892 IEEE/ACM TRANSACTIONS ON AUDIO, SPEECH, AND LANGUAGE PROCESSING, VOL. 24, NO. 5, MAY 2016
Algorithm 1.
Goal: Tracking T
1:n
t
which are contained in x
1:t
,giveny
1:t
and T
1
.
1) Initialize {x
(i)
1
}
N
i=1
. Set up all the fixed hyperparame-
ters and {w
(i)
1
}
N
i=1
=
1
N
. To initialize {x
(i)
1
}
N
i=1
,usethe
joint estimation technique based on the first period of
speech data y
1:T
1
, according to (14), see later. Then sam-
ple {s
(i)
1
}
N
i=1
based on a
1
, A
1
, B
1
,T
1
according to (2)
and (5). Set P
(i)
= T
1
.
2) for t =1:t
end
do
a) for i=1:N do
i) Set n
(i)
t
= n
(i)
(t−1)
.
ii) While t>P
(i)
:
A) Add a new pitch period, n
(i)
t
← n
(i)
t
+1.
B) Sample a new pitch period and other
coefficients:
T
(i)
n
t
∼ U(max[T
(i)
n
t−1
− σ
T
,T
low
],
min[T
(i)
n
t−1
+ σ
T
,T
upp
]),
a
n
(i)
t
(i),p
∼N(a
n
(i)
t
−1
(i),p
,σ
2
a,p
),
A
n
(i)
t
(i),k
∼N(A
n
(i)
t
−1
(i),k
,σ
2
A,k
),
B
n
(i)
t
(i),k
∼N(B
n
(i)
t
−1
(i),k
,σ
2
B,k
),
C) Update P
(i)
← P
(i)
+ T
(i)
n
t
.
iii) Sample new signal value: s
t
i
based on
a
n
(i)
t
i,p
,A
n
(i)
t
i,k
,B
n
(i)
t
i,k
,T
(i)
n
(i)
t
as (2) and (5). Now
[x
(i)
1:t
]=[x
(i)
1:t−1
,x
(i)
t
], as defined in (34).
iv) Compute importance weight w
(i)
t
of each
particle:
w
(i)
t
∝ w
(i)
t−1
p(y
t
|s
(i)
t
,σ
G
).
b) end for
c) Renormalize ˜w
(i)
t
=
w
(i)
t
N
i=1
w
(i)
t
, i = 1, 2,...,N.
d) If t = k ∗ BlockSize, where k is a positive integra,
i) Resample {x
(i)
1:t
}
N
i=1
when N
eff
<N/2. N
eff
denotes the effective sample size and is calcu-
lated as N
eff
=1/
N
i=1
˜w
(i)
t
.
ii)
ˆ
T
n
t
=
N
i=1
˜w
(i)
t
T
(i)
n
t
.
3) end for
track them [17]. For example, in the case of modeling input
sources as almost periodic signals, if 20 harmonics are assumed
to be existing in the input source (K =20) and a 11-order AR
model is used (M =11), the number of parameters involved
in the whole model is 2 ∗ K + M +1, which is 52. In order
to estimate a 52-dimensional vector using a moderate number
of particles, for example, 1000 particles, it will be necessary
to have a good initialization method at the beginning of the
algorithm to make the particle filter work.
B. Joint Source-Filter Estimation Method
It has been proposed in [8] that a joint source-filter optimiza-
tion approach can be used to estimate glottal flow using the LF
model of the glottal flow derivative when the input source is
modeled as glottal pulses. It is suggested in our paper that after
some modification on the model used in the input source, this
joint source-filter optimization approach can be also applied
here when the input source is modeled as almost periodic sig-
nals as a joint source-filter estimation technique to initialize the
parameters used in the whole model. Details of how this tech-
nique can be modified to apply when input sources are modeled
as almost periodic signals here are described in Appendix A.
Here we just display the results. If we write the parameters of
the proposed almost periodic source-filter model except for T
n
,
i.e., {a
p
,A
k
,B
k
}
p=1:M, k=0:K
(upper index n
t
omitted here,
see Appendix A), into a vector a, where
a =
a
1
,...,a
M
,A
0
,...,A
K
,B
0
,...,B
K
T
(13)
Then it is possible to jointly estimate the parameters in a using
the following equation:
a = R
−1
p (14)
where
R =
R
1
−R
2
−R
T
2
R
3
(15)
where
R
1
=
⎛
⎜
⎝
C
xx
(1, 1) ... C
xx
(M,1)
.
.
. ...
.
.
.
C
xx
(1,M) ... C
xx
(M,M)
⎞
⎟
⎠
(16)
R
2
=
R
2A
R
2B
(17)
where
R
2A
=
⎛
⎜
⎝
C
0
Ax
(0, 1) ... C
K
Ax
(0, 1)
.
.
. ...
.
.
.
C
0
Ax
(0,M) ... C
K
Ax
(0,M)
,
⎞
⎟
⎠
(18)
and
R
2B
=
⎛
⎜
⎝
C
0
Bx
(0, 1) ... C
K
Bx
(0, 1)
.
.
. ...
.
.
.
C
0
Bx
(0,M) ... C
K
Bx
(0,M)
,
⎞
⎟
⎠
(19)
R
3
=
⎛
⎜
⎜
⎜
⎜
⎜
⎜
⎝
C
0,0
CC
(0, 0) ... C
0,2K+2
CC
(0, 0)
C
1,0
CC
(0, 0) ... C
1,2K+2
CC
(0, 0)
.
.
.
.
.
. ...
.
.
.
.
.
.
C
2K,0
CC
(0, 0) ... C
2K,2K+1
CC
(0, 0)
C
2K+1,0
CC
(0, 0) ... C
2K+1,2K+1
CC
(0, 0)
,
⎞
⎟
⎟
⎟
⎟
⎟
⎟
⎠
(20)