close

Вход

Забыли?

вход по аккаунту

?

JPH0673996

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH0673996
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
music reproduction apparatus, and more particularly to a music reproduction apparatus
including an unnecessary sound cancellation apparatus for canceling an unnecessary sound at an
unnecessary unnecessary sound cancellation point of a music signal.
[0002]
2. Description of the Related Art Conventionally, as a music reproduction apparatus, a method of
creating a natural reproduction sound field using a plurality of music generation sources has
been known. FIG. 11 is a block diagram of a conventional car interior music reproduction
apparatus, 41 is a music reproduction source for reproducing music signals, 42FL, 42FR, 42RL,
42RR are music signals input from the music reproduction source and music signals are received
in the car interior Music output sources 43F and 43R are listeners who listen to music signals.
The listener 43F adjusts the volume sound quality of each of the music generation sources 42FL,
42FR, 42RL, 42RR and listens to the music signal so as to provide a natural reproduction sound
field at the ear of the listener.
[0003]
In the above-described music reproduction apparatus, the volume sound quality of each of the
08-05-2019
1
music generation sources 42FL, 42FR, 42RL, 42RR is set so that the listener 43F has a natural
sound field at his own ear. When adjusted, it is preferable for the listener 43R to have a natural
sound field, but since the music generators 42FL, 42RL, 42RR are separated from the listener
43F, the music generators 42FL, 42RL, 42RR Since the volume is set high and the listener 43R is
closer to the music sources 42RL and 42RR than the listener 43F, the listener 43R is generating
an unnecessary sound, and the listener 43R generates music. There was a problem that the music
signals from the sources 42RL and 42RR felt loud and painful. From the above, the object of the
present invention is to provide a music reproduction apparatus which does not give unnecessary
music signals to the listener 43R sitting in another seat even if it becomes a natural sound field at
the listener 43F's ear is there.
[0004]
SUMMARY OF THE INVENTION According to the present invention, according to the present
invention, there is provided a cancellation sound generation source for outputting a cancellation
sound in order to cancel an unnecessary music signal in a music reproduction apparatus, and an
unnecessary sound. A sensor for detecting a composite signal of an unnecessary sound and a
cancellation sound at a cancellation point, a synthetic signal at an unnecessary sound
cancellation point detected by the sensor, and a music signal reproduced from the music
reproduction device are input as a reference signal Adaptive signal processing is performed so as
to cancel an unnecessary sound at an unnecessary sound cancellation point using a reference
signal, and an unnecessary sound cancellation controller that inputs an unnecessary sound
cancellation signal to a cancellation sound generation source is achieved.
[0005]
The music reproduction source reproduces the music signal, and the music generation source
outputs the music signal.
Meanwhile, the music signal is input as a reference signal to the unnecessary sound cancellation
controller, and the unnecessary music signal detected by the sensor installed at the unnecessary
sound cancellation point and the unnecessary sound cancellation sound output from the
cancellation sound generation source The synthetic signal is input, and adaptive signal
processing is performed to minimize the synthetic signal, and the cancellation sound generation
source outputs an unnecessary sound cancellation sound. The unnecessary sound is canceled by
repeating this.
08-05-2019
2
[0006]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block diagram of an
embodiment of a vehicle interior music reproduction apparatus according to the present
invention. In the figure, 11 is a music reproduction source for reproducing music signals, 12FL,
12FR, 12RL and 12RR are music signal speakers for outputting music signals, and these music
reproduction sources and the music signal speakers are the same as the prior art. A music signal
is output. An unnecessary sound cancellation controller 13 having a DSP configuration that
performs adaptive signal processing for canceling unnecessary sound at the unnecessary sound
cancellation point receives a music signal generated from the music reproduction source 11 as a
reference signal, and the unnecessary sound cancellation point The synthetic signal of the
unnecessary sound and the cancellation sound in is input as an error signal by the error
microphones 14L and 14R, and adaptive signal processing is performed so as to minimize the
error signal, and the unnecessary sound cancellation signal is output.
