17412 - Bai Giang Xu Ly Tieng Noi

8/3/2019 17412 - Bai Giang Xu Ly Tieng Noi

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TRNG I HC HNG HI VIT NAM

KHOA CNG NGH THNG TIN

B MN H THNG THNG TIN

-----***-----

BI GING

X L TING NI

TN HC PHN : X L TING NIM HC PHN : 17412

TRNH O TO : I HC CHNH QUYDNG CHO SV NGNH : CNG NGH THNG TIN

HI PHNG - 2011


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MC LC

CHNG I: CC KIN THC C BN ............................................................................. 6

1.1 Tng quan v x l ting ni .................................................................................................. 6

1.1.1 Nhn dng ting ni t ng ................................................................................... 6

1.1.2 Chuyn i vn bn thnh ting ni ........................................................................ 7

1.1.3 H thng hiu ngn ng ni .................................................................................... 7

1.2 Cu trc ngn ng ni ............................................................................................................ 9

1.2.1 H thng ting ni con ngi .................................................................................. 9

1.2.2 Ng m hc v m v hc...................................................................................... 10

1.2.3 m tit v t ng................................................................................................... 11CHNG II: X L TN HIU S TRONG X L TING NI ................................. 13

2.1 X l tn hiu s ................................................................................................................... 13

2.1.1 Php bin i Fourier............................................................................................ 14

2.1.2 Php bin i Fourier ri rc ................................................................................. 14

2.1.3 Cc b lc s v ca s ......................................................................................... 15

2.2 Biu din tn hiu ting ni .................................................................................................. 15

2.2.1 Phn tch Fourier thi gian ngn ........................................................................... 15

2.2.2 M hnh m hc ca vic to ting ni ................................................................. 15

2.3 M ha ting ni ................................................................................................................... 19

2.3.1 Cc tnh cht ca b m ha ting ni .................................................................. 19

2.3.2 Cc b m ha dng sng ting ni v hng ...................................................... 20

CHNG III: NHN DNG TING NI........................................................................... 22

3.1 Cc h thng nhn dng ting ni ........................................................................................ 22

3.1.1 Nhn dng t ring l ............................................................................................ 22

3.1.2 Nhn dng t lin tc ............................................................................................ 243.2 Cc m hnh Markov n ....................................................................................................... 27

3.2.1 Chui Markov ....................................................................................................... 27

3.2.2 M hnh Markov .................................................................................................... 28

CHNG IV: CC H THNG CHUYN VN BN THNH GING NI .............. 30

4.1 Phn tch ng m v vn bn ............................................................................................... 30

4.1.1 T vng ................................................................................................................. 30

4.1.2 Xc nh cu trc ti liu....................................................................................... 30

4.1.3 Chun ha vn bn ................................................................................................ 31

4.1.4 Phn tch ngn ng................................................................................................ 32


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34.1.5 Chuyn i k t sang m thanh ........................................................................... 32

4.2 Tng hp ting ni ............................................................................................................... 33

4.2.1 Cc tnh cht ca tng hp ting ni ..................................................................... 33

4.2.2 Tng hp ting ni bng cc Formant ................................................................... 34

4.2.3 Tng hp ting ni bng ghp ni......................................................................... 344.2.4 nh gi cc h thng tng hp ting ni ............................................................. 36


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4Tn hc phn: X l ting ni Loi hc phn: 2B mn ph trch ging dy: H thng Thng tin Khoa ph trch: CNTT.M hc phn: 17412 Tng s TC: 4

Tng s tit L thuyt Thc hnh/Xemina T hc Bi tp ln n mn hc75 45 30 0 khng khng

iu kin tin quyt:Khng yu cu.

Mc tiu ca hc phn:Cung cp cc kin thc c bn v lnh vc x l ting ni, hiu cc h thng chuyn vn bn

thnh ting ni, cc h thng nhn dng ting ni.Ni dung ch yu:

Cc vn lin quan n ting ni v ng m hc; Cc h thng chuyn vn bn thnh tingni; C s x l tn hiu s trong x l ting ni; Nhn dng ting ni.Ni dung chi tit:

TN CHNG MCPHN PHI S TITTS LT TH BT KT

CHNG I: CC KIN THC C BN 15 9 61.1 Tng quan v x l ting ni 31.1.1 Nhn dng ting ni t ng1.1.2 Chuyn i vn bn thnh ting ni1.1.3 H thng hiu ngn ng ni1.2 Cu trc ngn ng ni 61.2.1 H thng ting ni con ngi1.2.2 Ng m hcv m v hc1.2.3 m tit v t ng

CHNG II: X L TN HIU S TRONG X LTING NI

15 9 6

2.1 X l tn hiu s 32.1.1 Php bin i Fourier2.1.2 Php bin i Fourier ri rc2.1.3 Cc b lc s v ca s2.2 Biu din tn hiu ting ni 32.2.1 M hnh m hc ca vic to ting ni2.3 M ha ting ni 32.3.1 Cc tnh cht ca b m ha ting ni

2.3.2 Cc b m ha dng sng ting ni v hngCHNG III: NHN DNG TING NI 21 12 93.1 Cc h thng nhn dng ting ni 33.1.1 Nhn dng t ring l3.1.2 Nhn dng t lin tc3.2 Cc m hnh Markov n 93.2.1 Chui Markov3.2.2 M hnh MarkovCHNG IV: CC H THNG CHUYN VN BNTHNH GING NI

24 15 9

4.1 Phn tch ng m v vn bn 64.1.1 T vng4.1.2 Xc nh cu trc ti liu4.1.3 Chun ha vn bn4.1.4 Phn tch ngn ng


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4.1.5 Chuyn i k t sang m thanh4.2 Tng hp ting ni 94.2.1 Cc tnh cht ca tng hp ting ni4.2.2 Tng hp ting ni bng cc Formant4.2.3 Tng hp ting ni bng ghp ni4.2.4 nh gi cc h thng tng hp ting ni

Nhim v ca sinh vin:Tham d cc bui hc l thuyt v thc hnh, lm cc bi tp c giao, lm cc bi thi gia

hc phn v bi thi kt thc hc phn theo ng quy nh.Ti liu hc tp:

1. Xuedong Huang, Alex Acero, Hsiao Wuen Hon, Spoken Language Processing- A Guideto Theory, Algorithm and System Development, Prentice Hall, 2001.

2. Lawrence R.Rabiner, Ronald W.Schafer,Digital Processing of Speech Signals, Prentice-Hall, Inc. Englewood Cliffs, NewJersey, 1978.

Hnh thc v tiu chun nh gi sinh vin:

- Hnh thc thi: thi vit.- Tiu chun nh gi sinh vin: cn c vos tham gia hc tp ca sinh vin trong cc buihc l thuyt v thc hnh, kt qu lm cc bi tp c giao, kt qu ca cc bi thi gia hc

phn v bi thi kt thc hc phn.Thang im: Thang im ch A, B, C, D, F.im nh gi hc phn: Z = 0,3X + 0,7Y.

Bi ging ny l ti liu chnh thc v thng nhtca B mn H thng Thng tin, KhoaCng ngh Thng tin v c dng ging dy cho sinh vin.

Ngy ph duyt: / /

Trng B mn


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CHNG I: CC KIN THC C BN

1.1 Tng quan v x l ting ni

K t khi xut hin, my tnh cng ngy cng chng t rng l mt cng c v cng

hu ch trgip con ngi x l thng tin. Cng vi spht trin ca x hi, khi lng thngtin m my tnh cn x l tng rt nhanh trong khi thi gian dnh cho nhng cng vic ny li

gim i. V vy, victng tc x l thng tin, trong c tc trao i thng tin gia con

ngi v my tnh, tr thnh mt yu cu cp thit. Hin ti, giao tip ngi-my c thc

hinbng cc thitb nh bn phm, chut, mn hnh,... vi tc tng i chm nn cn c

cc phng php trao i thng tin mi gip con ngi lm vic hiu qu hn vi my tnh. Mt

trong nhng hng nghin cu ny l s dng ting ni trong trao i thng tin ngi-my.

Nhng nghin cu ny lin quan trc tip ti cc kt qu ca chuyn ngnh x l ting ni,

trong c tng hp ting ni.

1.1.1Nhn dng ting ni t ngNhn dng ting nil mt qu trnhnhn dng mu, vi mc ch l phn lp (classify)

thng tin u vo l tn hiu ting ni thnh mt dy tun t cc mu c hc trc v lu

tr trong b nh. Cc mu l cc n v nhn dng, chng c th l cc t, hoc cc m v. Nu cc

mu ny l bt bin v khng thay i th cng vic nhn dng ting ni tr nn n gin bng cch

so snh d liu ting ni cn nhn dng vi cc mu c hc v lu tr trong b nh. Kh khn

c bn ca nhn dng ting ni l ting ni lun bin thin theo thi gian v c s khc bit ln

gia ting ni ca nhng ngi ni khc nhau, tc ni, ng cnh v mi trng m hc khc

nhau.

