Ti liu tham khoLa parole et son traitement automatique Calliope, Masson, 1989 Traitement de la parole Rene Boite et Murat Kunt, Presse Polytechnique Romandes, 1987 Fundamentals of Speech Signal Processing Saito S., Nakata K. , Academic Press, 1985 Digital Processing of Speech Signals Lawrence R. Rabiner, Ronald W. Schafer, Prentice-Hall .1978 PrenticeDiscrete-Time Processing of Speech Signals DiscreteJohn R. Deller, John G. Proakis, Hansen John H. L. 1999 Ting Vit hin i (Ng m, ng php, phong cch) Ti Vi hi (Ng ng ph c Nguyn Hu Qunh, H Ni, 1994 Nguy H Qu H Dn lun Ngn ng hc lu ng Nguyn Thin Gip, on Thin Thut , Nguyn Minh Thuyt, H Ni, 1994 Nguy Thi Gi o Thi Thu Nguy Thuy H1

X L TING NITrnh Vn Loan Tr B mn K thut My tnh K thu M t Khoa CNTT, HBK H Ni H

http://dce.hut.edu.vn

2

Ni dung1. Mt s khi nim c bn M s kh ni b 2. X l tn hiu ting ni X t hi ti n 3. M ho ting ni ho ti n 4. Tng hp ting ni T h ti n 5. Nhn dng ting ni Nh d ti n

1. Mt s khi nim c bnX l thng tin cha trong tn hiu ting ni ch t hi ti n nhm truyn, lu tr tn hiu ny hoc tng nh truy tr hi n ho t hp, nhn dng ting ni. nh d ti n Cc nghin cu c tin hnh x l c ti h ting ni yu cu nhng hiu bit trn nhiu ti n c nh hi bi nhi lnh vc ngy cng a dng: t ng m v v ng c d t ng v ngn ng hc cho n x l tn hiu... ng x t hi3 4

1

Mc chM ho mt cch c hiu qu tn hiu ho c c hi qu hi ting ni truyn v lu tr ting ni. ti n truy v tr ti n Tng hp v nhn dng ting ni tin h nh d ti n ti ti giao tip ngi-my bng ting ni. ti ng b ti n Tt c cc ng dng ca x l ting c d c x ti ni u cn phi da trn cc kt qu c ph d c k qu ca phn tch ting ni t ti n5

Mt s khi nim c bnPhn bit ting ni v m thanh bi ti n v Ting ni c phn bit vi cc m Ti n bi v c thanh khc bi cc c tnh m hc c kh b c t h c ngun gc t c ch to ting ni. ngu g t ch ti n C 2 loi ngun m lo ngu tun hon (dy thanh rung) tu ho tp m (dy thanh khng rung)6

B my pht m

B my pht m

7

8

2

B my pht m

S khi b my pht m

NASAL CAVITY: Khoang mi SOFT PALATE: Vm ming mm EPIGLOTTIS: Np thanh qun VOCAL FOLDS (CORDS): Dy thanh OESOPHAGUS: Thc qun TRACHEA: Kh qun PHARYNX: Hng

9

10

1. Mt s khi nim c bn s kh ni c

Thanh mn

Thanh mn cc v tr ht, th,pht m, ni th tho v tr th ,ph n th th

Thanh mn Dy thanh

A. Glotte pendant la respiration B. Glotte pour la phonation 1. Glotte 2. Cordes vocales 3. Epiglotte 5. Cartilages arytnodes11 12

3

Dy thanh trong mt chu k dao ng

Biu din tn hiu ting niDng sng theo thi gian s th

13

14

File WAVTn s ly mu: 8kHz, F1= 11025 Hz, s m 2F1, 4F1 (16kHz, 10kHz) S bit/mu: 8,16 bit/m Mono, Stereo

Biu din tn hiu ting niPh tn hiu ting ni Ph hi ti n

15

16

4

Biu din tn hiu ting niSpectrogram (Sonagram)

