Abstract: A voice communications terminal is provided having a microphone to receive an audio stream and a voice activity detector to determine whether the audio stream comprises voice signals and when the audio stream comprises voice signals, notify a communications server and/or provide at least a portion of the audio stream to the communications server.

Abstract: A voice activity detector (100) filters (204) out noise energy and then computes a high-frequency (2400 Hz to 4000 Hz) versus low-frequency (100 Hz to 2400 Hz) signal energy ratio (224), total voiceband (100 Hz to 4000 Hz) signal energy (214), and signal periodicity (208) on successive frames of signal samples. Signal periodicity is determined by estimating the pitch period (206) of the signal, determining a gain value of the signal over the pitch period as a function of the estimated pitch period, and estimating a periodicity of the signal over the pitch period as a function of the estimated pitch period and the gain value.

Abstract: A recently received portion of a transmit signal is utilized, and a pitch period of the received signal is determined. Then, the determined pitch period is utilized to search for similarities in the originally transmitted signal. This searching is done over a range of delays. Once the optimal delay is determined, it is then utilized as the delay between the transmitted signal and the received signal. Once this delay is known, the received signal can be time-aligned with the delayed signal.

Abstract: Determining the time delay between a transmitted signal and an echo. Then, the echo canceller is adjusted by the delay amount so that the echo canceller tail length is relatively short.

Abstract: Echo detection and monitoring systems and methods are provided. According to the invention, the outgoing and incoming voice bearer channels of a voice communication are monitored. The outgoing and incoming signals are time aligned, and measures are then taken to determine whether echo is present in the signal. In accordance with an embodiment of the present invention, the outgoing signal is fed through an adaptive filter.

Abstract: Echo detection and monitoring systems and methods are provided. According to the invention, the outgoing and incoming voice bearer channels of a voice communication are monitored. The outgoing and incoming signals are time aligned, and measures are then taken to determine whether echo is present in the signal. In accordance with an embodiment of the present invention, the outgoing signal is fed through an adaptive filter.

Abstract: Determining the time delay between a transmitted signal and an echo. Then, the echo canceller is adjusted by the delay amount so that the echo canceller tail length is relatively short.

Abstract: A recently received portion of a transmit signal is utilized, and a pitch period of the received signal is determined. Then, the determined pitch period is utilized to search for similarities in the originally transmitted signal. This searching is done over a range of delays. Once the optimal delay is determined, it is then utilized as the delay between the transmitted signal and the received signal. Once this delay is known, the received signal can be time-aligned with the delayed signal.

Abstract: A voice activity detector (100) filters (204) out noise energy and then computes a high-frequency (2400 Hz to 4000 Hz) versus low-frequency (100 Hz to 2400 Hz) signal energy ratio (224), total voiceband (100 Hz to 4000 Hz) signal energy (214), and signal periodicity (208) on successive frames of signal samples. Signal periodicity is determined by estimating the pitch period (206) of the signal, determining a gain value of the signal over the pitch period as a function of the estimated pitch period, and estimating a periodicity of the signal over the pitch period as a function of the estimated pitch period and the gain value.