Speech Enhancement - Digital Speech: Coding for Low Bit Rate Communication Systems - page 403

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Speech detection error-rate of VAD, E d

MD HD SD Theoretical limit

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Speech detection error-rate of VAD, E d

MD HD SD Theoretical limit Unprocessed

Figure 11.19 Comparison of SEGSNR improvement and ISD against the speech-
detection error-rate of VAD for helicopter noisy speech of 5 dB SNR

is called the hybrid. The role of the hybrid is to direct the signal energy
arriving from S1 or S2 to the upper or lower path of the four-wire circuit,
without allowing any leakage back to the source over the opposite direction
line. Because of impedance mismatching, however, some of the transmitted
signal returns to the original source, which hears a delayed version of its own