Xc nh nhng thng tin bin thin no ca ting ni l c ch v nhng thng tin no l

khng c ch i vi nhn dng ting ni l rt quan trng. y l mt nhim v rt kh khn m

ngay c vi cc k thut xc sut thng k mnh cng kh khn trong vic tng qut ho t cc mu

ting ni nhng bin thin quan trng cn thit trong nhn dng ting ni. Cc nghin cu v nhn dng ting ni da trn ba nguyn tc c bn:

- Tn hiu ting ni c biu din chnh xc bi cc gi tr ph trong mt khung thigian ngn (short-term amplitude spectrum). Nh vy ta c th trch ra cc c im ting

ni t nhng khong thi gian ngn v dng cc c im ny lm d liu nhn dng

ting ni.

- Ni dung ca ting ni c biu din di dng ch vit, l mt dy cc k hiu ngm. Do ngha ca mt pht m c bo ton khi chng ta phin m pht m thnh

dy cc k hiu ng m.
http://vi.wikipedia.org/wiki/Nh%E1%BA%ADn_d%E1%BA%A1ng_m%E1%BA%ABuhttp://vi.wikipedia.org/wiki/Nh%E1%BA%ADn_d%E1%BA%A1ng_m%E1%BA%ABuhttp://vi.wikipedia.org/w/index.php?title=%C3%82m_v%E1%BB%8B&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=%C3%82m_v%E1%BB%8B&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=%C3%82m_v%E1%BB%8B&action=edit&redlink=1http://vi.wikipedia.org/wiki/Nh%E1%BA%ADn_d%E1%BA%A1ng_m%E1%BA%ABu


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7- Nhn dng ting ni l mt qu trnh nhn thc. Thngtin v ng ngha (semantics) v

suy on (pragmatics) c gi tr trong qu trnh nhn dng ting ni, nht l khi thng tin

vm hcl khng r rng.

1.1.2 Chuyn i vn bn thnh ting niCc h thng chuyn i vn bn thnh ging ni c th c xem nh l h thng m ha

ting ni cho php la chn kiu cch ni, tc , cng v cc hiu ng. H thng chuyn vn

bn thnh ting ni (Text-to-Speech) l mt h thng c th sinh ra ting ni gn ging vi con

ngi t cc vn bn c a vo (cn c gi l h thng tng hp ting ni) S chuyn i

cc t di dng vit sang ting ni l mt cng vic kh khn v h thng TTS cn d liu t

vng rt lnv nhiu ng iu ca m thanh.

Cc thnh phn c bn ca mt h thng chuyn i vn bn thnh ting ni

- B phn tch vn bn: chun ha vn bn sang dng thch hp cho h thng TTS- B phn tch ng m chuyn i vn bn c x l thnh dy cc m tng ng sau

c phn tch ng iu xc nh trng m, ngt nhp, thi gian, ..

- Cui cng, b tng hp ting ni nhn cc tham s u vo t dy m v x l y

- Thnh phn phn tch vn bn:+ Xc nh cu trc ti liu, chuyn i k hiu, phn tch cu trc ngn ng+ Chuyn i cc k hiu sang dng chun.

+ Chuyn i cc s sang dng ch tng ng
http://vi.wikipedia.org/wiki/%C3%82m_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/%C3%82m_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/%C3%82m_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/%C3%82m_h%E1%BB%8Dc


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8+ Phn tch khong trng, du chm cu xc nh cu trc ngn ng

- Thnh phn phn tch ng m:+ Chuyn i cc t chun ha sang cc m v tng ng (vi thng tin nh trng

m, thi gian pht m)

1.1.3 H thng hiu ngn ng niTng hp ting ni l lnh vc ang c nghin cu kh rng ri trn th gii v cho

nhng ktqu kh tt. C ba phng php cbn dng tng hp ting ni l m phng b

my pht m, tng hp bng formant v tng hp bng cch ghp ni. Phng php m phng

b my pht m cho cht lng tt nhng i hi nhiu tnh ton v vic m phng chnh xc

b my pht m rt phc tp. Phng php tng hp formant khng i hi chi ph cao trong

tnh ton nhng cho kt qu cha tt. Phng php tng hp ghp ni cho cht lng tt, ch ph

tnh ton khng cao nhng s lng t vng phi rt ln. cc nc pht trin, nhng nghin cu x l ting ni, cho cc kt qu kh quan,

lm tin cho vic giao tip ngi-my bngting ni. Vit Nam, cc nghin cu trong lnh


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9vc ny tuy mi c pht trin trong nhng nmgny nhng cng c mt s kt qu kh

quan

1.2 Cu trc ngn ng ni

1.2.1 H thng ting ni con ngi

a) B my pht m

B my pht m bao gm cc thnh phn ring r nh phi, kh qun, thanh qun, v

cc ng dn ming, mi. Trong :

Thanh qun cha hai dy thanh c th dao ng to ra s cng hng cn thit to

ra m thanh.

Tuyn m l ng khng u btu t mi, kt thc bi dy thanh hoc thanh

qun.

Khoang mi l ng khng u bt u t mi, kt thc bi vm ming, c

di c nh khong 12cm i vi ngi ln.

Vm ming l cc np c chuyn ng.

1. Hc mi

2. Vm ming trn

3. rng

4. Vm ming mm

5. u li

6. Thn li

7. Li g

8. Cming

9. Yt hu

10. Npng ca thanh qun

11. Dy thanh gi12. Dy thanh

13. Thanh qun

14. Thc qun

b) C ch pht m

Trong qu trnh to m thanh khng phi l m mi, vm ming m, khoang mi

ng li, dng kh s ch i qua khoang mi. Khi pht m mi, vm ming h thp v dngkh s ch i qua khoang mi.

Tuyn m s c kch thch bi ngun nng lng chnh ti thanh mn. Ting ni c to ra


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10do tn hiu ngun t thanh mn pht ra, y khng kh c trong phi ln to thnh dng kh, va chm

vo hai dy thanh trong tuyn m. Hai dy thanh dao ng s to ra cng hng, dao ng m s c

lan truyn theo tuyn m (tnh t tuyn m n khoang ming) v sau khi i qua khoang mi v mi, s

to ra ting ni.

1.2.2 Ng m hc v m v hcNgnh nghin cu m thanh cho mt ngn ng c gi l m v hc. Ng m hc l mt

ngnh khoa hc nghin cu cc c im m thanh ca ting ni con ngi. Ng m hc nghin cu

cc ph qut m thanh. V d: Nh vo b my cu m, con ngi c th pht ra cc chui m thanh

khc nhau. Ng m hc chia cc loi m thanh ny thnh cc phm tr ng m khc nhau: nguyn

m, ph m, tc, xt Cn m v hc th khng nghin cu rng nh vy. m v hc nghin cu

xem trong mt ngn ng c bao nhiu n v m thanh l c chc nngkhu bit ngha. Hoc, trong

ngn ng, nhng nt ng m no tr thnh nhngnt khu bit v c ngha. Chnh v vy, ng mhc c s n v l v hn, quen gi l cc m t (sounds). Cn m v hc, c s n v hu hn,

m c. n v ca m v hc l m v (phonemes).

V mt ng m hc, 3 nguyn m ny u c ni dung ng m l nh nhau tt c cc ngn ng

trn th gii. V d nh [m] phn bit vi [p] v [b] c tnh [mi/khng mi]. [p] phn bit vi

[m] v [b] c tnh [+ v thanh]: +v thanh/ +hu thanh. Nhng i lp kiu nh vy th bt c

ngn ng no cng ging nhau. V vy, ch l cc thuc tnh ng m hc thun tu. Tuy nhin,

di con mt m v hc, ti nguyn ng m ca cc m v phi c la chn di con mt ca

ngi bn ng (native), c tn dng v chn la, c khai thc sao cho c li v hp vi h

thng (ci tng ca ngn ng) ca mnh nht. Ni tm li, cc nt ng m bin thnh cc nt m

v hc; t ci chung, ci ph qut tr thnh ci ring, ci c th. C mt tin trnh lch s pht trin

ca mt h thng ng m, t lc xa xa cho n ngy nay, suy cho cng, l s chn la v khai thc

ti nguyn nhn loi y cho tc ngi mnh, cho cng ng ni nng c th. Qu trnh chn la

cng cht vt, v c th ni l y mu v nc mt. Chnh v vy, cc nh m v hc hin i

khng quay lng li vi lch s ca mt ngn ng mtm ra nhng h thng c liu chc chncho vic chng minh nhng chc nng ca h m thanh mt ngn ng. Phng php lun ny khc

hon ton vi m v hc cu trc lun xa kia. V vy, c th ni, m v hc hin i l hnh nh thu


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11nh mt cch logic v c tnh hnh thc ho cao con ng pht trin ca mt h thng m thanh

mt ngn ng.

