Here's why:
* The arrival was not a dramatic event: It was a regular shipyard event. The Titanic was being built, not launched. It wasn't like a ship arriving at a harbor, where people might be alerted by its horn or the sound of its engines.
* Focus was on the building process: People working in the shipyard and nearby residents were likely more interested in the progress of the Titanic's construction than in hearing its arrival.
* No accounts of specific sounds: No historical records or eyewitness accounts mention any specific noises related to the Titanic's arrival in Belfast Lough.
It's important to remember that the Titanic's journey to Belfast Lough was simply a stage in its construction. The ship was being built in a shipyard, not travelling across an ocean.