Every rail transit system I've been around (mostly in CA but a little E.Coast too) makes a squealing noise on sharp curves. Commuter rail doesn't because the curves are usually not very sharp. It goes with the steel-wheel-steel-rail territory. Some systems have tried fancy wheels that reduce a noise a bit, but mostly are for improving noise levels inside the car not for the neighbors. A few low-floor streetcars and light rail cars have wheels that are independent from each other, which largely eliminates the squeal but introduces tracking problems. Most systems, though, have steel wheels on solid axles, and squeal when the curve is sharp enough as most curves posted for 25 mph or less probably are. To reduce wear on the track and wheels, some systems grease the rail on very sharp curves; that also reduces noise a bit.

An observation about the typical 2-body 3-truck articulated LR car: I think they're noiser and rougher riding than the older types (usually used in streetcars and heavy rail transit) that have 2 trucks per car with none shared between carbodies. Typical LR cars don't track very steadily, and hit the riders with a lot of sharp sideways jerks even on straight track. The older type of cars (recent experience in NY area) don't do that as much, except right over the trucks at each end. The center section over the middle truck of LR cars also lets a lot of noise into the car (I should wear earplugs...).