1.2.3 m tit v t ng

a) m titChui li ni m con ngi pht ra gm nhiu khc on di ngn khc nhau. n v pht

m ngn nht l m tit (syllable).

V phng din pht m, m tit c tnh cht ton vn, khng th phn chia c l bi n c

pht m bngmt t cng ca c tht ca b my pht m.

Khi pht m mt m tit, cc c tht ca b my pht m u phi tri qua ba giai on: tng

cng cng, nh im cng thng v gim cng.

Da vo cch kt thc, cc m tit c chia thnh hai loi ln: m v khp. Trong mi loi li

c hai loi nh hn. Nh vy c 4 loi m tit nh sau:

- Nhng m tit dc kt thc bng mtph m vang(/m, n, /...) c gi l nhngm tit

na khp.

- Nhng m tit c kt thc bng mtph m khng vang(/p, t, k/) c gi l nhng m

tit khp.

- Nhng m tit c kt thc bng mt bn nguyn m (/w, j/) c gi l nhngm tit nam.

- Nhng m tit c kt thc bng cchgi nguyn m sc ca nguyn m nh m tit th

c gi lm tit m.

b) c im ca m tit ting vit

- C tnh c lp cao:

+ Trong dng li ni, m tit ting Vit bao gi cng th hin kh y , r rng, c tchv ngt ra thnh tng khc on ring bit.

+ Khc vi m tit cc ngn ng chu u, m tit no ca ting Vit cng mang mt thanh

iu nht nh.

+ Do c th hin r rng nh vy nn vic vch ranh gii m tit ting Vit tr nn rt d

dng.

- C kh nng biu hin ngha

+ ting Vit,tuyt i a s cc m tit u c ngha. Hay, ting Vit, gn nh ton b

cc m tit u hot ng nh t...


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12+ C th ni, trong tin Vit, m tit khng ch l mt n v ng m n thun m cn l

mt n v t vng v ng php ch yu. y,mi quan h gia m v ngha trong m tit

cng cht ch v thng xuyn nh trong t ca cc ngn ng u chu, v chnh lmt nt

ctrng loi hnh ch o ca ting Vit.

- C mt cu trc cht ch

M hnh m tit ting Vit khng phi l mt khi khng th chia ct m l mt cu trc. Cu

trc m tit ting Vit l mt cu trc hai bc, dng y nht gm 5 thnh t, mi thnh t c

mt chc nng ring.

CU HI N TP

1. Trnh by khi nim v x l ting ni? nghatrong thc tin? Cho v d minh ha?

2. Trnh by cc nguyn tc c bn trong qu trnh nhn dng ting ni?

3. Trnh by h thng chuyn i vn bn thnh ging ni?

4. Trnh by cu trc ca ngn ng ni?


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CHNG II: X L TN HIU S TRONG X L TING NI

2.1 X l tn hiu s

Phn tch v thit k cc h thng tuyn tnh c thc hin d dng nhcc biu din min tn

sfrequency-domain representation) ca c cc tn hiu v h thng. Do vy, cn xt cc biu dinca bin i Fourier (Fourier Transform, FT) v ca bin i Z (Z - Transform, ZT) ca cc tn

hiu v h thng ri rc.

Bin i Z(ZT) : Biu din ZT ca dy c xc nh bi 2 phng trnh:

"Bin i Z" (ZT) hay "bin i trc tip" ca x(n) c xc nh bi (2a). Tng qua n, c th thy

X(z) l chui lytha v hn theo bin z-1, trong dy cc gi tr, x(n), ng vai tr cc h s

trong chui lu tha. Ni chung, cc chui lu tha ny s hi t n gi tr hu hn ch vi cc gi

tr xc nh caz.iu kin ca hi t l:

Tp hp cc gi tr m chui hi t xc nh mt min trn mt phng phc Z gi l min hi t.

Ni chung, min ny c dng:

C nhiu nh l v tnh cht ca biu din ZT tin dng cho vic nghin cu cc h thng thi gian

ri rc. Danh sch cc nh l quan trng cho trong bng 1. V hnh thc, cc nh l ny ging vi

cc nh l tng ng ca bin i Laplace cho cc hm thi gian lin tc. Tuy nhin, iu ny

khng c ngha l ZT l mt dng xp x no ca bin i Laplace. bin i Laplace l biu din

chnh xc ca cc hm thi gian lin tc, cn ZT l biu din chnh xc ca dy cc s


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14

2.1.1 Php bin i Fourier

Biu din bin i Fourier (FT) ca tn hiu thi gian ri rc cho bi cc phng trnh

2.1.2 Php bin i Fourier ri rc

Cng nh trong trng hp cc tn hiu tng t, nu dy tun hon vi chu k N,

thx (n) c th biu din bi tng ri rc ca cc ng hnh sin hn l bi dng tch phn nh

(5b). Cc biu din dng chui Fourier cho dy tun hon l:

l biu din chnh xc ca dy tun hon. Tuy nhin, ngita hay dng biu din khc ca (8).

Xt dy di hu hn, x(n), bng 0 ngoi on 0


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15- Bin i DFT, X(k), c th coi l bn mu ca bin i ZT (hoc bin i FT) ca dy

c di hu hn.

- Bin i DFT c cc tnh cht rt ging (c cc sa i do s tun hon ni ti) vinhiu tnh cht hu ch ca bin i ZT v FT.

- N gi tr ca X(k) c th tnh ton rt hiu qu (vi thi gian t l vi NlogN) bng tphp cc thut ton tnh ton c bit chung l bin i Fourier nhanh (Fast Fourier

Transform, FFT).

- DFT c dng rng ri tnh cc c lng ph(Spectrum estimate), hm tng

quan (Correlation function) v thc hin cc lc s.

2.1.3 Cc b lc s v ca s

Lc s l h thng bt bin dch chuyn tuyn tnh thi gian ri rc (Discrete -Time Linear Shift-

Invariant System). Nh rng vi h thng nh vy, ci vo v ci ra c quan h theo biu thc tch

chp (1). Quan h tng ng gia bin i ZT ca ci vo v ci ra cho bng 1

Y(z) = H(z)X(z) Bin i ZT ca p ng mu n v, H(z), c gi l hm h thng (system

function) ca h, bin i FT ca p ng xung n v,

2.2 Biu din tn hiu ting ni2.2.1 M hnh m hc ca vic to ting ni

Nhmn gin ho vic phn tch v nghin cu b my pht m, ngi

ta chia b my pht m ra lm hai phn cbn: ngun m v h thng p ng.

H thng p ng bao gm thanh mn, tuyn m, mi v mi. Vic m hnh ho

ny s dng hm truynt trong bini Z.

i vi cc m hu thanh, ngun m l mt dng sng tun hon c bit. Dng

sng ny c m phng bi p ng ca b lc thng

thp c hai im cc thc v tn s ct vo khong 100 Hz.


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16

Trong , l cc hng s c trng cho ngun m vi


17/52

17thun l sng truyn t thanh mn n mi, trong khi sng ngc li truyn l mi n thanh

mn.

Mi quan h gia sng thun v sng ngc trong nhng on k tip phim bo p sut v

thng lng lin tc c v thi gian v khng gian ti mi im trong h thng. Trong hnh 1.6.a

ta thy khi sng thun trong mt on gpphn thay i v thit din (mi ni gia hai on ktip), mt phn ca n truyn sang on k tip, mt phn kia li phn x di dng sng

ngc. Hon ton tng t, khi sng ngc gp mi ni, mt phn c chuyn tip sang

on trc , cn phn kia li phn x lidi dng sng thun.

Tuyn m c coi nh mt chui lin tip cc ng m hc v c m hnh ho


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18bi mt chui gm K b cng hng. Khi hm truyn t ca tuyn m c dng:

Mi b cng hngsto ra mt formant cc trngbi tn s trung tm, tnh theo

cng thc:

Vife l tn s ly mu ca tn hiu ly mu

Cui cng m thanh c pht ra mi, ni c coi nh mt ti m hc.

S tnx ca mi c biu dinbi hm truynt:

RzC1z1

Hm truyn t ca h thng c dng:

TzGz.Vz.Rz

Nu gi thit mt trong hai im cc ca thanh mn gn bng 1( = -1) ta c:

l hm truynt ca b lc o. T(z) l hm truyn t ca m hnh ton im cc. Cc hs ai ca b lc o s l cc tham s quan trng trong phng php d on tuyn tnh

xc nh cc formant ca tuyn m.

