Techniques for finding the source of perceptual audio degradation in an IP
telephony environment provide a hop-by-hop analysis of a network over
which IP telephony is laid, and may be performed by network switching
devices, such as routers, gateways and switches. Rather than monitoring
packet loss, these techniques employ perceptual measures to determine the
source of audio quality degradation in the network, as perceived by a
user or caller. Generally, a reference waveform is systematically sent to
intermediate network switching devices along the path between two
endpoints. Each intermediate device sends back a return waveform that is
based on the respective reference waveform received at each device. From
comparing the reference waveform with the return waveform, for each
round-trip along the path, the degradation of the audio quality is
computed for each round-trip path, from which audio degradation is
computed for each hop, from which the source of degradation is
determined.