As part of the packet loss challenge, there was an ASR word accuracy evaluation to see how PLC impacted intelligibility. See https://www.microsoft.com/en-us/research/academic-program/au...

The good news is that we were able to improve intelligibility slightly compared with filling with zeros (it's also a lot less annoying to listen to). The bad news is that you can only do so much with PLC, which is why we then pursued the Deep Redundancy (DRED) idea.