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B GIO DC V O TO Trng i hc Yersin Lt
Khoa Cng Ngh Thng Tin ------- -------
X L V NHN DNG
TING NI
LUN VN C NHN TIN HC
GIO VIN HNG DN:
TS Nguyn c Minh
Nin kha 2010 - 2014
1
NHN XT CA GIO VIN HNG DN
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Lt, ngythng.nm 2014
GIO VIN HNG DN
2
NHN XT CA GIO VIN PHN BIN
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3
LI CM N
Xin chn thnh cm n thy Nguyn c Minh tn tnh
hng dn em em c th hon thnh lun vn ny. Cc bui hc
cng thy trn khoa cng nhng ti liu m thy cung cp cho
em tht l qu gi, khng nhng thy dy kin thc chuyn
ngnh m cn truyn t nhng k nng v phng php hc ting
anh gip em ci thin hn vn ting anh hin c.
Em xin gi li cm n n cc thy c trong trng, c bit
l cc thy c trong khoa Cng Ngh Thng Tin to iu kin tt
nht em c th hc tp v nghin cu.
Em cng khng th khng nhc n s ng vin chm sc
ca gia nh, s cng tc gip v ng h tinh thn ca bn b.
Em xin c tri n tt c.
lt, thng 06 nm 2014
Trn Mnh Hi
4
MC LC
NHN XT CA GIO VIN HNG DN .............................................................. 1
NHN XT CA GIO VIN PHN BIN ................................................................ 2
LI CM N ............................................................................................................... 3
LI NI U .............................................................................................................. 5
DANH SCH HNH V ............................................................................................... 6
Chng I TNG QUAN V NHN DNG GING NI ........................................... 7
I. Nhn dng .................................................................................................................. 7
II. Cc tnh cht c trng ca nhn dng ting ni ...................................................... 11 1. Ting ni con ngi ...................................................................................................................... 11 2. Phn loi nhn dng ting ni ....................................................................................................... 11 3. Nhng kh khn ............................................................................................................................ 12
III. ng dng .................................................................................................................. 12
Chng II X L V RT TRCH C TRNG TING NI ............................... 13
I. Qu trnh x l v ly mu ....................................................................................... 13 1. M hnh tng quan ........................................................................................................................ 13
II. Rt trch c trng ................................................................................................... 14 1. Phn khung tn hiu....................................................................................................................... 15 2. Ly ca s ..................................................................................................................................... 16 3. Bin i tn hiu sang min tn s (Bin i Fourier ri rc - DFT) ............................................ 20 4. c trng MFCC (Mel Frenquency Cepstral Coefficients) .......................................................... 21 5. c trng M ha d on tuyn tnh (LPC)................................................................................ 25
III. Nhn xt ................................................................................................................... 30
Chng III NHN DNG BNG M HNH MNG NEURAL ............................... 31
I. Tng quan ................................................................................................................ 31
II. Qu trnh hot ng ................................................................................................. 32 1) T bo ca mng ........................................................................................................................... 32 2) Mng Neural truyn thng nhiu lp ............................................................................................ 34
a) M hnh c bn: ...................................................................................................................... 34 b) Lut hc ca mng: ................................................................................................................ 34
III. Qu trnh hun luyn ................................................................................................ 36 1) Thut ton lan truyn ngc ..................................................................................................... 36
a) Khi nim v tng ............................................................................................................. 36 b) M hnh minh ha ................................................................................................................... 36 c) Tnh ton cc gi tr v tham s ............................................................................................ 38 d) Cc bc xy dng thut ton ............................................................................................... 42
2) M phng trn Matlab v ng dng vo nhn dng ting ni ................................................ 44
IV. Kt lun .................................................................................................................... 50
KT LUN ................................................................................................................. 51
TI LIU THAM KHO: .......................................................................................... 53
5
LI NI U Ngy nay vi s pht trin mnh m ca cng ngh, con ngi t ng ha
kh nhiu cng vic m ngy trc phi tn sc ngi l chnh. Cc h thng
thng minh ra i nng cao nng sut cng nh cht lng ca cng vic. Tuy
nhin iu khin my mc, con ngi phi lm kh nhiu thao tc tn nhiu
thi gian v cn phi c o to. iu ny gy tr ngi khng t i vi vic s
dng cc my mc, thnh tu khoa hc k thut. Trong khi , nu iu khin my
mc thit b bng ting ni s d dng hn. Nhu cu iu khin my mc thit b
bng ting ni cng bc thit hn i vi cc thit b cm tay, nh: in thoi di
ng, my Palm/Pocket PC,
Con ngi d dng hiu nhau nh ngn ng, nhng iu l kh khn
i vi my mc. Nhng khng phi l khng lm c, trn th gii hnh
thnh cc h thng nhn dng ting ni t n gin ti cc h thng cc k phc
tp, chng t rng my mc sau qu trnh hun luyn ca con ngi th chng cng
c kh nng hiu chng ta qua ting ni.
Lun vn ny em tp trung vo nghin cu hai phn ln trong nhn dng ting
ni l rt trch c trng v phng php Neural cho nhn dng v hun luyn.
Lun vn gm cc phn chnh nh sau:
CHNG I: Cung cp ci nhn tng quan v tn hiu ting ni v nhn
dng ting ni.
CHNG II: X l v rt trch c trng. Gii thiu cc b lc c bn
cho x l tn hiu, m hnh v cc phng php rt trch c trng
CHNG III: Phng php nhn dng Mng Neural. Gii thiu v
mng Neural, phng php hun luyn trn mng.
