梅爾倒頻譜係數 (mel-frequency cepstral coefficients)
DESCRIPTION
梅爾倒頻譜係數 (Mel-frequency cepstral coefficients). 倒頻譜. 語音訊號可如下表示 :. 其中， X ( n ) 為語音訊號 θ ( n ) 為音源訊號 E ( n ) 為聲道的脈衝響應信號. 倒頻譜. 語音訊號之頻域表示方式 :. 倒頻譜. 對頻域的語音訊號加上絕對值與對數. 在對取完絕對值與對數的訊號，進行逆傅立葉轉換， 所對應的 c e ( n ) 會落在 n 值較大的地方，而 所對應的 c θ ( n ) 會存在 n 值較小處. 倒頻譜. 人類聽覺特性. - PowerPoint PPT PresentationTRANSCRIPT
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(Mel-frequency cepstral coefficients)
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:X(n) (n) E(n)
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:
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ce(n)n c(n)n
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(Masking Effect)
(Frequency Masking)(Temporal Masking)
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(narrowband sound stimulus)(Critical Band)
24
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105010021001502003200250300430035040054004505106510570630763070077087708409209920100010801010801170127011127013701480121480160017201317201850200014200021502320
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1523202500270016270029003150173150340037001837004000440019440048005300205300580064002164007000770022770085009500239500105001200024120001350015500
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(Mel Scale):
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22050Hz:11025Hz 3176.32Hz3176.32/(4+1)=635.264
0529.7011461.253097.585972.8311025
0635.2641270.5281905.7922541.0563176.32
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10529.7011461.252529.7011461.253097.5831461.253097.585972.8343097.585972.8311025
0529.7011461.253097.585972.8311025
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22050Hz400500Hz ?
=/: 22050/400=55.125Hz500/55.12510500Hz10
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Filtering
J j
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DCT:
LMFCC
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(Delta Cepstrum Coefficients)
m = 1,2,,L
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M1:Cm(t)Cm(t+)Cm(t-)
D1
D2
D4
D3
D5
D6
Frame1
Frame2
Frame3
Frame4
Frame5
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**