My car is a 2006 Toyota Yaris. I have started noticing that when driving the sound in the is louder and deeper. Why?

My apologies. I meant to write while in the back seat the sound of the car has grown louder. It is only intermittent and not all the time. However very noticeable as the car is usually quite quiet. The sound is deeper and louder if that makes any sense. Thanks for your time and help.

maybe like a hole or crack/rusted out in the tail pipe or muffler?