6
DANH SCH HNH V
Hnh 1. 1 Cu trc ca tai ngi _________________________________________________ 7 Hnh 1. 2 M hnh nhn dng ting ni ____________________________________________ 8 Hnh 1. 3 M hnh m phng phng php HMM ___________________________________ 10
Hnh 2. 1 S cc khi ca m hnh ly mu _____________________________________ 13 Hnh 2. 2 Trnh t rt trch c trng ____________________________________________ 14 Hnh 2. 3 Khung tn hiu vi N = 256 ____________________________________________ 15 Hnh 2. 4 Phn on ting ni thnh cc khung chng lp ____________________________ 16 Hnh 2. 5 Ca s Hamming theo min thi gian v tn s _____________________________ 17 Hnh 2. 6 Ca s Hann theo min thi gian v tn s. _______________________________ 18 Hnh 2. 7 Ca s Tam gic theo min thi gian v tn s _____________________________ 19 Hnh 2. 8 Minh ha ca s hnh ch nht _________________________________________ 19 Hnh 2. 9 m a theo ca s Hann _____________________________________________ 20 Hnh 2. 10 m a vi ca s Hamming _________________________________________ 20 Hnh 2. 11 Minh ha bin i Fourier ____________________________________________ 21 Hnh 2. 12 a) Mel v tn s_____________________________________________________ 22 Hnh 2. 13 Minh ha b lc tam gic _____________________________________________ 24 Hnh 2. 14 B lc tam gic thc t trn min tn s _________________________________ 25 Hnh 2. 15 S x l LPC dng cho trch c trng ting ni ________________________ 27
Hnh 3. 1 M hnh chi tit 1 t bo neural _________________________________________ 32 Hnh 3. 2 M hnh mng nhiu lp _______________________________________________ 34 Hnh 3. 3 M hnh tng qut 3 lp _______________________________________________ 37 Hnh 3. 4 M hnh chi tit c bn _______________________________________________ 37 Hnh 3. 5 Hnh minh ha th _________________________________________________ 44 Hnh 3. 6 Hnh minh ha qu trnh hun luyn _____________________________________ 46 Hnh 3. 7 th dng tam gic (xi) ______________________________________________ 46 Hnh 3. 8 Mng Neural s dng _________________________________________________ 47
7
Chng I TNG QUAN V NHN DNG GING NI
I. Nhn dng
Nh chng ta bit nhn bit c ting ni l mt kh nng tuyt vi m
to ha ban cho chng ta, nh i mt gip con ngi nhn thy c s chuyn
ng bin i ca th gii th i tai gip con ngi nghe c nhng m thanh
m mi trng xung quanh mun truyn t ti chng ta. Qu trnh nhn thc
c mt m than h, ting ni trong c th chng ta l mt qu trinh v cng
phc tp v tinh vi.
Sng m thanh c truyn vo trong tai ngi v to nn cc rung ng c
hc trn cc b phn trong tai. Trong cng ca tai l c tai, y l ni tn hiu
c phn tch thnh nhng khung tn s nht nh.
Hnh 1. 1 Cu trc ca tai ngi
8
Qu trnh x l v nhn dng trong b no con ngi l mt qu trnh
rt phc tp v chnh xc v cng cao. Cc m hnh nhn dng ting ni
v mt l thuyt u da trn s m phng ging nh tai ngi, v cu trc
ln hot cch thc hot ng.
Di y l m hnh nhn dng ting ni tng qut:
Xy dng c s d liu ting
ni
X l v rt trch c trng
Nhn dng so khp mu
Kt qu
Tn hiu hc Tn hiu cn nhn dng
Hun luyn
Tn hiu ting ni
Hnh 1. 2 M hnh nhn dng ting ni
9
Tn hiu ting ni c thu li thng qua cc thit b ghi m nh:
microphone v n c chuyn sang tn hiu in.
X l v rt trch c trng: l qu trnh tinh chnh tn hiu u vo, to
ra tn hiu mu tt nht. Sau s dng cc phng php rt trch
cc c trng c bn ca tn hiu .
Xy dng c s d liu ting ni: Tn hiu ting ni sau khi c x l
v rt trch c trng c lu li thng qua qu trnh hun luyn hay
hc bng cc m hnh nhn dng.
Nhn dng so snh khp mu: Tn hiu ting ni sau khi c x l v
rt trch c trng c th l tn hiu cn nhn dng. N c em so
snh vi mu bng cc phng php nhn dng ting ni. Nu nh tn
hiu so khp nht ng vi mt lp tn hiu no th h thng nhn
dng xc nh tn hiu thuc vo nhm tn hiu no vi mt t l
nht nh.
Kt qu: tn hiu u ra s phc v cho cc ng dng, ty ng dng m
kt qu u ra s khc nhau.
Cc m hnh nhn dng ting ni ph bin:
M hnh Markov - n (Hidden Markov Model HMM)
M hnh Markov n (Hidden Markov Model - HMM) l m hnh
thng k trong h thng c m hnh ha c cho l mt qu trnh Markov
vi cc tham s khng bit trc v nhim v l xc nh cc tham s n t cc
tham s quan st c, da trn s tha nhn ny. Cc tham s ca m hnh
c rt ra sau c th s dng thc hin cc phn tch k tip.
10
Trong mt m hnh Markov in hnh, trng thi c quan st trc
tip bi ngi quan st, v v vy cc xc sut chuyn tip trng thi l cc
tham s duy nht. M hnh Markov n thm vo cc u ra: mi trng thi c
xc sut phn b trn cc biu hin u ra c th. V vy, nhn vo dy ca cc
biu hin c sinh ra bi HMM khng trc tip ch ra dy cc trng thi.
M hnh mng Neural
(s c trnh by k chng III)
Hnh 1. 3 M hnh m phng phng php HMM
11
II. Cc tnh cht c trng ca nhn dng ting ni
1. Ting ni con ngi
Ting ni con ngi s dng hng ngy mang bn cht ca sng m
thanh, n lan truyn trong khng kh nh s gin n ca khng kh. Tn hiu
m thanh ting ni l tn hiu bin thin lin tc v mt thi gian. Di tn m
tai ngi c th nghe c l 20Hz n 20kHz.
Ting ni c to thnh t cc chui m v lin tip, s sp xp
nhng m v ny c chi phi bi cc quy lut ngn ng cho nn cc m
hnh ton hc khi c p dng th phi gn b mt thit vi cc quy lut
ngn ng.
Ba c trng:
m vc hay cao (Pitch) l cm nhn s rung ng ca
tn s ca m thanh trong mt khong thi gian. m no cng c mt cao
nht nh, trm bng ph thuc vo tn s giao ng v i vi ting ni
th tn s dao ng ca dy thanh quy nh quyt nh cao ca ging ni
con ngi. V mi ngi c mt cao ging ni khc nhau.
m nhn l cm nhn cng rung ng ca m thanh qua
mt khong thi gian v cao . Cng chnh l to nh ca m thanh,
cng cng ln th m cng truyn c xa hn, nu xt v mt sng m
th cng chnh l bin giao ng, n quyt nh nng lng ca sng
m.
m sc l mt thut ng trong m nhc, n th hin s hi ha
cc c tnh ng ca m thanh nh l iu bin, tng ln hay rt xung ca
tn hiu. Cng mt cao nhng mi ngi li c mt m sc khc nhau
2. Phn loi nhn dng ting ni
Nhn dng theo cc t hay cc m ri rc.
Nhn dng ting ni c lp hay ph thuc vo ngi ni.
