whine on deccelaration

I'm wondering if you can help with information. I have a 1992 SVX, 58,000 mi., It is in mint condition and had regular service. However, I've noticed a whine when I deccelerate. The sound doesn't vary with gear changes and seems most pronounced coming from about 40 mph. I trust friends like yourselves with experience more than my mechanic. If someone has had this problem or knows the casue, please drop a line. At this point the stereo is louder than the whine, but I'm concerned something is going wrong mechanically.

Thanks.