Biu din tn hiu ting ni

17

18

Biu din tn hiu ting ni

Biu din tn hiu ting niThu bng micro khc loi b kh lo

19

20

5

Biu din tn hiu ting niHai ging khc nhau cho cng mt m gi kh c m

Biu din tn hiu ting niCng ngi ni, cng mt m ng n c m

21

22

Nng lng, t l bin thin qua gi tr khng l t bi gi trfile:C:\wav\1-6-5-8-10-0.wav, ss,es:1, 43029, window length, shift (samples):160, 40, wtype:1 0.4 amplitude 0.2 0 -0.2 -0.4 -0.6 0 short-time energy 4 3 2 1 0.5 short-time magnitude 15 10 5 0.5 80 60 40 20 0 0.5 1 1.5 2 time in seconds 2.5 3 3.5 1 1.5 2 2.5 3 3.5 ZC 1 1.5 Mn 2 2.5 3 3.5 0.5 1

To m hu thanh Formant v antiformant3.5

Signal 1.5 En 2 2.5 3

zero crossing rate

23

24

6

To m v thanh

Mt s c im ng m ting Vitn m tit ti C thanh iu (6), bin i thanh iu i bi i km theo bin i ngha bi ngh Khng bin i hnh thi bi h th

25

26

Mt s c im ng m ting VitH thng m v: 14 nguyn m (11 th v nguyn m n, 3 nguyn m i, 22 ph m) n, i, ph1 2 3 4 5 6 7 8 9 10 11 i,y e a o u ch ch ch ch e d d a ha mt b ph ph n cn c t t t co ro l m27

Mt s c im ng m ting VitH thng m v: 22 ph m th v ph1 2 3 4 5 6 7 la tha, tha, lt l 8 9 10 11 b p v ph m t th d,gi n l bng bnh b p p vn v phi pha m mng m t ai tin tng t th thn th duyn, gi gi nng long lanh 12 13 14 15 16 17 18 19 20 21 22 tr s r ch nh ng,ngh c,k,q kh g,gh h x trng tr sinh vin rng chng nhc nh ng ngh con,kt,qua con,k khc kh g gh gh h h xa xi28

1

ia,y,ya,i (c ia, y) ua,u (c ua) a, a, (c a) a)

kia ka, yu k kiu, khuya, tin ki tin ti tua rua, lun

2 3

7

Mt s c im ng m ting VitPhn loi nguyn m theo nng lo ca li v chuyn ng ca li l v chuy c l nng Hng trc tr gia gi sau u i cao e o trung bnh b e a thp th

Mt s c im ng m ting VitPhn loi nguyn m theo m ca lo ming v chuyn ng ca li mi v chuy c lHng m hp hi hp h hi rng r rng ihng trc tr ia,y,ya,i hng sau khng trn mi hng sau trn mi

a

a

u ua o

e

29

30

Mt s c im ng m ting VitPhn loi ph m theo tc hay xt, lo ph t x hu thanh hay v thanh, mi ha h mV tr cu m Phng thc cu m Bt hi V thanh Tc n Khng bt hi Hu thanh Vang mi V thanh Hu thanh Vang bn p Mi u li Rng th t tr ch c,k,qu Vm ming Mt li Cui li Hng

Mt s c im ng m ting Vitm tc: ting n, pht sinh do lung kh t phi i ra b cn tr hon t ti n ph lu kh ph b tr ho ton, phi ph v s cn tr thot ra. to ph ph tr tho m xt: ting c xt, pht sinh do lung khng kh i ra b cn tr x ti c ph lu kh b tr khng hon ton (ch b kh khn), phi lch qua mt khe h nh v ho to (ch kh khn), ph l m h nh trong khi thot ra nh vy phi c xt vo thnh ca b my pht tho v ph c v th c b ph m. Ph m bn: u li tip xc vi li chn li thot ca khng kh, Ph bn: l ti x v l ch l tho c kh buc n phi lch qua khe h hai bn cnh li tip gip vi m bu n ph l h c l ti gi v m m ra ngoi to nn ting xt nh (l). ngo t ti x nh Lung khng kh thot ra ngoi b cn tr, to nn ting xt hay ting Lu kh tho ngo b tr t ti x ti n, dng tn hiu khng tun hon gi l ting ng (n). d t hi tu ho g l ti ( Trong khi pht m mt s ph m, dy thanh cng hot ng ng ph m s ph c ho thi to nn ting thanh. th t ti Ph m c t l ting ng ln hn gi l ph m n. Ph c ti l g l ph Ph m c t l ting thanh ln hn gi l ph m vang. Ph c ti l g l ph