Nhn dng vi t in c va, nh hay c ln.
Nhn dng vi mi trng nhiu cao hay thp.
12
3. Nhng kh khn
Tc ni ca ngi khc nhau, c ngi ni nhanh c ngi ni chm.
di ngn ca m khc nhau.
Kt qu phn tch hai ln i vi mt ngi ni khc nhau.
Cht ging theo vng min th cht ging khc nhau hoc l ging nam hay
ging n.
Cc yu t ca mi trng lm nhiu tn hiu, i khi b nhiu t chnh thit
b thu.
III. ng dng
iu khin giao tip khng dy: chng hn h thng my tnh nhn lnh iu
khin bng ting ni ca con ngi nh: chy chng trnh, tt my. Cc
h thng thng minh nhn lnh trc tip ca con ngi thng qua ting ni.
c chnh t: c s dng nhiu nht trong cc h nhn dng. Nhp liu
bng ting ni thay v bng cch th cng l ngi nh my.
in thoi lin lc: mt s h thng cho php ngi s dng c tn ngi
trong danh b thay v bm s. Truy cp cc ng dng, vit tin nhn bng ting
ni
13
Chng II X L V RT TRCH C TRNG TING NI
I. Qu trnh x l v ly mu
1. M hnh tng quan
Trong x l tn hiu, ly mu l chuyn i mt tn hiu lin tc thnh mt
tn hiu ri rc. Mc d c s t do trong vic la chn th t cc mu tnh hiu
c to ra t nhng tn hiu tng t. Nhng y ti xin a ra m hnh x l
v ly mu ti u nht, cc khi trong m hnh c th thay i v tr cho nhau, ty
vo tng trng hp.
Khi lc thp v chng bit danh: theo nh l ly mu Nyquist-
Shannon th tn s ly mu (fc) s l cao gp i rng ca di tn, hay tn s
ln nht. V vy, ta chn tn s ly mu s l 40 44kHz (gp i tn s nghe
ca tai ngi 20kHz). Nh vy c th chng Bit danh. Khi lc thp s lc
cc tn hiu c tn s cao to mn cho tn hiu u ra.
Khi lc cao: khi ny ct b cc tn hiu c tn s thp, to bin
thin nh nht.
Tin nhn: Tng cng tn hiu, lm r cc c trng ca tn hiu.
Lng t ha: vic biu din s tn hiu i hi lng t ha mi mu tn hiu
vi mt gi tr ri rc hu hn. Mi mu tn hiu c lng t ha, m ha ri
truyn i. Bn thu nhn tn hiu s gii m v thu c tn hiu tng t.
Hnh 2. 1 S cc khi ca m hnh ly mu
14
II. Rt trch c trng
cho vic nhn dng ting ni d dng hn v gim chi ph th vic rt
trch c trng tn hiu l mt phn v cng quan trng. Tn hiu th ban u c
dung lng rt ln, v phc tp cao. Vic rt trch cc c trng t tn hiu
s gip cho khu so snh khp mu d dng hn, v to ra chnh xc cao
hn.
Cc bc rt trch c trng:
X l v lm r tn hiu
Phn khung tn hiu
Ly ca s
Phn tch c trng
Tn
hiu
Hnh 2. 2 Trnh t rt trch c trng
15
1. Phn khung tn hiu
Tn hiu sau qu trnh ly mu c phn khung, chng hn mt lung
ca tn hiu m thanh c chuyn thnh tp cc khung tn hiu. Trong bc
ny tn hiu c chia thnh cc khung mi khung ng vi N mu, khong
cch gia cc khung l M mu.. di thi gian cho mi khung khong
20~30ms. Nu thi gian khung qu ln, chng ta khng th nm bt cc c
im khc nhau theo thi gian ca tn hiu. Ngc li, nu thi gian khung qu
nh, th chng ta khng th rt trch cc c trng hp l hoc c gi tr. Ni
chung, mt khung tn hiu cn cha vi chu k c bn ca tn hiu m thanh
nht nh, thng kch thc ca khung bng vi m c s 2 (chng hn 256,
512, 1024..) nh vy c kh nng bin i Fourier nhanh.
Nu chng ta mun gim bt s khc bit gia cc khung ln cn, chng
ta c th s dng cc khung chng lp nhau, thng thc hin chng lp 1/3
Hnh 2. 3 Khung tn hiu vi N = 256
16
hoc 2/3 ca khung tn hiu gc. Khung chng lp nhiu, yu cu tnh ton cng
nhiu hn. Nh hnh 1.2 minh ha chng lp 1/3. Khung th nht c N mu,
khung th hai bt u t mu th M v kt thc v tr M+N. Khi M N th s
khng c s chng lp gia cc khung k nhau, dn n mt s mu ting ni b
mt (tc l khng xut hin trong bt k khung no).
Hnh 2. 4 Phn on ting ni thnh cc khung chng lp
Gi s cc tn hiu m thanh trong mt khung l khng thay i, chng ta
c th trch cc c trng chng hn nh t l im qua zero, m lng, cao ,
MFCC, LPC,
Chng ta c th thc hin pht hin im u v cui ca tn hiu da t
l im qua zero v m lng, v gi li cc khung tn hiu c ting ni phn
tch v sau.
2. Ly ca s
Bc tip theo trong x l l ly ca s tn hiu ng vi mi khung gim
thiu s gin on tn hiu u v cui mi khung. Gi mu th n ca khung
th l l lhn , w(n) l hm ca s:
ln = lhn . w(n) n {0,1,, N-1}
Cc dng ca s tn hiu:
17
Trong x l tn hiu s, cc ca s thng dng c biu din thng qua
ca s Hamming:
= 0.54 0.46 cos 2
1
Hnh 2. 5 Ca s Hamming theo min thi gian v tn s
Vi ca s Hamming ph tn s ri xung mt cch nhanh chng, v th n
cho php c lp tn hiu tt nht. Tuy nhin, cc sng m c cao ln b gi li
hon ton mt cch bng phng v n che ph phn ln ph tn s. Mc d vy,
n vn ph bin nht nh vo tnh k tha.
Ca s Hann (Hanning): y l mt loi khc ca ca s Hamming. S khc
bit gia chng l ca s Hann t 0 cho n=0 v n= N-1. Gi tr Zero khc
ui c th c hoc khng mong mun ph thuc vo trng hp chng ta x l
tn hiu v gii thch cho iu ny l khi dn tin v Zero, mt d liu khng
c s dng. Tuy nhin trong nhn dng ging ni, n khng c vn g ht
bi v chng thng c va khung chng ln nhau trong vic tnh ton c
trng .
