1. Field of the Invention
This invention generally relates to voice communications. More specifically, aspects of the invention relate to voice communications over a network.
2. Description of Background Information
Voice communications systems enable at least two people who are not face-to-face to communicate as if they were. Latency, or delay, is an important consideration in the design and evaluation of such systems.
Because voice communications systems seek to emulate face-to-face communication, latency between a voice signal originating at the first person and the signal as it arrives at the second person must be kept to a minimum. When latency is below 100 milliseconds (ms), for instance, most people do not notice a delay when conversing with another person. Between approximately 100 ms and 300 ms, however, most people perceive a slight hesitation in the other person""s response. Above 300 ms, most people are very aware of the delay, and effective communication is inhibited. When a voice communications system becomes loaded with multiple connections, latency values may increase.
Voice communications are increasingly being realized over networks. For instance, VoIP (Voice over Internet Protocol) involves sending voice information in digital form in xe2x80x9cpacketsxe2x80x9d using the Internet Protocol. A number of factors contribute to latency in VoIP networks, including delays inherent in the physical transmission media, compression and decompression delays, and routing and other such network delays.
An attempt to measure latency due to compression and decompression in a VoIP network has been made in the art. DTMF tones are played and time-stamped by software at an originating channel, and the tones are time-stamped by software at a receiving channel following compression and decompression phases. The difference between the time stamps is designated as the latency.
However, when designing and evaluating voice communications systems, engineers require more exacting latency measurements than those afforded by software methodologies.
Therefore, what is needed is a system and method that accurately measures latency in voice communications systems.