b m ph v

n x d,gi l nh s r ng,ngh kh g31

Xt

n

h

32

8

Dng sng mt s t ting Vit

Dng sng mt s t ting Vit

ph

b

tr

tm

v

ch

tm33

nh34

Dng sng mt s t ting Vit

Dng sng mt s t ting VitCHUR.WAV, Fs = 11025Hz, 5669 samples, Time = 514ms 0.5

0.4

0.3

0.2

Amplitude

k

0.1

l

0

-0.1

-0.2

-0.3

-0.4

-0.5 0 50 100 150 200

kh

250 Time in ms

300

350

400

450

500

35

36

9

Dng sng mt s t ting Vit0.4 DDEER.WAV, Fs = 11025Hz, 5278 samples, Time = 479ms 0.3

Dng sng mt s t ting VitKHAR.WAV, Fs = 11025Hz, 7718 samples, Time = 700ms 0.4

0.2

0.2

0.10

Amplitude

0

Amplitude

-0.2

-0.1-0.4

-0.2

-0.3

-0.6

-0.4 0 50 100 150 200 250 Time in ms 300 350 400 450

-0.8

0

100

200

300 Time in ms

400

500

600

37

38

Dng sng mt s t ting VitN G H IR .W A V , F s 0 .3 = 1 1 0 2 5 H z , 6 7 0 7 s a m p le s , T im e = 6 0 8 m s

Dng sng mt s t ting VitXOA.WAV, Fs = 11025Hz, 7690 samples, Time = 697ms 0.6

0.40 .2

0 .1

0.2

Amplitude

0

-0 .1

Amplitude0 1 0 0 2 0 0 30 0 T im e in m s 4 0 0 5 0 0 6 0 0

0

-0.2

-0 .2

-0.4-0 .3

-0.6

-0.8

39

0

100

200

300 Time in ms

400

500

600

40

10

Dng sng mt s t ting VitP H A I R . W A V , F s = 1 1 0 2 5 H z , 6 9 3 4 s a m p le s , T im e = 6 2 9 m s 0.6

