Engine sounds like a vacuum cleaner...! help??

2008 328i. About 90k miles. Regular maintenance performed.



Noticed a loud, consistent, constant "vacuum cleaner" type noise from under the hood about a week ago. I've heard something similar when driving during hot days, but this noise appears even during short night drives now.



Popped the hood just a moment ago. I confess to not know a thing about the mechanics of the car, but I did notice a very large, fast-moving airflow being emitted from both sides of the engine - particularly the right side.



Any obvious diagnoses? Should I be concerned?



Thanks so much in advance.