Hnch ca m hnh ny l khng thto ra cc m xt hu thanh v cc m mi. i vi

cc m mi m hnh trn c ci tin bng cch thm vo phn c trng cho mi t song

song vi m hnh. Lc hm truynt ca h thng mi l:


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19H thng trn khng cn l h thng ton im cc m n cn xut hin cc im khng

trong mtphng Z. Vic xut hin cc im khng ny s gy kh khn cho phng php tin

on tuyn tnh l phng php p dng cho cc h thng ton im cc. Song ngi ta

khc phc c kh khn trn bng cch thay mt im khng bng hai im cc theo phng

php gim bc gnng, cng thc gimbc nh sau:

Tn hiu m thanh khng phi l tn hiu dng, do m hnh phic xy dng mt cch

lin tc, ngha l cc tham s ca m hnh phi bin thin theo thi gian. S bin thin ny rt

chm nn cc tham s c th coi nh khngi trong khong thi gian m tn hiu c coi l

dng: 20 ms.

2.3 M ha ting ni

2.3.1 Cc tnh cht ca b m ha ting ni

Da trn c s la chn cc cch biu din tn hiu v phng php x l, c rtnhiu cc

ng dng quan trng c trin khai. Hnh v di y s ch ra mt s ng dng trong lnh vc

x l ting ni.

Tng hp ting ni l qu trnh to ra tn hiu m thanh bng cch iu khin mt m hnh

mu vi mt tp cc tham s. Nu m hnh mu ny v cc tham sc xy dng mt cch

hon ho th ting ni tng hp c th ging vi ting ni t nhin. Hin c hai phng php

tng hp ting ni:

a. Tng hp ting ni theo cch pht m

y l cch tipcn trc tip m hnh ho h thng mt cch chi tit. Trong phng

php ny h thng tng hp c m phng ging nh qu trnh to ra m thanh v lan truyn

m thanh trong h thng pht m ca con ngi. Hng nghin cu ny vn ang tip tc v


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20cho mt s kt qu nht nh.

Phng php ny c th to ra hu ht cc ting ni t nhin.

b. Tng hp u cui t nhin

Theo hng m hnh ho ny, ngi ta da trn cc c tnh p ng tn

s ca dy thanh v tuyn m m phng li c ch to ting ni. M hnh ny gi l

m hnh ngun-lc. B tng hp ting ni theo hng ny c thc hin bng cch s

dng h thng tng tvi cch to ting ni ti nhng im quan st.

C quan pht m c m hnh ho thnh mt h thng bao gm mt ngun m

biu din cho thanh mn v mt b lc biu din cho tuyn m. Qu trnh tng hp s bao

gm hai phn cbn:

Tng hp tn hiu ngun da vo tn scbn v tnh cht tun hon ca ngun.

Xy dng li hm truyn t ca tuyn m (bao gm c mi v ming) da vo

cc tham s c trng cho tuyn m.

Hin nay ngi ta thng s dng hai b tham s c trng cho tuyn m:

B tham s formant

B tham s ca b lc o

Cc b tham s ny c thc tng ktt cc qu trnh phn tch ting ni.

2.3.2 Cc b m ha dng sng ting ni v hng

Nhn dng ting ni l lnh vc nghin cu vi mc ch to ra c mt thit b, my mc

hoc phn mm c kh nng nhn bit mt cch chnh xc ting ni ca con ngi t bt k

mt ngun pht m no. Nhn dng ting ni c hai ng dng chnh l nhn dng ting ni v

nhn dng ngi ni.

a. Nhn dng ng ngha

Thng thng iu khin cc thit b my mc ngi ta thng s dng cch giao

tip thng qua s vo ra ckh. Khi p dng ting ni vo giao tip, li ch ca n c th d dng

nhn thy: l tnh tin li, d s dng, tc giao tip cao... c th s dng ting ni nh

mt cng c giao tip th h thng cn c khnngting ni v ng ngha.Nhn dng ng ngha

bao gm nhn dng t v nhn dng cu.

b. Nhn dng ngi ni

Trong th gii ngy nay tn tinhiu h thng yu cu an tonbo mt cao. T ny sinh

ra yu cu phi nhn dng c ngi ni bng nhng cim ring bit m khng ai c th sao

chp c. Bn cnh cc cch thc nhn dng qua ch k, nh chn dung, ch vit..., ngy nay

ngi ta cn dng ting ni nhn dngbi v ting ni c nhng c tnh ring bit vi tng

ngi. Timt s cng ty xut hin nhng hthng kim tra ngi qua ca bng nhn dng

ting ni hoc nhn dng mi ngi qua th nhn dng m nhng thng tin lu tr trn th


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21chnh l cimv ting ni ca ngi .

Nguyn tc ca nhn dng ngi ni l s dng nhng t kho c xc nhttrc m

nhng t kho ny c trng cho tng ngi mt. C hai yu t khng nh s khc nhau trong

ting ni ca mi ngi:

- Cc c tnh cquan pht m khc nhau nh: di ca tuyn m, tn s cng hngca dy thanh, cc tn s formant, di thng, s bini ca ng bao ph... l tp

hp nhng c tnh c lin quan n tnh c lp ca ni dung m v ca t ng.

- S khc nhau trong cch pht m ca tng ngi: tc v chiu di t lun lun khcnhau.

Trong tt c cc c tnh trn ng bao ph v tn s c bn l hai c tnh quan trng nht.

ng bao ph c miu t bng nhng gi tr trung bnh ca cc b lc thng di, ca cc tn

s formant, ca cc h s tin on tuyn tnh, ca h s cepstre v cc tham s khc.

CU HI N TP

1. Trnh by ng dng ca x l tn hiu s trong x l ting ni ?

2. Trnh by m hnh m hc ca vic to ting ni ?

3. Trnh by cc tnh cht ca b m ha ting ni ?


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CHNG III: NHN DNG TING NI

3.1 Cc h thng nhn dng ting ni

3.1.1 Nhn dng t ring l

Trong ting Vit, ng ngha ca mt t ph thuc vo thanh iu. Khi thanh

iu thay i, ngha ca t cng thay i theo. C 6 thanh iu trong ting Vit:

khng du, huyn,sc, nng, hi, ng. Tng ng vi mi thanh iu, tn s c bn

thay i theo mt quy lut ring.

a. Khng du

Vi thanh iu khng du, tn s c bn khng thay i.

b. Du huyn

Vi du huyn, tn s c bn gim dn.

Nu gi F0 l tn s tng ng vi m khng du, th s thay i tn s

c bn ca du huyn c th c m t nh sau:

F0, F0-10, F0-20, F0-30, F0-50, F0-60c. Du sc


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Vi du sc, tn s c bn tng dn.Nu gi F0 l tn s tng ng vi m khng du, th s thay itn s

c bn ca du sc c thc m t nh sau:

F0-20, F0-20, F0-15, F0-10, F0-5, F0+5, F0+30, F0+70, F0+80

d. Du nng

Nu gi F0 l tn s tng ng vi m khng du, th s thay itn sc bn ca du nng c thc m tnh sau:

F0, F0, F0-35, F0-50, F0-90, F0-120, F0-140

e. Du hi


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Nu gi F0 l tn s tng ng vi m khng du, th s thay itn s

c bn ca du hi c thc m t nh sau:F0-30, F0-15, F0-20, F0-35, F0-55, F0-70, F0-75, F0-85, F0-90,F0-95, F0-90,

F0-80, F0-90, F0-30

f. Du ng

Nu gi F0 l tn s tng ng vi m khng du, th s thay itn s

c bn ca du ng c thc m t nh sau:

F0, F0-40, F0+20, F0+50, F0+60

3.1.2 Nhn dng t lin tcS thay i cc thng s ca tn hiu ting ni khi pht m mt cu trong ting Vit

kh phc tp, v vic pht m ny ph thuc vo nhiu yu t nh loi cu (cu hi, cutrn thut, cu cm thn...), hon cnh pht m (ni chuyn, c,...), a phng... cc nhng hiu bit v vic pht m mt cu trong ting Vit cn c nhng nghin cu y.

Vi mcch thnghim vic ghp t to thnh cu trong ting Vit, phn ny sa ra mt s nhn xt v s bin i ca tn hiu ting ni khi pht m hai loi cu inhnh cating Vit: cu trn thut v cu hi. Nhng nhn xt ny c rt ra qua s so snh

vi cu khng c ng iu.

a. Cu trn thut


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25Khi pht m cu trn thut, tu theo hon cnh c th c mt s t no c nhn

mnh. Vic xc nh t cn nhn mnh trong cu trn thut lin quan ti phn tchbccao v khng ccp tiy. n gin, gi s khng c t no c nhn mnh rrng trong cu.

So snh hai cch pht m c th rt ra cc nhn xt sau: V thi gian pht m: Do khng c t nhn mnh nn cc t trong cu khng ngiu v cu trn thut c pht m trong khong thi gian gn nh nhau.V bin tn hiu: Cc t trong cu khng ng iu c pht m vi bin tng i u. Bin cc t trong cu trn thut gim dn cui cu.