Dng sng mt s t ting VitMEJ.WAV, Fs = 11025Hz, 4922 samples, Time = 446ms 0.2

0.150.4

0.10.2

0.05Amplitude 0

Amplitude0 100 200 300 T im e in m s 400 500 600

0

-0 . 2

-0.05

-0 . 4

-0.1

-0 . 6

-0.15

41

-0.2 0 50 100 150 200 250 Time in ms 300 350 400

42

Dng sng mt s t ting VitBUF.WAV, Fs = 11025Hz, 6779 samples, Time = 615ms 0.6

Dng sng mt s t ting VitTAMS.WAV, Fs = 11025Hz, 4989 samples, Time = 452ms 0.4

0.3

0.40.2

0.1

0.20

Amplitude

Amplitude

-0.1

0

-0.2

-0.2

-0.3

-0.4

-0.4

-0.5

-0.6

-0.6 0 100 200 300 Time in ms 400 500 600

43

0

50

100

150

200 Time in ms

250

300

350

400

450

44

11

Dng sng mt s t ting VitGIAF.WAV, Fs = 11025Hz, 8772 samples, Time = 796ms 0.4

Dng sng mt s t ting VitVIF.WAV, Fs = 11025Hz, 9872 samples, Time = 895ms 0.3

0.30.2

0.2

0.1

0.1

0 AmplitudeAmplitude 0

-0.1

-0.2-0.1

-0.3

-0.4

-0.2

-0.5

450 100 200 300 400 Time in ms 500 600 700

-0.3 0 100 200 300 400 500 Time in ms 600 700 800

46

Dng sng mt s t ting VitKHOONG.WAV, Fs = 11025Hz, 6743 samples, Time = 612ms 0.4

Dng sng mt s t ting VitNHAAN.WAV, Fs = 11025Hz, 5713 samples, Time = 518ms

0.6

0.20.4

0 AmplitudeAmplitude

0.2

-0.2

0

-0.4

-0.2

-0.6

-0.4

470 100 200 300 Time in ms 400 500 600

0

50

100

150

200

250 Time in ms

300

350

400

450

500

48

12

Dng sng mt s t ting VitLAJ.WAV, Fs = 11025Hz, 5442 samples, Time = 494ms

Dng sng mt s t ting VitTRIJ.WAV, Fs = 11025Hz, 4108 samples, Time = 373ms 0.4

0.40.3

0.2

0.2

Amplitude

Amplitude

0

0.1

0

-0.2-0.1

-0.4-0.2

-0.6

-0.3

0

50

100

150

200

250 Time in ms

300

350

400

450

49

0

50

100

150

200 Time in ms

250

300

350

50

Dng sng mt s t ting VitSOOS.WAV, Fs = 11025Hz, 8888 samples, Time = 806ms 0.4

Dng sng mt s t ting VitTIMF.WAV, Fs = 11025Hz, 5589 samples, Time = 507ms 0.6

0.3

0.40.2

0.1

0.2 Amplitude

Amplitude

0

0

-0.1

-0.2

-0.2-0.3

-0.4

-0.4

-0.5 0 100 200 300 400 Time in ms 500 600 700 800

510 50 100 150 200 250 Time in ms 300 350 400 450 500

52

13

M hnh to ting ni (Fant-1960)u(n)T0

M hnh ton im cc (AR)Ti bc x Tib x bc x R(z) R(z)

Lc thng Lc thng thp G(z) thp G(z)

Tuyn m Tuy m Tuyn V(z) V(z)

T( z ) = G ( z )V ( z )R ( z ) =x(n)

A( z )

G(z ) =

A (1 + z 1 )(1 + z 1 )V(z ) = BK

R ( z ) = C(1 z 1 )

A(z): Hm truyn t ca b lc o H truy c b T( z ) = A( z )A(z) = 1 +p2K +1 i =1

azi

i

A(z) = a i z ii =0

p

a0 = 1

(1 + b1k z 1 + b 2k z 2 )k =153

x( n ) + a i x ( n i ) = u ( n )i =1

P = 2K+154

M hnh ARMA1 2 C( z ) + = T( z ) = A1 ( z ) A 2 ( z ) A( z )

Di thngBin C( z ) = c i z -ii=0 q

c0 = 1

1 1/ 2 Di thng Bk

x( n ) + a i x( n i ) = c i u ( n i )i =1 i =0

p

q

Fk55

Tn s

56

14

2. X l tn hiu ting niPhn tch ph t phB lc hiu chnh Ca s Hamming FFT Log |.|

x(n)

N

B lc hiu chnh H(z) = 1 az-1, a = 0,95..0,98 hi ch57

frame

0

58

X l ng hnh (homomorphic)s(n)=h(n)*e(n) S() = H().E() S( H( ).E( log[S()]= log[H()]+ log[E()] log[S( log[H( log[E( F-1{log[S()]} = F-1{log[H()]} + F-1{log[E()]} {log[S( {log[H( {log[E( -1{log[S()]} = $ F {log[S( s(n) $ F-1{log[H()]} = h(n) {log[H( -1{log[H()]} = $ F {log[H( e(n)

S khi x l ng hnh

B lc hiu chnh

Ca s Hamming

FFT

Log |.|

FFT-1

$ $ $ s(n) = h(n) + e(n)59

$ s(n)60

15

V dc(n)T0 T0

Tin on tuyn tnh (Linear Prediction Coding)M hnh AR hTin on o Sai s tin on s o Sai s bnh phng ton phn s to ph Ti thiu ha sai s thi h s61

x(n) + ai x(n i) = u(n)i=1

p

$ $ x(n) = ai x(n i)i=1

p

$ e(n) = x(n) x(n)E = e2 (n)n

) h(n)

E $ ai

= 0, i = 1,2,...,p62

Xc nh tn s c bnGi tr F0 ph thuc vo gii tnh v Gi tr ph thu v gi t v la tui tu Ging nam: 80..250 Hz Gi Ging n: 150..500 Hz Gi nTinTn hiu ting ni

