146040.fig.003a
(a)
146040.fig.003b
(b)
146040.fig.003c
(c)
146040.fig.003d
(d)
Figure 3: Results of endpoint detection based on frame energy and employing an edge detection filter in a car-noise environment: (a) noisy speech signal at SNR −5 dB, (b) clean speech signal, (c) frame energy of signal (a), and (d) detection output of edge filter with state transition model ( is lower threshold; is upper threshold).