At least I think that is how you type the sound. Ha!! We started demonstrating to Madeleine a while back that cars, trucks, etc go “vrooooom”. Not with the intention of her making that sound, necessarily. Just as we were playing with her, we’d make it. Since then, she has made her own cute little sound for it, and whenever she plays with her dump truck or train, she now makes this sound.
She’s doing lots of cute little things like this these days as her brain soaks up all of this new information around her. It seems like every day she is doing something new or making some new sound.