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HHT and Applications in Music Signal Processing. 電信一 R01942128 陳昱安. About the Presenter. Research area: MER Not quite good at difficult math. About the Topic. HHT : abbreviation of Hilbert-Huang Transform Decided after the talk given by Dr. Norden E. Huang. Why HHT?.
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HHT and Applications in Music Signal Processing 電信一 R01942128 陳昱安
About the Presenter • Research area: MER • Not quite good at difficult math
About the Topic • HHT : abbreviation ofHilbert-Huang Transform • Decided after the talk given byDr. Norden E. Huang
Why HHT? • Fourier is nice, but not good enough • Clarity • Non-linear and non-stationary signals
Hilbert-Huang Transform Hilbert Transform Empirical Mode Decomposition
Hilbert Transform • Not integrable at τ=t • Defined using Cauchy principle value
Dealing with 1/(τ-t) =0 -∞ ∞ τ=t
I know how to compute Hilbert Transform
That’s cool… SO WHAT?
exp(jz) =cos(z) + jsin(z) • exp(jωt) =cos(ωt) + jsin(ωt) • θ(t) = arctan(sin(ωt)/cos(ωt)) • Freq.=dθ/dt
S(t) = u(t) + jH{u(t)} • θ(t) = arctan(Im/Re) • Freq.=dθ/dt • What happen if u(t) = cos(ωt) ? Hint: H{cos(t)} = sin(t)
Frequency Analysis with HT • Input : u(t) • Calculate v(t) = H{u(t)} • Set s(t) = u(t) + jv(t) • θ(t) = arctan(v(t)/u(t)) • fu(t)= d θ(t) /dt
Congrats!!! Forgot something?
Hilbert-Huang Transform Hilbert Transform Empirical Mode Decomposition
0 8 F = 1Hz
0 8 F = 1Hz
0 8 F = 1Hz
0 8 F = 1/8Hz 1Hz
= +
To make instantaneous frequency MEANINGFUL
Need to decompose signals into “BASIC” components
Empirical Mode Decomposition • Decompose the input signal • Goal: find “basic” components • Also know as IMF • Intrinsic Mode Functions • BASIC means what?
Criteria of IMF • num of extrema - num of zero-crossings≤ 1 • At any point, the mean value of the envelope defined by the local maxima and the envelope defined by the local minima is zero.
TO BE SHORT
IMFs are signals
Around 0 0
Review: EMD • Empirical Mode Decomposition • Used to generate IMFs EMD
Review: EMD • Empirical Mode Decomposition • Used to generate IMFs Hint: Empirical means NO PRIOR KNOWLEDGES NEEDED EMD
Problem Source Separation
What if… We apply STFT, then extract different components from different freq. bands?
Problem Solved? No!
I see… So how to make sure we do it right?
How to win Doraemon in paper-scissor-stone? Easy. Paper always win.
Single-MixtureAudio Source Separationby Subspace Decompositionof Hilbert Spectrum Khademul Islam Molla, and Keikichi Hirose
Approximation of sources Desired result
PHASE I: Construction of possible source model
IMFs EMD HilbertTransform HilbertSpectra Original Signal IMF 1 IMF 2 IMF 3 ∶ Spectrum of
Spectrum of original signal Spectrum of IMF1 Spectrum of IMF2 X1 X2 X3 X4 X5 X6 X1 X2 X3 X4 X5 X6 X1 X2 X3 X4 X5 X6 ... frequency
Original Signal Projection 2 IMF1 Projection1 IMF2
AFTER SOME PROCESSING
RESULTS IN