Mt s phng php xc nh FoDa vo hm t tng quan v h t Da vo hm vi sai bin trung bnh v h b Dng b lc o v hm t tng b v t quan X l ng hnh h

Xc nh Fo

nh gi kt qu

x l

63

64

16

Da vo hm t tng quanTnh hm t tng quan R(k) ca tn hiu ting ni h t t hi ti n x(n) N 1 k

Phng php t tng quan c ci tinHn ch, loi b |x| < CL ch lo b

R(k ) =

n =0 Fs = 10 kHz, N = 300, K = 150.Tm cc i trong khong (0, K) 150.T c kho

x(n) x(n + k ) k = 0,1,..., K

65

66

Da vo hm vi sai bin trung bnh (Average Magnitude Difference Function)D (k ) = x(n + m) x(n + m k ) k = 0,1,..., Km=02 D(iP) = 0, i = 0,1,... N u (n) N u (n) n=0 n=0

V d0.3 0.3 0.2 0.2 0.1 0.1 0 0 -0.1 -0.1 -0.2 -0.2 700 700 0.015 0.015 0.01 0.01 0.005 0.005 0 0 -0.005 -0.005 -0.01 0 -0.01 0.2 0.2 0.15 0.15 D(k) D(k) 0.1 0.1 750 750 800 800 850 850 900 900 950 n 950 n 1000 1000 1050 1050 1100 1100 1150 1150

N 1

1

1 N-1 D(k ) = [ x(n + m) x(n + m k )]2 N m=0 1/ 2 1 k = 0,1,..., K = [2r (0) 2r (k )] N vi < 167

1/2

r(k) r(k)

x(n) x(n)

N 1

1

N 1

1/ 2

0

50 50

100 100

150 k 150 k

200 200

250 250

300 300

0.05 0.05 0 0 0 50 50 100 100 150 k 150 k 200 200 250 250 300 300

0

68

17

Dng b lc o (Simplified InverseFilter Tracking)10kHz

X l ng hnh

Thng thp th 4700Hz

Thng thp 900Hz

1-z-1

W(n) W(n)

LPC(p=4) LPC(p=4)

A(z)

Hm t tng quan

HT/VTnh gi kt qu Ni suy Tm cc i

Fo69 70

Xc nh formantTham s cn xc nh s x Formant Fk Di thng Bk

X l ng hnhTn hiu ting ni

B lc hiu chnh

Ca s

FFT

Phng php ph X l ng hnh h LPCLog10|.| FFT-1 FFT

Wc(n)71 72

18

X l ng hnh

Phng php LPCB lc hiu chnh

Ca s

Tnh h s ai Tm cc i Quyt nh

s(n)Tnh1/ |A(ej)| bng FFT

Fk,Bk

Tnh nghim ca A(z)73 74

3. M ha ting niDy thao tc m ho v gii m t ho giNhiu, suy gim, sai s

Mt s tnh cht thng k ca tn hiu ting niMt xc sut su N : s lng mu x(n) l mc bin trong khong [-/2, +/2] kho [ /2, /2]

Lc1 Lc1Nhiu, suy gim, sai s

AD AD

M ho M ho

Gii m Gii m

DA DA

Lc2 Lc2

n [-N,...,N] ,...,N x egodic v dng v

px ( ) = lim [ N /(2 N + 1)]N 075 76

19

Gi tr trung bnh v phng saiGi tr trung bnh ca tn hiu dng Gi tr b c t hi d N 1 x = px ( ) d = lim N x(n) N 2 N + 1 n = vi tn hiu ting ni x = 0 t hi ti n Phng sai

Lng t tc thi (khng nh)Lut lng t y = Q(x) c nh ngha: Lu l t Q(x) ngh (L+1) mc tn hiu x(0), x(1), ..., x(L) m t hi L mc lng t ho m l t ho

x2 =

2 px ( ) d = lim

N 1 N x 2 (n) N 2 N + 1 n =77

Mi mc lng t ho biu din bng t b bit m l t ho bi di b t L = 2b. Sai s lng t (tp m lng t) e = Q(x) - x s l t (t l t Bc lng t : hiu 2 mc tn hiu k nhau B l t hi m t hi k (i) = x(i)-x(i-1) x(i)-x(iThng lng I = bFs (bit/s). Fs : tn s ly mu l t s m

