That theory has been tested, and shown that bikes are not loud enough for anyone to hear you coming. https://www.autoweek.com/news/industry-news/a35952569/loud-p...

The accident stats also fail to backup this idea, and even suggest that loud pipes might be giving some riders a false sense of safety and leading to more accidents than otherwise. https://canadamotoguide.com/2016/07/29/the-truth-about-loud-...