V tn s cbn: Trong cu khng ngiu, tn s cbn ca cc t (khng cthanh iu) i theo ng nm ngang. Tn s c bn ca t trong cu trn thutgim dn.

Nh vy, cc t trong cu trn thut c pht m vi bin v tn s

c bn gim dn v pha cui cu.


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26b. Cu hi

Trong cu hi, ngi ni thng nhn mnh vo t cn hi. Nhng tcn hi ny thngkhng c v tr c nh trong cu.

V d: Cng mt cu hiAnh i? Nu mun hi v ch ng (anh hoc ai ) thngi hi s nhn mnh vo t anh, nu mun hi v hnh ng (i hoc chy) th ngi

hi s nhn mnh vo t i.Vic xc nh t hi trong cu lin quan ti vic phn tch bc cao

trong qu trnh tng hp v khng ccp y.n gin, thi


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trong cc cu thnghim c coi l tcui cu. Cu hi sc so snh vicu khng c ngiu.

Diy l hnh nh dng sng v tn s cbn ca cu: Anh n cha

(khng c ng iu) v cuAnh n cha? (t hi l cha)

So snh hai cch pht m c th rt ra cc nhn xt sau:

V thi gian pht m: Cc t trong cu khng ngiu c pht m trong

khong thi gian gn nh nhau. Thi trong cu hi (cha) c pht

m di hn (0.45s) cc tanh (0.35s) v n (0.20s) trong cu ny.


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V bin tn hiu: Cc t trong cu khng ngiu c pht mvi bin tngiu. Thicha trong cu hic pht m vi bin ln hn t cha trong cu khng ng iu.

Vtn s cbn: Trong cu khng ngiu, tn s cbn ca cc t (khng cthanh iu) i theo ng nm ngang. Tn s cbn ca t anh v n trong cuhi khng tng dn. Tn s cbn ca tcha trong cu hitng dn.

Nh vy, cc t hi trong cu hic pht m di hn,vi bin

ln hn v tn s c bn tng dn so vi cu khng ngiu.

3.2 Cc m hnh Markov n

3.2.1 Chui Markov

Trongton hc, mtxch Markovhaychui Markov(thi gian ri rc), t theo tn nh ton

hc ngi Nga Andrei Andreyevich Markov, l mtqu trnh ngu nhinthi gian ri rc

vitnh cht Markov. Trong mt qu trnh nh vy, qu kh khng lin quan n vic tin on

tng lai m vic ch ph thuc theo kin thc v hin ti.

Xch Markov l mt dy X1,X2,X3, ... gm ccbin ngu nhin. Tp tt c cc gi tr c th c

ca cc bin ny c gi lkhng gian trng thi S, gi tr caXnl trng thi ca qu trnh (h)

ti thi imn.

Nu vic xc nh (d on) phn bxc sut c iu kincaXn+1khi cho bit cc trng thi

qu kh l mt hm ch ph thucXnth:

trong xl mt trng thi no ca qu trnh (xthuckhng gian trng thi S) . lthuc

tnh Markov.

Mt cch n gin hnh dung mt kiu chui Markop c th l qua mttmat hu

hn(finite state machine). Nu h trng thiyti thi imnth xc sut m h s chuyn ti

trng thixti thi imn+1khng ph thuc vo gi tr ca thi imnm ch ph thuc vo

trng thi hin tiy. Do , ti thi imnbt k, mt xch Markov hu hn c th c biu din

bng mt ma trn xc sut, trong phn tx,yc gi tr bng v c

lp vi ch s thi giann(ngha l xc nh trng thi k tip, ta khng cn bit ang thi im

no m ch cn bit trng thi thi im l g). Cc loi xch Markov hu hn ri rc ny cn

c th c biu din bng th c hng, trong cc cung c gn nhn bng xc sutchuyn t trng thi ti nh (vertex) u sang trng thi ti nh cui ca cung .
http://vi.wikipedia.org/wiki/To%C3%A1n_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/To%C3%A1n_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/To%C3%A1n_h%E1%BB%8Dchttp://vi.wikipedia.org/w/index.php?title=Andrei_Andreyevich_Markov&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=Andrei_Andreyevich_Markov&action=edit&redlink=1http://vi.wikipedia.org/wiki/Qu%C3%A1_tr%C3%ACnh_ng%E1%BA%ABu_nhi%C3%AAnhttp://vi.wikipedia.org/wiki/Qu%C3%A1_tr%C3%ACnh_ng%E1%BA%ABu_nhi%C3%AAnhttp://vi.wikipedia.org/wiki/Qu%C3%A1_tr%C3%ACnh_ng%E1%BA%ABu_nhi%C3%AAnhttp://vi.wikipedia.org/wiki/T%C3%ADnh_ch%E1%BA%A5t_Markovhttp://vi.wikipedia.org/wiki/T%C3%ADnh_ch%E1%BA%A5t_Markovhttp://vi.wikipedia.org/wiki/T%C3%ADnh_ch%E1%BA%A5t_Markovhttp://vi.wikipedia.org/wiki/D%C3%A3y_(to%C3%A1n)http://vi.wikipedia.org/wiki/Bi%E1%BA%BFn_ng%E1%BA%ABu_nhi%C3%AAnhttp://vi.wikipedia.org/wiki/Bi%E1%BA%BFn_ng%E1%BA%ABu_nhi%C3%AAnhttp://vi.wikipedia.org/wiki/Bi%E1%BA%BFn_ng%E1%BA%ABu_nhi%C3%AAnhttp://vi.wikipedia.org/wiki/Bi%E1%BA%BFn_ng%E1%BA%ABu_nhi%C3%AAnhttp://vi.wikipedia.org/wiki/X%C3%A1c_su%E1%BA%A5t_c%C3%B3_%C4%91i%E1%BB%81u_ki%E1%BB%87nhttp://vi.wikipedia.org/wiki/X%C3%A1c_su%E1%BA%A5t_c%C3%B3_%C4%91i%E1%BB%81u_ki%E1%BB%87nhttp://vi.wikipedia.org/wiki/X%C3%A1c_su%E1%BA%A5t_c%C3%B3_%C4%91i%E1%BB%81u_ki%E1%BB%87nhttp://vi.wikipedia.org/wiki/Thu%E1%BB%99c_t%C3%ADnh_Markovhttp://vi.wikipedia.org/wiki/Thu%E1%BB%99c_t%C3%ADnh_Markovhttp://vi.wikipedia.org/wiki/Thu%E1%BB%99c_t%C3%ADnh_Markovhttp://vi.wikipedia.org/wiki/Thu%E1%BB%99c_t%C3%ADnh_Markovhttp://vi.wikipedia.org/w/index.php?title=%C3%94t%C3%B4mat_h%E1%BB%AFu_h%E1%BA%A1n&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=%C3%94t%C3%B4mat_h%E1%BB%AFu_h%E1%BA%A1n&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=%C3%94t%C3%B4mat_h%E1%BB%AFu_h%E1%BA%A1n&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=%C3%94t%C3%B4mat_h%E1%BB%AFu_h%E1%BA%A1n&action=edit&redlink=1http://vi.wikipedia.org/wiki/%C4%90%E1%BB%93_th%E1%BB%8B_c%C3%B3_h%C6%B0%E1%BB%9Bnghttp://vi.wikipedia.org/wiki/%C4%90%E1%BB%93_th%E1%BB%8B_c%C3%B3_h%C6%B0%E1%BB%9Bnghttp://vi.wikipedia.org/wiki/%C4%90%E1%BB%93_th%E1%BB%8B_c%C3%B3_h%C6%B0%E1%BB%9Bnghttp://vi.wikipedia.org/wiki/%C4%90%E1%BB%93_th%E1%BB%8B_c%C3%B3_h%C6%B0%E1%BB%9Bnghttp://vi.wikipedia.org/w/index.php?title=%C3%94t%C3%B4mat_h%E1%BB%AFu_h%E1%BA%A1n&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=%C3%94t%C3%B4mat_h%E1%BB%AFu_h%E1%BA%A1n&action=edit&redlink=1http://vi.wikipedia.org/wiki/Thu%E1%BB%99c_t%C3%ADnh_Markovhttp://vi.wikipedia.org/wiki/Thu%E1%BB%99c_t%C3%ADnh_Markovhttp://vi.wikipedia.org/wiki/X%C3%A1c_su%E1%BA%A5t_c%C3%B3_%C4%91i%E1%BB%81u_ki%E1%BB%87nhttp://vi.wikipedia.org/wiki/Bi%E1%BA%BFn_ng%E1%BA%ABu_nhi%C3%AAnhttp://vi.wikipedia.org/wiki/D%C3%A3y_(to%C3%A1n)http://vi.wikipedia.org/wiki/T%C3%ADnh_ch%E1%BA%A5t_Markovhttp://vi.wikipedia.org/wiki/Qu%C3%A1_tr%C3%ACnh_ng%E1%BA%ABu_nhi%C3%AAnhttp://vi.wikipedia.org/w/index.php?title=Andrei_Andreyevich_Markov&action=edit&redlink=1http://vi.wikipedia.org/wiki/To%C3%A1n_h%E1%BB%8Dc


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Markov a ra cc kt qu u tin (1906) v cc qu trnh ny. Andrey Nikolaevich

Kolmogorov (1936) a ra mt suy rng ti cc khng gian trng thi v hn m c.