18
= 0.5 1 cos 2
1
Vi ca s Hamming th cc tn s thp ri xung mt cch nhanh chng v
sau gn nh tr thnh phng vi cc tn s cao. Mt khc, ca s Hann ri
chm hn mt cht vi tn s cao nhng nhanh chng vi tn s thp. V vy,
vi mi loi u c u im hoc hn ch ring ca chng.
Ca s Tam gic: nh tn gi th n ch l mt tam gic vi nh nm
trung tm ca ca s (n =
2). Ca s ny quan trng v thng c s dng
trong phng php MFCC. Biu thc ca ca s tam gic:
= 1 2 + 1
1
Hnh 2. 6 Ca s Hann theo min thi gian v tn s.
19
Nh ph tn s hnh 1.5 th n ri xung kh t ngt. Cc sng c tn s
cao c rng nhiu hn so vi hai ca s trn.
Ca s hnh ch nht:
= 1, 0 0,
Hnh 2. 7 Ca s Tam gic theo min thi gian v tn s
Hnh 2. 8 Minh ha ca s hnh ch nht
20
Mt s v d minh ha:
3. Bin i tn hiu sang min tn s (Bin i Fourier ri rc - DFT)
Bc tip theo trong vic x l tn hiu ting ni c th tnh ton c
cc c trng quang ph l bin i Fourier ri rc trn cc ca s tn hiu.
=
2
1
=0
= ()
2
1
=0
Hnh 2. 9 m a theo ca s Hann
Hnh 2. 10 m a vi ca s Hamming
21
Khi k = {0,1,,N-1} l ch s ca min tn s vi k = 0 tng ng vi thnh phn DC v k = N/2 ng vi tn s gp.
Php bin i nhanh fourier ri rc (FFT)
Php bin i nhanh ny u da trn k thut phn chia theo c s 2,
ngha l thay v bin i trn ton b tn hiu th php bin i ny s phn chia
chui tn hiu thnh 2 chui tn hiu con, v li p dng php bin i ln na
cho 2 phn ny mt cch quy. Do php chia cho 2, nn chui tn hiu i hi
phi c chiu di l ly tha ca 2 (iu ny c th d dng gii quyt c
bng cch tng kch thc chui tn hiu ln v in 0 vo).
4. c trng MFCC (Mel Frenquency Cepstral Coefficients)
nh ngha Mel (Melody): Mel l t vit tt ca m iu (melody), n l
mt n v ca m vc.N c xc nh l bng vi 1000 Pitch trong mt tn
s m vc 1000 Hz vi bin l 40dB nm trn ngng nghe.
Hnh 2. 11 Minh ha bin i Fourier
22
c trng trch ra nh da trn kh nng cm nhn m ca thnh gic con
ngi, v thang o trong h thng nhn dng ca con ngi khng phi l thang
tuyn tnh. ng vi MFCC th ta dng thang Mel.
Qu trnh trch c trng bng MFCC:
a)
b)
DFT
Lc vi thang Mel v Log()
Bin i Cosin
Tn
hiu
Ma trn tn hiu
Hnh 2. 12 a) Mel v tn s
b) Mel v tn s c chia trn thang Log
23
Ta c cng thc nh ngha cho MFCC:
= 2 1
2
1
=0
Trong lCm l bin i cosin ri rc (DCT) :
= 2
Thang Mel: =
= {0,1, , 1
Ma trn l ma trn th (m,k) ca ma trn , {: }
H s am:
= 1
, = 0
2
, > 0
24
Lc tn hiu theo thang Mel
Hnh 2. 13 Minh ha b lc tam gic
Dy b lc Mel-scale bao gm mt dy cc b lc tam gic chng ln
nhau vi tn s v rng dy tnh theo t l tn s Mel. T l tn s Mel, ging
nh t l Bark s dng cho phng php PLP, c da trn nhng kt qu nghin
cu tm l t con ngi. Mi khong ngh trong t l Mel ng vi mt cao
tng i ca mt tone m con ngi cm nhn.
25
Hnh 2. 14 B lc tam gic thc t trn min tn s
Sau chng ta ly Logaric v bin i Cosin (DCT) chng ta s c c
cc ma trn c trng.
5. c trng M ha d on tuyn tnh (LPC)
LPC l mt trong nhng phng php c s dng nhiu nht trong lnh vc
x l ting ni. Bi l n cung cp cng c d tm mt cch ng n v tc
tnh ton nhanh. Ngun gc c bn ca phng php ny l cc mu tn hiu ting
ni c xp x ha nh l t hp tuyn tnh ca mt s mu trong qu kh.
Nguyn l c bn ca LPC lin h mt thit vi m hnh tng hp ting ni, trong
ch ra rng tn hiu ting ni c th c coi nh l kt qu u ra ca h tuyn
26
tnh bin i theo thi gian v c kch thch bi cc xung tun hon hay l cc
nhiu ngu nhin.
tng c bn ca phng php LPC l ti thi im n, mu ting ni s(n)
c th c xp x bi mt t hp tuyn tnh ca p mu trc .
= (1)
=1
V sai s d on l :
= = + (2
=1
)
Bi ton c bn ca phn tch tin on tuyn tnh l xc nh tp hp cc
h s tin on ai trc tip t tin hiu ting ni. Bi v bn cht thay i theo thi
gian ca tn hiu ting ni nn cc h s tin on phi c tnh trong cc on
ngn tn hin. Cch tip cn c bn l tm mt tp cc h s tin on m sai s
tin on l nh nht i vi mt on ngn tn hiu.
Vi cch tip cn trn s hng n mt vi kt qu hu ch m c th khng
c quan st thy ngay lp tc, nhng c th iu chnh bng nhiu cch. i vi
xung tun hon, n c ngha rng e(n) s bao gm mt chui cc xung ; V d, e(n)
s tr nn nh trong phn ln thi gian. Do , vic tm cc m ti thiu ho sai
s tin on ph hp vi nhn xt ny. Th hai, da vo thc t l nu tn hiu
c sinh ra bi cng thc (l) vi khng c s bin i v thi gian ca cc h s
v c kch thch bng cch mt xung n l hay mt chui nhiu trng khng
thay i, th n c th thy rng cc h s d on c kt qu t vic ti thiu ho
bnh phng sai s tin on ging vi h s ca cng thc (l). Cui cng, s iu
chnh hp l cho vic ti thiu ho sai s hnh phng trung hnh, sai s tin on
nh l c s cho vic xc nh cc tham s ca m hnh l cch tip cn hng n
tp ca cc cng thc tuyn tnh.