78

Thng lngTn hiu lng t 8 bit (256 mc), Fs = 8 hi l t m kHz Thng lng = 64 kbit/s l Tn hiu lng t 16 bit (65536 mc), hi l t m Fs = 16 kHz Thng lng = 256 kbit/s , l 1 gi ting ni ~100 Mbyte gi ti n ~100 Cn phi m ho tn hiu ting ni (MPEG, ph ho hi ti n GSM, G723, ...) truyn ting ni trn mng ti n truy m hoc lu tr ho tr79

Thng lngTn s ly s mu (kHz) 48 44,1 32 22 8 S bit cho 1 mu m 16 16 16 12 8 Thng lung kbit/s lu 768 705,6 512 264 64 Dung lng / l pht (kbyte) ph 11520 10584 7680 3960 960 Lnh vc v Ghi m chuyn nghip nghi CD Audio Radio FM Radio AM in thoi i tho80

20

Lng t uTng qut, bc lng t l hm ca bin tn qu b l t c hiu x (lng t khng u) n gin nht l hi (l t gi nh l lng t u. l t Mc lng t c chn gia 2 mc tn hiu l t ch gi m t hi y(i) = (1/2)[x(i-1)+x(i)] (1/2)[x(iLut lng t u v i xng c trng bi: Lu l t v x b cc mc bo ho xs m ho mc lng t L hoc (L+1) = 2b. l t ho Bc lng t = 2xs/L B l t

Lng t uL=9

81

82

Lng t u1 1

Lng t uL = 161 1 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2

0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0 00

-0.2 -0.2 -0.4 -0.4 -0.6 -0.6 -0.8 -0.8 -1 -1 0

0

-0.2 -0.2 -0.4 -0.4 -0.6 -0.6 -0.8 -0.8

0

2

2

4

4

6

6

8

8

10 10

12 12

14 14

-1 -1 0

0

2

2

4

4

6

6

8

8

10 10

12 12

14 14

83

84

21

Lng t u1 0 1 0

Cc tnh cht lng t uMt xc sut sai s lng t su s l t l pe ( ) = p x (i + ), l = ( L 1) / 2i = l

-1 -1 0 0 1 1 0 0

2

2

4

4

6

6

8

8

10 10

12 12

-1 -1 0 0 1 1 0 0

2

2

4

4

6

6

8

8

10 10

12 12

phn b u gia - /2 v + /2 b gi v pe ( ) = 1/ , / 2 = 0, > / 2 Trung bnh tp m /lng t = 0 b t l t 2 2 Phng sai e = 2 / d = 2 /1285

-1 -1 0 0 0.2 0.2 0 0

2

2

4

4

6 Quantific ation E rror 6 Quantific ation E rror

8

8

10 10

12 12

-0.2 -0.2 0

0

2

2

4

4

6

6

8

8

10 10

12 12

/ 2

86

Cc tnh cht lng t uT s tn hiu trn nhiu hi nhi xs SN = 10 lg (d B) = 6, 02b + 4, 77 20 lg x 2 x 2 e

T s tn hiu trn nhiuSN = Nng lng tn hiu Ws = Nng lng nhiu Wn

SN dB = 10 log 10 SNhoc ho

Nu xs = 4 max SN (d B) = 6b 7,3Vi b 6, tng 6 dB mi khi tng 1 bit lng t. bit l t c cht lng thch hp cn c b 11 ch l th h c c87

SN dB = 20 log 10

Bi n tn hiu Bi n nhiu88

22

T s tn hiu trn nhiuNng lng l Tn hiu = Nhiu hi Nhi Tn hiu = 2 Nhiu hi Nhi Tn hiu = 10 Nhiu hi Nhi Tn hiu = 100 Nhiu hi Nhi Tn hiu = 1000 Nhiu hi Nhi Tn hiu = 10N Nhiu hi Nhi SN (dB) 0 2 10 20 30 N x 1089

