, (4a) to
(4n) are adaptive filters, (5a) to (5n) are signal processing circuits, (6a) to (6n) are D / A
converters, (7a) to (7) 7n) is a noise control speaker, (8) is an error detection microphone for
error detection, (9) is a second A / D converter, 0ω is an arithmetic circuit, and (lla) (lln) is an
extractor. is there. The relationship between the components and their operation will be
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described below. The noise source (1a) is detected by the noise detection microphone (2a) and
converted to a digital signal by the A / D converter (3a).
This signal passes through the adaptive filter (4a) that is adaptively controlled, is converted to an
analog signal by the D / A converter (6a), and is emitted by the noise control speaker (7a).
Similarly, the noise source (1b) is detected by the noise detection microphone (2b) and converted
to a digital signal by the A / D converter (3b). This signal passes through the adaptive filter (4b)
that is adaptively controlled, is converted to an analog signal by the D / conversion converter
(6b), and is emitted by the noise control speaker (7b). Similarly, noise is detected by the noise
detection microphone (2n) and the noise source (In) is similarly converted into a digital signal by
the A / D converter (3n). This signal passes through an adaptively controlled adaptive filter (4n),
is converted to an analog signal by a D / A converter (6n), and is emitted by a noise control
speaker (7n). Further, noise signals converted into digital signals by the A / D converters (3a) to
(3n) enter the signal processing circuits (5a) to (5n). Now, these configurations can be expressed
as transfer functions as follows. Here, Ns I WJ, Ns 2 (1A +, ,, N5n (W) are transfer functions from
the noise sources (1a) to (1n) to the evaluation point where the error detection microphone (8) is
installed. M I H, M 2 W),..., M n W) are transfer functions HI H, H 2 W) from noise sources (1a) to
(1) to noise detection microphones (2a) to (2n) ,, Hn W), transfer functions S 1 (W), 326 Al) of the
adaptive filters (4 a) to (4 n),,, S new) are noise control speakers (7 a) to ( It is a transfer function
from 7n) to the evaluation point. Evaluation points, that is, in the error detection microphone (8),
(Jv) = G1 fvl) + G2 fvl) +, 000. +Gn6+1l−=(4)となる。 Finally, this signal is converted
to a digital signal by the second A / D converter (9). Here, G (b) is the noise generated in the
space. Therefore, subtraction is performed in the arithmetic circuit 0, G I W), G 2 f vl),..., G n M
are extracted by the extractors (10a) to (Ion). In the signal processing circuits (5a) to (5n), the
signals from the extractors (10a) to (Ion) are processed so as to be minimum, and the coefficients
of the adaptive filters (4a) to (4n) are calculated. Since the transfer functions of G I W), G 2 W),...,
G n H are also set in the circuit all), similar filter coefficients are sent.
Incidentally, in the operation of the arithmetic circuit 00), in each system of the noise sources
(1a) to (1n), the unknown transfer function in the equation (3) is the number H of transmissions
of the adaptive filter, and B) The coefficients of the adaptive filter are set to change the transfer
function H (good) so that it becomes 、, but since the transfer function of the system is
determined when the characteristics of the adaptive filter are determined, they are subtracted
from each other To extract a specific G (good). FIG. 2 shows another embodiment in which the
number of noise sources is two. The operation is the same as in the configuration operation, but
the description will be omitted. In this manner, the noise at the listening point can be controlled
in real time for a plurality of noise sources. As is apparent from the above description, the
present invention detects noise signals from a plurality of noise sources and sets up an adaptive
filter for adaptive control on each of the noise signals so as to control noise at a listening point
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by a noise control speaker. In that case, although multiple noises reach the listening point, it is
possible to separate and extract each noise and perform noise control independently to reduce
the noise as a whole. Therefore, even for a plurality of noise sources, it has a great effect of being
able to create the minimum condition environment of noise at the listening point in real time.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a block diagram showing the configuration of a noise control apparatus according to an
embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a
noise control apparatus according to another embodiment of the present invention, and FIG. It is
a block diagram showing a control device.
(1a) to (1n) ······ Noise source, (2a) to (2n) ······· Noise detection microphone (noise detector), (4a) to
(4n) ··· · · Adaptive filter, (5a) to (5n) ······ Signal processing circuit, (7a) to (7n) ······· Noise control
speaker, (8) ······ Error Microphone for detection (error detector), 0... Arithmetic circuit, (lla) to
(lln)... Name of Agent Attorney Shigetaka Ogino or one person "" ""--1 @ 龜 轡 岨 N 冑-嘴
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