27
Da vo phng php d on tuyn tnh ngi ta p dng n vi nhiu
phng thc khc nhau ty vo m hnh sng tn hiu ting ni. Mt s phng
php :
Phng php hip phng sai
Phng php t tng quan
Phng php ro
Phng php b lc o
Phng php d ph
Phng php kh nng cc i
Phng php dn xut ni b
Trong thc t th phng php t tng quan l thng c s dng nht.
Hnh xx trnh by qu trnh x l LPC rt trch c trng ting ni. Cc
bc tin hnh c bn sau:
Phn tch tng quan: Mi khung sau khi c ly ca s s c a qua
bc phn tch t tng quan v cho ra (p + 1) h s t tng quan
Ma trn vector c trng
Phn tch tng quan
Phn tch LPC
Phn tch Cepstral
Tn
hiu
p
Hnh 2. 15 S x l LPC dng cho trch c trng ting ni
28
=
1
=0
+ 1
0
Phn tch LPC: Bc ny, ta s chuyn mi khung gm (p + 1) h s t tng
quan thnh p h s LPC bng cch dng thut ton Levinson Durbin.
nh ngha E:
(0) = (0)
for (q = 1 to Q),
1.
=
1( )
1=1
(1)
2.
()
=
3. for (j = 1 to Q)
()
= (1)
(1)
endfor
() = 1 2
(1)
endfor
Lc ny, ta c th dng cc h s LPC lm vector c trng cho tng
khung. Tuy nhin, c mt php bin i to ra dng h s khc c tp trung cao
hn t cc h s LPC, l php phn tch Cepstral.
29
Phn tch Cepstral: T p h s LPC mi khung, ta dn xut ra q h s
cepstral c(m) theo cng thc quy sau:
0 = 2
= +
1
=1
1
=
1
=1
Trong 2 c gi l li ca m hnh, ta thng chn
3
2
t trng s cho cc h s Cepstral: Do nhy ca cc h s cepstral
cp thp lm cho ph b dc v do nhy ca cc h s cepstral cp cao gy ra
nhiu nn ta thng s dng k thut t trng s lm gim thiu cc nhy
ny:
i(m) = c(m). w(m)
Trng s w(m):
= 1 +
2sin
1
Nhn xt
M hnh LPC l m hnh c bit thch hp cho tn hiu ting ni. Vi min
ting ni hu thanh c trng thi gn n nh, m hnh tt c cc im cc i ca
LPC cho ta mt xp x tt i vi ng bao ph m, vi ting ni v thanh, m
hnh LPC t ra t hu hiu hn so vi hu thanh, nhng n vn l m hnh hu ch
30
cho cc mc ch nhn dng ting ni. M hnh LPC n gin v d ci t trn
phn cng ln phn mm.
III. Nhn xt Rt trch c trng mt gia on quan trng, vi cc c trng thu c
sau qu trnh x l th s c dng vo qu trnh hc hay nhn dng sau ny. V
vy i hi cc c trng c rt trch ra ca tnh hiu l cc c trng phi
c xem l duy nht ca tnh hiu , trnh vic trng lp cc tn hiu mc d
chng l hai tn hiu khc nhau lc u.
Cc phng php bin i tn hiu c cp n trong Lun vn l
MFCC v LPC l hai phng php kh ph bin, tuy chng vn cn tn ti nhng
hn ch nhng khng th ph nhn s mnh m ca chng.
31
Chng III NHN DNG BNG M HNH MNG NEURAL
I. Tng quan
Mng neural nhn to l m hnh tnh ton da trn m phng hot ng ca
no b con ngi. Trong nhng nm gn y, mng neural c quan tm pht
trin v c ng dng vo cc h thng nhn dng ng, h thng d on v cc
h thng iu khin t ng. Mng neural l h thng nhng c trng c hc t
cc v d ch khng phi l c lp trnh nh mt thc bnh thng.
Mng neural c th c chia thnh hai loi theo cu trc : mng truyn
thng v mng hi quy.
Mng truyn thng: trong mng ny, cc n ron c nhm li thnh cc
lp. Tn hiu theo t lp ng vo v i n ng ra thng qua cc kt ni n
hng. Cc t bo n ron c kt ni t lp ny n lp khc, nhng khng kt
ni vi cc t bo trong cng mt lp.
Mng hi quy: trong mng kin trc loi ny, cc t bo n ron u ra
c php phn hi thng tin li cc t bo n ron ging n hay cc t bo trong
cc lp song song vi n. Do , tn hiu c th theo c hai hng l truyn
thng v truyn ngc. Mng hi quy c mt b nh ng, u ra ca chng phn
nh ngay lp tc u vo hin ti cng nh u vo v u ra trc .
Phn loi theo phng php hun luyn th c hai loi chnh l hun
luyn c gim st v khng c gim st. Ngoi ra cn mt phng php th ba
l hun luyn tng cng.
Hun luyn c gim st: Thut ton hc gim st iu chnh thng s ca
cc trng s u vo ca t bo n ron. Tp hun luyn bao gm mt tp hp cc
mu u vo v cc kt qu u ra mong mun tng ng vi mu u vo. Cc
mng nron iu chnh trng s lin kt ca n tm hiu mi quan h gia cc
cp u vo - u ra. Mng nron c hun luyn thnh cng th c th h c
s dng tm u ra ph hp nht i vi bt k u vo hp l.
Hun luyn khng c gim st: Thut ton hun luyn khng c gim
st khng yu cu u ra mong mun c bit trc. Trong khi hun luyn, ch c
32
tp mu u vo v mng t ng m phng nhng trng s cho cc kt ni theo
tng cm tp mu trong nhm vi c trng tng ng.
Hun luyn tng cng: Nh cc phng php trc , hun luyn
tng cng l mt trng hp c bit. Thay v hun luyn ch cho chng u ra
mong mun th thut ton hun luyn tng cng s dng ch mt nh ph bnh
nh gi im tt nht ca mng neural.
II. Qu trnh hot ng
1) T bo ca mng
Gii thch thng s:
x1, x2, , xn: Cc tn hiu u vo (Input). C th l tn hiu cn nhn
dng hoc tn hiu dng hun luyn.
wj1, wji, wjn: L cc trng s (weights) ng vi tng ng vo xn.
f(.) : Hm ngng (threshold function). C th l hm ngng n
thun hay hm Xch ma hay hm tip tuyn Hyperbol hoc cng c th l
hm radial.
