The transmission of live voice or music. It implies that there is no delay at the receiving side, or at most, imperceptible delays. True real-time audio is a two-way conversation such as voice over IP (VoIP). One-way audio programs broadcast live, as well as streaming audio, might be considered real time. However, a podcast or audio clip that is downloaded first and then played is not. See streaming audio, VoIP, UDP and real-time video.