[0007]
FIG. 2 is a block diagram of an apparatus for realizing unnecessary sound cancellation. 21 is a
music reproduction source for reproducing a music signal, 22 is a music signal speaker for
outputting a music signal, and 23 is an unnecessary sound cancellation controller , The reference
signal Xn is input, and a synthesized signal of the unnecessary sound Snn and the cancellation
sound Scn at the unnecessary sound cancellation position (observation point) in the vehicle
compartment is input as the error signal en, and the error signal is adapted to be minimized.
Signal processing is performed to output an unnecessary sound cancellation signal yan. The
unnecessary sound cancellation controller 23 is based on the adaptive signal processing unit
23a, the adaptive filter 23b of the digital filter configuration, and the transfer function of the
cancellation sound propagation system (secondary sound propagation system) from the
unnecessary sound cancellation speaker to the unnecessary sound cancellation point. And the
filter 23c to which the reference signal Xn is input. An unnecessary sound cancellation speaker
24 emits an unnecessary sound cancellation sound Scn, and an error microphone 25 disposed at
the unnecessary sound cancellation point detects a synthesized sound of the unnecessary sound
Snn and the cancellation sound Scn and outputs a synthesized signal as an error signal en It is.
The DA converter, the AD converter, etc. are omitted.
[0008]
08-05-2019
3
The adaptive signal processing unit 23a receives the error signal en at the unnecessary sound
cancellation point and the reference signal Rn for signal processing inputted via the filter 23c,
and uses these signals to generate an unnecessary sound at the unnecessary sound cancellation
point. Adaptive signal processing is performed to cancel, and the coefficients of the adaptive filter
23b are determined. For example, the adaptive signal processing unit 23a determines the
coefficient of the adaptive filter 23b so as to minimize the error signal en input from the error
microphone 25 in accordance with a known LMS (Least Mean Square) adaptive algorithm. The
adaptive filter 23b performs digital filter processing on the reference signal Xn according to the
coefficient determined by the adaptive signal processing unit 23a, and outputs the unnecessary
sound cancellation sound Scn from the unnecessary sound cancellation speaker 24. The
reference signal Xn must be a signal highly correlated with the unwanted sound Snn to be
canceled, and a signal not correlated with the reference signal is not deleted.
[0009]
When reproduction of a music signal by the music reproduction source 21 is started, the music
signal is input to the unwanted sound cancellation controller 23 as a reference signal Xn. At the
same time, the music signal is also output from the music signal speaker 22, and propagates
through a propagation system (primary sound propagation system) having a predetermined
transfer function to reach an unnecessary sound cancellation point. Therefore, the level of the
unnecessary sound Snn at the unnecessary sound cancellation point is slightly weakened and
slightly delayed as shown in FIG. 3 (b). First, the unnecessary sound cancellation controller 23
outputs, for example, an unnecessary sound cancellation signal yan whose phase is opposite to
that of the reference signal Xn, and the cancellation sound Scn shown in FIG. However, since the
phase is different from the level of the unnecessary sound Snn, the unnecessary sound is not
canceled by the cancellation sound Scn, and the error signal en is generated. The unnecessary
sound cancellation controller 23 performs adaptive signal processing so as to minimize the error
signal en to determine the coefficient of the adaptive filter 23b. In the ideal case, the cancellation
sound is finally determined as shown in FIG. 3 (d). The phase of Scn is reversed in phase with the
phase of the unwanted sound Snn, and the levels are matched to cancel out the unwanted sound.
