I have just listen to CoronaPD - Blue. The present feed as well as several times from yesterday and the day before from the archives.
I hear noting also. I suspect there may be a problem either with the feed or the scanner from the feed. It shows 4 users right now, but obvious can not tell what if anything they are hearing.
I will let the feed provider know about what is happening and if there is a issue, hopefully the provider will be able to correct it users can hear it.
Ri'c
EdiT: It appears that the feed is by the City of Corona, not an individual. Again I am guessing that they may be having issues and not aware of it.