Mt s biu thc ca hm f:
wj1
f(.)
x1
xi
xn
wji
wjn
yj
Hnh 3. 1 M hnh chi tit 1 t bo neural
33
Loi hm ngng Hm
Hm tuyn tnh f(s) = s
Hm ngng = +, > , <
Hm Xch ma f(s) = 1/(1 + exp(-s))
y(j): u ra ca tn hiu (Output) sau khi c hun luyn hay nhn dng.
Cng thc tnh:
= .
=1
Neuron ny s hot ng nh sau: gi s c N gi tr u vo xn, th
neuron s c N trng s wjn tng ng vi N ng truyn u vo. Sau
neuron s ly u vo th nht (x1), nhn vi trng s trn ng vo th nht
(wj1), ly gi tr u vo th hai nhn vi trng s ca ng vo th hai v.v...,
ri ly tng ca tt c cc kt qu thu c.
34
2) Mng Neural truyn thng nhiu lp
a) M hnh c bn:
Ch : y l m hnh gm 3 lp c bn: lp u vo, lp n v lp u ra. M hnh ch mang tnh cht minh ha, trn thc t s neuron c th nhiu hn hoc s lp n c th nhiu hn mt.
b) Lut hc ca mng:
Lut hc l mt th tc sa i cc trng s v h s hiu chnh ca
mng neuron (Th tc ny cng c th c gi l mt thut ton hun luyn)
Mc ch ca lut hc l hun luyn mng thc hin mt s nhim v. C
nhiu loi lut hc hun luyn mng neuron. Chng gm ba loi chnh: lut hc
c gim st, lut hc khng gim st v lut hc tng cng.
Trong lut hc c gim st, lut hc a ra mt tp hp cc mu c quy
tc v tng thch vi mng:
{(x(k)
, d(k)
)} k = 1, 2, 3, .., p
Hnh 3. 2 M hnh mng nhiu lp
35
x(k)
l mt u vo mng v d(k) tng ng vi u ra mong mun.
Khi cc u vo c p dng vo mng, cc kt qu u ra mng c so snh
vi cc mc tiu. Lut hc sau c s dng iu chnh trng s (wjk) v h
s hiu chnh ca mng dch chuyn u ra gn vi cc mc tiu hn.
Lut hc khng gim st: trng s v h s hiu chnh c sa i
p ng vi u vo mng. C mc tiu khng l u ra c sn. iu ny
dng nh khng thc t. Lm th no bn c th hun luyn mt mng nu bn
khng bit n phi lm g? Hu ht cc thut ton thc hin s hot ng phn
cm. Chng c luyn phn loi cc m hnh u vo thnh mt s hu hn
cc lp. iu ny c bit hu ch trong cc ng dng nh l lng t ha vector.
Lut hc gia tng tng t lut hc c gim st, ngoi tr vic, thay
v a ra cc u ra chnh xc cho mi u vo mng, thut ton ch cho mt lp.
Lp l thc o cho s hot ng ca mng trn mt chui u vo. y l loi
lut hc hin nay t ph bin hn so vi lut hc c gim st. N dng nh l
ph hp nht kim sot cc ng dng h thng.
Lut hc Adaline (Adaptive linear Element):
wj = (d(k) wTx(k))xj(k)
Lut ny cn c gi l lut hc Widrow-Hoff, hay cng c gi l
lut LMS (Least Mean Square), lut hc ny c s dng cho mng n mt lp
bao gm mt mng Adalines cn gi l mng tuyn tnh v Adaline c lp vi
cc phn khc. Trong lut hc Adaline cc trng s c khi to vi mt gi tr
bt k v c so snh vi cc trng s trong lut hc: wj = rx(t), tn hiu
hc:
r = d y = d - wTx
36
III. Qu trnh hun luyn
1) Thut ton lan truyn ngc
a) Khi nim v tng
Biu thc thut ton hun luyn lan truyn ngc l mt thut ton quan
trng nht trong lch s pht trin ca mng Neural. Thut ton ny c s dng
trong mng truyn thng nhiu lp bao gm cc thnh phn x l vi hm lin
tc kh vi. Nh nhng mng lin kt vi biu thc hc lan truyn ngc c gi
l mng lan truyn ngc. Cho mt tp u vo-ra {(x(k), d(k))} k = 1, 2, 3, .., p,
thut ton cung cp mt th tc thay i trng s sao cho mu tn hiu u vo
ph hp. iu c bn cho biu thc cp nht trng s ny n gin ch l phng
php gradient-descent (tin dn ti cc tiu a phng) c s dng cho mt
Perceptron n vi thnh phn kh vi.
Cho cp gi tr vo-ra mong mun (x(k), d(k)). Vi thut ton ny chng ta s
c hai giai on cn biu din trn lu lng d liu. Th nht, mu u vo x(k)
c lan truyn t lp vo cho ti lp ra, nh l kt qu ca lng d liu truyn
thng. u ra y(k) nhn gi tr tht ca qu trnh lan truyn thng. Sau kt qu
tn hiu sai s c a ra t s khc nhau gia u ra mong mun d(k) v u ra
thc t y(k) v c lan truyn ngc li t lp ra ti cc lp trc n cp nht
li cc trng s w.
b) M hnh minh ha
Hnh 1.1 m t kin trc c bn ca mt mng lan truyn ngc. Gm ba
lp c bn: lp u vo, lp n v lp u ra. Tn hiu theo lp u vo lan
truyn cho ti lp ra, sau xc nh c sai s da trn s khc nhau ca tn
hiu ra mong mun v tn hiu ra thc t, t lan truyn ngc li cc lp iu
chnh trng s u ra gn nht vi u ra mong mun.
37
Lan truyn ngc cc tn
hiu sai s
Lan truyn thng Lan truyn ngc
Hnh 3. 3 M hnh tng qut 3 lp
Trng s (wqm)
Hnh 3. 4 M hnh chi tit c bn
yi (i = 1, , n)
Gi tr u ra
Gi tr u vo
xj (j = 1,.,m )
Lp ng vo (Input layer)
Lp n (Hidden layer)
zq (q = 1,, g)
Lp ng ra (Output layer)
38
Hnh 1.2 m t chi tit v thut ton lan truyn ngc, kt qu c th d dng
m rng vi bt k lp no. Trong hnh 1.2, chng ta c m PE u vo ng vi m
tn hiu u vo x, g PE lp n v n PE lp u ra tng ng vi n tn hiu ng ra
y. Cc ng gch lin th hin tn hiu lan truyn theo hng thng (t lp vo
n lp ra), ng gch t th hin tn hiu sai s c lan truyn ngc (t lp
u ra v cc lp trc ).
c) Tnh ton cc gi tr v tham s
Cho mt mu gi tr u vo x th mt PE g lp n s nhn mt gi tr net u
vo: (2.1)
= .