Cc xch Markov c lin quan tichuyn ng Brown(Brownian motion) vTng hp ergodic,

hai ch quan trng ca vt l trong nhng nm u ca th k 20, nhng Markov c v phi

tham gia vo qu trnh pht trin ca ton hc, cn gi l s m rng ca lut s lncho cc s

kin c lp.

3.2.2 M hnh Markov

M hnh Markov n(ting Anh lHidden Markov Model-HMM) lm hnh thng ktrong

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,

v d cho cc ng dngnhn dng mu.

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 nthm 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 biHMMkhng trc tip ch ra dy cc trng thi.

Cc chuyn tip trng thi trong m hnh Markov
http://vi.wikipedia.org/wiki/Andrey_Nikolaevich_Kolmogorovhttp://vi.wikipedia.org/wiki/Andrey_Nikolaevich_Kolmogorovhttp://vi.wikipedia.org/wiki/Chuy%E1%BB%83n_%C4%91%E1%BB%99ng_Brownhttp://vi.wikipedia.org/wiki/Chuy%E1%BB%83n_%C4%91%E1%BB%99ng_Brownhttp://vi.wikipedia.org/wiki/Chuy%E1%BB%83n_%C4%91%E1%BB%99ng_Brownhttp://vi.wikipedia.org/w/index.php?title=T%E1%BB%95ng_h%E1%BB%A3p_ergodic&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=T%E1%BB%95ng_h%E1%BB%A3p_ergodic&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=T%E1%BB%95ng_h%E1%BB%A3p_ergodic&action=edit&redlink=1http://vi.wikipedia.org/wiki/Th%E1%BA%BF_k%E1%BB%B7_20http://vi.wikipedia.org/wiki/Th%E1%BA%BF_k%E1%BB%B7_20http://vi.wikipedia.org/wiki/Th%E1%BA%BF_k%E1%BB%B7_20http://vi.wikipedia.org/wiki/Lu%E1%BA%ADt_s%E1%BB%91_l%E1%BB%9Bnhttp://vi.wikipedia.org/wiki/Lu%E1%BA%ADt_s%E1%BB%91_l%E1%BB%9Bnhttp://vi.wikipedia.org/wiki/Lu%E1%BA%ADt_s%E1%BB%91_l%E1%BB%9Bnhttp://vi.wikipedia.org/w/index.php?title=M%C3%B4_h%C3%ACnh_th%E1%BB%91ng_k%C3%AA&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=M%C3%B4_h%C3%ACnh_th%E1%BB%91ng_k%C3%AA&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=M%C3%B4_h%C3%ACnh_th%E1%BB%91ng_k%C3%AA&action=edit&redlink=1http://vi.wikipedia.org/wiki/Qu%C3%A1_tr%C3%ACnh_Markovhttp://vi.wikipedia.org/w/index.php?title=Quan_s%C3%A1t&action=edit&redlink=1http://vi.wikipedia.org/wiki/Nh%E1%BA%ADn_d%E1%BA%A1ng_m%E1%BA%ABuhttp://vi.wikipedia.org/wiki/Nh%E1%BA%ADn_d%E1%BA%A1ng_m%E1%BA%ABuhttp://vi.wikipedia.org/wiki/Nh%E1%BA%ADn_d%E1%BA%A1ng_m%E1%BA%ABuhttp://vi.wikipedia.org/wiki/Nh%E1%BA%ADn_d%E1%BA%A1ng_m%E1%BA%ABuhttp://vi.wikipedia.org/w/index.php?title=Quan_s%C3%A1t&action=edit&redlink=1http://vi.wikipedia.org/wiki/Qu%C3%A1_tr%C3%ACnh_Markovhttp://vi.wikipedia.org/w/index.php?title=M%C3%B4_h%C3%ACnh_th%E1%BB%91ng_k%C3%AA&action=edit&redlink=1http://vi.wikipedia.org/wiki/Lu%E1%BA%ADt_s%E1%BB%91_l%E1%BB%9Bnhttp://vi.wikipedia.org/wiki/Th%E1%BA%BF_k%E1%BB%B7_20http://vi.wikipedia.org/w/index.php?title=T%E1%BB%95ng_h%E1%BB%A3p_ergodic&action=edit&redlink=1http://vi.wikipedia.org/wiki/Chuy%E1%BB%83n_%C4%91%E1%BB%99ng_Brownhttp://vi.wikipedia.org/wiki/Andrey_Nikolaevich_Kolmogorovhttp://vi.wikipedia.org/wiki/Andrey_Nikolaevich_Kolmogorov


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S tin ha ca m hnh Markov

Biu trn y lm ni bt cc chuyn tip trng thi ca m hnh Markov n. N cng c ch

biu din r rng s tin ha ca m hnh theo thi gian, vi cc trng thi ti cc thi im khc

nhau t1 v t2 c biu din bng cc tham bin khc nhau, x(t1) v x(t2).

Trong biu ny, n c hiu rng thi gian chia ct ra (x(t),y(t)) m rng ti cc thi gian

trc v sau nh mt s cn thit. Thng thng lt ct sm nht l thi gian t=0 hayt=1.

CU HI N TP

1. Trnh by phng php nhn dng t ring l ?

2. Trnh by phng php nhn dng t lin tc ?

3. Trnh by m hnh Markov v ng dng ca m hnh ny trong h thng x l ting ni ?


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CHNG IV: CC H THNG CHUYN VN BN THNH

GING NI

4.1 Phn tch ng m v vn bn

4.1.1 T vngCu trong vn bn c ngn cch vi nhau bi cc du cu. Cc du cu c cho trong

bng. Cn ch rng khi nim cuy nhm ch cc loi cu khc nhau (trn thut, hi...)

xc nh s bin i catn s cbn v c th khng cht chv ng php.

Loi du cu Cch vit

Du chm .

Du phy ,Du chm phy ;

Du hai chm :

Du chm than !

Du chm hi ?

Cc du ngoc ( ) [ ] { }

Do chng trnh ch xt cc vn bn didng text nn ton bvn bn c coi nh mt xu k

t.Cc cu c xc nh theo lu thut ton sau:

4.1.2 Xc nh cu trc ti liu

Sau khi c xc nh, cu c phn loi x l. Vi mcch th


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nghim tng hp cu, bo co ny ch chia cu lm ba loi:

Loi 1 (cu trn thut): tng ng vi cc du: ., ;), ], }

Loi 2 (cu hi): tng ng vidu cu: ?

Loi 3 (cu hi ln ging cui cu): du ,, !

S bin i cc thng s ca tn hiu ting ni tng hp ph thuc vo tng loi cu.

Vn ny c trnh by chi tit trong mc 4.6.2.

Cn c vo s bin i cc thng s ca tn hiu ting ni, cu c phn tch thnh cc t

i km vi cc thng s ca t. Cc thng s ca t bao gm:

S bin itn s c bn

Bin

TrngHnh di minh ho s bin i tn s cbn ca cc t theo sbin i tn s c bn ca cu.

Cc tc nhn mnh trong cu (v d thi trong cu hi) c bin

v trng ca t ny ln hn cc t khc.

Vic tch t trong cu c thc hin theo lu thut ton trn.


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4.1.3 Chun ha vn bn

tin x l v sau (s dng cc bng m ting Vit khc nhau), trc khi tch thnh hai

diphone tc chuyn thnh dng telex. Du ca tc vit cui t.

V d: t trng c chuyn thnh truwowngf

Vic chuyn t dng ting Vit thng thng sang dng telex tu thuc vo loi bng m

c sdng. Chng trnh s dng bng m 8 bit TCVN3- ABC4.1.4 Phn tch ngn ng

4.1.5 Chuyn i k t sang m thanh

Tdng biu din telex c tch thnh hai diphonebt u v kt thc tngng.

Diphone bt u c phn bit bng du _ pha trc, diphone kt thc c du _ pha

sau.

V d: t truwowngfc tch thnh hai diphone _truw v uwowng_

Mu cht ca vic tch mt t thnh hai diphone l pht hin c v tr bt u v ktthc ca nguyn m u tin (theo chiu t tri sang phi).

V d: nu tm c nguyn m (uw) th d dng tch t truwowng

thnh truw v uwowng.

