Variation in the arrival times between packets, also called jitter, causes unnatural-sounding voice instead of a smooth voice stream. If a packet does not arrive in time to fit into the voice stream, the previous packet is replayed. This can seriously detract from voice quality. Since the jitter buffer adds to the overall delay of voice transmissions, the optimal jitter buffer should fit the network's differential delay. Adaptive jitter buffering continuously monitors the network delay and adjusts the queuing period accordingly.
A portion of memory specifically allocated to storing IP packets awaiting transmission, or to storing received IP packets. The buffer facilitates flow control by capturing IP packets and then transmitting packets as "playback" using speeds and rates of delay that the destination device can handle without causing packet loss through overloading.