=1
v gi tr u ra: (2.2)
= = .
=1
Gi tr net u vo cho mt PE i trong lp ra: (2.3)
= . =
=1
.
=1
=1
v u ra thc t yi : (2.4)
= = . =
=1
.
=1
=1
39
Cc biu thc trn y ch ra qu trnh lan truyn thng ca tn hiu ng vo
i qua cc lp. Tip theo, chng ta s xem xt tn hiu li v lan truyn ngc
chng.
Biu thc tnh sai s: (2.5)
() =1
2
2 = 1
2 .
=1
2
=1
=1
Trng s trong kt ni t lp n n lp ra c cp nht bng: (2.6)
=
S dng biu thc 2.3 2.5, chng ta c: (2.7)
=
=
Khi l tn hiu sai s nt th i trong lp u ra. Biu thc ca tn hiu sai
s: (2.8)
=
=
Khi neti l net u vo n PE i ca lp u ra v a(neti) = a(neti)/ (neti).
Kt qu ny ging tng t nh lut hc delta : (2.9)
40
=
=
()
()
()
()
cho mt PE lp n c u vo by gi l zq ca lp n.
Vic cp nht trong s trong kt ni t u vo n lp n, chng ta s dng
quy tc dy chuyn vi phng php gradient-descent (tin dn ti cc tiu a
phng) v trng s c cp nht trn trng s kt ni PE j trong lp u vo n
PE q trong lp n,
=
=
=
T biu thc (2.5), n r rng l mi sai s [di yi], i = 1, 2, , n l hm s ca
zq. Chng ta c: (2.10)
=
=1
Chng ta s dng vi cho biu thc 2.10: (2.11)
= .
=1
=
hq l tn hiu sai s ca PE q trong lp n v biu thc ca n l: (2.12)
=
=
=1
41
Khi netq l net u vo n PE q ca lp n (2.1), tn hiu sai s ca PE trong
lp n th khc vi tn hiu sai s ca PE trong lp u ra nh hai biu thc (2.8)
v(2.12). V s khc nhau ny, th tc cp nht trng s trn c gi l lut hc
delta tng qut. Tn hiu sai s hq ca mt PE lp n q c th c xc nh bi cc
tn hiu sai s vi ca cc PE v yi, chng l ngun cung cp d liu. Nhng h s ch
l nhng trng s c s dng cho vic lan truyn thng, nhng y chng l lan
truyn ngc cc tn hiu li thay v lan truyn tn hiu theo ng thng. l cc
ng gch t theo Hnh 1.2(M hnh chi tit c bn). iu quan trng ca biu
thc cp nht - lan truyn ngc l vic tnh ton s thay i trng s cho mt kt
ni, chng ta ch cn mt cp tn hiu c sn c hai u ca kt ni.
Vi s lp ty , lut cp nht lan truyn ngc s c dng tng qut nh sau:
= = . (2.13)
Khi u vo j v u ra i l hai u ca kt ni t PE j n PE i, xj l gi tr
u vo t mt PE lp n hay u vo t bn ngoi, i l tn hiu hc m chng ta
xc nh n ti biu thc 2.8 cho nhng trng s kt ni ca lp u ra v biu thc
2.12 cho tt c cc lp khc. Khi hm sigmoid lng cc c s dng nh l hm
kch hot v sau s dng biu thc 2.x th biu thc 2.8 v 2.12 tr thnh:
=
=
1
2 1 2 2.
=
=
42
v
=
=
=1
d) Cc bc xy dng thut ton
Xt mt mng gm Q lp truyn thng, q = 1, 2, , Q, qneti v qyj biu din
net u vo v u ra ca n v th i trong lp th q. Mng ny c m im u
vo v n im u ra. qwij s biu din trng s kt ni t q-1
yj n qyi.
u vo: a vo mt tp cc cp hun luyn {(x(k) , d(k))| k =1, 2, , p},
khi vector u vo c tng ln vi phn t cui cng l -1 , tc l =1()
= 1.
Bc 0: Khi to
Chn > 0 v Emax (sai s chp nhn c). Khi to trng s
gi tr ngu nhin nh nht v t E=0, k=1.
Bc 1: Vng hun luyn
p dng mu ng vo th k cho lp ng vo (q =1)
qyi =
1yi =
() cho tt c i
Bc 2: Lan truyn thng
Lan truyn tn hiu thng thng qua mng s dng biu thc:
=
=
. 1
=1
Gi tr ca i v q chy ti khi cc ng ra ca lp cui cng Qyj
c xc nh
Bc 3: o c sai s ng ra
43
Tnh ton gi tr sai s v nhng tn hiu sai s Qi cho lp ng ra:
=1
2
()
2
+
=1
(Ch : Cng dn sai s)
= ()
Bc 4: Lan truyn ngc sai s
Lan truyn ngc nhng tn hiu sai s cp nhp nhng
trng s v tnh ton nhng tn hiu sai s q-1i cho nhng lp trc:
=
1
= +
1 = 1
.
= , 1, , 2
Bc 5: Mt chu k lp:
Kim tra ton b tp hun luyn trong vng lp thc hin.
Nu k < p, th k = k + 1 v quay li bc 1. Ngc li ta chuyn sang
bc 6.
Bc 6: Kim tra tng sai s
Kim tra tng sai s ng ra, nu E
44
2) M phng trn Matlab v ng dng vo nhn dng ting ni
Ni dung m phng: Hun luyn mng Neural chuyn i th hnh tam
gic sang hnh Sin.
tng: Xy dng cc cp d liu: u vo m n c dng m phng
th dng tam gic v u ra tng ng s l m phng th hnh sin.
a) th hnh Tam gic b) th hnh sin
Xy dng chng trnh:
N = 100;
for i=1:N
t(i)=i*2*pi/N;
end
d = sin(t);
for i=1:N
if i
45
end
x2(1)=0;
for i=2:N
x2(i)=x1(i-1);
end
plot(t,x1,'black'); % v hnh tam gic
p=[x1;x2];
net = newff(p,d,3);
y=sim(net,p);
net.trainParam.epochs = 200;
net.trainParam.goal = 0.001;
net = train(net,p,d);
y = sim(net,p);
for i=1:N
t(i)=i*2*pi/N;
end
d = sin(t);
for i=1:N
if i
46
Kt qu:
Tn hiu ng ra mong mun d
Tn hiu u ra thc t y
Hnh 3. 7 th dng tam gic (xi)
Hnh 3. 6 Hnh minh ha qu trnh hun luyn
47
Hnh 3. 8 Mng Neural s dng
ng dng vo nhn dng ting ni:
Cho mng Neural nhiu lp truyn thng, trong qu trnh hun luyn v
nhn dng ty vo chnh xc v tc nhn dng s iu chnh li s lp n v
s t bo neuron trong mng.
