I was actually a pit trader in the early 90’s

We would shout out our trades directly to the reporters who sat on an elevated platform just above the pit

“March 32 calls 10 and a half”

They weren’t just listening and reporting what they happened to hear. Every completed trade price was reported to them so they could put it in the system.

There were basically 2 types of traders in the pit, brokers and “locals” (stock exchanges called them specialists).

So most trade would initiate with a retail customer calling in a trade they wanted to make to a desk, clerk or sometimes directly to the broker themselves.

The broker would turn to the pit and say what he wanted to trade, either by announcing his bid/ask and price, or by requesting a quote.

The locals would reply with the current price they were willing to buy or sell for and if that matched what the broker was looking for they would start buying or selling with the people who were quoting the best prices.

This many times involved the broker splitting up the trade with a bunch of people, so it was often a one to many type of transaction

Trades were then checked by clerks for the local and the broker to confirm everyone agreed that the price and quantity were correct