"heard it announced" is correct and usable in written English.
You can use it when you are talking about something that was announced, like a plan or an event that you heard about. Example sentence: I heard it announced that the company picnic was cancelled due to weather.
"I was thinking of them as I heard it announced that we'd won today.
Referring to the list of candidates to succeed Major Ingram in the hot seat, which had been read out by Tarrant on September 9, Mr Hilliard said: "Of course, they have heard it announced that Mr Whittock will be on the show that night".
When Aaron Voorhees, 37, heard it announced on the radio last week, he and his wife immediately called to get tickets.
When you hear it announced that such-and-such an issue cannot be raised now because it is "political dynamite," the implication is that you yourself are mixed up in a cheap trick perpretrated by one section of the people on another section.
Ring the bell as soon as you see the street or hear it announced by the operator or computer system.
We passed about a mile from the Missouri just as the surrender was being signed, and I got a kick out of hearing it announced over the radio as I saw it through a porthole.
The app has yet to be announced, so you heard it here first….
It heard arguments on Monday, and it announced its decision the next evening, Dec. 12, which was the official deadline for certifying electoral college votes".
The boy ran to answer it, and they heard him announce, "Yes, Mummy's here.
Three and a half hours since I'd heard him announce D-Day, it was then broadcast.
Macaulay secured new employment, and a few days after the hearing it was announced that he would play professional cricket in Wales.