Lng t logaritSau khi ly logarit bin tn hiu s m ho tuyn l ) hi s ho tuy y(n) tnh y(n) x(n) log[] log[] signe[] signe[] y'(n) x'(n) x'(n)

Q[] Q[]

M ha M ha

c(n)

c(n)

Gii m Gii m

exp[] exp[]

signe[x(n)]90

Lng t logaritHai gii php dng cho in thoi gi ph d i tho Lut (dng M) Lu (d

Lng t logaritHai gii php dng cho in thoi gi ph d i tho Lut A(dng chu u) Lu A(d u)1 + log A x 1 + log AA = 87,56

y =

log(1 + x ) log(1 + )

y =

= 255

8 bit logarit ~ 12 bit lng t u bit bit l t 91 92

23

Lng t thch nghiBc lng t tu thuc vo bin tn hiu B l t tu thu v hi Thch nghi trc Th tr y(n)= x(n) G(n) x(n) y(n)

Lng t thch nghi Thch nghi sau Thx(n) c(n) y(n) Q[] Q[] y(n)

M ha M ha

Q[] Q[]

M ha M ha

c(n)

Thch nghi Thch nghi k.i k.i

G(n)

G(n)

G(n)

y'(n)

Thch nghi Thch nghi k.i k.i Gii m Gii m Thch nghi Thch nghi k.i k.i c(n)

y'(n) x'(n) = G'(n)

:

y'(n)

Gii m Gii m

c(n) G(n)93

y'(n) x'(n) = G'(n)G(n)

:

94

Mt s chun m ho m thanh/ting niG.721 : ADPCM, 32 kbps, 4bits, 8kHz ADPCM, 4bits, 8kHz G.722 : ~ADPCM, 48 n 64 kbps, ~ADPCM, G.723 : ~ADPCM, 24 kbps, 3 bits, 8kHz ~ADPCM, kbps, 8kHz G.728 : 16 Kbps 16 Kbps GSM : in thoi di ng, 13 kbps i tho Linear Predictive Encoding (Xerox), 5 kbps Code Excited Linear Prediction (CELP) Digital Video Interactive : ~ADPCM, 4 n 8 bits ~ADPCM, VoIP: G723.1 (6.4kbits/s), G728, G729 (8kbits/s)95

4. Tng hp ting niTo ting ni xut pht t biu din ti n xu ph t bi di ng m ca li ni ng c l n K thut tng hp ting ni: thu t h ti n Tng hp trc tip h tr ti Tng hp da trn m hnh h d hB tng hp formant h B tng hp dng LPC h d B tng hp m phng b my pht m h ph b ph96

24

Phn loiCht lng b tng hp: Mc t nhin Ch l b h M Mc r Thanh iu i Ng iu Ng i

Tng hp trc tipGhi m ting ni t nhin ti n t - n v ghi m v - Ghp cc n v ghi m: t, cu. Gh c v t n v ghi m v 97

S lng t vng: l t Hn ch ch Khng hn ch h ch

B tng hp ting ni t vn bn (Text-toh ti n t b (Text- toSpeech)

m v v m tit (diphone) ti t t hp t t cu98

Tng hp formantF0 A1 To xung To xung A2 Khoang ming mi A3 Knh mi Knhm mi A4 To tp m Tot m tp

Tng hp LPCF1 F2 F3F0 To xung To xung A

B lc s B lc s s bc p bc pTo tp m Tot m tp a1 a2 ... ap

B1

B2 B399

Synthesis-by-Analysis100

25

M phng b my pht mNgun m Ngu Tuyn m Tuy

M hnh ngun m

Tham s iu khin s i khi

M phng ngun m (ngun tun hon) ph ngu (ngu tu hoM phng dy thanh:M hnh mt khi, M hnh ph h m kh h hai khi, M hnh nhiu khi, M hnh hai dm... kh h nhi kh h d

M hnh 2 khi

M hnh nhiu khi101

M hnh 2 dm

102

M phng tuyn m

M hnh phn xGi thit Gi thiRi rc ha

Vch ngn cng c Sng truyn n hng (dc theo trc truy h (d tr ng)ch xt cc tn s < 5000 Hz, bin t s ng)ch c bi thin din tch khng qu t ngt t ng di qu B qua tn hao: tnh lng, truyn nhit t t l truy nhi

