Speaker Volume Fluctuates

[PtBaller]

I've been experiencing this problem with my audio for awhile now. Whenever I'm driving the volume seems to increase and decrease its usually louder while the car is traveling at a higher speeds and when I slow down and brake the volume decrease. I was convinced that my alternator was the culprit since I had recently purchased a new optima red top. I replaced my old alternator with a 130amp highlander alternator and am still experiencing this problem. Also sometimes my headunit just shuts off all of a sudden and turns back on while im driving. I am going to get my battery checked soon as well as the alternator. What other possible causes are there?

[Dj-torn]

Does your radio have the feature that as you drive faster the volume goes up to compensate for the road noise.