Alternator will whistle, and sometimes rumble or groan if the bearings are bad. Power steering pump would be most likely, if I'm imagining the noise correctly. I guess you've checked the fluids? You can take the belt off, and start it for a short time to see if the sound is belt driven, and not a tranny pump or something like that. If the noise is gone with the belt off, you can spin all the pulleys and see which seems to have any drag or gravely feel to it. Sometimes A/C compressors can be the cause also. But just because it makes noise doesn't always mean it needs replaced, not right away, anyhow.