I have a 2001 Galant ES. My car is very loud, but only when it is in motion. When I'm idling, everything is very quiet. However, when I accelerate, the car becomes progressively louder until it reaches about 43 mph. The noise level sort of reduces a little until I reach 50 mph and it progressively gets louder until I reach 70 mph, again the noise seems to reduce a little.

I've tried to pinpoint exactly where the noise is coming from, however I am not confident in my observation that it seems to be coming from the front left side of the car.

Any ideas?

 

Does the noise come under the hood, or from one of the tires?

From your description, the noise peaks at ~43 mph and ~70 mph. Have you also correlated the noise with the engine rpm?