[0010]
The above is an example in which one cancellation sound generation source (unwanted sound
cancellation speaker) and one unnecessary sound cancellation point (observation point) are
provided in order to simplify the description. However, in actuality, there are a plurality of points
(observation points) where it is desired to cancel the unwanted sound. Therefore, one
08-05-2019
4
unnecessary sound cancellation speaker can not cancel the unnecessary sound at each
observation point, and a plurality of unnecessary sound cancellation speakers also exist. FIG. 4 is
a block diagram of the unnecessary sound cancellation device when M unnecessary sound
cancellation speakers and L observation points are used. An unnecessary sound cancellation
controller 31 having a DSP (digital signal processor) configuration which operates to cancel an
unnecessary sound at each observation point, and an unnecessary sound propagates from a
music signal speaker (not shown) to each observation point Primary sound virtual propagation
system (unnecessary sound propagation system) that represents the system to be used, and 33
are secondary sound propagation that represents the system through which the cancellation
sound propagates from each cancellation speaker to each observation point, including the
characteristics of the unnecessary sound cancellation speaker System (canceled sound
propagation system), 34 is a signal synthesis unit that expresses the function of the microphone
at each observation point, the addition units 341 to 341 'correspond to the microphones at the
first observation point, and the addition units 342 to 342' The adders 34L to 34L 'correspond to
the microphones at the L-th observation point. ddln to ddLn are external noise not to be canceled
at each observation point. The DA converter, the AD converter, etc. are omitted.
[0011]
The unnecessary sound cancellation controller 31 is composed of a DSP, and is divided into an
adaptive filter 31a, a filter for generating a filtered X signal 31b, and an adaptive signal
processing unit 31c. The adaptive filter 31a performs predetermined filtering processing on the
input reference signal Xn to generate unnecessary sound cancellation signals yaln to yaMn, and
inputs the unnecessary sound cancellation signals to the respective unnecessary sound
cancellation speakers. Filtered X signal creation filter 31b convolutes each element (propagation
element) of the transfer function matrix of secondary sound propagation system 33 into
reference signal Xn to generate a reference signal (filtered X signal) r11n to rLMn for signal
processing. Output. The adaptive signal processing unit 31c receives the error signals e1 n to e L
n at each observation point and the filtered X signals r 11 n to r L Mn output from the filter 31 b,
and uses these signals to adaptively cancel unwanted sounds at each observation point. Signal
processing is performed to determine the coefficients of the adaptive filter 31a.
[0012]
FIG. 5 is an explanatory view of a virtual primary sound propagation system 32. As shown in FIG.
5 (a), the music signal generated from the music signal speaker MG has a primary sound
propagation system having a predetermined frequency / phase characteristic. It propagates 32 to
08-05-2019
5
reach the microphones (MIC1 to MICL) provided at each observation point. Therefore, assuming
that the transfer function of the propagation system in which the music signal from the music
signal speaker MG reaches the j-th microphone MICj is Hj, the primary sound virtual propagation
system 22 is expressed as shown in FIG. The transfer function matrix (H) is as follows.
[0013]
[Equation 1]
[0014]
Each element Hj of the transfer function matrix (H) is modeled by the FIR type digital filter shown
in FIG.
That is, a digital signal comprising a delay element DL which delays an input signal sequentially
by one sampling time, a multiplication unit ML which multiplies each delay element output by
coefficients h0, h1, h2..., And an addition unit AD which adds outputs of the multiplication units
Model with Filter FIG. 7 is an explanatory view of the secondary sound propagation system 33.
As shown in FIG. 7A, the unnecessary sound cancellation sound generated from each of the
cancellation speakers SP1 to SPM has two predetermined frequency / phase characteristics. The
next sound propagation system 33 is propagated to reach the microphones (MIC1 to MICL)
provided at each observation point. Therefore, assuming that the transfer characteristic of the
secondary sound propagation system in which the cancellation sound based on the i-th unwanted
sound cancellation signal yain reaches the j-th microphone MICj is Cji, the secondary sound
propagation system 33 is as shown in FIG. Modeled as shown, its transfer function matrix (C) is
[0015]
[Equation 2]
[0016]
As in the case of the primary sound virtual propagation system 32, each element of the transfer
function matrix (C) is modeled by an FIR type digital filter shown in FIG.
