Here is KB8WFH’s truly superb replica station, showing what a rotary spark gap transmitter would have sounded like for the man at the key.
What about how it sounded to listeners on the air? For that, here is VK7RO’s tape recording of another re-creation project, this one probably from the 1960’s, under the aegis of the Antique Wireless Association. It is meant to be what people heard on 600 meters in the early 1920’s.
The Radio Ranch 