Thut ton xc nh v tr bt u v kt thc ca nguyn m u tin

c cho trong hnh 4.7.

Trong lu 4.7. * ng vi qu trnh kim tra xem hai k t lin tip c phi l aa, aw,

ee, oo, ow, uw hay khng.

Vic xc nh diphone kt thc phi i km vi vic xc nh du ca t,


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v c trng hp diphone kt thc khng thto thnh t diphone khng du.

V d: tcc v ccu c diphone kt thc l ac_, diphone ny khng thto thnh

t diphone khng du nn phi cn c vo du ca t xc nh diphone l acs_ hay acj_.

Cc trng hp ny tng ng vi nhng diphone in m trong bng 4.1. a s cc

diphone clu trong csdliu vi tn l cch biu din diphone, v d diphone an_ ctn l an_ trong c s d liu, nhng vi diphone c cch biu din di, v duwowng_, th

tn lu trong c s d liu khc vi cch biu din wog_(tn ca cc diphone trong csd

liu vi kch thc 4 byte) nnc n chuyn i cch biu din diphone ph hp vi tn trong c

s d liu.

4.2 Tng hp ting ni

4.2.1 Cc tnh cht ca tng hp ting ni

Tng hp ting ni l pht sinh ting ni t sng ting ni. Trong vi thp nin gny, cc

b tng hp ting ni c cht lng ngy cng cao.Tuy nhin cht lng ca cc phng php


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hin nay mi ch t n mc ph hp cho mt vi ng dng, chng hnnha phng tin v

truyn thng.

Hin nay c ba phng php tng hp ting ni. Phng php n gin nht pht sinh

ting ni tng hp l pht cc mu ting ni thu t ting ni t nhin (nh cc t hoc cu).

Phng php ny cho cht lng tng i tt nhng gp phi hn ch l s lng tvng trongcsdliurt ln. Bn cnh ting ni cng c th to ra bng cch m phng h thng

pht m. Phng php ny cho cht lng rt tt nhng thc hin kh phc tp. Mt phng

php na cng c dng tng hp ting ni l tng hp formant. Cc phng php tng

hp ting ni cng vi nhng cim cbn nht s c gii thiu trong phn tip theo.

4.2.2 Tng hp ting ni bng cc Formant

Phng php tng hp formant (formant synthesis) yu cu phi tng hp c ti thiu 3formant hiuc ting ni, v c c ting ni cht lng cao th cn ti 5 formant.

Ting ni c to ra t cc b tng hp formant vi thnh phn chnh l cc b cng hng.

Tu theo cch b tr cc b cng hng m ta c b tng hp formant l ni tip hay song song.

a. B tng hp formant ni tip

B tng hp formant ni tip l mt b tng hp formant c cc tng ni tip, u ra ca b

cng hng ny l u vo ca b cng hng kia.

b. B tng hp formant song songB tng hp formant song song bao gm cc b cng hng mc song song. u ra l kt

hp ca tn hiu ngun v ttc cc formant. Cu trc song song cn nhiu thng tin iu khin

hn.

4.2.3 Tng hp ting ni bng ghp ni

Tng hp bng cch ghp ni cc m c tng hp t cc li ni t nhin c thu

t trc c l l cch d nht sn sinh li ni. Phng php tng hp ghp ni cho cht

lng cao v tng i t nhin. Phng php ny rt ph hp vi cc h thng pht thanhv cc h thng thng tin. Tuy nhin phng php ny thng ch p dng cho mt ging v phi

s dng nhiu b nh hn cc phng php khc do s lng t vng rt ln. khc phc

nhc im ny ngi ta xy dng cc phng php tng hp ghp ni t nhng n v nh

nh m v, m tit, diphone (m v kp)... Ngoi cc diphone, chng ta cn s dng

triphone, tetraphone hay syllable, demisyllable, nhng ch yu vn l cc diphone, c thu t

ting ni t nhin. Cc diphone c ct ra t tn hiu ri sau c tng hp li theo yu cu

da trn mt thut ton ghp ni.Phng php ny c mt s khc bit so vi cc phng php khc:


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Xuthin s bin dng ca ting ni tng hp do tnh khng lin tc ca vic ghp

ni cc diphone vi nhau. V vy phi s dng bin php lm trn tn hiu.

B nhyu cu cao, nht l khi cc n v ktni di nh l cc m v hay cc t.

Su tm v gn nhn d liu ting ni cn nhiu thi gian v cng sc. V l

thuyt tt c cc mucn phic lu tr. S lng v chtlng cc mu lu tr

l mt vn cn gii quyt khi tin hnh lu tr.

Hin nay phng php ny ang c s dng rng ri trn th gii v ngy cng cho

cht lng tt hn nh s tr gip ca my tnh.

Phn tip theo s gii thiu v mt phng php tng hp ghp ni c

p dng ph bin cho tn hiu ting ni, phng php ghp ni da trn gii thut PSOLA.

a. Phng php tng hp PSOLA

PSOLA (Pitch Synchronous Overlap Add) l phng php tng hp da trn s phn tch

mt tn hiu thnh mt chui cc tn hiu thnh phn. Khi cng xp chng (overlap-add) cc

tn hiu thnhphn ta c thkhi phc li tn hiu ban u.

PSOLA thao tc trc tip vi tn hiu dng sng, khng dng btc loi m hnh no nn

khng lm mt thng tin ca tn hiu. PSOLA cho php iu khin c lp tn s c bn, chu

k c bn v cc formant ca tn hiu. u im chnh ca phng php PSOLA l gi

nguyn ng bao ph khi thay i tn scbn (pitch shifting). Phng php ny cho php

bin i tn hiu ngay trn min thi gian nn chi ph tnh ton rt thp. PSOLA c dungrt ph bin vi tn hiu ting ni.

b. Cc phin bn ca PSOLA

Da trn PSOLA, ngi ta a ra nhiu phin bn khc nhau, di y l cc phin bn chnh:

TD-PSOLA

Phng php TD-PSOLA (Time Domain- Pitch Synchronous Overlap Add) l phin bn

min thi gian ca PSOLA (TD-PSOLA). Phng php ny thao tc vi tn hiu trn min thi

gian nn c s dng nhiu v hiu qu trong tnh ton ca n. Phng php ny s c

trnh by chi tit trong chng tip theo.

FD-PSOLA

Phng php tng hp FD-PSOLA (Frequency Domain- Pitch

Synchronous Overlap Add) l phng php bao gm cc bc ging nh TD- PSOLA

nhng thao tc trn mintn s. Phng php ny c chi ph tnh ton cao hn TD-PSOLA.

i vi mi trng hp ring bit th mi phng php

s cho hiu qu khc nhau, nnphi da vo tng hon cnh chn phng php thch hp. LP-PSOLA


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Ngoi cc phng php trn min thi gian, min tn s, cn c mt phng php

gi l phng php d on tuyn tnh (Linear Prediction - Pitch Synchronous Overlap

Add). Phng php don tuyn tnh cthit k

m ho ting ni nhng phng php ny cng c th dng cho tng hp.

C s ca phng php d on tuyn tnh da trn cc muy(n) c th ly xp xhoc d on tp mu trc y(n-l) ny(n-p) vi sai s nh nht. Tn hiu kch thch

c ly xp x bng mt dy cc tn hiu ting ni v nhiu ngu nhin. Tn hiu ngun

c cho qua b lc s vi h s a(k).

Phng php LP-PSOLA cho kt qu cha tt. Ngi ta ci bin

phng php ny thu c chtlng tt hn, m i din l phng php WLP (Warped

Linear Prediction).

4.2.4 nh gi cc h thng tng hp ting ni

Sau khi gii thiu nhng cimcbn nht ca cc phng php tng hp ting

ni ta c th rt ra mt s nhn xt v cc phng php ny. Cc nhn xt ny nhm

mc nh a ra nh gi v ba phng php da trn cht lng ting ni tng hp, chi ph

tnh ton v kch thc d liu.

Vchtlng ca tingni tng hp: Trong baphng php ni trn

th phng php m phng b my pht m v nguyn tc s cho cht lng tt

nht.tc iu ny th vn quan trng l lm sao m phng chnh xcb my pht m ca con ngi. Cng vic ny hon ton khng n gin, mc

d c s tr gip ca my tnh nhng do cu trc phc tp ca b my pht

m nn chi ph tnh ton

srt ln. Trong hai phng php cn li th thc t cho thy phng php ghp ni

thng cho cht lng tt hn.

Vhiu qu tnh ton: R rng l phng php m phng b my pht m i hi

chi ph tnh ton ln nht v phi m phng mt cch chnh xc nht b my phtm phc tp ca con ngi. Hai phng php cn li c chi ph tnh ton thp

hn do cim cc thut ton c

s dng.