08-05-2019
6
That is, a digital filter comprising a delay element DL for sequentially delaying an input signal by
one sampling time, a multiplication ML for multiplying each delay element output by coefficients
C0, C1, C2, ..., and an adder AD for adding an output of the multiplier Modeled by FIG. 8 is a
block diagram of a filtered X signal creation filter 31b created using each element Cij of the
transfer function matrix (C) of the secondary sound propagation system 33. As shown in FIG. The
adaptive signal processing unit 31c performs adaptive signal processing on the basis of the
reference signal Xn and a synthesized signal (error signal) e1n to eLn of the unnecessary sound
and the cancellation sound at each observation point to update the coefficient of the adaptive
filter, The adaptive filter 31a receives the reference signal Xn, generates unnecessary sound
cancellation signals yaln to yaMn, inputs them to the unnecessary sound cancellation speaker,
and cancels the unnecessary sound at each observation point.
[0017]
The unnecessary sound cancellation signals yaln to yaMn output from the adaptive filter 31a do
not reach the observation point as they are but reach under the influence of the frequency /
phase characteristics of the secondary sound propagation system 33. Therefore, the adaptive
signal processing unit 31c does not use the reference signal Xn as it is, but uses a filtered X LMS
(MEFX LMS) algorithm that uses a signal obtained by adding the characteristics of the secondary
sound propagation system 33 to the reference signal. Advanced unwanted sound cancellation
control is performed. That is, in the filtered X LMS algorithm, the coefficient updating of the
adaptive filter 31a is performed using a signal (filtered X signal) obtained by filtering the
reference signal Xn by the filter 31b and an error signal at the observation point.
[0018]
In FIG. 8, C ij is an FIR type digital filter for realizing each element C ij (see FIG. 7) of the transfer
function matrix (C) in the secondary sound propagation system 33. The filter 31b convolutes the
characteristics of all the propagation elements into the reference signal Xn (passes the filters
corresponding to all the propagation elements) and outputs the filtered X signals r11 n to rLM n.
That is, propagation elements C11 to CL1 from the first speaker to all observation points are
applied to the reference signal Xn to output filtered X signals r11 n to rL1 n, and all observation
points from the second speaker to the reference signal Xn The propagation elements C12 to CL2
up to the point are operated to output the filtered X signals r12 n to rL2 n,..., The propagation
elements C1 M to CLM from the Mth speaker to all observation points to the reference signal Xn
The de-X signals r1Mn to rLMn are output. R1 = (r11 n r21 n... R L1 n) R2 = (r12 n r22 n... R L2
n)... RM = (r1 Mn r2 Mn... RLM n)
08-05-2019
7
[0019]
FIG. 9 is a block diagram of the multi-output adaptive filter 31a, which has the same structure as
the secondary sound propagation system 33. As shown in FIG. A1n to AMn are formed by FIR
type digital filters, and for example, delay elements DL1, DL2... Which sequentially delay an input
signal by one sampling time, and respective delay element outputs are multiplied by coefficients
a0, a1, a2. .., And adders AD1, AD2... Which add the outputs of the multipliers. The number of
delay stages is not limited to two. By inputting the reference signal Xn to the digital filter A1n,
the unnecessary sound cancellation signal yaln to be input to the first cancellation speaker is
obtained, and by inputting the reference signal Xn to the digital filter A2n, it is input to the
second cancellation speaker The unnecessary sound cancellation signal ya2 n is obtained,... And
the unnecessary sound cancellation signal yaMn input to the M-th cancellation speaker is
obtained by inputting the reference signal Xn to the digital filter AMn.
[0020]
When each of the FIR digital filters A1n to AMn in the adaptive filter 31a is constituted by three
coefficients (two stages of delay), the adaptive signal processing unit 31c is arranged for each of
the three coefficients of the FIR digital filters A1n to AMn. Adaptive signal processing is
performed to determine coefficient values. That is, the coefficients a0, a1, and a2 are determined
by performing the calculation of the coefficient updating equation shown below for the
coefficients a0, a1, and a2 of one FIR digital filter Ai.
