It's possible you're referring to the impact of the iceberg itself. While some accounts describe the initial collision as a "shudder", most survivors described it as a jarring, grinding sound. This is likely due to the iceberg scraping along the starboard side of the ship, rather than a sudden impact.
It's crucial to rely on documented accounts and historical evidence when discussing the Titanic tragedy. Misinformation can easily spread, so it's important to verify any claims you encounter.