Yes, however the sound is coming directly from the alternator, not the speakers. If windows are closed while driving it is only slightly hearable on lower speads and lower rpms. On speeds >35mph or revs > 3000 rpm engine and/or wind noise will be louder than the alternator sound.

The alternator (voltage regulator included) is about 1 month old and is whistling from the beginning. However the old alternator was also whistling.

That's why it would be great to compare my sound with other people who have already replaced their alternator with an aftermarket one.

Of course Icould measure it with an o-scope, however I don't have one here and I think we already know that the problem is inside the alternator