[0021]
[Equation 3]
[0022]
In the equation (1), (n) is the value of the current sampling time, (n-1) is the value one sampling
time before, (n-2) is the value before the sampling time, (n + 1) is It means the value from the
current time to the next sampling time.
08-05-2019
8
Therefore, Ri (n−2) is a filter output according to the reference signal two sampling times
before, and Ri (n) is a filter output according to the reference signal at the current sampling time.
Also, μ is a constant (step size parameter) equal to or less than 1 that determines the step of
updating the coefficient of the adaptive filter, and is set to an appropriate value according to the
unwanted sound cancellation device. The larger the value of the step size parameter μ, the faster
the coefficient of the adaptive filter approaches the optimum value and the follow-up
performance is improved. However, the overshoot occurs and the stability decreases. Further, the
smaller the step size parameter μ, the slower the speed approaching the optimum coefficient
value and the worse the followability, but the overshoot after approaching the optimum value is
small and the stability is good. en is a synthetic signal of an unwanted sound and a cancellation
sound at L observation points, and R ij and en are respectively expressed as follows. Ri = (r1in
r2in ... rLin) Ri (n) = (C1i, C2i, C3i ..., CLi) Xn (n) Ri (n-1) = (C1i, C2i, C3i ..., CLi) Xn (n-1) Ri (n-2) =
(C1i, C2i, C3i..., CLi) Xn (N-2)
[0023]
[Equation 4]
[0024]
According to such an unnecessary sound canceling apparatus, the adaptive signal processing unit
31 combines the filtered X signals r11n to rLMn which are the output of the filter 31b with the
synthesized signal (error signal) of the unnecessary sound and the cancellation sound at each
observation point. Adaptive signal processing is performed based on e1 n to e L n to determine
the coefficients of each of the FIR digital filters A 1 n to AM n constituting the adaptive filter 31
a, and the adaptive filter 31 a receives the reference signal X n and the unnecessary sound
cancellation signal ya 1 n Each of the cancel speakers generates cancel sound and acts to cancel
unnecessary sound at each observation point.
[0025]
FIG. 10 is a block diagram of a specific unnecessary sound cancellation device in the case of the
unnecessary sound cancellation speaker number M = 2 and the number of observation points
(the number of microphones) L = 2. For example, in the two seats behind the car It is used to
cancel unwanted sound.
13a is an adaptive filter composed of two FIR digital filters A1n and A2n, and 13b is a filter
composed of the respective propagation elements C11, C21, C12 and C22 of the transfer
08-05-2019
9
function matrix (C) of the secondary sound propagation system with digital filters Filter for
creating X signal, 13c-1 and 13c-2 are adaptive signal processing units (MEFX LMS algorithm),
15L and 15R are speakers provided on each rear door, 14L and 14R are for each observation
point (the passenger's ear In the vicinity).
The operations of each adaptive signal processing unit, adaptive filter, and filter for creating
filtered X signal are executed by a DSP (digital signal processor). As mentioned above, although
the present invention was explained by the example, the present invention can be variously
modified in accordance with the gist of the present invention described in the claims, and the
present invention does not exclude these.
[0026]
As described above, according to the present invention, in the music reproduction apparatus, a
cancellation sound generation source for outputting cancellation sound and a sensor for
detecting a synthetic signal of an unnecessary sound and a cancellation sound at an unnecessary
sound cancellation point The synthetic signal at the unnecessary sound cancellation point
detected by the sensor and the music signal reproduced from the music reproducing apparatus
are input as a reference signal, and the unnecessary signal at the unnecessary sound cancellation
point is canceled using the reference signal. An unnecessary sound cancellation controller that
performs adaptive signal processing and inputs an unnecessary sound cancellation signal to the
cancellation sound generation source can cancel unnecessary music signals, and when there are
multiple listeners, one listener's Even if it becomes a natural sound field at the ear, it is possible
not to give other listeners unnecessary music signals.
08-05-2019
10
Документ
Категория
Без категории
Просмотров
0
Размер файла
20 Кб
Теги
jph0673996
1/--страниц
Пожаловаться на содержимое документа