A method for detecting the presence of voice, single tone and dual tone signals compares a ratio r which equals the square of the maximum value of the received signal (A max) during a sampling period divided by a measure E of the energy to three different thresholds. If r is less than the first threshold...http://www.google.fr/patents/US5533118?utm_source=gb-gplus-shareBrevet US5533118 - Voice activity detection method and apparatus using the same
Voice activity detection method and apparatus using the same