103

104

26

ng tit din u, khng tn haong tit din u v ti di v ng dy tng ng

Tng t m hc in hcm hc h p: p sut su u: Thng lng lv(l,t)=0

in hc i h v: in p i i: Dng in i L: in cm i c C: in dung i

0/A: in cm m hc i c h A/0c2: in dung m hc A/ i h

H phng trnh Webster trx x u p u ( x, t) = u + t u t + = 0 c c x A t u A p x x c = p ( x, t ) = u + t + u t + 0 x 0 c 2 t c c A u: thng lng, p: p sut, : mt khng kh, c: vn tc sng m thng l su m kh v t s105

106

Xt trong min tn sSng ti v sng phn x c dng t v ph xj(t ) j ( t + ) x x c c u+ t = K +e , u t + = K e c c x x

p ng tn su ( l , t ) = U ( l , ) e j t 1 x = l U ( l, ) = U G ( ) cos ( l / c ) 1 p ng tn s H () = U (l, ) = t s U G () cos(l / c)

Ti mi

iu kin bin ti thanh mn i ki t

u (0, t ) = uG (t ) = U G ()e jt iu kin bin ti mi p (l, t ) = 0 i ki tp(x, t) = jZ0 sin[(l x)/ c] cos[(l x)/ c] UG ()e jt , u(x, t) = UG ()e jt cos l / c cos l / c

Z 0 ( ) = j

0A

107

H () vi (2n + 1)c f = 4l l = 17,5 cm, c=350 m/s f = 500,1500, 2500... Hz

108

27

M hnh phn x khng tn hao (Kelly-Lochbaum)+ + u k + 1 (t) u k + 1 (t - k + 1 ) + u k (t) + u k (t - k )

M hnh phn x khng tn hao (Kelly-Lochbaum)Tnh lin tc ca p sut v thng lng t c su v lp k (l, t) = p k +1 (0, t) u k (l, t) = u k +1 (0, t) 2 A k+1 A Ak + u k+1 (t) = u + (t - ) + k+1 u k +1 (t) k A k+1 + A k A k+1 + A k A Ak + 2 Ak u (t+ ) = k+1 u k (t - ) + u +1 (t) k k A k+1 + A k A k+1 + A k

u k (t)

u k (t + k ) u k + 1 (t) u k + 1 (t + k + 1 )

0

lktit din Ak0

l k +1tit din Ak+1

Cc ng c bn c cng chiu di k = k +1 = b c chi d

l = c109

t h s phn x h ph x

rk =

A k+1 A k A k+1 + A k

u + (t) = (1 + rk ) u + (t - ) + rk u k +1 (t) k+1 k + u k (t+ ) = rk u k (t - ) + (1 rk ) u +1 (t) k

110

Phn b sngu+ (t) k

Hiu ng ca cc tn haotr + uk+1(t )

tr

u+ (t ) (1+ rk ) u+ (t) k+1 k

Tn hao do dch chuyn khng kh trong tuyn m d chuy kh tuy Do tnh lng ca khng kh t l c kh Do truyn nhit truy nhi Do rung vch ngn vtnh lng

rk

rk

uk (t)

tr ng k

u (t +) k

(1 rk ) uk+1(t)

tr ng k+1

uk+1(t+)

0

lTip gip

0

l

truyn nhit111

rung

112

28

Hiu ng ca cc tn haoTn hao do bc x ti mi b x M hnh qu bng v hn h qu h

Hiu ng chung ca cc tn haoDi thng

Bc x ti mi

Tr khng bc x Tr kh b x

Zr =

j Lr Rr p () = U (, l) Rr + j Lr

RungNhit+lng

128 8a Rr = 2 , Lr = 3 c 9 a: bn knh m ti mi113 114

5. Nhn dng ting niHai giai on: hun luyn (hc) nhn dng o hu luy (h nh d Phn loi theo lo S lng t vng l t T ri rc lin tc r t Mt ngi ni nhiu ngi ni ng n nhi ng n Nhn dng t cu Nh d t

Phn loi theo phc tpNhn dng t ring l, t vng t (