Sau qu trnh x l tn hiu v rt trch c trng ta thu c cc ma trn
c trng ca tnh hiu ban u:
1 1
Vi n s lng c trng, ma trn ny l ma trn c dng vo hai vic: C
th l dng n hun luyn mng hay n l tn hiu cn nhn dng.
Th nht, vic dng ma trn c trng hun luyn mng.
Phng php hun luyn ngh s dng l phng php lan truyn ngc.
V ta c n c trng nn u vo s c n ng, v lc ny cp d liu mong mun
s l (xn , yn) tng ng u vo xn v u ra mong mun yn
Cc bc hun luyn:
Bc 0: Khi to
Chn > 0 v Emax (sai s chp nhn c). Khi to trng s
gi tr ngu nhin nh nht v t E=0, k=1.
48
Bc 1: Vng hun luyn
p dng mu ng vo th k cho lp ng vo (q =1)
qyi =
1yi = x(k)
i
Bc 2: Lan truyn ti
Tn hiu x trong ma trn c trng s c a vo ng vo ca
mng Neural. V tn hiu c lan truyn thng qua tng lp ca
mng cho ti lp cui cng. Tn hiu u ra tun theo hm:
=
=
. 1
=1
Gi tr ca i v q chy ti khi cc ng ra ca lp cui cng Qyj c
xc nh, c u ra nh mong mun th chng ta cn t mt
hm hp l ti y. Trng s chn ban u l nh nht cho mng, sau
qu trnh cp nht li trng s th n s c thay th bng trng s
mi.
Bc 3: o c sai s: ti bc ny sai s s c tnh ton c th
cp nht li cc trng s cho mng.
Bc 4: Lan truyn ngc sai s: Lan truyn ngc nhng tn hiu sai
s cp nhp nhng trng s v tnh ton nhng tn hiu sai scho
nhng lp trc
Bc 5: Chu k lp: Kim tra s neuron trong mng tnh ton ht
cha, nu cha th quay li Bc1 nu tnh ton ht th qua Bc 6.
Bc 6: Kim tra tng sai s ng ra. Nu E
49
Trn y l tm lc cc qu trnh c bn cho bi ton lan truyn ngc
dnh hun luyn tn hiu theo mu ma trn c trung ban u. Nh vy, kt
thc qu trnh ta s c kt qu l khi a mt tn hiu u vo tng t nh tn
hiu u vo ca mng th u ra s l kt qu mong mun (y).
Th hai, nhn dng tn hiu vi cc ma trn c trng ban u:
Ma trn c trng ng vi mt tn hiu no cn nhn dng c
a vo mng, thng qua qu trnh lan truyn thng, tnh ton th mng s cho ra
mt kt qu tng ng, nu kt qu tha u ra mong mun (c sai s nh
gi ng) th chng ta chn u ra mong mun.
50
IV. Kt lun
Ngoi nhng thnh cng ca gii thut hc lan truyn ngc, vn cn c
mt s kha cnh lm cho gii thut tr nn cha c bo m l mi lc u tt.
Kh khn ch yu l qu trnh hun luyn lu. C th do nhp hc v ng lc
khng ti u. S sai st trong vic hun luyn ni chung xut hin t hai ngun
mng lit v nhng cc tiu a phng.
Mng lit xy ra khi nhng trng s c iu chnh ti nhng gi tr rt
ln. Bi v s h dc, mng c th b mc by ti mt cc tiu a phng khi
c nhiu cc tiu thp hn gn bn cnh. Nhng phng php thng k c th gip
trnh ci by ny, nhng chng lm chm. Mt phng n khc l tng thm s
lng n v n. Nh vy s lm vic trong khng gian sai s nhiu chiu, nn c
hi gp by nh hn. Tuy nhin vic tng cng c gii hn trn, khi vt qua gii
hn ny, c hi mc by li tng ln.
51
KT LUN
Sau qu trnh nghin cu nhn dng ging ni, lun vn lm c mt s
cng vic sau:
a ra mt ci nhn tng quan v nhn dng ging ni.
X l tn hiu m thanh v a ra mt s phng php rt trch
cc c trng ca tn hiu.
Nghin cu phng php nhn dng s dng mng Neural, v
phng php hun luyn lan truyn ngc.
Trong gii hn thi gian v sc lc ca mt ngi, em mi ch c khi u
tip cn nghin cu v nhn dng ting ni, v vy chc chn trong lun vn cn
nhiu thiu st, so vi s pht trin nhn dng th cc kt qu t c trong lun
vn khng ng k, nhng em mong rng lun vn ny s gp mt phn vo vic
thc y nghin cu v ng dng ca h nhn dng ting ni.
Hng pht trin: kim nghim v cc u im cng nh khuyt im
m mng Neural, phng php hun luyn cng nh cc qu trnh rt trch c
trng th em mong mun n c ng dng thc t vo cc h thng thng minh,
h thng nhn dng ting ni, h thng iu khin bng ting ni. V gn hn l
ng dng vi h thng nhn dng ngn ng ting Vit. V trc mt th ng dng
vi cc chng trnh m phng c ci nhn rng hn v c im ca chng.
52
53
TI LIU THAM KHO:
[1] Homayoon Beigi, Fundamentals of Speaker Recognition, Springer Science
Business Media, 2011
[2] C.T.Lin & C.S.G.Lee, Neural fuzzy system
[3] F.J.Owens, Signal Processing of Speech, Printed in Hong Kong
[4] Duc Truong Pham and Liu Xing, Neural networks for Identification,
Prediction and Control, Printed in Great Britain
[5] Roberto Pieraccini, The Voice in the Machine, Printed and bound in the
United States of America.
[6] PGS.TS Nguyn Hu Phng, X L Tn Hiu S, Nh Xut Bn Thng
K, 09/2003
[7] Quch Tun Ngc, X L Tn Hiu S, Nh Xut bn Gio Dc, 04/1998