Pitch Estimation and Voiced–Unvoiced Classification of Speech - Digital Speech: Coding for Low Bit Rate Communication Systems - page 166

20.0

15.0

10.0

5.0

Original Speech Spectrum
Flattened Speech Spectrum ( β = 0.8)

0.0

− 5.0

0.0 1000.0 2000.0 3000.0 4000.0

Frequency (Hz)

Figure 6.15 Influence of the spectrum-flattening filter

β

1.0

0.8

30 60 Tracked Pitch (in samples)

Figure 6.16 Value of the flattening factor β against tracked pitch

functions used for flattening the spectrum are shown in Figure 6.17 where,

x + CL ; x ≤− CL

y = clc(x) = x − CL ; x ≥ CL (6.29)

0 ;− CL < x < CL