V kch thc d liu: Phng php ghp ni c kch thc d liu ln nht do

s lng t vng l rt ln. Hai phng php cn li do khng phi lu tr cc

mu nn c kch thc d liu nh hn.

CU HI N TP1. Trnh by ngha ca vic chun ha vn bn?


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2. Trnh by qu trnh chuyn i k t sang m thanh?

3. Trnh by cc tnh cht ca tng hp ting ni?

4. Trnh by tng hp ting ni bng cc Formant?

5. Trnh by tng hp ting ni bng phng php ghp ni?


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MT S THI MU


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Trng i Hc Hng Hi Vit NamKhoa Cng ngh Thng tin

B MN H THNG THNG TIN-----***-----

THI KT THC HC PHN

Tn hc phn:X L TING NINm hc: 2009- 2010

thi s: K duyt :

1Thi gian: 60 pht

Cu 1: (3 im)

- Trnh by khi nim chung v cc ng dng ca x l ting ni?- Phn bit 2 h thng: nhn dng ting ni v tng hp ting ni?- Cc tnh cht c th thay i c trong tn hiu ting ni?

Cu 2: (3 im)- Trnh by phng php biu din tn hiu ting ni di dng sng theo thi gian? - M ha ting ni dng sng v hng: xung tuyn tnh?

Cu 3: (4 im)

- M hnh chung ca h thng nhn dng ting ni?- M hnh markov? ng dng ca Markov trong nhn dng ting ni?

----------------------------***HT***----------------------------

Lu : -Khng sa, xa thi, np li sau khi thi


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THI KT THC HC PHN


thi s: K duyt :

2Thi gian: 60 pht

Cu 1: (3 im)

- Trnh by khi nim chung v cc ng dng ca x l ting ni?- Phn bit 2 h thng: nhn dng ting ni v tng hp ting ni?

Cu 2: (3 im)- Trnh by phng php biu din tn hiu ting ni trong min khng gian 3 chiu:Spectrogram.?

- M ha ting ni dng sng v hng: xung tuyn tnh?Cu 3: (4 im)

- Trnh by h thng chuyn i vn bn thnh ging ni?- Cc tnh cht c th thay i c trong tn hiu ting ni?

----------------------------***HT***----------------------------



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THI KT THC HC PHN


thi s: K duyt :

3Thi gian: 60 pht

Cu 1: (3 im)


Cu 2: (3 im)- Trnh by phng php biu din tn hiu ting ni trong min tn s? - Trnh by v Formant v Antiformant?

Cu 3: (4 im)

- M hnh chung ca h thng nhn dng ting ni?- Cc tnh cht c th thay i c trong tn hiu ting ni?

----------------------------***HT***----------------------------



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THI KT THC HC PHN


thi s: K duyt :

4Thi gian: 60 pht

Cu 1: (3 im)


Cu 2: (3 im)- Trnh by phng php biu din tn hiu ting ni trong min tn s? - M ha ting ni dng sng v hng: xung tuyn tnh?

Cu 3: (4 im)

- Cc phng php nhn dng ting ni?- Cc tnh cht c th thay i c trong tn hiu ting ni?

----------------------------***HT***----------------------------



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THI KT THC HC PHN


thi s: K duyt :

5Thi gian: 60 pht

Cu 1: (3 im)


Cu 2: (3 im)- Trnh by phng php biu din tn hiu ting ni trong min khng gian 3 chiu:Spectrogram.?

- Phn tch c tnh ng m, m hc ca ting ni?Cu 3: (4 im)

- Trnh by h thng chuyn i vn bn thnh ging ni?- Cc tnh cht c th thay i c trong tn hiu ting ni?

----------------------------***HT***----------------------------Lu : - Khngsa, xa thi, np li sau khi thi


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THI KT THC HC PHN


thi s: K duyt :

6Thi gian: 60 pht

Cu 1: (3 im)


Cu 2: (3 im)- Trnh by phng php biu din tn hiu ting ni trong min khng gian 3 chiu:

Spectrogram.?- Trnh by v Formant v Antiformant?

Cu 3: (4 im)

- Trnh by h thng chuyn i vn bn thnh ging ni?- Trnh by cu trc ca m hnh Markov? Cc vn trong m hnh Markov?

----------------------------***HT***----------------------------



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THI KT THC HC PHN


thi s: K duyt :

7Thi gian: 60 pht

Cu 1: (3 im)


Cu 2: (3 im)- Trnh by phng php biu din tn hiu ting ni trong min khng gian 3 chiu:

Spectrogram.?- Phn tch c tnh ng m, m hc ca ting ni?

Cu 3: (4 im)

- Trnh by h thng chuyn i vn bn thnh ging ni?- M hnh markov? ng dng ca Markov trong nhn dng ting ni?

----------------------------***HT***----------------------------



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THI KT THC HC PHN


thi s: K duyt :

8Thi gian: 60 pht

Cu 1: (3 im)


Cu 2: (3 im)- Phn tch c tnh ng m, m hc ca ting ni?- M ha ting ni dng sng v hng: xung tuyn tnh?

Cu 3: (4 im)

- Cc phng php nhn dng ting ni?- Trnh by cu trc ca m hnh Markov? Cc vn trong m hnh Markov?

----------------------------***HT***----------------------------



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THI KT THCHC PHN

Tn hc phn:X L TING NINm hc: x

thi s: K duyt :

xx

Thi gian: 60 pht

Cu 1: (2 im)m tit l g? Trnh by c im v cu trc ca m tit ting Vit.

Cu 2: (2 im)Trnh by kin trc chung ca h thng chuyn vn bn thnh ting ni v chc nng catng thnh phn.

Cu 3: (3 im)a) Tm bin i Fourier X(ej) ca dy x(n) = nnu(n-2) vi ||


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THI KT THCHC PHN


thi s: K duyt :

xx

Thi gian: 60 pht

Cu 1: (2 im)Trnh by hiu bit ca bn v c im m hc ca cc loi nguyn m, ph m. Ly v d.

Cu 2: (2 im)Trnh by gii php tng hp ting ni ting Vit bng cch ghp cc m v kp (diphone).

Cu 3: (3 im)a) Tm bin i Fourier X(ej) ca dy x(n) = nnu(-n+2) vi ||>1b) Tm bin i Fourier ri rc N im X(k) ca dy x(n),

Cu 4: (3 im)a) Ph ca tn hiu ting ni l g? Cc loi tn s c s dng khi v th ph? b) nh ph ca tn hiu ting ni l g? Trnh by cc bc thc hin phn tch ph tn hiu

ting ni?

----------------------------***HT***----------------------------



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THI KT THCHC PHN


thi s: K duyt :

xx

Thi gian: 60 pht

Cu 1: (2 im)Trnh by qu trnh chun ha vn bn trong h thng chuyn vn bn thnh ting ni.

Cu 2: (2 im)Trnh by gii php tng hp ting ni ting Vit bng cch ghp ph m u v phn vn.

Cu 3: (3 im)a) Tm bin i Fourier X(ej) ca dy x(n) = nnu(-n-2) vi ||>1b) Tm bin i Fourier ri rc N im X(k) ca dy x(n) = ej(2/N)k0 vi 0 n N-1

Cu 4: (3 im)a) Ph ca tn hiu ting ni l g? Cc loi tn s c s dng khi v th ph? b) nh ph ca tn hiu ting ni l g? Trnhby cc bc thc hin phn tch ph tn hiu

ting ni?

----------------------------***HT***----------------------------



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THI KT THCHC PHN


thi s: K duyt :

xx

Thi gian: 60 pht

Cu 1: (2 im)Trnh by vn to ng iu khi tng hp ting ni.

Cu 2: (2 im)Trnh by cc vn gp phi khi tng hp ting ni bng cch ghp ni cc n v m.

Cu 3: (3 im)a) Tm bin i Fourier X(ej) ca dy x(n):

b) Tm bin i Fourier ri rc N im X(k) ca dy x(n):

Cu 4: (3 im)a) Ph ca tn hiu ting ni lg? Cc loi tn s c s dng khi v th ph? b) nh ph ca tn hiu ting ni l g? Trnh by cc bc thc hin phn tch ph tn hiu

ting ni?

----------------------------***HT***----------------------------



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Khoa Cng ngh Thng tinB MN H THNG THNG TIN

-----***-----

THI KT THCHC PHN


thi s: K duyt :

xx

Thi gian: 60 pht

Cu 1: (2 im)Trnh by hiu bit ca bn v c im m hc ca cc loi nguyn m, ph m. Ly v d.

Cu 2: (2 im)Trnh by v nhn dng ting ni bng phng php da vo nhn dng mu.

Cu 3: (3 im)a) Tm bin i Fourier X(ej) ca dy x(n)= (n+1)nu(n) vi ||

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17412 - Bai Giang Xu Ly Tieng Noi